Note: Hollow cathode lamp with integral, high optical efficiency isolation valve: A modular vacuum ultraviolet source

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sloan Roberts, F.; Anderson, Scott L.

2013-12-15

The design and operating conditions of a hollow cathode discharge lamp for the generation of vacuum ultraviolet radiation, suitable for ultrahigh vacuum (UHV) application, are described in detail. The design is easily constructed, and modular, allowing it to be adapted to different experimental requirements. A thin isolation valve is built into one of the differential pumping stages, isolating the discharge section from the UHV section, both for vacuum safety and to allow lamp maintenance without venting the UHV chamber. The lamp has been used both for ultraviolet photoelectron spectroscopy of surfaces and as a “soft” photoionization source for gas-phase massmore » spectrometry.« less

Outgassing measurement of the aluminum alloy UHV chamber

NASA Technical Reports Server (NTRS)

Miyamoto, M.; Itoh, T.; Komaki, S.; Narushima, K.; Ishimaru, H.

1986-01-01

A large vacuum chamber (580 mm diameter) was fabricated from an aluminum alloy surface treated by a special process normally used on small chambers. The chamber was tested unbaked and baked at various temperatures, pressures, and holding periods. The chamber was filled with N2 gas, and the outgassing rate was measured after one hour. Then the ultimate pressure was measured. Outgassing rates for baked and unbaked groups were compared. It is concluded that the same surface treatment technique can be used on both large and small chambers produced by the same special extrusion process.

Characterization of the CEBAF 100 kV DC GaAs Photoelectron Gun Vacuum System

DOE Office of Scientific and Technical Information (OSTI.GOV)

Stutzman, M L; Adderley, P; Brittian, J

A vacuum system with pressure in the low ultra-high vacuum (UHV) range is essential for long photocathode lifetimes in DC high voltage GaAs photoguns. A discrepancy between predicted and measured base pressure in the CEBAF photoguns motivated this study of outgassing rates of three 304 stainless steel chambers with different pretreatments and pump speed measurements of non-evaporable getter (NEG) pumps. Outgassing rates were measured using two independent techniques. Lower outgassing rates were achieved by electropolishing and vacuum firing the chamber. The second part of the paper describes NEG pump speed measurements as a function of pressure through the lower partmore » of the UHV range. Measured NEG pump speed is high at pressures above 5×10 -11 Torr, but may decrease at lower pressures depending on the interpretation of the data. The final section investigates the pump speed of a locally produced NEG coating applied to the vacuum chamber walls. These studies represent the first detailed vacuum measurements of CEBAF photogun vacuum chambers.« less

NOVEL CHAMBER DESIGN FOR AN IN-VACUUM CRYO-COOLED MINI-GAP UNDULATOR.

DOE Office of Scientific and Technical Information (OSTI.GOV)

HU, J.-P.; FOERSTER, C.L.; SKARITKA, J.R.

2006-05-24

A stainless steel, Ultra-High Vacuum (UHV) chamber, featuring a large vertical rectangular port (53''W by 16''H), has been fabricated to house the one-meter magnet assembly of a newly installed undulator insertion device for beamline X-25 at the National Synchrotron Light Source. To achieve UHV, the new chamber is equipped with a differential ion pump, NEG pump, nude ion gauge, residual gas analyzer, and an all metal roughing valve. Temperature of the magnet assembly is maintained below 90 C during vacuum bake. The large rectangular port cover is sealed to the main flange of the chamber using a one-piece flat aluminummore » gasket and special sealing surfaces developed exclusively by Nor-Cal Products, Inc. The large flange provides easy access to the gap of the installed magnet girders for in situ magnetic measurements and shimming. Special window ports were designed into the cover and chamber for manipulation of optical micrometers external to the chamber to provide precise measurements of the in-vacuum magnet gap. The vacuum chamber assembly features independently vacuum-isolated feedthroughs that can be used for either water-or-cryogenic refrigeration-cooling of the monolithic magnet girders. This would allow for cryogenic-cooled permanent magnet operation and has been successfully tested within temperature range of +100 C to -150 C. Details of the undulator assembly for beamline X-25 is described in the paper.« less

A cryogen-free low temperature scanning tunneling microscope capable of inelastic electron tunneling spectroscopy.

PubMed

Zhang, Shuai; Huang, Di; Wu, Shiwei

2016-06-01

The design and performance of a cryogen-free low temperature scanning tunneling microscope (STM) housed in ultrahigh vacuum (UHV) are reported. The cryogen-free design was done by directly integrating a Gifford-McMahon cycle cryocooler to a Besocke-type STM, and the vibration isolation was achieved by using a two-stage rubber bellow between the cryocooler and a UHV-STM interface with helium exchange gas cooling. A base temperature of 15 K at the STM was achieved, with a possibility to further decrease by using a cryocooler with higher cooling power and adding additional low temperature stage under the exchange gas interface. Atomically sharp STM images and high resolution dI/dV spectra on various samples were demonstrated. Furthermore, we reported the inelastic tunneling spectroscopy on a single carbon monoxide molecule adsorbed on Ag(110) surface with a cryogen-free STM for the first time. Being totally cryogen-free, the system not only saves the running cost significantly but also enables uninterrupted data acquisitions and variable temperature measurements with much ease. In addition, the system is capable of coupling light to the STM junction by a pair of lens inside the UHV chamber. We expect that these enhanced capabilities could further broaden our views to the atomic-scale world.

A cryogen-free low temperature scanning tunneling microscope capable of inelastic electron tunneling spectroscopy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Shuai; Huang, Di; Wu, Shiwei, E-mail: swwu@fudan.edu.cn

The design and performance of a cryogen-free low temperature scanning tunneling microscope (STM) housed in ultrahigh vacuum (UHV) are reported. The cryogen-free design was done by directly integrating a Gifford-McMahon cycle cryocooler to a Besocke-type STM, and the vibration isolation was achieved by using a two-stage rubber bellow between the cryocooler and a UHV-STM interface with helium exchange gas cooling. A base temperature of 15 K at the STM was achieved, with a possibility to further decrease by using a cryocooler with higher cooling power and adding additional low temperature stage under the exchange gas interface. Atomically sharp STM imagesmore » and high resolution dI/dV spectra on various samples were demonstrated. Furthermore, we reported the inelastic tunneling spectroscopy on a single carbon monoxide molecule adsorbed on Ag(110) surface with a cryogen-free STM for the first time. Being totally cryogen-free, the system not only saves the running cost significantly but also enables uninterrupted data acquisitions and variable temperature measurements with much ease. In addition, the system is capable of coupling light to the STM junction by a pair of lens inside the UHV chamber. We expect that these enhanced capabilities could further broaden our views to the atomic-scale world.« less

Characterization and Evaluation of Ti-Zr-V Non-evaporable Getter Films Used in Vacuum Systems

NASA Astrophysics Data System (ADS)

Ferreira, M. J.; Seraphim, R. M.; Ramirez, A. J.; Tabacniks, M. H.; Nascente, P. A. P.

Among several methods used to obtain ultra-high vacuum (UHV) for particles accelerators chambers, it stands out the internal coating with metallic films capable of absorbing gases, called NEG (non-evaporable getter). Usually these materials are constituted by elements of great chemical reactivity and solubility (such as Ti, Zr, and V), at room temperature for oxygen and other gases typically found in UHV, such as H2, CO, and CO2. Gold and ternary Ti-Zr-V films were produced by magnetron sputtering, and their composition, structure, morphology, and aging characteristics were characterized by energy-dispersive X-ray spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), field emission gun sc anning electronmicroscopy (FEG-SEM), atomic force microscopy (AFM), high resolution transmission electron microscopy (HRTEM). The comparison between the produced films and commercial samples indicated that the desirable characteristics depend on the nanometric structure of the films and that this structure is sensitive to the heat treatments.

The Nickel(111)/Alkaline Electrolyte Interface

NASA Technical Reports Server (NTRS)

Wang, Kuilong; Chottiner, G. S.; Scherson, D. A.; Reid, Margaret A.

1991-01-01

The electrochemical properties of Ni (111) prepared and characterized in ultra high vacuum, UHV, by surface analytical techniques have been examined in alkaline media by cyclic voltammetry using an UHV-electrochemical cell transfer system designed and built in this laboratory. Prior to the transfer, the Ni(111) surfaces were exposed to saturation coverages of CO in UHV in an attempt to protect the surface from possible contamination with other gases during the transfer. Temperature Programmed Desorption, TPD, of CO-dosed Ni (111) surfaces displaying sharp c(4x2), LEED patterns, subsequently exposed to water-saturated Ar at atmospheric pressure in an auxiliary UHV compatible chamber and finally transferred back to the main UHV chamber, yielded CO2 and water as the only detectable products. This indicates that the CO-dosed surfaces react with water and/or bicarbonate and hydroxide as the most likely products. Based on the integration of the TPD peaks, the combined amounts of H2O and CO2 were found to be on the order of a single monolayer. The reacted c(4x2)CO/Ni(111) layer seems to protect the surface from undergoing spontaneous oxidation in strongly alkaline solutions. This was evidenced by the fact that the open circuit potential observed immediately after contact with deaerated 0.1 M KOH was about 0.38 V vs. DHE, drifting slightly towards more negative values prior to initiating the voltametric scans. The average ratio of the integrated charge obtained in the first positive linear scan in the range of 0.35 to 1.5 V vs. DHE (initiated at the open circuit potential) and the first (and subsequent) linear negative scans in the same solution yielded for various independent runs a value of 3.5 +/- 0.3. Coulometric analysis of the cyclic voltammetry curves indicate that the electrochemically formed oxyhydroxide layer involves a charge equivalent to 3.2 +/- 0.4 layers of Ni metal.

Portable mini-chamber for temperature dependent studies using small angle and wide angle x-ray scattering

NASA Astrophysics Data System (ADS)

Dev, Arun Singh; Kumar, Dileep; Potdar, Satish; Pandit, Pallavi; Roth, Stephan V.; Gupta, Ajay

2018-04-01

The present work describes the design and performance of a vacuum compatible portable mini chamber for temperature dependent GISAXS and GIWAXS studies of thin films and multilayer structures. The water cooled body of the chamber allows sample annealing up to 900 K using ultra high vacuum compatible (UHV) pyrolytic boron nitride heater, thus making it possible to study the temperature dependent evolution of structure and morphology of two-dimensional nanostructured materials. Due to its light weight and small size, the chamber is portable and can be accommodated at synchrotron facilities worldwide. A systematic illustration of the versatility of the chamber has been demonstrated at beamline P03, PETRA-III, DESY, Hamburg, Germany. Temperature dependent grazing incidence small angle x-ray scattering (GISAXS) and grazing incidence wide angle x-ray scattering (GIWAXS) measurements were performed on oblique angle deposited Co/Ag multilayer structure, which jointly revealed that the surface diffusion in Co columns in Co/Ag multilayer enhances by increasing temperature from RT to ˜573 K. This results in a morphology change from columnar tilted structure to densely packed morphological isotropic multilayer.

A multipurpose ultra-high vacuum-compatible chamber for in situ X-ray surface scattering studies over a wide range of temperature and pressure environment conditions

NASA Astrophysics Data System (ADS)

Ferrer, P.; Rubio-Zuazo, J.; Heyman, C.; Esteban-Betegón, F.; Castro, G. R.

2013-03-01

A low/high temperature (60-1000K) and pressure (10-10-3x103 mbar) "baby chamber", specially adapted to the grazing-incidence X-ray scattering station, has been designed, developed and installed at the Spanish CRG BM25 SpLine beamline at European Synchrotron Radiation Facility. The chamber has a cylindrical form with 100 mm of diameter, built on a 360° beryllium nipple of 150 mm height. The UHV equipment and a turbo pump are located on the upper part of the chamber to leave a wide solid angle for exploring reciprocal space. The chamber features 4 CF16 and 5 CF40 ports for electrical feed through and leak valves, ion gun, etc. The heat exchanger is a customized compact LN2 (or LHe) continuous flow cryostat. The sample is mounted on a Mo support on the heat exchanger, which has in the back side a BORALECTRIC® Heater Elements. Experiments of surfaces/interfaces/ multilayer materials, thin films or single crystals in a huge variety of environments can be performed, also in situ studies of growth or evolution of the samples. Data measurement can be collected with a punctual and a bi-dimensional detector, being possible to simultaneously use them.

Design and performance of an ultra-high vacuum spin-polarized scanning tunneling microscope operating at 30 mK and in a vector magnetic field

NASA Astrophysics Data System (ADS)

von Allwörden, Henning; Eich, Andreas; Knol, Elze J.; Hermenau, Jan; Sonntag, Andreas; Gerritsen, Jan W.; Wegner, Daniel; Khajetoorians, Alexander A.

2018-03-01

We describe the design and performance of a scanning tunneling microscope (STM) that operates at a base temperature of 30 mK in a vector magnetic field. The cryogenics is based on an ultra-high vacuum (UHV) top-loading wet dilution refrigerator that contains a vector magnet allowing for fields up to 9 T perpendicular and 4 T parallel to the sample. The STM is placed in a multi-chamber UHV system, which allows in situ preparation and exchange of samples and tips. The entire system rests on a 150-ton concrete block suspended by pneumatic isolators, which is housed in an acoustically isolated and electromagnetically shielded laboratory optimized for extremely low noise scanning probe measurements. We demonstrate the overall performance by illustrating atomic resolution and quasiparticle interference imaging and detail the vibrational noise of both the laboratory and microscope. We also determine the electron temperature via measurement of the superconducting gap of Re(0001) and illustrate magnetic field-dependent measurements of the spin excitations of individual Fe atoms on Pt(111). Finally, we demonstrate spin resolution by imaging the magnetic structure of the Fe double layer on W(110).

Design and performance of an ultra-high vacuum spin-polarized scanning tunneling microscope operating at 30 mK and in a vector magnetic field.

PubMed

von Allwörden, Henning; Eich, Andreas; Knol, Elze J; Hermenau, Jan; Sonntag, Andreas; Gerritsen, Jan W; Wegner, Daniel; Khajetoorians, Alexander A

2018-03-01

We describe the design and performance of a scanning tunneling microscope (STM) that operates at a base temperature of 30 mK in a vector magnetic field. The cryogenics is based on an ultra-high vacuum (UHV) top-loading wet dilution refrigerator that contains a vector magnet allowing for fields up to 9 T perpendicular and 4 T parallel to the sample. The STM is placed in a multi-chamber UHV system, which allows in situ preparation and exchange of samples and tips. The entire system rests on a 150-ton concrete block suspended by pneumatic isolators, which is housed in an acoustically isolated and electromagnetically shielded laboratory optimized for extremely low noise scanning probe measurements. We demonstrate the overall performance by illustrating atomic resolution and quasiparticle interference imaging and detail the vibrational noise of both the laboratory and microscope. We also determine the electron temperature via measurement of the superconducting gap of Re(0001) and illustrate magnetic field-dependent measurements of the spin excitations of individual Fe atoms on Pt(111). Finally, we demonstrate spin resolution by imaging the magnetic structure of the Fe double layer on W(110).

In situ sputter cleaning of thin film metal substrates for UHV-TEM corrosion studies.

NASA Technical Reports Server (NTRS)

Heinemann, K.; Poppa, H.

1973-01-01

A prerequisite for conducting valid corrosion experiments by in situ electron microscopy techniques is not only the achievement of UHV background pressure conditions at the site of the specimen but also the ability to clean the surface of the thin metal substrate specimen before initiation of the corrosive interaction. A miniaturized simple ion gun has been constructed for this purpose. The gun is small enough to be incorporated into an UHV electron microscope specimen chamber with hot stage in such a way as to permit bombardment of the substrate specimen while observing it by transmission electron microscopy TEM. It is shown that the ion beam generated is confined well enough to cause a sputtering removal of substrate material at a rate of approximately 5-10 A/min and to prevent the sputter deposition of contaminating material from the specimen holder.

The fabrication of a double-layer atom chip with through silicon vias for an ultra-high-vacuum cell

NASA Astrophysics Data System (ADS)

Chuang, Ho-Chiao; Lin, Yun-Siang; Lin, Yu-Hsin; Huang, Chi-Sheng

2014-04-01

This study presents a double-layer atom chip that provides users with increased diversity in the design of the wire patterns and flexibility in the design of the magnetic field. It is more convenient for use in atomic physics experiments. A negative photoresist, SU-8, was used as the insulating layer between the upper and bottom copper wires. The electrical measurement results show that the upper and bottom wires with a width of 100 µm can sustain a 6 A current without burnout. Another focus of this study is the double-layer atom chips integrated with the through silicon via (TSV) technique, and anodically bonded to a Pyrex glass cell, which makes it a desired vacuum chamber for atomic physics experiments. Thus, the bonded glass cell not only significantly reduces the overall size of the ultra-high-vacuum (UHV) chamber but also conducts the high current from the backside to the front side of the atom chip via the TSV under UHV (9.5 × 10-10 Torr). The TSVs with a diameter of 70 µm were etched through by the inductively coupled plasma ion etching and filled by the bottom-up copper electroplating method. During the anodic bonding process, the electroplated copper wires and TSVs on atom chips also need to pass the examination of the required bonding temperature of 250 °C, under an applied voltage of 1000 V. Finally, the UHV test of the double-layer atom chips with TSVs at room temperature can be reached at 9.5 × 10-10 Torr, thus satisfying the requirements of atomic physics experiments under an UHV environment.

Variable Temperature Scanning Tunneling Microscopy

DTIC Science & Technology

1991-07-01

Tomazin, both Electrical Engineering. Build a digital integrator for the STM feedback loop: Kyle Drewry, Electrical Engineering. Write an AutoLisp ...program to automate the AutoCad design of UHV-STM chambers: Alfred Pierce (minority), Mechanical Engineering. Design a 32-bit interface board for the EISA

All-aluminum-alloy UHV chamber for molecular beam epitaxy, 1

NASA Astrophysics Data System (ADS)

Suemitsu, M.; Miyamoto, N.

1984-03-01

The first all aluminum alloy (ex. JIS.6263-t6,2219-t87 etc) MBE chamber is constructed and described. After exposure to atmosphere, the chamber is drown to 10(-9) torr in 24 hours, and reaches an ultrahigh vacuum of 1.6x10(-10) torr by a 115 C, 24 bakeout process. The light weight and low cost as well as the short pump-down time and the law outgassing rate of the all aluminum alloy vacuum system seems to have a considerable applicative potentiality for equipment used in semiconductor ultrahigh vacuum processes.

Chemical Warfare Agent Surface Adsorption: Hydrogen Bonding of Sarin and Soman to Amorphous Silica

DTIC Science & Technology

2014-03-17

Prior to experiments, the gas manifold and dosing lines were heated, under vacuum, to 100 °C to minimize water contamination. A stainless steel ...23 L UHV chamber constructed out of 316L stainless steel with all ports equipped with con-flat flanges (Kurt J. Lesker Company). The chamber is...dosed as a neat vapor using a multivalved stainless steel high-vacuum manifold. The entire path of the manifold was evacuated and heated to 100 °C

Augmentation Award for Surface Science Research Training.

DTIC Science & Technology

1996-11-01

atomic force microscopy facility. In particular, he designed an anechoic chamber for minimizing acoustical noise in our air and electrochemistry imaging...well as our new air/electochemical STM/AFM. In addition to the UHV-STM, the 11/20/96 10:43 e773 702 5863 J.F.I. I•On7 new air- levitated vactium rhnrher

Application of the double paddle oscillator for quantifying environmental, surface mass variation

NASA Astrophysics Data System (ADS)

Wei, Haoyan; Pomeroy, Joshua

2016-04-01

Sub-monolayer sensitivity to controlled gas adsorption and desorption is demonstrated using a double paddle oscillator (DPO) installed within an ultra-high vacuum (UHV) environmental chamber equipped with in situ film deposition, (multi)gas admission and temperature control. This effort is intended to establish a robust framework for quantitatively comparing mass changes due to gas loading and unloading on different materials systems selected or considered for use as mass artefacts. Our apparatus is composed of a UHV chamber with gas introduction and temperature control and in situ materials deposition for future materials testing enabling in situ preparation of virgin surfaces that can be monitored during initial exposure to gasses of interest. These tools are designed to allow us to comparatively evaluate how different materials gain or lose mass due to precisely controlled environmental excursions, with a long term goal of measuring changes in absolute mass. Herein, we provide a detailed experimental description of the apparatus, an evaluation of the initial performance, and demonstration measurements using nitrogen adsorption and desorption directly on the DPO.

Application of the double paddle oscillator for quantifying environmental, surface mass variation

PubMed Central

Wei, Haoyan; Pomeroy, Joshua

2016-01-01

Sub-monolayer sensitivity to controlled gas adsorption and desorption is demonstrated using a double paddle oscillator (DPO) installed within an UHV (ultra-high vacuum) environmental chamber equipped with in situ film deposition, (multi)gas admission and temperature control. This effort is intended to establish a robust framework for quantitatively comparing mass changes due to gas loading and unloading on different materials systems selected or considered for use as mass artifacts. Our apparatus is composed of a UHV chamber with gas introduction and temperature control and in-situ materials deposition for future materials testing enabling in situ preparation of virgin surfaces that can be monitored during initial exposure to gasses of interest. These tools are designed to allow us to comparatively evaluate how different materials gain or lose mass due to precisely controlled environmental excursions, with a long term goal of measuring changes in absolute mass. Herein, we provide a detailed experimental description of the apparatus, an evaluation of the initial performance, and demonstration measurements using nitrogen adsorption and desorption directly on the DPO. PMID:27212736

A low-energy metal-ion source for primary ion deposition and accelerated ion doping during molecular-beam epitaxy

NASA Astrophysics Data System (ADS)

Hasan, M.-A.; Knall, J.; Barnett, S. A.; Rockett, A.; Sundgren, J.-E.

1987-10-01

A single-grid electron-impact ultrahigh vacuum (UHV) compatible low-energy ion gun capable of operating with a low vapor pressure solid source material such as In is presented. The gun consists of a single chamber which integrates the functions of an effusion cell, a vapor transport tube, and a glow discharge ionizer. The initial results of experiments designed to study the role of ion/surface interactions during nucleation and the early stages of crystal growth in UHV revealed that, for deposition on amorphous substrates, the use of a partially ionized In(+) beam resulted in a progressive shift towards larger island sizes, a decreased rate of secondary nucleation, and a more uniform island size distribution.

Successful Cleaning and Study of Contamination of Si(001) in Ultrahigh Vacuum

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gheorghe, N. G.; Lungu, G. A.; Husanu, M. A.

2011-10-03

This paper presents the very first surface physics experiment performed in ultrahigh vacuum (UHV) in Romania, using a new molecular beam epitaxy (MBE) installation. Cleaning of a Si(001) wafer was achieved by using a very simple technique: sequences of annealing at 900-1000 deg. C in ultrahigh vacuum: low 10{sup -8} mbar, with a base pressure of 1.5x10{sup -10} mbar. The preparation procedure is quite reproducible and allows repeated cleaning of the Si(001) after contamination in ultrahigh vacuum. The Si(001) single crystal surface is characterized by low energy electron diffraction (LEED), reflection high energy electron diffraction (RHEED), and Auger electron spectroscopymore » (AES). The latter technique is utilized in order to investigate the sample contamination by the residual gas in the UHV chamber, as determined by a residual gas analyzer (RGA). Unambiguous assignment of oxidized and unoxidized silicon is provided; also, an important feature is that the LVV Auger peak at 90-92 eV cannot be solely attributed to clean Si (i.e. Si surrounded only by Si), but also to silicon atoms bounded with carbon. Even with a sum of partial pressures of oxygen and carbon containing molecules in the range of 5x10{sup -10} mbar, the sample is contaminated very quickly, having a (1/e) lifetime of about 76 minutes.« less

An MBE growth facility for real-time in situ synchrotron x-ray topography studies of strained-layer III-V epitaxial materials

NASA Astrophysics Data System (ADS)

Whitehouse, C. R.; Barnett, S. J.; Soley, D. E. J.; Quarrell, J.; Aldridge, S. J.; Cullis, A. G.; Emeny, M. T.; Johnson, A. D.; Clarke, G. F.; Lamb, W.; Tanner, B. K.; Cottrell, S.; Lunn, B.; Hogg, C.; Hagston, W.

1992-01-01

This paper describes a unique combined UHV MBE growth x-ray topography facility designed to allow the first real-time synchrotron radiation x-ray topography study of strained-layer III-V growth processes. This system will enable unambiguous determination of dislocation nucleation and multiplication processes as a function of controlled variations in growth conditions, and also during post-growth thermal processing. The planned experiments have placed very stringent demands upon the engineering design of the system, and design details regarding the growth chamber; sample manipulator, x-ray optics, and real-time imaging systems are described. Results obtained during a feasibility study are also presented.

An MBE growth facility for real-time in situ synchrotron x-ray topography studies of strained-layer III--V epitaxial materials

DOE Office of Scientific and Technical Information (OSTI.GOV)

Whitehouse, C.R.; Barnett, S.J.; Soley, D.E.J.

1992-01-01

This paper describes a unique combined UHV MBE growth x-ray topography facility designed to allow the first real-time synchrotron radiation x-ray topography study of strained-layer III--V growth processes. This system will enable unambiguous determination of dislocation nucleation and multiplication processes as a function of controlled variations in growth conditions, and also during post-growth thermal processing. The planned experiments have placed very stringent demands upon the engineering design of the system, and design details regarding the growth chamber; sample manipulator, x-ray optics, and real-time imaging systems are described. Results obtained during a feasibility study are also presented.

Versatile variable temperature and magnetic field scanning probe microscope for advanced material research

NASA Astrophysics Data System (ADS)

Jung, Jin-Oh; Choi, Seokhwan; Lee, Yeonghoon; Kim, Jinwoo; Son, Donghyeon; Lee, Jhinhwan

2017-10-01

We have built a variable temperature scanning probe microscope (SPM) that covers 4.6 K-180 K and up to 7 T whose SPM head fits in a 52 mm bore magnet. It features a temperature-controlled sample stage thermally well isolated from the SPM body in good thermal contact with the liquid helium bath. It has a 7-sample-holder storage carousel at liquid helium temperature for systematic studies using multiple samples and field emission targets intended for spin-polarized spectroscopic-imaging scanning tunneling microscopy (STM) study on samples with various compositions and doping conditions. The system is equipped with a UHV sample preparation chamber and mounted on a two-stage vibration isolation system made of a heavy concrete block and a granite table on pneumatic vibration isolators. A quartz resonator (qPlus)-based non-contact atomic force microscope (AFM) sensor is used for simultaneous STM/AFM operation for research on samples with highly insulating properties such as strongly underdoped cuprates and strongly correlated electron systems.

Plasma diagnostic development and UHV testing for the ALPHA collaboration at Marquette University

NASA Astrophysics Data System (ADS)

Tharp, T. D.; Alpha Collaboration

2017-10-01

At Marquette, we are developing the next generation of nonneutral plasma diagnostics for the ALPHA experiment at CERN. ALPHA is building a new vertical experiment to test the gravitational interaction of antihydrogen with Earth. This expansion requires significant changes to the design of our plasma diagnostic suites: the next generation of tools must be able to measure plasmas from two directions, and must be capable of operating in a horizontal position. The diagnostic suite includes measurements of plasma density, shape, and temperature. The hardware used includes a MicroChannel Plate (MCP), a Faraday Cup, and an electron gun. In addition, we are building a vacuum chamber to test the viability of 3-d printed components for UHV compatibility, with target pressures of 10-10 mbar.

Dual analyzer system for surface analysis dedicated for angle-resolved photoelectron spectroscopy at liquid surfaces and interfaces

DOE Office of Scientific and Technical Information (OSTI.GOV)

Niedermaier, Inga; Kolbeck, Claudia; Steinrück, Hans-Peter

The investigation of liquid surfaces and interfaces with the powerful toolbox of ultra-high vacuum (UHV)-based surface science techniques generally has to overcome the issue of liquid evaporation within the vacuum system. In the last decade, however, new classes of liquids with negligible vapor pressure at room temperature—in particular, ionic liquids (ILs)—have emerged for surface science studies. It has been demonstrated that particularly angle-resolved X-ray Photoelectron Spectroscopy (ARXPS) allows for investigating phenomena that occur at gas-liquid and liquid-solid interfaces on the molecular level. The results are not only relevant for IL systems but also for liquids in general. In all ofmore » these previous ARXPS studies, the sample holder had to be tilted in order to change the polar detection angle of emitted photoelectrons, which restricted the liquid systems to very thin viscous IL films coating a flat solid support. We now report on the concept and realization of a new and unique laboratory “Dual Analyzer System for Surface Analysis (DASSA)” which enables fast ARXPS, UV photoelectron spectroscopy, imaging XPS, and low-energy ion scattering at the horizontal surface plane of macroscopically thick non-volatile liquid samples. It comprises a UHV chamber equipped with two electron analyzers mounted for simultaneous measurements in 0° and 80° emission relative to the surface normal. The performance of DASSA on a first macroscopic liquid system will be demonstrated.« less

Dose controlled low energy electron irradiator for biomolecular films

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kumar, S. V. K., E-mail: svkk@tifr.res.in; Tare, Satej T.; Upalekar, Yogesh V.

2016-03-15

We have developed a multi target, Low Energy Electron (LEE), precise dose controlled irradiator for biomolecular films. Up to seven samples can be irradiated one after another at any preset electron energy and dose under UHV conditions without venting the chamber. In addition, one more sample goes through all the steps except irradiation, which can be used as control for comparison with the irradiated samples. All the samples are protected against stray electron irradiation by biasing them at −20 V during the entire period, except during irradiation. Ethernet based communication electronics hardware, LEE beam control electronics and computer interface weremore » developed in house. The user Graphical User Interface to control the irradiation and dose measurement was developed using National Instruments Lab Windows CVI. The working and reliability of the dose controlled irradiator has been fully tested over the electron energy range of 0.5 to 500 eV by studying LEE induced single strand breaks to ΦX174 RF1 dsDNA.« less

Low conductive support for thermal insulation of a sample holder of a variable temperature scanning tunneling microscope

NASA Astrophysics Data System (ADS)

Hanzelka, Pavel; Vonka, Jakub; Musilova, Vera

2013-08-01

We have designed a supporting system to fix a sample holder of a scanning tunneling microscope in an UHV chamber at room temperature. The microscope will operate down to a temperature of 20 K. Low thermal conductance, high mechanical stiffness, and small dimensions are the main features of the supporting system. Three sets of four glass balls placed in vertices of a tetrahedron are used for thermal insulation based on small contact areas between the glass balls. We have analyzed the thermal conductivity of the contacts between the balls mutually and between a ball and a metallic plate while the results have been applied to the entire support. The calculation based on a simple model of the setup has been verified with some experimental measurements. In comparison with other feasible supporting structures, the designed support has the lowest thermal conductance.

Low conductive support for thermal insulation of a sample holder of a variable temperature scanning tunneling microscope.

PubMed

Hanzelka, Pavel; Vonka, Jakub; Musilova, Vera

2013-08-01

We have designed a supporting system to fix a sample holder of a scanning tunneling microscope in an UHV chamber at room temperature. The microscope will operate down to a temperature of 20 K. Low thermal conductance, high mechanical stiffness, and small dimensions are the main features of the supporting system. Three sets of four glass balls placed in vertices of a tetrahedron are used for thermal insulation based on small contact areas between the glass balls. We have analyzed the thermal conductivity of the contacts between the balls mutually and between a ball and a metallic plate while the results have been applied to the entire support. The calculation based on a simple model of the setup has been verified with some experimental measurements. In comparison with other feasible supporting structures, the designed support has the lowest thermal conductance.

Development of a quadrupole-based Secondary-Ion Mass Spectrometry (SIMS) system at Lewis Research Center

NASA Technical Reports Server (NTRS)

Vargas-Aburto, Carlos; Aron, Paul R.; Liff, Dale R.

1990-01-01

The design, construction, and initial use of an ion microprobe to carry out secondary ion mass spectrometry (SIMS) of solid samples is reported. The system is composed of a differentially pumped custom-made UHV (Ultra High Vacuum) chamber, a quadrupole mass spectrometer and a telefocus A-DIDA ion gun with the capability of producing beams of Cesium, as well as inert and reactive gases. The computer control and acquisition of the data were designed and implemented using a personal computer with plug-in boards, and external circuitry built as required to suit the system needs. The software is being developed by using a FORTH-like language. Initial tests aimed at characterizing the system, as well as preliminary surface and depth-profiling studies are presently underway.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nguyen, Luan; Tao, Franklin, E-mail: franklin.tao.2011@gmail.com; Department of Chemical and Petroleum Engineering, University of Kansas, Lawrence, Kansas 66045

Tracking surface chemistry of a catalyst during catalysis is significant for fundamental understanding of catalytic performance of the catalyst since it allows for establishing an intrinsic correlation between surface chemistry of a catalyst at its working status and its corresponding catalytic performance. Ambient pressure X-ray photoelectron spectroscopy can be used for in-situ studies of surfaces of different materials or devices in a gas. To simulate the gaseous environment of a catalyst in a fixed-bed a flowing gaseous environment of reactants around the catalyst is necessary. Here, we report the development of a new flowing reaction cell for simulating in-situ studymore » of a catalyst surface under a reaction condition in gas of one reactant or during catalysis in a mixture of reactants of a catalytic reaction. The homemade reaction cell is installed in a high vacuum (HV) or ultrahigh vacuum (UHV) environment of a chamber. The flowing gas in the reaction cell is separated from the HV or UHV environment through well sealings at three interfaces between the reaction cell and X-ray window, sample door and aperture of front cone of an energy analyzer. Catalyst in the cell is heated through infrared laser beam introduced through a fiber optics interfaced with the reaction cell through a homemade feedthrough. The highly localized heating on the sample holder and Au-passivated internal surface of the reaction cell effectively minimizes any unwanted reactions potentially catalyzed by the reaction cell. The incorporated laser heating allows a fast heating and a high thermal stability of the sample at a high temperature. With this cell, a catalyst at 800 °C in a flowing gas can be tracked readily.« less

Development of a reaction cell for in-situ/operando studies of surface of a catalyst under a reaction condition and during catalysis.

PubMed

Nguyen, Luan; Tao, Franklin Feng

2016-06-01

Tracking surface chemistry of a catalyst during catalysis is significant for fundamental understanding of catalytic performance of the catalyst since it allows for establishing an intrinsic correlation between surface chemistry of a catalyst at its working status and its corresponding catalytic performance. Ambient pressure X-ray photoelectron spectroscopy can be used for in-situ studies of surfaces of different materials or devices in a gas. To simulate the gaseous environment of a catalyst in a fixed-bed a flowing gaseous environment of reactants around the catalyst is necessary. Here, we report the development of a new flowing reaction cell for simulating in-situ study of a catalyst surface under a reaction condition in gas of one reactant or during catalysis in a mixture of reactants of a catalytic reaction. The homemade reaction cell is installed in a high vacuum (HV) or ultrahigh vacuum (UHV) environment of a chamber. The flowing gas in the reaction cell is separated from the HV or UHV environment through well sealings at three interfaces between the reaction cell and X-ray window, sample door and aperture of front cone of an energy analyzer. Catalyst in the cell is heated through infrared laser beam introduced through a fiber optics interfaced with the reaction cell through a homemade feedthrough. The highly localized heating on the sample holder and Au-passivated internal surface of the reaction cell effectively minimizes any unwanted reactions potentially catalyzed by the reaction cell. The incorporated laser heating allows a fast heating and a high thermal stability of the sample at a high temperature. With this cell, a catalyst at 800 °C in a flowing gas can be tracked readily.

Construction and evaluation of an ultrahigh-vacuum-compatible sputter deposition source

NASA Astrophysics Data System (ADS)

Lackner, Peter; Choi, Joong Il Jake; Diebold, Ulrike; Schmid, Michael

2017-10-01

A sputter deposition source for the use in ultrahigh vacuum (UHV) is described, and some properties of the source are analyzed. The operating principle is based on the design developed by Mayr et al. [Rev. Sci. Instrum. 84, 094103 (2013)], where electrons emitted from a filament ionize argon gas and the Ar+ ions are accelerated to the target. In contrast to the original design, two grids are used to direct a large fraction of the Ar+ ions to the target, and the source has a housing cooled by liquid nitrogen to reduce contaminations. The source has been used for the deposition of zirconium, a material that is difficult to evaporate in standard UHV evaporators. At an Ar pressure of 9 ×1 0-6 mbar in the UHV chamber and moderate emission current, a highly reproducible deposition rate of ≈1 ML in 250 s was achieved at the substrate (at a distance of ≈50 mm from the target). Higher deposition rates are easily possible. X-ray photoelectron spectroscopy shows a high purity of the deposited films. Depending on the grid voltages, the substrate gets mildly sputtered by Ar+ ions; in addition, the substrate is also reached by electrons from the negatively biased sputter target.

Small-volume, ultrahigh-vacuum-compatible high-pressure reaction cell for combined kinetic and in situ IR spectroscopic measurements on planar model catalysts

NASA Astrophysics Data System (ADS)

Zhao, Z.; Diemant, T.; Häring, T.; Rauscher, H.; Behm, R. J.

2005-12-01

We describe the design and performance of a high-pressure reaction cell for simultaneous kinetic and in situ infrared reflection (IR) spectroscopic measurements on model catalysts at elevated pressures, between 10-3 and 103mbars, which can be operated both as batch reactor and as flow reactor with defined gas flow. The cell is attached to an ultrahigh-vacuum (UHV) system, which is used for sample preparation and also contains facilities for sample characterization. Specific for this design is the combination of a small cell volume, which allows kinetic measurements with high sensitivity under batch or continuous flow conditions, the complete isolation of the cell from the UHV part during UHV measurements, continuous temperature control during both UHV and high-pressure operation, and rapid transfer between UHV and high-pressure stage. Gas dosing is performed by a designed gas-handling system, which allows operation as flow reactor with calibrated gas flows at adjustable pressures. To study the kinetics of reactions on the model catalysts, a quadrupole mass spectrometer is connected to the high-pressure cell. IR measurements are possible in situ by polarization-modulation infrared reflection-absorption spectroscopy, which also allows measurements at elevated pressures. The performance of the setup is demonstrated by test measurements on the kinetics for CO oxidation and the CO adsorption on a Au /TiO2/Ru(0001) model catalyst film at 1-50 mbar total pressure.

Quantitative study of sniffer leak rate and pressure drop leak rate of liquid nitrogen panels of SST-1 tokamak

NASA Astrophysics Data System (ADS)

Pathan, F. S.; Khan, Z.; Semwal, P.; Raval, D. C.; Joshi, K. S.; Thankey, P. L.; Dhanani, K. R.

2008-05-01

Steady State Super-conducting (SST-1) Tokamak is in commissioning stage at Institute for Plasma Research. Vacuum chamber of SST-1 Tokamak consists of 1) Vacuum vessel, an ultra high vacuum (UHV) chamber, 2) Cryostat, a high vacuum (HV) chamber. Cryostat encloses the liquid helium cooled super-conducting magnets (TF and PF), which require the thermal radiation protection against room temperature. Liquid nitrogen (LN2) cooled panels are used to provide thermal shield around super-conducting magnets. During operation, LN2 panels will be under pressurized condition and its surrounding (cryostat) will be at high vacuum. Hence, LN2 panels must have very low leak rate. This paper describes an experiment to study the behaviour of the leaks in LN2 panels during sniffer test and pressure drop test using helium gas.

New experimental perspectives for soft x-ray absorption spectroscopies at ultra-low temperatures below 50 mK and in high magnetic fields up to 7 T

DOE Office of Scientific and Technical Information (OSTI.GOV)

Beeck, T., E-mail: torben.beeck@desy.de; Baev, I.; Gieschen, S.

2016-04-15

A new ultra-low temperature experiment including a superconducting vector magnet has been developed for soft x-ray absorption spectroscopy experiments at third generation synchrotron light sources. The sample is cooled below 50 mK by a cryogen free {sup 3}He-{sup 4}He dilution refrigerator. At the same time, magnetic fields of up to ±7 T in the horizontal direction and ±0.5 T in the vertical direction can be applied by a superconducting vector magnet. The setup allows to study ex situ and in situ prepared samples, offered by an attached UHV preparation chamber with load lock. The transfer of the prepared samples betweenmore » the preparation section and the dilution refrigerator is carried out under cryogenic temperatures. First commissioning studies have been carried out at the Variable Polarization XUV Beamline P04 at PETRA III and the influence of the incident photon beam to the sample temperature has been studied.« less

A Low Temperature, Ultrahigh Vacuum, Microwave-Frequency-Compatible Scanning Tunneling Microscope

DTIC Science & Technology

1994-05-01

vibrationally decoupled from the chamber using a Subadmed oo -3.- 21 April 1994 Reviw of Sdent* k Immownu Low Topasom UHV ACS7M Stranick et al...molecules, two isolated clusters of benzene molecules on the upper terrace, and several vacancy defects in the Cu(111) surface on the lower terrace...fine and is easily removed and replaced. 11. National Electrostatics Corporation, Middleton, WI. 12. K . Besocke, Surf. Sci. 181, 145 (1987); J. Frohn, J

Characterization of a Compact Cryogenic Package Approach to Ion Trap Quantum Comuting

NASA Astrophysics Data System (ADS)

Spivey, Robert; Vrijsen, Geert; Ahn, Byeong-Hyeon; Hudek, Kai; Crain, Stephen; van Rynbach, Andre; Rachel, Noek; Kim, Jungsang

One challenge for the expansion of trapped ion systems to a large scale is the lack of repeatable integration technology to realize compact and stable operating environment. In this work, we present a novel ion trapping environment where conventional ultra-high vacuum (UHV) chambers are replaced with a sealed ceramic package operating in a cryogenic environment. A microfabricated surface ion trap mounted on a 100-pin ceramic pin grid array (CPGA) package is placed in a UHV environment. A titanium lid with windows for optical access is then attached to the CPGA via an indium seal which maintains the UHV conditions for the ion trap. The trap package assembly is operated at cryogenic temperatures (5K) in order to freeze out most of the residual background gas. Activated charcoal is used to pump remaining helium and hydrogen molecules. Metallic Yb ablated using a Q-switched Nd:YAG laser at 1,064 nm is used as the atomic source. A compact radio frequency resonant circuit is used to create the RF potential for trapping. A low output impedance amplifier drives a superconducting inductor of value 2 uH in series with the trap capacitance in order to produce 200V at 26 MHz with low heating at 5K. We present the experimental progress towards trapping ions in this compact cryogenic setup.

New XAFS Facility for In-Situ Measurements at Beamline C at HASYLAB

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rickers, K.; Drube, W.; Schulte-Schrepping, H.

2007-02-02

A XAFS-experiment allowing for in-situ experiments has been set up at DORIS bending magnet beamline C. For that purpose, a new double-crystal, UHV-compatible monochromator with fast scanning capability was designed. This fixed-exit monochromator uses two crystal sets on a common central rotation axis driven by an ex-vacuo goniometer. Bragg angles range from 5 deg. to 55.5 deg. resulting in a total energy range 2.3 - 43.4 keV using Si(111)/(311) crystal sets. Crystal pairs can be remotely selected by translating the vacuum chamber. Energy encoding is performed using an optical encoder system. The standard XAFS sample environment is set-up in vacuomore » and can be adapted for special sample environments. For in-situ experiments, the beamline is equipped with twelve gas lines. An exhaust line allows toxic/reactive gases to be handled. As an initial performance test of the instrument, Ti, Cr, Fe and Cu XAFS and Ce K-shell QEXAFS measurements were performed.« less

High performance a-Si solar cells and new fabrication methods for a-Si solar cells

NASA Astrophysics Data System (ADS)

Nakano, S.; Kuwano, Y.; Ohnishi, M.

1986-12-01

The super chamber, a separated UHV reaction-chamber system has been developed. A conversion efficiency of 11.7% was obtained for an a-Si solar cell using a high-quality i-layer deposited by the super chamber, and a p-layer fabricated by a photo-CVD method. As a new material, amorphous superlattice-structure films were fabricated by the photo-CVD method for the first time. Superlattice structure p-layer a-Si solar cells were fabricated, and a conversion efficiency of 10.5% was obtained. For the fabrication of integrated type a-Si solar cell modules, a laser pattering method was investigated. A thermal analysis of the multilayer structure was done. It was confirmed that selective scribing for a-Si, TCO and metal film is possible by controlling the laser power density. Recently developed a-Si solar power generation systems and a-Si solar cell roofing tiles are also described.

Effect of Water Vapor Pressure on Fatigue Crack Growth in Al-Zn-Cu-Mg Alloy Over Wide-Range Stress Intensity Factor Loading

DTIC Science & Technology

2014-05-07

impacts: (a) crack closure, (b) transport of water vapor molecules within the fatigue crack (47], and (c) tensile stress-plastic strain range...sealed stainless steel UHV chamber. Pure water vapor was introduced from a sealed glass flask containing triply distilled water, via a precision leak...lamellar for H1 flow in a fatigue crack in steel ; specifically, flow is dominated by the low dynamic viscosity of a gas (particularly at low pressures) and

A diamond-based scanning probe spin sensor operating at low temperature in ultra-high vacuum

DOE Office of Scientific and Technical Information (OSTI.GOV)

Schaefer-Nolte, E.; Wrachtrup, J.; 3rd Institute of Physics and Research Center SCoPE, University Stuttgart, 70569 Stuttgart

2014-01-15

We present the design and performance of an ultra-high vacuum (UHV) low temperature scanning probe microscope employing the nitrogen-vacancy color center in diamond as an ultrasensitive magnetic field sensor. Using this center as an atomic-size scanning probe has enabled imaging of nanoscale magnetic fields and single spins under ambient conditions. In this article we describe an experimental setup to operate this sensor in a cryogenic UHV environment. This will extend the applicability to a variety of molecular systems due to the enhanced target spin lifetimes at low temperature and the controlled sample preparation under UHV conditions. The instrument combines amore » tuning-fork based atomic force microscope (AFM) with a high numeric aperture confocal microscope and the facilities for application of radio-frequency (RF) fields for spin manipulation. We verify a sample temperature of <50 K even for strong laser and RF excitation and demonstrate magnetic resonance imaging with a magnetic AFM tip.« less

Portable ultrahigh-vacuum sample storage system for polarization-dependent total-reflection fluorescence x-ray absorption fine structure spectroscopy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Watanabe, Yoshihide, E-mail: e0827@mosk.tytlabs.co.jp; Nishimura, Yusaku F.; Suzuki, Ryo

A portable ultrahigh-vacuum sample storage system was designed and built to investigate the detailed geometric structures of mass-selected metal clusters on oxide substrates by polarization-dependent total-reflection fluorescence x-ray absorption fine structure spectroscopy (PTRF-XAFS). This ultrahigh-vacuum (UHV) sample storage system provides the handover of samples between two different sample manipulating systems. The sample storage system is adaptable for public transportation, facilitating experiments using air-sensitive samples in synchrotron radiation or other quantum beam facilities. The samples were transferred by the developed portable UHV transfer system via a public transportation at a distance over 400 km. The performance of the transfer system was demonstratedmore » by a successful PTRF-XAFS study of Pt{sub 4} clusters deposited on a TiO{sub 2}(110) surface.« less

System to measure accurate temperature dependence of electric conductivity down to 20 K in ultrahigh vacuum.

PubMed

Sakai, C; Takeda, S N; Daimon, H

2013-07-01

We have developed the new in situ electrical-conductivity measurement system which can be operated in ultrahigh vacuum (UHV) with accurate temperature measurement down to 20 K. This system is mainly composed of a new sample-holder fixing mechanism, a new movable conductivity-measurement mechanism, a cryostat, and two receptors for sample- and four-probe holders. Sample-holder is pushed strongly against the receptor, which is connected to a cryostat, by using this new sample-holder fixing mechanism to obtain high thermal conductivity. Test pieces on the sample-holders have been cooled down to about 20 K using this fixing mechanism, although they were cooled down to only about 60 K without this mechanism. Four probes are able to be touched to a sample surface using this new movable conductivity-measurement mechanism for measuring electrical conductivity after making film on substrates or obtaining clean surfaces by cleavage, flashing, and so on. Accurate temperature measurement is possible since the sample can be transferred with a thermocouple and∕or diode being attached directly to the sample. A single crystal of Bi-based copper oxide high-Tc superconductor (HTSC) was cleaved in UHV to obtain clean surface, and its superconducting critical temperature has been successfully measured in situ. The importance of in situ measurement of resistance in UHV was demonstrated for this HTSC before and after cesium (Cs) adsorption on its surface. The Tc onset increase and the Tc offset decrease by Cs adsorption were observed.

Evaluation of Ti-Zr-V (NEG) Thin Films for their pumping speed and pumping Capacity

NASA Astrophysics Data System (ADS)

Bansod, Tripti; Sindal, B. K.; Kumar, K. V. A. N. P. S.; Shukla, S. K.

2012-11-01

Deposition of NEG thin films onto the interior walls of the vacuum chambers is an advanced technique to convert a vacuum chamber from a gas source to an effective pump. These films offer considerably large pumping speed for reactive gases like CO, H2 etc. A UHV compatible pumping speed measurement system was developed in-house to measure the pumping speed of NEG coated chambers. To inject the fixed quantity of CO and H2 gas in pumping speed measurement set-up a calibrated leak was also developed. Stainless steel chambers were sputter coated with thin film of Ti-Zr-V getter material using varied parameters for different compositions and thickness. Pumping capacity which is a function of sorbed gas quantities was also studied at various activation temperatures. In order to optimize the activation temperature for maximum pumping speed for CO and H2, pumping speeds were measured at room temperature after activation at different temperatures. The experimental system detail, pumping performance of the NEG film at various activation temperatures and RGA analysis are presented.

Novel Ultrahigh Vacuum System for Chip-Scale Trapped Ion Quantum Computing

NASA Astrophysics Data System (ADS)

Chen, Shaw-Pin; Trapped Team

2011-05-01

This presentation reports the experimental results of an ultrahigh vacuum (UHV) system as a scheme to implement scalable trapped-ion quantum computers that use micro-fabricated ion traps as fundamental building blocks. The novelty of this system resides in our design, material selection, mechanical liability, low complexity of assembly, and reduced signal interference between DC and RF electrodes. Our system utilizes RF isolation and onsite-filtering topologies to attenuate AC signals generated from the resonator. We use a UHV compatible printed circuit board (PCB) material to perform DC routing, while the RF high and RF ground received separated routing via wire-wrapping. The standard PCB fabrication process enabled us to implement ceramic-based filter components adjacent to the chip trap. The DC electrodes are connected to air-side electrical feed through using four 25D adaptors made with polyether ether ketone (PEEK). The assembly process of this system is straight forward and in-chamber structure is self-supporting. We report on initial testing of this concept with a linear chip trap fabricated by the Sandia National Labs.

Novel recirculating loop reactor for studies on model catalysts: CO oxidation on Pt/TiO2(110)

NASA Astrophysics Data System (ADS)

Tenney, Samuel A.; Xie, Kangmin; Monnier, John R.; Rodriguez, Abraham; Galhenage, Randima P.; Duke, Audrey S.; Chen, Donna A.

2013-10-01

A novel recirculating loop microreactor coupled to an ultrahigh vacuum (UHV) chamber has been constructed for the kinetic evaluation of model catalysts, which can be fully characterized by UHV surface science techniques. The challenge for this reactor design is to attain sufficient sensitivity to detect reactions on model single-crystal surfaces, which have a low number of active sites compared to conventional catalysts of equivalent mass. To this end, the total dead volume of the reactor system is minimized (32 cm3), and the system is operated in recirculation mode so that product concentrations build up to detectable levels over time. The injection of gas samples into the gas chromatography column and the refilling of the recirculation loop with fresh feed gas are achieved with computer-controlled, automated switching valves. In this manner, product concentrations can be followed over short time intervals (15 min) for extended periods of time (24 h). A proof of principle study in this reactor for CO oxidation at 145-165 °C on Pt clusters supported on a rutile TiO2(110) single crystal yields kinetic parameters that are comparable to those reported in the literature for CO oxidation on Pt clusters on powdered oxide supports, as well as on Pt(100). The calculated activation energy is 16.4 ± 0.7 kcal/mol, the turnover frequency is 0.03-0.06 molecules/(site.s) over the entire temperature range, and the reaction orders in O2 and CO at 160 °C are 0.9 ± 0.2 and -0.82 ± 0.03, respectively.

Phase transition on the Si(001) clean surface prepared in UHV MBE chamber: a study by high-resolution STM and in situ RHEED

PubMed Central

2011-01-01

The Si(001) surface deoxidized by short annealing at T ~ 925°C in the ultrahigh vacuum molecuar beam epitaxy chamber has been in situ investigated using high-resolution scanning tunneling microscopy (STM)and redegreesected high-energy electron diffraction (RHEED. RHEED patterns corresponding to (2 × 1) and (4 × 4) structures were observed during sample treatment. The (4 × 4) reconstruction arose at T ≲ 600°C after annealing. The reconstruction was observed to be reversible: the (4 × 4) structure turned into the (2 × 1) one at T ≳ 600°C, the (4 × 4) structure appeared again at recurring cooling. The c(8 × 8) reconstruction was revealed by STM at room temperature on the same samples. A fraction of the surface area covered by the c(8 × 8) structure decreased, as the sample cooling rate was reduced. The (2 × 1) structure was observed on the surface free of the c(8 × 8) one. The c(8 × 8) structure has been evidenced to manifest itself as the (4 × 4) one in the RHEED patterns. A model of the c(8 × 8) structure formation has been built on the basis of the STM data. Origin of the high-order structure on the Si(001) surface and its connection with the epinucleation phenomenon are discussed. PACS 68.35.B-·68.37.Ef·68.49.Jk·68.47.Fg PMID:21711733

Trapping ultracold gases near cryogenic materials with rapid reconfigurability

DOE Office of Scientific and Technical Information (OSTI.GOV)

Naides, Matthew A.; Turner, Richard W.; Lai, Ruby A.

We demonstrate an atom chip trapping system that allows the placement and high-resolution imaging of ultracold atoms within microns from any ≲100 μm-thin, UHV-compatible material, while also allowing sample exchange with minimal experimental downtime. The sample is not connected to the atom chip, allowing rapid exchange without perturbing the atom chip or laser cooling apparatus. Exchange of the sample and retrapping of atoms has been performed within a week turnaround, limited only by chamber baking. Moreover, the decoupling of sample and atom chip provides the ability to independently tune the sample temperature and its position with respect to the trapped ultracoldmore » gas, which itself may remain in the focus of a high-resolution imaging system. As a first demonstration of this system, we have confined a 700-nK cloud of 8 × 10{sup 4} {sup 87}Rb atoms within 100 μm of a gold-mirrored 100-μm-thick silicon substrate. The substrate was cooled to 35 K without use of a heat shield, while the atom chip, 120 μm away, remained at room temperature. Atoms may be imaged and retrapped every 16 s, allowing rapid data collection.« less

The possibly important role played by Ga{sub 2}O{sub 3} during the activation of GaN photocathode

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fu, Xiaoqian, E-mail: ise-fuxq@ujn.edu.cn, E-mail: 214808748@qq.com; Institute of Electronic Engineering and Optoelectronic Technology, Nanjing University of Science and Technology, Nanjing 210094; Wang, Honggang

2015-08-14

Three different chemical solutions are used to remove the possible contamination on GaN surface, while Ga{sub 2}O{sub 3} is still found at the surface. After thermal annealing at 710 °C in the ultrahigh vacuum (UHV) chamber and activated with Cs/O, all the GaN samples are successfully activated to the effective negative electron affinity (NEA) photocathodes. Among all samples, the GaN sample with the highest content of Ga{sub 2}O{sub 3} after chemical cleaning obtains the highest quantum efficiency. By analyzing the property of Ga{sub 2}O{sub 3}, the surface processing results, and electron affinity variations during Cs and Cs/O{sub 2} deposition on GaNmore » of other groups, it is suggested that before the adsorption of Cs, Ga{sub 2}O{sub 3} is not completely removed from GaN surface in our samples, which will combine with Cs and lead to a large decrease in electron affinity. Furthermore, the effective NEA is formed for GaN photocathode, along with the surface downward band bending. Based on this assumption, a new dipole model Ga{sub 2}O{sub 3}-Cs is suggested, and the experimental effects are explained and discussed.« less

Development of High Quantum Efficiency UV/Blue Photocathode Epitaxial Semiconductor Heterostructures for Scintillation and Cherenkov Radiation Detection

NASA Technical Reports Server (NTRS)

Leopold, Daniel J.

2002-01-01

The primary goal of this research project was to further extend the use of advanced heteroepitaxial-semiconductor crystal growth techniques such as molecular beam epitaxy (MBE) and to demonstrate significant gains in UV/blue photonic detection by designing and fabricating atomically-tailored heteroepitaxial GaAlN/GaInN photocathode device structures. This NASA Explorer technology research program has focused on the development of photocathodes for Cherenkov and scintillation radiation detection. Support from the program allowed us to enhance our MBE system to include a nitrogen plasma source and a magnetic bearing turbomolecular pump for delivery and removal of high purity atomic nitrogen during GaAlN/GaInN film growth. Under this program we have also designed, built and incorporated a cesium activation stage. In addition, a connected UHV chamber with photocathode transfer/positioner components as well as a hybrid phototube stage was designed and built to make in-situ quantum efficiency measurements without ever having to remove the photocathodes from UHV conditions. Thus we have constructed a system with the capability to couple atomically-tailored MBE-grown photocathode heterostructures with real high gain readout devices for single photon detection evaluation.

The EMIL project at BESSY II: Beamline design and performance

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hendel, Stefan, E-mail: stefan.hendel@helmholtz-berlin.de; Schäfers, Franz; Reichardt, Gerd

2016-07-27

The Energy Materials In-Situ Laboratory Berlin (EMIL) at BESSY-II is currently under construction. Two canted undulators for soft- and hard X-rays will be installed into the BESSY II storage ring in one straight section, complex beamlines with more than twenty optical elements will be set up and a new laboratory building attached to BESSY II will host three endstations and a large UHV-transfer system connecting various HV- and UHV-deposition systems. The undulators, UE48 and U17, provide a broad energy spectrum of 80 - 10000 eV, of which the harder radiation (>700 eV) is provided by a cryogenic in-vacuum device. Threemore » monochromators (two plane grating monochromators (PGM) and one LN{sub 2}-cooled double crystal monochromator (DCM)) disperse the radiation into separate pathways of 65 m length, while downstream of the monochromators split-mirror chambers distribute the photon beam to one (or simultaneously to two) of five upcoming endstations. Three of these endstations are designed for the full energy range with spatial overlap of the soft and hard foci, whereas one endstation (PEEM) uses only the soft and another one (PINK) only the hard branch, respectively.« less

High field electron paramagnetic resonance spectroscopy under ultrahigh vacuum conditions—A multipurpose machine to study paramagnetic species on well defined single crystal surfaces

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rocker, J.; Cornu, D.; Kieseritzky, E.

2014-08-01

A new ultrahigh vacuum (UHV) electron paramagnetic resonance (EPR) spectrometer operating at 94 GHz to investigate paramagnetic centers on single crystal surfaces is described. It is particularly designed to study paramagnetic centers on well-defined model catalysts using epitaxial thin oxide films grown on metal single crystals. The EPR setup is based on a commercial Bruker E600 spectrometer, which is adapted to ultrahigh vacuum conditions using a home made Fabry Perot resonator. The key idea of the resonator is to use the planar metal single crystal required to grow the single crystalline oxide films as one of the mirrors of themore » resonator. EPR spectroscopy is solely sensitive to paramagnetic species, which are typically minority species in such a system. Hence, additional experimental characterization tools are required to allow for a comprehensive investigation of the surface. The apparatus includes a preparation chamber hosting equipment, which is required to prepare supported model catalysts. In addition, surface characterization tools such as low energy electron diffraction (LEED)/Auger spectroscopy, temperature programmed desorption (TPD), and infrared reflection absorption spectroscopy (IRAS) are available to characterize the surfaces. A second chamber used to perform EPR spectroscopy at 94 GHz has a room temperature scanning tunneling microscope attached to it, which allows for real space structural characterization. The heart of the UHV adaptation of the EPR experiment is the sealing of the Fabry-Perot resonator against atmosphere. To this end it is possible to use a thin sapphire window glued to the backside of the coupling orifice of the Fabry Perot resonator. With the help of a variety of stabilization measures reducing vibrations as well as thermal drift it is possible to accumulate data for a time span, which is for low temperature measurements only limited by the amount of liquid helium. Test measurements show that the system can detect paramagnetic species with a density of approximately 5 × 10{sup 11} spins/cm{sup 2}, which is comparable to the limit obtained for the presently available UHV-EPR spectrometer operating at 10 GHz (X-band). Investigation of electron trapped centers in MgO(001) films shows that the increased resolution offered by the experiments at W-band allows to identify new paramagnetic species, that cannot be differentiated with the currently available methodology.« less

Surface development of a brazing alloy during heat treatment-a comparison between UHV and APXPS

NASA Astrophysics Data System (ADS)

Rullik, L.; Johansson, N.; Bertram, F.; Evertsson, J.; Stenqvist, T.; Lundgren, E.

2018-01-01

In an attempt to bridge the pressure gap, APXPS was used to follow the surface development of an aluminum brazing sheet during heating in an ambient oxygen-pressure mimicking the environment of an industrial brazing furnace. The studied aluminum alloy brazing sheet is a composite material consisting of two aluminum alloy standards whose surface is covered with a native aluminum oxide film. To emphasize the necessity of studies of this system in ambient sample environments it is compared to measurements in UHV. Changes in thickness and composition of the surface oxide were followed after heating to 300 °C, 400 °C, and 500 °C. The two sets presented in this paper show that the surface development strongly depends on the environment the sample is heated in.

Design of an Operando Positron Annihilation Gamma Spectrometer (OPAGS)

NASA Astrophysics Data System (ADS)

Satyal, Suman; Shastry, Kartik; Kalaskar, Sushant; Lim, Larry; Joglekar, Vibek; Weiss, Alexander

2009-10-01

Surface properties measured under UHV conditions cannot be extended to surfaces interacting with gases under realistic pressures due to surface reconstruction and other strong perturbations of the surface. Many surface probing techniques used till now have required UHV conditions to avoid data loss due to scattering of outgoing particles. Here we describe the design of an Operando Positron Annihilation Gamma Spectrometer (OPAGS) currently under construction at the University of Texas at Arlington. The new system will be capable of obtaining surface and defect specific chemical and charge state information from surfaces under realistic pressures. Differential pumping will be used to maintain the sample in a gas environment while the rest of the beam is under UHV. The Elemental content of the surface interacting with the gas environment will be determined from the Doppler broadened gamma spectra. This system will also include a time of flight (TOF) positron annihilation induced Auger spectrometer (TOF-PAES) for use in combined annihilation induced Auger and annihilation gamma measurements made under low pressure conditions.

Method for producing an atomic oxygen beam

NASA Technical Reports Server (NTRS)

Outlaw, Ronald A. (Inventor)

1989-01-01

A method for producing an atomic oxygen beam is provided by the present invention. First, a material 10' is provided which dissociates molecular oxygen and dissolves atomic oxygen into its bulk. Next, molecular oxygen is exposed to entrance surface 11' of material 10'. Next, material 10' is heated by heater 17' to facilitate the permeation of atomic oxygen through material 10' to the UHV side 12'. UHV side 12' is interfaced with an ultra-high vacuum (UHV) environment provided by UHV pump 15'. The atomic oxygen on the UHV side 12' is excited to a non-binding state by exciter 14' thus producing the release of atomic oxygen to form an atomic oxygen beam 35'.

Scanning tunneling microscopy study of low temperature silicon epitaxy on hydrogen/silicon(001) and phosphine adsorption on silicon(111)-7x7

NASA Astrophysics Data System (ADS)

Ji, Jeong-Young

A three-chamber ultra-high-vacuum (UHV) system with preparation, scanning tunneling microscopy (STM), and chemical vapor deposition (CVD) chambers was designed and built. Here, one can perform surface preparation, STM e-beam lithography, precursor gas dosing, ion sputtering, silicon epitaxy, and various measurements such as reflection high energy electron diffraction (RHEED), low energy electron diffraction (LEED), and Auger electron spectroscopy (AES). Processes performed in the ultra-clean preparation and gas-filled CVD chambers can be monitored by transferring the samples back to the STM chamber to take topographical images. Si deposition on H-terminated Si(001)-2x1 surfaces at temperatures 300--530 K was studied by scanning tunneling microscopy. Hydrogen apparently hinders Si adatom diffusion and enhances surface roughening. Post-growth annealing transfers the top layer atoms downward to fill in vacancies in the lower layer, restoring the crystallinity of the thin film. Hydrogen is shown to remain on the growth front up to at least 10 ML. Si deposition onto the H/Si(001)-3x1 surface at 530 K suggests that dihydride units further suppress Si adatom diffusion and increase surface roughness. PH3 adsorption on Si(111)-7x7 was studied for various exposures between 0.3--60 L at room temperature by means of the scanning-tunneling-microscopy (STM). PH3-, PH2-, H-reacted, and unreacted adatoms can be identified by analyzing STM images at different sample biases. Most of PH3 adsorbs dissociatively on the surface at initial exposure, generating H and PH2 adsorption sites, followed by molecular adsorption of PH3. Rest atoms are more reactive than the adatoms and PH 2-reacted rest atom sites are also observed in STM images. Statistical analysis shows that center adatoms are more reactive than corner adatoms and the saturation P coverage is ˜0.22 ML. Finally, 900 K annealing of a PH 3 dosed surface results in a disordered, partially P-covered surface and PH3 dosing at 900 K forms the same surface reconstruction as a P2-adsorbed surface at similar temperature.

Europlanet Research Infrastructure: Planetary Simulation Facilities

NASA Astrophysics Data System (ADS)

Davies, G. R.; Mason, N. J.; Green, S.; Gómez, F.; Prieto, O.; Helbert, J.; Colangeli, L.; Srama, R.; Grande, M.; Merrison, J.

2008-09-01

EuroPlanet The Europlanet Research Infrastructure consortium funded under FP7 aims to provide the EU Planetary Science community greater access for to research infrastructure. A series of networking and outreach initiatives will be complimented by joint research activities and the formation of three Trans National Access distributed service laboratories (TNA's) to provide a unique and comprehensive set of analogue field sites, laboratory simulation facilities, and extraterrestrial sample analysis tools. Here we report on the infrastructure that comprises the second TNA; Planetary Simulation Facilities. 11 laboratory based facilities are able to recreate the conditions found in the atmospheres and on the surfaces of planetary systems with specific emphasis on Martian, Titan and Europa analogues. The strategy has been to offer some overlap in capabilities to ensure access to the highest number of users and to allow for progressive and efficient development strategies. For example initial testing of mobility capability prior to the step wise development within planetary atmospheres that can be made progressively more hostile through the introduction of extreme temperatures, radiation, wind and dust. Europlanet Research Infrastructure Facilties: Mars atmosphere simulation chambers at VUA and OU These relatively large chambers (up to 1 x 0.5 x 0.5 m) simulate Martian atmospheric conditions and the dual cooling options at VUA allows stabilised instrument temperatures while the remainder of the sample chamber can be varied between 220K and 350K. Researchers can therefore assess analytical protocols for instruments operating on Mars; e.g. effect of pCO2, temperature and material (e.g., ± ice) on spectroscopic and laser ablation techniques while monitoring the performance of detection technologies such as CCD at low T & variable p H2O & pCO2. Titan atmosphere and surface simulation chamber at OU The chamber simulates Titan's atmospheric composition under a range of pressures and temperatures and through provision of external UV light and or electrical discharge can be used to form the well known Titan Aerosol species, which can subsequently be analysed using one of several analytical techniques (UV-Vis, FTIR and mass spectrometry). Simulated surfaces can be produced (icy surfaces down to 15K) and subjected to a variety of light and particles (electron and ion) sources. Chemical and physical changes in the surface may be explored using remote spectroscopy. Planetary Simulation chamber for low density atmospheres INTA-CAB The planetary simulation chamber-ultra-high vacuum equipment (PSC-UHV) has been designed to study planetary surfaces and low dense atmospheres, space environments or any other hypothetic environment at UHV. Total pressure ranges from 7 mbar (Martian conditions) to 5x10-9 mbar. A residual gas analyzer regulates gas compositions to ppm precision. Temperature ranges from 4K to 325K and most operations are computer controlled. Radiation levels are simulated using a deuterium UV lamp, and ionization sources. 5 KV electron and noble-gas discharge UV allows measurement of IR and UV spectra and chemical compositions are determined by mass spectroscopy. Planetary Simulation chamber for high density planetary atmospheres at INTA-CAB The facility allows experimental study of planetary environments under high pressure, and was designed to include underground, seafloor and dense atmosphere environments. Analytical capabilities include Raman spectra, physicochemical properties of materials, e.a. thermal conductivity. P-T can be controlled as independent variables to allow monitoring of the tolerance of microorganisms and the stability of materials and their phase changes. Planetary Simulation chamber for icy surfaces at INTA-CAB This chamber is being developed to the growth of ice samples to simulate the chemical and physical properties of ices found on both planetary bodies and their moons. The goal is to allow measurement of the physical properties of ice samples formed under planetary conditions to assess how rheology varies with pressure and temperature and grain size to gain a far better understanding of how tectonics may operate on icy moons. Hot planetary surfaces simulation chamber at DLR The planetary simulation chamber is to study the behaviour of planetary analogue materials on the surface of hot (airless) bodies in the solar system. Samples can be heated up to temperatures of 500°C simulating conditions found on the surface of Mercury and Venus. This enables highly accurate thermal emission measurements using the integrated infrared spectrometer and calibrated sources. Thermal gradients can be applied to samples to simulate diurnal thermal cycles and examine thermal stresses in materials. The chamber can be placed under vacuum or purged with gas. In addition, to the high temperature chamber a number of further planetary simulation chambers are available equipped with LIBS and Raman-spectroscopy equipment. Dust analogue simulation chamber at INAF/OACN This facility produces and characterises dust analogues (arc discharge, laser ablation, grinding of minerals, ices) in a variety of simulation chambers under variable pressure (10-6 - 10-3 mbar), temperature (80 - 330 K) and gas composition. Dust and analogues are characterised by a variety of Spectroscopic (absorption, transmission, diffuse-specular reflectance) and imaging techniques (SEM) and can be subjected to thermal annealing, ion bombardment and UV irradiation. Dust accelerator facility at Max Planck Institüt Nuclear Physics, Heidelberg. This facility allows the investigation of hypervelocity dust impacts onto various materials. Dust grain materials from nano to micron sizes are accelerated using a 2 MV Vande- Graaff to velocities between 1 and 60 km/s comparable to the planetary rings of the giant gas planets and impact ejecta processes on the surface of small bodies (asteroids, comets) as well as moons and planetary surfaces. Potential phenomena for study include dust charging, dust magentosphere interactions, dust impact flashes and the possibility of obtaining compositional measurements of impact plasma plumes. Mars surface simulation Laboratory, Aberystwyth University. A Planetary Analogue Terrain Laboratory facilitates comprehensive mission operations emulation experiments designed to interpret and maximise scientific data return from robotic instruments. This facility includes Mars Soil Simulant and `science target' rocks that have been fully characterised. The terrain also has an area for sub-surface sampling. An Access Grid Node allows simulation of remote control operation and diminishes the need for direct onsite attendance. PAT Lab has a large selection of software tools for rover, robot arm and instrument modelling and simulation, and for the processing and visualisation of captured instrument data. Instrument motion is measured using a Vicon motion capture system with a resolution < 0.1 mm. Dusty wind tunnel at Aarhus University, Denmark The Aarhus wind tunnel simulates wind driven dust exposure on Mars. This allows study into analogue materials, dust/surface processes, meteorological condition and microbiological survival under Martian conditions. The multipurpose facility is used to quantify dust deposition (i.e. on optical surfaces, electrical or mechanical components) and examine the operation of instrumentation in dusty/windy environment under Martian conditions (pressure, gas composition & temperature). This includes calibration of wind flow instrumentation and dust sensors.

Auger electron spectroscopy at high spatial resolution and nA primary beam currents

NASA Technical Reports Server (NTRS)

Todd, G.; Poppa, H.; Moorhead, D.; Bales, M.

1975-01-01

An experimental Auger microprobe system is described which incorporates a field-emission electron gun and total beam currents in the nanoampere range. The distinguishing characteristics of this system include a large multistation UHV specimen chamber, pulse counting and fully digital Auger signal-processing techniques, and digital referencing methods to eliminate the effects of beam instabilities. Some preliminary results obtained with this system are described, and it is concluded that field-emission electron sources can be used for high-resolution Auger electron spectroscopy with primary-beam spots of less than 100 nm and beam currents of the order of 1 nA.

Rapid prototyping of versatile atom chips for atom interferometry applications.

NASA Astrophysics Data System (ADS)

Kasch, Brian; Squires, Matthew; Olson, Spencer; Kroese, Bethany; Imhof, Eric; Kohn, Rudolph; Stuhl, Benjamin; Schramm, Stacy; Stickney, James

2016-05-01

We present recent advances in the manipulation of ultracold atoms with ex-vacuo atom chips (i.e. atom chips that are not inside to the UHV chamber). Details will be presented of an experimental system that allows direct bonded copper (DBC) atom chips to be removed and replaced in minutes, requiring minimal re-optimization of parameters. This system has been used to create Bose-Einstein condensates, as well as magnetic waveguides with precisely tunable axial parameters, allowing double wells, pure harmonic confinement, and modified harmonic traps. We investigate the effects of higher order magnetic field contributions to the waveguide, and the implications for confined atom interferometry.

Four-probe measurements with a three-probe scanning tunneling microscope.

PubMed

Salomons, Mark; Martins, Bruno V C; Zikovsky, Janik; Wolkow, Robert A

2014-04-01

We present an ultrahigh vacuum (UHV) three-probe scanning tunneling microscope in which each probe is capable of atomic resolution. A UHV JEOL scanning electron microscope aids in the placement of the probes on the sample. The machine also has a field ion microscope to clean, atomically image, and shape the probe tips. The machine uses bare conductive samples and tips with a homebuilt set of pliers for heating and loading. Automated feedback controlled tip-surface contacts allow for electrical stability and reproducibility while also greatly reducing tip and surface damage due to contact formation. The ability to register inter-tip position by imaging of a single surface feature by multiple tips is demonstrated. Four-probe material characterization is achieved by deploying two tips as fixed current probes and the third tip as a movable voltage probe.

Electron stimulated desorption of atomic oxygen from silver

NASA Technical Reports Server (NTRS)

Outlaw, R. A.; Peregoy, W. K.; Hoflund, Gar B.; Corallo, Gregory R.

1987-01-01

The electron stimulated desorption (ESD) of neutral oxygen atoms from polycrystalline silver and of oxygen ions from Ag(110) has been studied. Polycrystalline Ag charged with (16)O2 and (18)O2 and bombarded by low-energy electrons (approx 100 eV) under ultrahigh vacuum (UHV) conditions emitted O atom flux levels of 1 x 10 to the 12th power/sq cm/s at a Ag temperature of 300 C. The flux was detected with a quadrupole mass spectrometer operating in the appearance potential mode. The neutral cross section at about 100 C was determined to be 7 x 10 to the -19 sq cm. Ancillary experiments conducted in a UHV chamber equipped with a cylindrical mirror analyzer and rigged for ion energy distribution and ion angular distribution were used to study O ions desorbed from Ag(110). Two primary O(+) energies of 2.4 and 5.4 eV were detected from the Ag(110) after having been dosed with 2500 L of (16)O2. It also appears that in both experiments there was strong evidence for directionality of the emitted flux. The results of this study serve as a proof of concept for the development of a laboratory atomic oxygen beam generator that simulates the gas flux environment experienced by orbiting vehicles.

Multilayer Thin Film Polarizer Design for Far Ultraviolet using Induced Transmission and Absorption Technique

NASA Technical Reports Server (NTRS)

Kim, Jongmin; Zukic, Muamer; Wilson, Michele M.; Park, Jung Ho; Torr, Douglas G.

1994-01-01

Good theoretical designs of far ultraviolet polarizers have been reported using a MgF2/Al/MgF2 three layer structure on a thick Al layer as a substrate. The thicknesses were determined to induce transmission and absorption of p-polarized light. In these designs Al optical constants were used from films produced in ultrahigh vacuum (UHV: 10(exp -10) torr). Reflectance values for polarizers fabricated in a conventional high vacuum (p approx. 10(exp -6 torr)) using the UHV design parameters differed dramatically from the design predictions. Al is a highly reactive material and is oxidized even in a high vacuum chamber. In order to solve the problem other metals have been studied. It is found that a larger reflectance difference is closely related to higher amplitude and larger phase difference of Fresnel reflection coefficients between two polarizations at the boundary of MgF2/metal. It is also found that for one material a larger angle of incidence from the surface normal brings larger amplitude and phase difference. Be and Mo are found good materials to replace Al. Polarizers designed for 121.6 nm with Be at 60 deg and with Mo at 70 deg are shown as examples.

Operando Positron Annihilation Gamma Spectrometer (OPAGS)

NASA Astrophysics Data System (ADS)

Satyal, S.; Shastry, K.; Mukherjee, S.; Weiss, A. H.

2009-03-01

Surface properties measured under UHV conditions cannot be extended to surfaces interacting with gases under realistic pressures due to surface reconstruction and other strong perturbations of the surface. Surface probing techniques require UHV conditions to perform efficiently and avoid data loss due to scattering of outgoing particles. This poster describes the design of an Operando Positron Annihilation Gamma Spectrometer (OPAGS) currently under construction at the University of Texas at Arlington. The new system will be capable of obtaining surface and defect specific chemical and charge state information from surfaces under realistic pressures. Differential pumping will be used to maintain the sample in a gas environment while the rest of the beam is under UHV. Elemental content of the surface interacting with the gas environment will be determined from the Doppler broadened gamma spectra. This system will also include a time of flight (TOF) Auger spectrometer which correlates with the results of the Doppler measurements at lower pressures. By employing the unique capabilities of OPAGS together with those of the TOF PAES spectroscopy the charge transfer mechanisms at the surface in catalytic systems can be understood.

A facility to study the particles released by ion sputtering process

NASA Astrophysics Data System (ADS)

de Angelis, E.; di Lellis, A. M.; Vannaroni, G.; Orsini, S.; Mangano, V.; Milillo, A.; Massetti, S.; Mura, A.; Vertolli, N.

2007-08-01

Research on the planetary surface erosion and planetary evolution could be enriched with the detection of the escaping material, in terms of energy and direction, caused by ions sputtering. A complete study of emitted neutral distribution from which infers the processes occurring on the impacted surface requires dedicated instrumentation, tailored on the peculiarity on the low energy profile of the sputtered signal. We propose a comprehensive facility at INAF/IFSI in Rome intended to provide the opportunity to investigate the interaction of selectable ion beam with planetary analogues through the detection of sputtered neutral atoms. The laboratory is equipped with a high volume UHV chamber, ion selectable sources in the range 0 to 10 keV, a set of 3D sample/sensor orientation motion actuation motors down to 1/100 deg resolution. The laboratory will support a set of neutral sensor heads sets derived from the Emitted for Low Energetic Neutral Atoms (ELENA) instrument under development for the ESA BepiColombo Mercury mission able to detect neutral atoms (few eV-up to 5 keV).

Four-probe measurements with a three-probe scanning tunneling microscope

DOE Office of Scientific and Technical Information (OSTI.GOV)

Salomons, Mark; Martins, Bruno V. C.; Zikovsky, Janik

2014-04-15

We present an ultrahigh vacuum (UHV) three-probe scanning tunneling microscope in which each probe is capable of atomic resolution. A UHV JEOL scanning electron microscope aids in the placement of the probes on the sample. The machine also has a field ion microscope to clean, atomically image, and shape the probe tips. The machine uses bare conductive samples and tips with a homebuilt set of pliers for heating and loading. Automated feedback controlled tip-surface contacts allow for electrical stability and reproducibility while also greatly reducing tip and surface damage due to contact formation. The ability to register inter-tip position bymore » imaging of a single surface feature by multiple tips is demonstrated. Four-probe material characterization is achieved by deploying two tips as fixed current probes and the third tip as a movable voltage probe.« less

Electron spectroscopy analysis

NASA Technical Reports Server (NTRS)

Gregory, John C.

1992-01-01

The Surface Science Laboratories at the University of Alabama in Huntsville (UAH) are equipped with x-ray photoelectron spectroscopy (XPS or ESCA) and Auger electron spectroscopy (AES) facilities. These techniques provide information from the uppermost atomic layers of a sample, and are thus truly surface sensitive. XPS provides both elemental and chemical state information without restriction on the type of material that can be analyzed. The sample is placed into an ultra high vacuum (UHV) chamber and irradiated with x-rays which cause the ejection of photoelectrons from the sample surface. Since x-rays do not normally cause charging problems or beam damage, XPS is applicable to a wide range of samples including metals, polymers, catalysts, and fibers. AES uses a beam of high energy electrons as a surface probe. Following electronic rearrangements within excited atoms by this probe, Auger electrons characteristic of each element present are emitted from the sample. The main advantage of electron induced AES is that the electron beam can be focused down to a small diameter and localized analysis can be carried out. On the rastering of this beam synchronously with a video display using established scanning electron microscopy techniques, physical images and chemical distribution maps of the surface can be produced. Thus very small features, such as electronic circuit elements or corrosion pits in metals, can be investigated. Facilities are available on both XPS and AES instruments for depth-profiling of materials, using a beam of argon ions to sputter away consecutive layers of material to reveal sub-surface (and even semi-bulk) analyses.

Optimization and testing of solid thin film lubrication deposition processes

NASA Astrophysics Data System (ADS)

Danyluk, Michael J.

A novel method for testing solid thin films in rolling contact fatigue (RCF) under ultra-high vacuum (UHV) and high rotational speeds (130 Hz) is presented in this thesis. The UHV-RCF platform is used to quantify the adhesion and lubrication aspects of two thin film coatings deposited on ball-bearings using a physical vapor deposition ion plating process. Plasma properties during ion plating were measured using a Langmuir probe and there is a connection between ion flux, film stress, film adhesion, process voltage, pressure, and RCF life. The UHV-RCF platform and vacuum chamber were constructed using off-the-shelf components and 88 RCF tests in high vacuum have been completed. Maximum RCF life was achieved by maintaining an ion flux between 10 13 to 1015 (cm-2 s-1) with a process voltage and pressure near 1.5 kV and 15 mTorr. Two controller schemes were investigated to maintain optimal plasma conditions for maximum RCF life: PID and LQR. Pressure disturbances to the plasma have a detrimental effect on RCF life. Control algorithms that mitigate pressure and voltage disturbances already exist. However, feedback from the plasma to detect disturbances has not been explored related to deposition processes in the thin-film science literature. Manometer based pressure monitoring systems have a 1 to 2 second delay time and are too slow to detect common pressure bursts during the deposition process. Plasma diagnostic feedback is much faster, of the order of 0.1 second. Plasma total-current feedback was used successfully to detect a typical pressure disturbance associated with the ion plating process. Plasma current is related to ion density and process pressure. A real-time control application was used to detect the pressure disturbance by monitoring plasma-total current and converting it to feedback-input to a pressure control system. Pressure overshoot was eliminated using a nominal PID controller with feedback from a plasma-current diagnostic measurement tool.

Surface Structure of TiO2 Rutile (011) Exposed to Liquid Water

PubMed Central

2017-01-01

The rutile TiO2(011) surface exhibits a (2 × 1) reconstruction when prepared by standard techniques in ultrahigh vacuum (UHV). Here we report that a restructuring occurs upon exposing the surface to liquid water at room temperature. The experiment was performed in a dedicated UHV system, equipped for direct and clean transfer of samples between UHV and liquid environment. After exposure to liquid water, an overlayer with a (2 × 1) symmetry was observed containing two dissociated water molecules per unit cell. The two OH groups yield an apparent “c(2 × 1)” symmetry in scanning tunneling microscopy (STM) images. On the basis of STM analysis and density functional theory (DFT) calculations, this overlayer is attributed to dissociated water on top of the unreconstructed (1 × 1) surface. Investigation of possible adsorption structures and analysis of the domain boundaries in this structure provide strong evidence that the original (2 × 1) reconstruction is lifted. Unlike the (2 × 1) reconstruction, the (1 × 1) surface has an appropriate density and symmetry of adsorption sites. The possibility of contaminant-induced restructuring was excluded based on X-ray photoelectron spectroscopy (XPS) and low-energy He+ ion scattering (LEIS) measurements. PMID:29285204

The design and implementation of on-line monitoring system for UHV compact shunt capacitors

NASA Astrophysics Data System (ADS)

Tao, Weiliang; Ni, Xuefeng; Lin, Hao; Jiang, Shengbao

2017-08-01

Because of the large capacity and compact structure of the UHV compact shunt capacitor, it is difficult to take effective measures to detect and prevent the faults. If the fault capacitor fails to take timely maintenance, it will pose a threat to the safe operation of the system and the life safety of the maintenance personnel. The development of UHV compact shunt capacitor on-line monitoring system can detect and record the on-line operation information of UHV compact shunt capacitors, analyze and evaluate the early fault warning signs, find out the fault capacitor or the capacitor with fault symptom, to ensure safe and reliable operation of the system.

Highly precise and compact ultrahigh vacuum rotary feedthrough.

PubMed

Aiura, Y; Kitano, K

2012-03-01

The precision and rigidity of compact ultrahigh vacuum (UHV) rotary feedthroughs were substantially improved by preparing and installing an optimal crossed roller bearing with mounting holes. Since there are mounting holes on both the outer and inner races, the bearing can be mounted directly to rotary and stationary stages without any fixing plates and housing. As a result, it is possible to increase the thickness of the bearing or the size of the rolling elements in the bearing without increasing the distance between the rotating and fixing International Conflat flanges of the UHV rotary feedthrough. Larger rolling elements enhance the rigidity of the UHV rotary feedthrough. Moreover, owing to the structure having integrated inner and outer races and mounting holes, the performance is almost entirely unaffected by the installation of the bearing, allowing for a precise optical encoder to be installed in the compact UHV rotary feedthrough. Using position feedback via a worm gear system driven by a stepper motor and a precise rotary encoder, the actual angle of the compact UHV rotary feedthrough can be controlled with extremely high precision.

Highly precise and compact ultrahigh vacuum rotary feedthrough

NASA Astrophysics Data System (ADS)

Aiura, Y.; Kitano, K.

2012-03-01

The precision and rigidity of compact ultrahigh vacuum (UHV) rotary feedthroughs were substantially improved by preparing and installing an optimal crossed roller bearing with mounting holes. Since there are mounting holes on both the outer and inner races, the bearing can be mounted directly to rotary and stationary stages without any fixing plates and housing. As a result, it is possible to increase the thickness of the bearing or the size of the rolling elements in the bearing without increasing the distance between the rotating and fixing International Conflat flanges of the UHV rotary feedthrough. Larger rolling elements enhance the rigidity of the UHV rotary feedthrough. Moreover, owing to the structure having integrated inner and outer races and mounting holes, the performance is almost entirely unaffected by the installation of the bearing, allowing for a precise optical encoder to be installed in the compact UHV rotary feedthrough. Using position feedback via a worm gear system driven by a stepper motor and a precise rotary encoder, the actual angle of the compact UHV rotary feedthrough can be controlled with extremely high precision.

Large area scanning probe microscope in ultra-high vacuum demonstrated for electrostatic force measurements on high-voltage devices.

PubMed

Gysin, Urs; Glatzel, Thilo; Schmölzer, Thomas; Schöner, Adolf; Reshanov, Sergey; Bartolf, Holger; Meyer, Ernst

2015-01-01

The resolution in electrostatic force microscopy (EFM), a descendant of atomic force microscopy (AFM), has reached nanometre dimensions, necessary to investigate integrated circuits in modern electronic devices. However, the characterization of conducting or semiconducting power devices with EFM methods requires an accurate and reliable technique from the nanometre up to the micrometre scale. For high force sensitivity it is indispensable to operate the microscope under high to ultra-high vacuum (UHV) conditions to suppress viscous damping of the sensor. Furthermore, UHV environment allows for the analysis of clean surfaces under controlled environmental conditions. Because of these requirements we built a large area scanning probe microscope operating under UHV conditions at room temperature allowing to perform various electrical measurements, such as Kelvin probe force microscopy, scanning capacitance force microscopy, scanning spreading resistance microscopy, and also electrostatic force microscopy at higher harmonics. The instrument incorporates beside a standard beam deflection detection system a closed loop scanner with a scan range of 100 μm in lateral and 25 μm in vertical direction as well as an additional fibre optics. This enables the illumination of the tip-sample interface for optically excited measurements such as local surface photo voltage detection. We present Kelvin probe force microscopy (KPFM) measurements before and after sputtering of a copper alloy with chromium grains used as electrical contact surface in ultra-high power switches. In addition, we discuss KPFM measurements on cross sections of cleaved silicon carbide structures: a calibration layer sample and a power rectifier. To demonstrate the benefit of surface photo voltage measurements, we analysed the contact potential difference of a silicon carbide p/n-junction under illumination.

Design of an Operando Positron Annihilation Gamma Spectrometer (OPAGS)

NASA Astrophysics Data System (ADS)

Satyal, S.; Joglekar, P.; Kalaskar, S.; Shastry, K.; Weiss, A. H.

2010-03-01

Surface properties measured under UHV conditions cannot be extended to surfaces interacting with gases under realistic pressures due to surface reconstruction and other strong perturbations of the surface. We present the design of an Operando Positron Annihilation Gamma Spectrometer (OPAGS) currently under construction at the University of Texas at Arlington. This new system will enable us to probe the surface and gather defect specific chemical and charge state information from surfaces under realistic pressures. Differential pumping will be used to maintain the sample in a gas environment while the rest of the beam is maintained under UHV. The Elemental content of the surface interacting with the gas environment will be determined from the Doppler broadened gamma spectra. This system will include a time of flight (TOF) positron annihilation induced Auger spectrometer (TOF-PAES) which correlates with the Doppler measurements at lower pressures. These new technique help to understand the charge transfer mechanisms at the surface.

X-Ray Scattering Studies of the Liquid-Vapor Interface of Gallium.

NASA Astrophysics Data System (ADS)

Kawamoto, Eric Hitoshi

A UHV system was developed for performing X-ray scattering studies and in situ analyses of liquid metal surfaces. A nearly ideal choice for this study, gallium has a melting point just above room temperature; is amenable to handling in both air and vacuum; its surface oxides can be removed while its cleanliness is maintained and monitored. Using argon glow-discharge sputtering techniques to remove intervening surface oxides, thin wetting layers of gallium were prepared atop nonreactive substrates, to be used as samples suited for liquid surface scattering experiments. Preliminary measurements of X-ray reflectivity from the liquid-vapor interface of gallium were performed with the X-ray UHV chamber configured for use in conjunction with liquid surface spectrometers at two synchrotron beamlines. A novel technique for carrying out and interpreting scattering measurements from curved liquid surfaces was demonstrated. The energy tunability and intense focused white beam flux from a wiggler source was shown to place within reach the large values of wavevector transfer at which specular reflectivity data yield small length scale information about surface structure. Various theoretical treatments and simulations predict quasi-lamellar ordering of atoms near the free surface of metallic liquids due to energetics particular to metals (electron delocalization, the dependence of system energy on ion and electron densities, surface tension and electrostatic energy). However, the experimental data reported to date is insufficient to distinguish between a monotonic, sigmoidal electron density profile found at the free surfaces of dielectric liquids, and the damped oscillatory layer-like profiles anticipated for metallic liquids. Out to a wavevector transfer of Q = 0.55 A ^{-1}, the reflectivity data measured from a curved Ga surface is not inconsistent with what is expected for a liquid-vapor electron density profile of Gaussian width sigma = 1.3 +/- 0.2 A. Subsequent measurements roughly tripled the range of Q, but an oxidized surface led to poor data and hindered interpretation. The analysis presented is speculative at best, but within the context of the thermally excited capillary wave model of simple liquid surfaces, there seems to be no serious deviation from the simple Gaussian interfacial profile with the aforementioned roughness.

Reference binding energies of transition metal carbides by core-level x-ray photoelectron spectroscopy free from Ar+ etching artefacts

NASA Astrophysics Data System (ADS)

Greczynski, G.; Primetzhofer, D.; Hultman, L.

2018-04-01

We report x-ray photoelectron spectroscopy (XPS) core level binding energies (BE's) for the widely-applicable groups IVb-VIb transition metal carbides (TMCs) TiC, VC, CrC, ZrC, NbC, MoC, HfC, TaC, and WC. Thin film samples are grown in the same deposition system, by dc magnetron co-sputtering from graphite and respective elemental metal targets in Ar atmosphere. To remove surface contaminations resulting from exposure to air during sample transfer from the growth chamber into the XPS system, layers are either (i) Ar+ ion-etched or (ii) UHV-annealed in situ prior to XPS analyses. High resolution XPS spectra reveal that even gentle etching affects the shape of core level signals, as well as BE values, which are systematically offset by 0.2-0.5 eV towards lower BE. These destructive effects of Ar+ ion etch become more pronounced with increasing the metal atom mass due to an increasing carbon-to-metal sputter yield ratio. Systematic analysis reveals that for each row in the periodic table (3d, 4d, and 5d) C 1s BE increases from left to right indicative of a decreased charge transfer from TM to C atoms, hence bond weakening. Moreover, C 1s BE decreases linearly with increasing carbide/metal melting point ratio. Spectra reported here, acquired from a consistent set of samples in the same instrument, should serve as a reference for true deconvolution of complex XPS cases, including multinary carbides, nitrides, and carbonitrides.

Operational adaptability evaluation index system of pumped storage in UHV receiving-end grids

NASA Astrophysics Data System (ADS)

Yuan, Bo; Zong, Jin; Feng, Junshu

2017-01-01

Pumped storage is an effective solution to deal with the emergency reserve shortage, renewable energy accommodating and peak-shaving problems in ultra-high voltage (UHV) transmission receiving-end grids. However, governments and public opinion in China tend to evaluate the operational effectiveness of pumped storage using annual utilization hour, which may result in unreasonable and unnecessary dispatch of pumped storage. This paper built an operational adaptability evaluation index system for pumped storage in UHV-receiving end grids from three aspects: security insurance, peak-shaving and renewable energy accommodating, which can provide a comprehensive and objective way to evaluate the operational performance of a pumped storage station.

Evaluation and optimization of quartz resonant-frequency retuned fork force sensors with high Q factors, and the associated electric circuits, for non-contact atomic force microscopy.

PubMed

Ooe, Hiroaki; Fujii, Mikihiro; Tomitori, Masahiko; Arai, Toyoko

2016-02-01

High-Q factor retuned fork (RTF) force sensors made from quartz tuning forks, and the electric circuits for the sensors, were evaluated and optimized to improve the performance of non-contact atomic force microscopy (nc-AFM) performed under ultrahigh vacuum (UHV) conditions. To exploit the high Q factor of the RTF sensor, the oscillation of the RTF sensor was excited at its resonant frequency, using a stray capacitance compensation circuit to cancel the excitation signal leaked through the stray capacitor of the sensor. To improve the signal-to-noise (S/N) ratio in the detected signal, a small capacitor was inserted before the input of an operational (OP) amplifier placed in an UHV chamber, which reduced the output noise from the amplifier. A low-noise, wideband OP amplifier produced a superior S/N ratio, compared with a precision OP amplifier. The thermal vibrational density spectra of the RTF sensors were evaluated using the circuit. The RTF sensor with an effective spring constant value as low as 1000 N/m provided a lower minimum detection limit for force differentiation. A nc-AFM image of a Si(111)-7 × 7 surface was produced with atomic resolution using the RTF sensor in a constant frequency shift mode; tunneling current and energy dissipation images with atomic resolution were also simultaneously produced. The high-Q factor RTF sensor showed potential for the high sensitivity of energy dissipation as small as 1 meV/cycle and the high-resolution analysis of non-conservative force interactions.

Pt-black catalysts sintered at different temperatures: Surface analysis and activity in reactions of n-hexane

DOE Office of Scientific and Technical Information (OSTI.GOV)

Paal, Z.; Xu, X.L.; Paal-Lukacs, J.

Pt-black catalysts sintered at 473 and 633 K ({open_quotes}Pt-473{close_quotes} and {open_quotes}Pt-633{close_quotes}), respectively, have been characterized by X-ray diffraction and analyzed by XPS, UPS, and AES after carrying out n-hexane reactions. The analysis has been repeated after O{sub 2}-H{sub 2} regeneration in the preparation chamber of the UHV apparatus. The surface of the blacks contains some carbon and oxygen impurities even after regeneration. Both Pt-473 and Pt-633 show high Pt 4f line intensity. Decomposition of the C 1s line reveals a higher amount of oxidized carbon polymers on Pt-633. This sample is free from lattice strain. The likely higher abundance ofmore » exposed hexagonal symmetry faces, namely the (111) plane and analogous stepped and kinked structures, may be one of the reasons why fragmentation and aromatization are favored on Pt-633, as opposed to the higher selectivity of isomerization and C{sub 5}-cyclization on Pt-473. The higher amount of oxidized carbonaceous polymer overlayer (serving as {open_quotes}hydrogen catcher{close_quotes}) on Pt-633 as well as the less-retained hydrogen by its crystallites without lattice strain may also contribute to the different selectivity and hydrogen pressure response of the n-hexane reaction over the two samples. Product ratios are suggested as an additional diagnostic tool for characterizing the hydrogen availability on the catalysts. 59 refs., 9 figs., 5 tabs.« less

Versatile, low-cost, computer-controlled, sample positioning system for vacuum applications

NASA Technical Reports Server (NTRS)

Vargas-Aburto, Carlos; Liff, Dale R.

1991-01-01

A versatile, low-cost, easy to implement, microprocessor-based motorized positioning system (MPS) suitable for accurate sample manipulation in a Second Ion Mass Spectrometry (SIMS) system, and for other ultra-high vacuum (UHV) applications was designed and built at NASA LeRC. The system can be operated manually or under computer control. In the latter case, local, as well as remote operation is possible via the IEEE-488 bus. The position of the sample can be controlled in three linear orthogonal and one angular coordinates.

Experimental system for drilling simulated lunar rock in ultrahigh vacuum

NASA Technical Reports Server (NTRS)

Roepke, W. W.

1975-01-01

An experimental apparatus designed for studying drillability of hard volcanic rock in a simulated lunar vacuum of 5 x 10 to the minus 10th power torr is described. The engineering techniques used to provide suitable drilling torque inside the ultrahigh vacuum chamber while excluding all hydrocarbon are detailed. Totally unlubricated bearings and gears were used to better approximate the true lunar surface conditions within the ultrahigh vacuum system. The drilling system has a starting torque of 30 in-lb with an unloaded running torque of 4 in-lb. Nominal torque increase during drilling is 4.5 in-lb or a total drilling torque of 8.5 in-lb with a 100-lb load on the drill bit at 210 rpm. The research shows conclusively that it is possible to design operational equipment for moderate loads operating under UHV conditions without the use of sealed bearings or any need of lubricants whatsoever.

Activation and evaluation of GaN photocathodes

NASA Astrophysics Data System (ADS)

Qian, Yunsheng; Chang, Benkang; Qiao, Jiangliang; Zhang, Yijun; Fu, Rongguo; Qiu, Yafeng

2009-09-01

Gallium Nitride (GaN) photocathodes are potentially attractive as UV detective materials and electron sources. Based on the activation and evaluation system for GaAs photocathode, which consists of ultra-high vacuum (UHV) activation chamber, multi-information measurement system, X-ray photoelectron spectroscopy (XPS), and ultraviolet ray photoelectron spectroscopy (UPS), the control and measurement system for the activation of UV photocathodes was developed. The developed system, which consists of Xenon lamp, monochromator with scanner, signal-processing module, power control unit of Cs and O source, A/D adapter, digital I/O card, computer and software, can control the activation of GaN photocathodes and measure on-line the spectral response curves of GaN photocathodes. GaN materials on sapphire substrate were grown by Metal-Organic Chemical Vapor Deposition (MOCVD) with p-type Mg doping. The GaN materials were activated by Cs-O. The spectral response and quantum efficiency (QE) were measured and calculated. The experiment results are discussed.

A UHV compatible source for a highly polarized thermal atomic beam of radioactive 8Li

NASA Astrophysics Data System (ADS)

Jänsch, H. J.; Kirchner, G.; Kühlert, O.; Lisowski, M.; Paggel, J. J.; Platzer, R.; Schillinger, R.; Tilsner, H.; Weindel, C.; Winnefeld, H.; Fick, D.

2000-12-01

A beam of the radioactive isotope 8Li is prepared at thermal velocities. The nuclei are highly spin polarized by transverse optical pumping of the thermal beam. The installation is ultra-high vacuum (UHV) compatible in a non-UHV accelerator environment. Since the atomic beam is used in a surface science experiment, where contamination must be avoided, special emphasis is given to the vacuum coupling of the accelerator/ 8Li production/surface experimental areas. The atomic beam is produced by stopping the nuclear reaction products and evaporating them again from high-temperature graphite. To enhance the atomic beam, a novel tubular thermalizer is applied. The thermal polarized atomic beam intensity is approximately 5×10 8 atoms/s sr.

Isolation, identification, and characterization of novel arenaviruses, the etiological agents of boid inclusion body disease.

PubMed

Hetzel, Udo; Sironen, Tarja; Laurinmäki, Pasi; Liljeroos, Lassi; Patjas, Aino; Henttonen, Heikki; Vaheri, Antti; Artelt, Annette; Kipar, Anja; Butcher, Sarah J; Vapalahti, Olli; Hepojoki, Jussi

2013-10-01

Boid inclusion body disease (BIBD) is a progressive, usually fatal disease of constrictor snakes, characterized by cytoplasmic inclusion bodies (IB) in a wide range of cell types. To identify the causative agent of the disease, we established cell cultures from BIBD-positive and -negative boa constrictors. The IB phenotype was maintained in cultured cells of affected animals, and supernatants from these cultures caused the phenotype in cultures originating from BIBD-negative snakes. Viruses were purified from the supernatants by ultracentrifugation and subsequently identified as arenaviruses. Purified virus also induced the IB phenotype in naive cells, which fulfilled Koch's postulates in vitro. One isolate, tentatively designated University of Helsinki virus (UHV), was studied in depth. Sequencing confirmed that UHV is a novel arenavirus species that is distinct from other known arenaviruses including those recently identified in snakes with BIBD. The morphology of UHV was established by cryoelectron tomography and subtomographic averaging, revealing the trimeric arenavirus spike structure at 3.2-nm resolution. Immunofluorescence, immunohistochemistry, and immunoblotting with a polyclonal rabbit antiserum against UHV and reverse transcription-PCR (RT-PCR) revealed the presence of genetically diverse arenaviruses in a large cohort of snakes with BIBD, confirming the causative role of arenaviruses. Some snakes were also found to carry arenavirus antibodies. Furthermore, mammalian cells (Vero E6) were productively infected with UHV, demonstrating the potential of arenaviruses to cross species barriers. In conclusion, we propose the newly identified lineage of arenaviruses associated with BIBD as a novel taxonomic entity, boid inclusion body disease-associated arenaviruses (BIBDAV), in the family Arenaviridae.

Isolation, Identification, and Characterization of Novel Arenaviruses, the Etiological Agents of Boid Inclusion Body Disease

PubMed Central

Hetzel, Udo; Sironen, Tarja; Laurinmäki, Pasi; Liljeroos, Lassi; Patjas, Aino; Henttonen, Heikki; Vaheri, Antti; Artelt, Annette; Kipar, Anja; Butcher, Sarah J.; Vapalahti, Olli

2013-01-01

Boid inclusion body disease (BIBD) is a progressive, usually fatal disease of constrictor snakes, characterized by cytoplasmic inclusion bodies (IB) in a wide range of cell types. To identify the causative agent of the disease, we established cell cultures from BIBD-positive and -negative boa constrictors. The IB phenotype was maintained in cultured cells of affected animals, and supernatants from these cultures caused the phenotype in cultures originating from BIBD-negative snakes. Viruses were purified from the supernatants by ultracentrifugation and subsequently identified as arenaviruses. Purified virus also induced the IB phenotype in naive cells, which fulfilled Koch's postulates in vitro. One isolate, tentatively designated University of Helsinki virus (UHV), was studied in depth. Sequencing confirmed that UHV is a novel arenavirus species that is distinct from other known arenaviruses including those recently identified in snakes with BIBD. The morphology of UHV was established by cryoelectron tomography and subtomographic averaging, revealing the trimeric arenavirus spike structure at 3.2-nm resolution. Immunofluorescence, immunohistochemistry, and immunoblotting with a polyclonal rabbit antiserum against UHV and reverse transcription-PCR (RT-PCR) revealed the presence of genetically diverse arenaviruses in a large cohort of snakes with BIBD, confirming the causative role of arenaviruses. Some snakes were also found to carry arenavirus antibodies. Furthermore, mammalian cells (Vero E6) were productively infected with UHV, demonstrating the potential of arenaviruses to cross species barriers. In conclusion, we propose the newly identified lineage of arenaviruses associated with BIBD as a novel taxonomic entity, boid inclusion body disease-associated arenaviruses (BIBDAV), in the family Arenaviridae. PMID:23926354

Scanning Tunneling Microscopy Studies of Diamond Films and Optoelectronic Materials

NASA Technical Reports Server (NTRS)

Perez, Jose M.

1996-01-01

We present a summary of the research, citations of publications resulting from the research and abstracts of such publications. We have made no inventions in the performance of the work in this project. The main goals of the project were to set up a Chemical Vapor Deposition (CVD) diamond growth system attached to an UltraHigh Vacuum (UHV) atomic resolution Scanning Tunneling Microscopy (STM) system and carry out experiments aimed at studying the properties and growth of diamond films using atomic resolution UHV STM. We successfully achieved these goals. We observed, for the first time, the atomic structure of the surface of CVD grown epitaxial diamond (100) films using UHV STM. We studied the effects of atomic hydrogen on the CVD diamond growth process. We studied the electronic properties of the diamond (100) (2x1) surface, and the effect of alkali metal adsorbates such as Cs on the work function of this surface using UHV STM spectroscopy techniques. We also studied, using STM, new electronic materials such as carbon nanotubes and gold nanostructures. This work resulted in four publications in refereed scientific journals and five publications in refereed conference proceedings.

Oxygen accumulation on metal surfaces investigated by XPS, AES and LEIS, an issue for sputter depth profiling under UHV conditions

NASA Astrophysics Data System (ADS)

Steinberger, R.; Celedón, C. E.; Bruckner, B.; Roth, D.; Duchoslav, J.; Arndt, M.; Kürnsteiner, P.; Steck, T.; Faderl, J.; Riener, C. K.; Angeli, G.; Bauer, P.; Stifter, D.

2017-07-01

Depth profiling using surface sensitive analysis methods in combination with sputter ion etching is a common procedure for thorough material investigations, where clean surfaces free of any contamination are essential. Hence, surface analytic studies are mostly performed under ultra-high vacuum (UHV) conditions, but the cleanness of such UHV environments is usually overrated. Consequently, the current study highlights the in principle known impact of the residual gas on metal surfaces (Fe, Mg, Al, Cr and Zn) for various surface analytics methods, like X-ray photoelectron spectroscopy (XPS), Auger electron spectroscopy (AES) and low-energy ion scattering (LEIS). The investigations with modern, state-of-the-art equipment showed different behaviors for the metal surfaces in UHV during acquisition: (i) no impact for Zn, even after long time, (ii) solely adsorption of oxygen for Fe, slight and slow changes for Cr and (iii) adsorption accompanied by oxide formation for Al and Mg. The efficiency of different counter measures was tested and the acquired knowledge was finally used for ZnMgAl coated steel to obtain accurate depth profiles, which exhibited before serious artifacts when data acquisition was performed in an inconsiderate way.

Transmission Technologies and Operational Characteristic Analysis of Hybrid UHV AC/DC Power Grids in China

NASA Astrophysics Data System (ADS)

Tian, Zhang; Yanfeng, Gong

2017-05-01

In order to solve the contradiction between demand and distribution range of primary energy resource, Ultra High Voltage (UHV) power grids should be developed rapidly to meet development of energy bases and accessing of large-scale renewable energy. This paper reviewed the latest research processes of AC/DC transmission technologies, summarized the characteristics of AC/DC power grids, concluded that China’s power grids certainly enter a new period of large -scale hybrid UHV AC/DC power grids and characteristics of “strong DC and weak AC” becomes increasingly pro minent; possible problems in operation of AC/DC power grids was discussed, and interaction or effect between AC/DC power grids was made an intensive study of; according to above problems in operation of power grids, preliminary scheme is summarized as fo llows: strengthening backbone structures, enhancing AC/DC transmission technologies, promoting protection measures of clean energ y accessing grids, and taking actions to solve stability problems of voltage and frequency etc. It’s valuable for making hybrid UHV AC/DC power grids adapt to operating mode of large power grids, thus guaranteeing security and stability of power system.

Full membrane spanning self-assembled monolayers as model systems for UHV-based studies of cell-penetrating peptides

DOE Office of Scientific and Technical Information (OSTI.GOV)

Franz, Johannes; Graham, Daniel J.; Schmüser, Lars

2015-03-01

Biophysical studies of the interaction of peptides with model membranes provide a simple yet effective approach to understand the transport of peptides and peptide based drug carriers across the cell membrane. Therein, the authors discuss the use of self-assembled monolayers fabricated from the full membrane-spanning thiol (FMST) 3-((14-((4'-((5-methyl-1-phenyl-35-(phytanyl)oxy-6,9,12,15,18,21,24,27,30,33,37-undecaoxa-2,3-dithiahenpentacontan-51-yl)oxy)-[1,1'-biphenyl]-4-yl)oxy)tetradecyl)oxy)-2-(phytanyl)oxy glycerol for ultrahigh vacuum (UHV) based experiments. UHV-based methods such as electron spectroscopy and mass spectrometry can provide important information about how peptides bind and interact with membranes, especially with the hydrophobic core of a lipid bilayer. Moreover, near-edge x-ray absorption fine structure spectra and x-ray photoelectron spectroscopy (XPS) data showed thatmore » FMST forms UHV-stable and ordered films on gold. XPS and time of flight secondary ion mass spectrometry depth profiles indicated that a proline-rich amphipathic cell-penetrating peptide, known as sweet arrow peptide is located at the outer perimeter of the model membrane.« less

Design and optimization of a modular setup for measurements of three-dimensional spin polarization with ultrafast pulsed sources.

PubMed

Pincelli, T; Petrov, V N; Brajnik, G; Ciprian, R; Lollobrigida, V; Torelli, P; Krizmancic, D; Salvador, F; De Luisa, A; Sergo, R; Gubertini, A; Cautero, G; Carrato, S; Rossi, G; Panaccione, G

2016-03-01

ULTRASPIN is an apparatus devoted to the measurement of the spin polarization (SP) of electrons ejected from solid surfaces in a UHV environment. It is designed to exploit ultrafast light sources (free electron laser or laser high harmonic generation) and to perform (photo)electron spin analysis by an arrangement of Mott scattering polarimeters that measure the full SP vector. The system consists of two interconnected UHV vessels: one for surface science sample cleaning treatments, e-beam deposition of ultrathin films, and low energy electron diffraction/AES characterization. The sample environment in the polarimeter allows for cryogenic cooling and in-operando application of electric and magnetic fields. The photoelectrons are collected by an electrostatic accelerator and transport lens that form a periaxial beam that is subsequently directed by a Y-shaped electrostatic deflector to either one of the two orthogonal Mott polarimeters. The apparatus has been designed to operate in the extreme conditions of ultraintense single-X-ray pulses as originated by free electron lasers (up to 1 kHz), but it allows also for the single electron counting mode suitable when using statistical sources such as synchrotron radiation, cw-laser, or e-gun beams (up to 150 kcps).

Design and optimization of a modular setup for measurements of three-dimensional spin polarization with ultrafast pulsed sources

NASA Astrophysics Data System (ADS)

Pincelli, T.; Petrov, V. N.; Brajnik, G.; Ciprian, R.; Lollobrigida, V.; Torelli, P.; Krizmancic, D.; Salvador, F.; De Luisa, A.; Sergo, R.; Gubertini, A.; Cautero, G.; Carrato, S.; Rossi, G.; Panaccione, G.

2016-03-01

ULTRASPIN is an apparatus devoted to the measurement of the spin polarization (SP) of electrons ejected from solid surfaces in a UHV environment. It is designed to exploit ultrafast light sources (free electron laser or laser high harmonic generation) and to perform (photo)electron spin analysis by an arrangement of Mott scattering polarimeters that measure the full SP vector. The system consists of two interconnected UHV vessels: one for surface science sample cleaning treatments, e-beam deposition of ultrathin films, and low energy electron diffraction/AES characterization. The sample environment in the polarimeter allows for cryogenic cooling and in-operando application of electric and magnetic fields. The photoelectrons are collected by an electrostatic accelerator and transport lens that form a periaxial beam that is subsequently directed by a Y-shaped electrostatic deflector to either one of the two orthogonal Mott polarimeters. The apparatus has been designed to operate in the extreme conditions of ultraintense single-X-ray pulses as originated by free electron lasers (up to 1 kHz), but it allows also for the single electron counting mode suitable when using statistical sources such as synchrotron radiation, cw-laser, or e-gun beams (up to 150 kcps).

Design and optimization of a modular setup for measurements of three-dimensional spin polarization with ultrafast pulsed sources

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pincelli, T., E-mail: pincelli@iom.cnr.it; Rossi, G.; Laboratorio TASC, IOM-CNR, S.S. 14 km 163.5, Basovizza, 34149 Trieste

2016-03-15

ULTRASPIN is an apparatus devoted to the measurement of the spin polarization (SP) of electrons ejected from solid surfaces in a UHV environment. It is designed to exploit ultrafast light sources (free electron laser or laser high harmonic generation) and to perform (photo)electron spin analysis by an arrangement of Mott scattering polarimeters that measure the full SP vector. The system consists of two interconnected UHV vessels: one for surface science sample cleaning treatments, e-beam deposition of ultrathin films, and low energy electron diffraction/AES characterization. The sample environment in the polarimeter allows for cryogenic cooling and in-operando application of electric andmore » magnetic fields. The photoelectrons are collected by an electrostatic accelerator and transport lens that form a periaxial beam that is subsequently directed by a Y-shaped electrostatic deflector to either one of the two orthogonal Mott polarimeters. The apparatus has been designed to operate in the extreme conditions of ultraintense single-X-ray pulses as originated by free electron lasers (up to 1 kHz), but it allows also for the single electron counting mode suitable when using statistical sources such as synchrotron radiation, cw-laser, or e-gun beams (up to 150 kcps).« less

Spontaneous desorption and phase transitions of self-assembled alkanethiol and alicyclic thiol monolayers chemisorbed on Au(111) in ultrahigh vacuum at room temperature.

PubMed

Ito, Eisuke; Kang, Hungu; Lee, Dongjin; Park, Joon B; Hara, Masahiko; Noh, Jaegeun

2013-03-15

Scanning tunneling microscopy (STM) and X-ray photoelectron spectroscopy (XPS) were used to examine the surface structure and adsorption conditions of hexanethiol (HT) and cyclohexanethiol (CHT) self-assembled monolayers (SAMs) on Au(111) as a function of storage period in ultrahigh vacuum (UHV) conditions of 3×10(-7) Pa at room temperature (RT). STM imaging revealed that after storage for 7 days, HT SAMs underwent phase transitions from c(4×2) phase to low coverage 4×√3 phase. This transition is due to a structural rearrangement of hexanethiolates that results from the spontaneous desorption of chemisorbed HT molecules on Au(111) surface. XPS measurements showed approximately 28% reduction in sulfur coverage, which indicates desorption of hexanethiolates from the surfaces. Contrary to HT SAMs, the structural order of CHT SAMs with (5×2√3)R35° phase completely disappeared after storage for 3 or 7 days. XPS results show desorption of more than 80% of the cyclohexanethiolates, even after storage for 3 days. We found that spontaneous desorption of CHT molecules on Au(111) in UHV at RT occurred quickly, whereas spontaneous desorption of HT molecules was much slower. Thermal desorption spectroscopy (TDS) results suggest CHT SAMs in UHV at RT can desorb more efficiently than HT SAMs due to formation of thiol desorption fragments that result from chemical reactions between surface hydrogen atoms and thiolates on Au(111) surfaces. This study clearly demonstrated that organic thiols chemisorbed on gold surfaces are desorbed spontaneously in UHV at RT and van der Waals interactions play an important role in determining the structural stability of thiolate SAMs in UHV. Copyright © 2012 Elsevier Inc. All rights reserved.

Scanning tunneling microscopy studies of pulse deposition of dinuclear organometallic molecules on Au(111)

NASA Astrophysics Data System (ADS)

Guo, Song; Alex Kandel, S.

2008-01-01

Ultrahigh-vacuum scanning tunneling microscopy (STM) was used to study trans-[Cl(dppe)2Ru(CC)6Ru(dppe)2Cl] [abbreviated as Ru2, diphenylphosphinoethane (dppe)] on Au(111). This large organometallic molecule was pulse deposited onto the Au(111) surface under ultrahigh-vacuum (UHV) conditions. UHV STM studies on the prepared sample were carried out at room temperature and 77K in order to probe molecular adsorption and to characterize the surface produced by the pulse deposition process. Isolated Ru2 molecules were successfully imaged by STM at room temperature; however, STM images were degraded by mobile toluene solvent molecules that remain on the surface after the deposition. Cooling the sample to 77K allows the solvent molecules to be observed directly using STM, and under these conditions, toluene forms organized striped domains with regular domain boundaries and a lattice characterized by 5.3 and 2.7Å intermolecular distances. When methylene chloride is used as the solvent, it forms analogous domains on the surface at 77K. Mild annealing under vacuum causes most toluene molecules to desorb from the surface; however, this annealing process may lead to thermal degradation of Ru2 molecules. Although pulse deposition is an effective way to deposit molecules on surfaces, the presence of solvent on the surface after pulse deposition is unavoidable without thermal annealing, and this annealing may cause undesired chemical changes in the adsorbates under study. Preparation of samples using pulse deposition must take into account the characteristics of sample molecules, solvent, and surfaces.

Custom sample environments at the ALBA XPEEM.

PubMed

Foerster, Michael; Prat, Jordi; Massana, Valenti; Gonzalez, Nahikari; Fontsere, Abel; Molas, Bernat; Matilla, Oscar; Pellegrin, Eric; Aballe, Lucia

2016-12-01

A variety of custom-built sample holders offer users a wide range of non-standard measurements at the ALBA synchrotron PhotoEmission Electron Microscope (PEEM) experimental station. Some of the salient features are: an ultrahigh vacuum (UHV) suitcase compatible with many offline deposition and characterization systems, built-in electromagnets for uni- or biaxial in-plane (IP) and out-of-plane (OOP) fields, as well as the combination of magnetic fields with electric fields or current injection. Electronics providing a synchronized sinusoidal signal for sample excitation enable time-resolved measurements at the 500MHz storage ring RF frequency. Copyright © 2016 Elsevier B.V. All rights reserved.

Tools to Study Interfaces for Superconducting, Thermoelectric, and Magnetic Materials at the University of Houston

DTIC Science & Technology

2016-09-01

The MBE system, which grows crystalline thin films in ultrahigh vacuum (UHV) with precise control of thickness, composition, and morphology, will...used on our sputtering system to fabricate thin films with interfaces. - The electronic structures of these materials will be investigated using the...magnetization/transport measurements. The MBE system, which grows crystalline thin films in ultrahigh vacuum (UHV) with precise control of thickness, composition

A compact sub-Kelvin ultrahigh vacuum scanning tunneling microscope with high energy resolution and high stability.

PubMed

Zhang, L; Miyamachi, T; Tomanić, T; Dehm, R; Wulfhekel, W

2011-10-01

We designed a scanning tunneling microscope working at sub-Kelvin temperatures in ultrahigh vacuum (UHV) in order to study the magnetic properties on the nanoscale. An entirely homebuilt three-stage cryostat is used to cool down the microscope head. The first stage is cooled with liquid nitrogen, the second stage with liquid (4)He. The third stage uses a closed-cycle Joule-Thomson refrigerator of a cooling power of 1 mW. A base temperature of 930 mK at the microscope head was achieved using expansion of (4)He, which can be reduced to ≈400 mK when using (3)He. The cryostat has a low liquid helium consumption of only 38 ml/h and standing times of up to 280 h. The fast cooling down of the samples (3 h) guarantees high sample throughput. Test experiments with a superconducting tip show a high energy resolution of 0.3 meV when performing scanning tunneling spectroscopy. The vertical stability of the tunnel junction is well below 1 pm (peak to peak) and the electric noise floor of tunneling current is about 6fA/√Hz. Atomic resolution with a tunneling current of 1 pA and 1 mV was achieved on Au(111). The lateral drift of the microscope at stable temperature is below 20 pm/h. A superconducting spilt-coil magnet allows to apply an out-of-plane magnetic field of up to 3 T at the sample surface. The flux vortices of a Nb(110) sample were clearly resolved in a map of differential conductance at 1.1 K and a magnetic field of 0.21 T. The setup is designed for in situ preparation of tip and samples under UHV condition.

Structural Characterization and Gas Reactions of Small Metal Particles by High Resolution In-situ TEM and TED. [Transmission Electron Microscopy and Transmission Electron Diffraction

NASA Technical Reports Server (NTRS)

Heinemann, K.

1985-01-01

A commercial electron microscope with flat-plate upper pole piece configuration of the objective lens and top entry specimen introduction was modified to obtain 5 x 10 to the minus 10th power mbar pressure at the site of the specimen while maintaining the convenience of a specimen airlock system that allows operation in the 10 to the 10th power mbar range within 15 minutes after specimen change. The specimen chamber contains three wire evaporation sources, a specimen heater, and facilities for oxygen or hydrogen plasma treatment to clean as-introduced specimens. Evacuation is achieved by dural differential pumping, with fine entrance and exit apertures for the electron beam. With the microscope operating at .000001 mbar, the first differential pumping stage features a high-speed cryopump operating in a stainless steel chamber that can be mildly baked and reaches 1 x 10 to the minus 8th power mbar. The second stage, containing the evaporation sources and a custom ionization gauge within 10 cm from the specimen, is a rigorously uncompromised all-metal uhv-system that is bakable to above 200 C throughout and is pumped with an 80-liter ion pump. Design operating pressures and image quality (resolution of metal particles smaller than 1 nm in size) was achieved.

Live event reconstruction in an optically read out GEM-based TPC

NASA Astrophysics Data System (ADS)

Brunbauer, F. M.; Galgóczi, G.; Gonzalez Diaz, D.; Oliveri, E.; Resnati, F.; Ropelewski, L.; Streli, C.; Thuiner, P.; van Stenis, M.

2018-04-01

Combining strong signal amplification made possible by Gaseous Electron Multipliers (GEMs) with the high spatial resolution provided by optical readout, highly performing radiation detectors can be realized. An optically read out GEM-based Time Projection Chamber (TPC) is presented. The device permits 3D track reconstruction by combining the 2D projections obtained with a CCD camera with timing information from a photomultiplier tube. Owing to the intuitive 2D representation of the tracks in the images and to automated control, data acquisition and event reconstruction algorithms, the optically read out TPC permits live display of reconstructed tracks in three dimensions. An Ar/CF4 (80/20%) gas mixture was used to maximize scintillation yield in the visible wavelength region matching the quantum efficiency of the camera. The device is integrated in a UHV-grade vessel allowing for precise control of the gas composition and purity. Long term studies in sealed mode operation revealed a minor decrease in the scintillation light intensity.

Design of a -1 MV dc UHV power supply for ITER NBI

NASA Astrophysics Data System (ADS)

Watanabe, K.; Yamamoto, M.; Takemoto, J.; Yamashita, Y.; Dairaku, M.; Kashiwagi, M.; Taniguchi, M.; Tobari, H.; Umeda, N.; Sakamoto, K.; Inoue, T.

2009-05-01

Procurement of a dc -1 MV power supply system for the ITER neutral beam injector (NBI) is shared by Japan and the EU. The Japan Atomic Energy Agency as the Japan Domestic Agency (JADA) for ITER contributes to the procurement of dc -1 MV ultra-high voltage (UHV) components such as a dc -1 MV generator, a transmission line and a -1 MV insulating transformer for the ITER NBI power supply. The inverter frequency of 150 Hz in the -1 MV power supply and major circuit parameters have been proposed and adopted in the ITER NBI. The dc UHV insulation has been carefully designed since dc long pulse insulation is quite different from conventional ac insulation or dc short pulse systems. A multi-layer insulation structure of the transformer for a long pulse up to 3600 s has been designed with electric field simulation. Based on the simulation the overall dimensions of the dc UHV components have been finalized. A surge energy suppression system is also essential to protect the accelerator from electric breakdowns. The JADA contributes to provide an effective surge suppression system composed of core snubbers and resistors. Input energy into the accelerator from the power supply can be reduced to about 20 J, which satisfies the design criteria of 50 J in total in the case of breakdown at -1 MV.

Ultra high vacuum test setup for electron gun

NASA Astrophysics Data System (ADS)

Pandiyar, M. L.; Prasad, M.; Jain, S. K.; Kumar, R.; Hannurkar, P. R.

2008-05-01

Ultra High Vacuum (UHV) test setup for electron gun testing has been developed. The development of next generation light sources and accelerators require development of klystron as a radio frequency power source, and in turn electron gun. This UHV electron gun test setup can be used to test the electron guns ranging from high average current, quasi-continuous wave to high peak current, single pulse etc. An electron gun has been designed, fabricated, assembled and tested for insulation up to 80 kV under the programme to develop high power klystron for future accelerators. Further testing includes the electron emission parameters characterization of the cathode, as it determines the development of a reliable and efficient electron gun with high electron emission current and high life time as well. This needs a clean ultra high vacuum to study these parameters particularly at high emission current. The cathode emission current, work function and vapour pressure of cathode surface material at high temperature studies will further help in design and development of high power electron gun The UHV electron gun test setup consists of Turbo Molecular Pump (TMP), Sputter Ion Pump (SIP), pressure gauge, high voltage and cathode power supplies, current measurement device, solenoid magnet and its power supply, residual gas analyser etc. The ultimate vacuum less than 2×10-9 mbar was achieved. This paper describes the UHV test setup for electron gun testing.

Design and performance of a Near Ultra High Vacuum Helium Ion Microscope

NASA Astrophysics Data System (ADS)

Poelsema, Bene; van Gastel, Raoul; Hlawacek, Gregor; Zandvliet, Harold J. W.

2012-02-01

The advent of He Ion Microscopy (HIM) as a new nanoscopic technique to image materials has enabled a new look at materials that is based on the interaction of swift light ions with matter. Initial HIM instruments have demonstrated high-resolution imaging, combined with great surface sensitivity, the ability to neutralize charge very efficiently, and with enhanced materials contrast when ion induced secondary electrons are used for imaging. To achieve ultimate performance, the chamber vacuum of the existing platform may be improved. For instance, carbon deposits due to beam interaction are readily seen due to the surface sensitivity of the technique. At high current densities the sharply focused beam may very efficiently decompose residual hydrocarbons. Not only can this obscure a clear view of the sample, thereby negating the benefits of the small spot size, it also limits the available acquisition time. This has proven extremely useful for nanopatterning for sensors, and other device fabrication applications at the sub-10nm level. However, it is undesirable when the instrument is used for materials characterization. We will discuss the basic considerations that went into the design of a Near-UHV He Ion Microscope [1]. First applications that the instrument was used for will be highlighted and its impact in surface physics and other research areas that require increased imaging sensitivity will be discussed. [4pt] [1] R.van Gastel et al, Microscopy and Microanalysis 17, 928-929 (2011)

NanoBench: An Individually Addressable Nanotube Array

DTIC Science & Technology

2006-03-25

17 (1999). 5 Cai, L., H. Tabata and T. Kawai, "Probing electrical properties of oriented DNA by conducting atomic force microscopy", Nanotechnology 12...the e-beam hits the other side of the NanoBench. This allows the cells to be kept alive in a biological medium while they are being tested. The key...advantage of the NanoBench is that the e-beam never hits the sample. UHV Technologies Inc. 7 NanoBench: An Individually Addressable Nanotube Array Final

The research of full automatic oil filtering control technology of high voltage insulating oil

NASA Astrophysics Data System (ADS)

Gong, Gangjun; Zhang, Tong; Yan, Guozeng; Zhang, Han; Chen, Zhimin; Su, Chang

2017-09-01

In this paper, the design scheme of automatic oil filter control system for transformer oil in UHV substation is summarized. The scheme specifically includes the typical double tank filter connection control method of the transformer oil of the UHV substation, which distinguishes the single port and the double port connection structure of the oil tank. Finally, the design scheme of the temperature sensor and respirator is given in detail, and the detailed evaluation and application scenarios are given for reference.

A fibre-coupled UHV-compatible variable angle reflection-absorption UV/visible spectrometer

NASA Astrophysics Data System (ADS)

Stubbing, J. W.; Salter, T. L.; Brown, W. A.; Taj, S.; McCoustra, M. R. S.

2018-05-01

We present a novel UV/visible reflection-absorption spectrometer for determining the refractive index, n, and thicknesses, d, of ice films. Knowledge of the refractive index of these films is of particular relevance to the astrochemical community, where they can be used to model radiative transfer and spectra of various regions of space. In order to make these models more accurate, values of n need to be recorded under astronomically relevant conditions, that is, under ultra-high vacuum (UHV) and cryogenic cooling. Several design considerations were taken into account to allow UHV compatibility combined with ease of use. The key design feature is a stainless steel rhombus coupled to an external linear drive (z-shift) allowing a variable reflection geometry to be achieved, which is necessary for our analysis. Test data for amorphous benzene ice are presented as a proof of concept, the film thickness, d, was found to vary linearly with surface exposure, and a value for n of 1.43 ± 0.07 was determined.

Recent approaches for bridging the pressure gap in photoelectron microspectroscopy

PubMed Central

Kolmakov, Andrei; Gregoratti, Luca; Kiskinova, Maya; Günther, Sebastian

2016-01-01

Ambient-pressure photoelectron spectroscopy (APPES) and microscopy are at the frontier of modern chemical analysis at liquid-gas, solid-liquid and solid-gas interfaces, bridging science and engineering of functional materials. Complementing the current state-of-the art of the instruments, we survey in this short review several alternative APPES approaches, developed recently in the scanning photoelectron microscope (SPEM) at the Elettra laboratory. In particular, we report on experimental setups for dynamic near-ambient pressure environment, using pulsed-gas injection in the vicinity of samples or reaction cells with very small apertures, allowing for experiments without introducing additional differential pumping stages. The major part of the review is dedicated to the construction and performance of novel environmental cells using ultrathin electron-transparent but molecularly impermeable membranes to isolate the gas or liquid ambient from the electron detector operating in ultra-high vacuum (UHV). We demonstrate that two dimensional materials, such as graphene and derivatives, are mechanically robust to withstand atmospheric - UHV pressure differences and are sufficiently transparent for the photoelectrons emitted from samples immersed in the liquid or gaseous media. There are many unique opportunities for APPES using X-rays over a wide energy range. We show representative results that illustrate the potential of these ‘ambient-pressure’ approaches. Combined with the ca 100 nm lateral resolution of SPEM, they can overcome the pressure gap challenges and address the evolution of chemical composition and electronic structure at surface and interfaces under realistic operation conditions with unprecedented lateral and spectral resolution. PMID:28008215

Real time viability detection of bacterial spores

DOEpatents

Vanderberg, Laura A.; Herdendorf, Timothy J.; Obiso, Richard J.

2003-07-29

This invention relates to a process for detecting the presence of viable bacterial spores in a sample and to a spore detection system, the process including placing a sample in a germination medium for a period of time sufficient for commitment of any present viable bacterial spores to occur, mixing the sample with a solution of a lanthanide capable of forming a fluorescent complex with dipicolinic acid, and, measuring the sample for the presence of dipicolinic acid, and the system including a germination chamber having inlets from a sample chamber, a germinant chamber and a bleach chamber, the germination chamber further including an outlet through a filtering means, the outlet connected to a detection chamber, the detection chamber having an inlet from a fluorescence promoting metal chamber and the detection chamber including a spectral excitation source and a means of measuring emission spectra from a sample, the detection chamber further connected to a waste chamber. A germination reaction mixture useful for promoting commitment of any viable bacterial spores in a sample including a combination of L-alanine, L-asparagine and D-glucose is also described.

Mesocorticolimbic Connectivity and Volumetric Alterations in DCC Mutation Carriers.

PubMed

Vosberg, Daniel E; Zhang, Yu; Menegaux, Aurore; Chalupa, Amanda; Manitt, Colleen; Zehntner, Simone; Eng, Conrad; DeDuck, Kristina; Allard, Dominique; Durand, France; Dagher, Alain; Benkelfat, Chawki; Srour, Myriam; Joober, Ridha; Lepore, Franco; Rouleau, Guy; Théoret, Hugo; Bedell, Barry J; Flores, Cecilia; Leyton, Marco

2018-05-16

The axon guidance cue receptor DCC (deleted in colorectal cancer) plays a critical role in the organization of mesocorticolimbic pathways in rodents. To investigate whether this occurs in humans, we measured (1) anatomical connectivity between the substantia nigra/ventral tegmental area (SN/VTA) and forebrain targets, (2) striatal and cortical volumes, and (3) putatively associated traits and behaviors. To assess translatability, morphometric data were also collected in Dcc -haploinsufficient mice. The human volunteers were 20 DCC +/- mutation carriers, 16 DCC +/+ relatives, and 20 DCC +/+ unrelated healthy volunteers (UHVs; 28 females). The mice were 11 Dcc +/- and 16 wild-type C57BL/6J animals assessed during adolescence and adulthood. Compared with both control groups, the human DCC +/- carriers exhibited the following: (1) reduced anatomical connectivity from the SN/VTA to the ventral striatum [ DCC +/+ : p = 0.0005, r ( effect size ) = 0.60; UHV: p = 0.0029, r = 0.48] and ventral medial prefrontal cortex ( DCC +/+ : p = 0.0031, r = 0.53; UHV: p = 0.034, r = 0.35); (2) lower novelty-seeking scores ( DCC +/+ : p = 0.034, d = 0.82; UHV: p = 0.019, d = 0.84); and (3) reduced striatal volume ( DCC +/+ : p = 0.0009, d = 1.37; UHV: p = 0.0054, d = 0.93). Striatal volumetric reductions were also present in Dcc +/- mice, and these were seen during adolescence ( p = 0.0058, d = 1.09) and adulthood ( p = 0.003, d = 1.26). Together these findings provide the first evidence in humans that an axon guidance gene is involved in the formation of mesocorticolimbic circuitry and related behavioral traits, providing mechanisms through which DCC mutations might affect susceptibility to diverse neuropsychiatric disorders. SIGNIFICANCE STATEMENT Opportunities to study the effects of axon guidance molecules on human brain development have been rare. Here, the identification of a large four-generational family that carries a mutation to the axon guidance molecule receptor gene, DCC , enabled us to demonstrate effects on mesocorticolimbic anatomical connectivity, striatal volumes, and personality traits. Reductions in striatal volumes were replicated in DCC -haploinsufficient mice. Together, these processes might influence mesocorticolimbic function and susceptibility to diverse neuropsychiatric disorders. Copyright © 2018 the authors 0270-6474/18/384655-11$15.00/0.

Electrical Measurements and Nanomechanics Using Scanning Probe Microscopy

NASA Astrophysics Data System (ADS)

Chang, Yong

2002-10-01

In the early 1980s, G. Binnig et al. invented the Scanning Tunneling Microscopy (STM) [1], making it possible to obtain atomic resolution images of conducting surfaces. After that, many different types of Scanning Probe Microscopy (SPM) were invented and some of the most useful representatives are Atomic Force Microscopy (AFM) [2], Electrostatic Force Microscopy (EFM) [3] and Kelvin Probe Force Microscopy (KPFM) [4,5]. In 1985, G. Binnig et al. [2] invented the AFM, which now is used as a fundamental tool in many fields of research. Developed from AFM, Y. Martin et al. [3] invented EFM in 1987. The development of AC mode AFM allows the detection of weak long-range forces. EFM has also been used to study other systems and phenomena, such as thin liquid films on solid surfaces [6], electrically stressed gold nanowires [7], and spatial charge distribution in quantum wires [8]. In 1991, M. Nonnenmacher et al. [5] invented Kelvin Probe Force Microscopy. KPFM is used to study any property that affects the tip-surface Contact Potential Difference (CPD), such as voltage signals in integrated circuits (IC) [9], charged grain boundaries in polycrystalline silicon [10] and surface potential variations in multilayer semiconductor devices [11]. The aim of this poster is to discuss the application of SPM to electrical measurements. The theory of SPM was presented. The AFM was firstly introduced as it was developed before the other two. The design and theory were discussed. The force-distance curve was introduced. After this EFM was presented. EFM was developed from AC mode AFM. The technique was achieved by applying a DC voltage between the tip and the sample. The design, theory and features of it were surveyed. KPFM was also discussed. KPFM was developed from EFM. The central part of this technique is to measure the CPD. Experimental measurements of SPM were described after theory part. Research work using AFM was presented. The newest technique of AFM, UHV-AFM has been used in investigating the nano-mechanical properties of different materials. Normally common AFM has shortcomings as it has either strict limit resolution or difficulties in interpreting the data from the measurements. In order to solve these problems, Ultra High Vacuum (UHV) conditions were applied to acquire quantitative results. A typical UHV-AFM uses a cantilever whose spring constant is relatively high (>100 N/m) to obtain high-resolution image. Experimental measurements using KPFM was presented after AFM. Researchers are using KPFM to acquire the topography and measuring the CPD of semiconductor or metal surfaces. Similarly as in AFM, KPFM works best in UHV environment. A typical UHV-KPFM also uses a cantilever whose spring constant is relatively high. A UHV-KPFM may be able to achieve a high resolution in CPD images. In the past 20 years many different kinds of SPM were invented and used. AFM, EFM, and KPFM are representatives of them. Researchers are still developing new techniques. However, in recent years, they pay more attention in improving the measurement accuracy instead of trying to invent new SPM. These three SPM continue to be frequently used. The current capabilities of SPM do not satisfy us completely. We still cant measure the Electrical field directly. We actually measure the capacitance gradient. There are also some other questions. This is because the electrostatic force depends very strongly on the geometry of the probe at all length scales, so any model is subject to two big problems. First, the geometry is not known with complete accuracy; and second, the tip shape can change during an experiment due to wear. In the future, maybe the problems could be overcome by using a tip with a very well defined shape, such as a carbon nanotube, for which a realistic geometrical model could be more easily constructed, and the wear could be avoided or reduced.

Electrospray deposition of organic molecules on bulk insulator surfaces.

PubMed

Hinaut, Antoine; Pawlak, Rémy; Meyer, Ernst; Glatzel, Thilo

2015-01-01

Large organic molecules are of important interest for organic-based devices such as hybrid photovoltaics or molecular electronics. Knowing their adsorption geometries and electronic structures allows to design and predict macroscopic device properties. Fundamental investigations in ultra-high vacuum (UHV) are thus mandatory to analyze and engineer processes in this prospects. With increasing size, complexity or chemical reactivity, depositing molecules by thermal evaporation becomes challenging. A recent way to deposit molecules in clean conditions is Electrospray Ionization (ESI). ESI keeps the possibility to work with large molecules, to introduce them in vacuum, and to deposit them on a large variety of surfaces. Here, ESI has been successfully applied to deposit triply fused porphyrin molecules on an insulating KBr(001) surface in UHV environment. Different deposition coverages have been obtained and characterization of the surface by in-situ atomic force microscopy working in the non-contact mode shows details of the molecular structures adsorbed on the surface. We show that UHV-ESI, can be performed on insulating surfaces in the sub-monolayer regime and to single molecules which opens the possibility to study a variety of complex molecules.

Surface friction of rock in terrestrial and simulated lunar environments

NASA Technical Reports Server (NTRS)

Roepke, W. W.; Peng, S. S.

1975-01-01

The conventional probe-on-the rotating-disk concept was used to determine the surface friction in mineral probe/specimen interfaces. Nine rocks or minerals and two stainless steels were tested in both new (NT) and same track (ST) tests under three different pressure environments-atmospheric, UHV, and dry nitrogen. Each environment was further subdivided into two testing conditions, that is, ambient and elevated (135 C) temperatures. In NT tests, friction was the lowest in an atmospheric pressure condition for all rock types and increased to the largest in UHV ambient condition except for pyroxene and stainless steel. Friction values measured in dry nitrogen ambient condition lie between the two extremes. Heating tends to increase friction in atmospheric and dry nitrogen environment but decreases in UHV environment with the exception of stainless steel, basalt, and pyroxene. In ST tests, friction was the lowest in the first run and increased in subsequent runs except for stainless steel where the reverse was true. The increases leveled off after a few runs ranging from the second to the seventh depending on rock types.

Ultrahigh Vacuum Scanning Tunneling Microscopy and Spectroscopy of Single-Walled Carbon Nanotubes Interfaced with Silicon Surfaces

NASA Astrophysics Data System (ADS)

Albrecht, Peter; Lyding, Joseph

2008-03-01

The UHV-STM was used to examine SWNTs directly interfaced with hydrogen-passivated Si(100). Dry contact transfer (DCT) [1] enabled the UHV deposition of SWNTs with minimal disruption of the atomically flat Si(100)-2x1:H surface. Isolated, rather than bundled, SWNTs could be routinely located for atomically resolved imaging, tunneling I-V spectroscopy [2], lateral manipulation [3], and proximal substrate modification. Weakly adsorbed SWNTs initially unstable in the presence of the rastered STM tip could be stabilized by depassivating the underlying H-Si(100) surface via UHV-STM electron-stimulated H desorption [4], which in the case of one chiral semiconducting SWNT also promoted the local alignment of the zigzag symmetry direction on the underside of the tube with the clean Si dimer rows [5]. The growing body of first-principles simulations of the SWNT/Si(100) system [6] was drawn upon in our interpretation of such local perturbations. [1] APL 83, 5029 (2003). [2] Nanotechnology 18, 095204 (2007). [3] Small 3, 146 (2007). [4] Nanotechnology 18, 125302 (2007). [5] Small 3, 1402 (2007). [6] JAP 100, 124304 (2006).

An Einzel lens apparatus for deposition of levitated graphene on a substrate in UHV

NASA Astrophysics Data System (ADS)

Coppock, Joyce; Nagornykh, Pavel; McAdams, Ian; Kane, Bruce

The goal of our research is to levitate a charged micron-scale graphene flake in an electrical AC quadrupole trap in ultra-high vacuum (UHV) in order to study its properties and dynamics while decoupled from any substrate. As a complement to the optical measurements that can be performed on the levitated flake, we are developing a method of depositing the same flake on a substrate, which can be removed from the system for further study using such probes as atomic force microscopy (AFM) and scanning tunneling microscopy (STM). As the flake is released from the trap and propelled toward the substrate, its trajectory will be controlled by an Einzel (electrostatic) lens to achieve accurate positioning on the substrate. This talk will discuss the design of the lens as well as particle tracing simulations to determine the proper lens voltage to focus the particle's trajectory. In the future, deposited graphene may be used to passivate H-terminated silicon. The method is expected to be generalizable to achieve deposition of 2D materials on surfaces in a clean UHV environment.

Harmonic voltage excess problem test and analysis in UHV and EHV grid particular operation mode

NASA Astrophysics Data System (ADS)

Lv, Zhenhua; Shi, Mingming; Fei, Juntao

2018-02-01

The test and analysis of the power quality of some 1000kV UHV transmission lines and 500kV EHV transmission lines is carried out. It is found that there is harmonic voltage excess problems when the power supply of the UHV and EHV voltage line is single-ended or single-loop, the problem basically disappeared after the operation mode change, different operating conditions, the harmonic current has not been greatly affected, indicating that the harmonic voltage changes mainly caused by the system harmonic impedance. With the analysis of MATLAB Simulink system model, it can be seen that there are specific harmonic voltage excess in the system under the specific operating mode, which results in serious distortion of the specific harmonic voltage. Since such phenomena are found in 500kV and 1000kV systems, it is suggested that the test evaluation work should be done under the typical mode of operation in 500kV, 1000kV Planning and construction process to prevent the occurrence of serious distortion and the regional harmonic current monitoring and suppression work should be done.

Alumina-supported sub-nanometer Pt 10 clusters: Amorphization and role of the support material in a highly active CO oxidation catalyst

DOE PAGES

Yin, Chunrong; Negreiros, Fabio R.; Barcaro, Giovanni; ...

2017-02-03

Catalytic CO oxidation is unveiled on size-selected Pt 10 clusters deposited on two very different ultrathin (≈0.5–0.7 nm thick) alumina films: (i) a highly ordered alumina obtained under ultra-high vacuum (UHV) by oxidation of the NiAl(110) surface and (ii) amorphous alumina obtained by atomic layer deposition (ALD) on a silicon chip that is a close model of real-world supports. Notably, when exposed to realistic reaction conditions, the Pt 10/UHV-alumina system undergoes a morphological transition in both the clusters and the substrate, and becomes closely akin to Pt 10/ALD-alumina, thus reconciling UHV-type surface-science and real-world experiments. The Pt 10 clusters, thoroughlymore » characterized via combined experimental techniques and theoretical analysis, exhibit among the highest CO oxidation activity per Pt atom reported for CO oxidation catalysts, due to the interplay of ultra-small size and support effects. Lastly, a coherent interdisciplinary picture then emerges for this catalytic system.« less

Ultrahigh-viscosity hydroxypropylmethylcellulose blunts postprandial glucose after a breakfast meal in women.

PubMed

Dow, Shireen; Pritchett, Kelly L; Hawk, Susan; Herrington, Stefanie J; Gee, David L

2012-04-01

To determine the effects of two water-soluble dietary fibers, ultrahigh-viscosity hydroxypropylmethylcellulose (UHV-HPMC, nonfermentable) and psyllium fiber (fermentable), on postprandial glucose and second meal effects. In a single-blind crossover design, 12 healthy adult subjects were given standardized, premeasured breakfast and lunch meals with either 4 g of the fiber supplements or a placebo. Blood glucose was measured with a continuous blood glucose monitoring system (DexCom Seven Plus, San Diego, CA). Subjects consuming UHV-HPMC had significantly (p < 0.05) lower blood glucose area under the curve (AUC) 2 hours after breakfast than those receiving a placebo. Subjects consuming psyllium also tended to have lower glucose levels than the placebo group. Peak glucose concentration following breakfast was significantly (p < 0.01) less with UHV-HPMC when compared with the placebo. No significant differences in AUC or peak glucose concentration between treatments following the second meal (lunch) were detected, suggesting no residual effect from the fiber supplements. Supplementation with viscous water-soluble fibers may be an effective means of reducing the glycemic response of a meal in healthy adults.

In situ surface/interface x-ray diffractometer for oxide molecular beam epitaxy

NASA Astrophysics Data System (ADS)

Lee, J. H.; Tung, I. C.; Chang, S.-H.; Bhattacharya, A.; Fong, D. D.; Freeland, J. W.; Hong, Hawoong

2016-01-01

In situ studies of oxide molecular beam epitaxy by synchrotron x-ray scattering has been made possible by upgrading an existing UHV/molecular beam epitaxy (MBE) six-circle diffractometer system. For oxide MBE growth, pure ozone delivery to the chamber has been made available, and several new deposition sources have been made available on a new 12 in. CF (ConFlat, a registered trademark of Varian, Inc.) flange. X-ray diffraction has been used as a major probe for film growth and structures for the system. In the original design, electron diffraction was intended for the secondary diagnostics available without the necessity of the x-ray and located at separate positions. Deposition of films was made possible at the two diagnostic positions. And, the aiming of the evaporation sources is fixed to the point between two locations. Ozone can be supplied through two separate nozzles for each location. Also two separate thickness monitors are installed. Additional features of the equipment are also presented together with the data taken during typical oxide film growth to illustrate the depth of information available via in situ x-ray techniques.

In situ surface/interface x-ray diffractometer for oxide molecular beam epitaxy.

PubMed

Lee, J H; Tung, I C; Chang, S-H; Bhattacharya, A; Fong, D D; Freeland, J W; Hong, Hawoong

2016-01-01

In situ studies of oxide molecular beam epitaxy by synchrotron x-ray scattering has been made possible by upgrading an existing UHV/molecular beam epitaxy (MBE) six-circle diffractometer system. For oxide MBE growth, pure ozone delivery to the chamber has been made available, and several new deposition sources have been made available on a new 12 in. CF (ConFlat, a registered trademark of Varian, Inc.) flange. X-ray diffraction has been used as a major probe for film growth and structures for the system. In the original design, electron diffraction was intended for the secondary diagnostics available without the necessity of the x-ray and located at separate positions. Deposition of films was made possible at the two diagnostic positions. And, the aiming of the evaporation sources is fixed to the point between two locations. Ozone can be supplied through two separate nozzles for each location. Also two separate thickness monitors are installed. Additional features of the equipment are also presented together with the data taken during typical oxide film growth to illustrate the depth of information available via in situ x-ray techniques.

GOLD's coating and testing facilities for ISSIS-WSO

NASA Astrophysics Data System (ADS)

Larruquert, Juan I.; Méndez, José Antonio; Aznárez, José Antonio; Vidal-Dasilva, Manuela; García-Cortés, Sergio; Rodríguez-de Marcos, Luis; Fernández-Perea, Mónica

2011-09-01

ISSIS imager has been thought as an open purpose instrument within the World Space Observatory (WSO) international space mission. The highest priorities of ISSIS, an instrument to be developed by Spain, are to guarantee high spatial resolution and high sensitivity down to the far ultraviolet (FUV). The paper displays the capacities of GOLD for multilayer deposition and FUV reflectometry, among other metrologies, for ISSIS optical elements. Deposition of coatings for ISSIS-WSO will be carried out in a new UHV system with a 75-cm diameter deposition chamber. The purpose of the new laboratory is the deposition of coatings satisfying the constraints for FUV space optics. The first target coating to be developed in this new laboratory is Al protected with MgF2, with optimum reflectance down to ˜120 nm. GOLD's existing reflectometer is able to characterize flat pieces both by transmittance and reflectance, and the latter from near-normal to grazing incidence, in the range from 12 to 200 nm. Other metrologies that will be available at GOLD for ISSIS's coatings and filters include optical thickness of filters to assure parfocality, filter wedge, and coating and filter scattering.

The organometallic chemical vapor deposition of transition metal carbides: The use of homoleptic alkyls

DOE Office of Scientific and Technical Information (OSTI.GOV)

Healy, M.D.; Smith, D.C.; Springer, R.W.

1993-12-31

The organometallic chemical vapor deposition of transition metal carbides (M = Ti, Zr, Hf, and Cr) from tetraneopentyl-metal precursors has been carried out. Metal carbides can be deposited on Si, Al{sub 2}O{sub 3}, and stainless steel substrates from M[CH{sub 2}C(CH{sub 3}){sub 3}]{sub 4} at temperatures in the range of 300 to 750 C and pressures from 10{sup {minus}2} to 10{sup {minus}4} Torr. Thin films have also been grown using a carrier gas (Ar, H{sub 2}). The effects of variation of the metal center, deposition conditions, and reactor design on the resulting material have been examined by SEM, XPS, XRD, ERDmore » and AES. Hydrocarbon fragments generated in the deposition chamber have been studied in by in-situ mass spectrometry. Complementary studies examining the UHV surface decomposition of Zr[CH{sub 2}C(CH{sub 3}){sub 3}]{sub 4} have allowed for a better understanding of the mechanism leading to film growth.« less

Thermal stability of MBE-grown epitaxial MoSe2 and WSe2 thin films

NASA Astrophysics Data System (ADS)

Chang, Young Jun; Choy, Byoung Ki; Phark, Soo-Hyon; Kim, Minu

Layered transition metal dichalcogenides (TMDs) draw much attention, because of its unique optical properties and band structures depending on the layer thicknesses. However, MBE growth of epitaxial films demands information about thermal stability of stoichiometry and related electronic structure for high temperature range. We grow epitaxial MoSe2 and WSe2 ultrathin films by using molecular beam epitaxy (MBE). We characterize stoichiometry of films grown at various growth temperature by using various methods, XPS, EDX, and TOF-MEIS. We further test high temperature stability of electronic structure for those films by utilizing in-situ ellipsometry attached to UHV chamber. We discuss threshold temperatures up to 700~1000oC, at which electronic phases changes from semiconductor to metal due to selenium deficiency. This information can be useful for potential application of TMDs for fabrication of Van der Waals multilayers and related devices. This research was supported by Nano.Material Technology Development Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Science, ICT and Future Planning. (2009-0082580), NRF-2014R1A1A1002868.

Development of in situ two-coil mutual inductance technique in a multifunctional scanning tunneling microscope.

PubMed

Duan, Ming-Chao; Liu, Zhi-Long; Ge, Jian-Feng; Tang, Zhi-Jun; Wang, Guan-Yong; Wang, Zi-Xin; Guan, Dandan; Li, Yao-Yi; Qian, Dong; Liu, Canhua; Jia, Jin-Feng

2017-07-01

Superconducting thin films have been a focal point for intensive research efforts since their reduced dimension allows for a wide variety of quantum phenomena. Many of these films, fabricated in UHV chambers, are highly vulnerable to air exposure, making it difficult to measure intrinsic superconducting properties such as zero resistance and perfect diamagnetism with ex situ experimental techniques. Previously, we developed a multifunctional scanning tunneling microscope (MSTM) containing in situ four-point probe (4PP) electrical transport measurement capability in addition to the usual STM capabilities [Ge et al., Rev. Sci. Instrum. 86, 053903 (2015)]. Here we improve this MSTM via development of both transmission and reflection two-coil mutual inductance techniques for in situ measurement of the diamagnetic response of a superconductor. This addition does not alter the original STM and 4PP functions of the MSTM. We demonstrate the performance of the two-coil mutual inductance setup on a 10-nm-thick NbN thin film grown on a Nb-doped SrTiO 3 (111) substrate.

Dispensing of very low volumes of ultra high viscosity alginate gels: a new tool for encapsulation of adherent cells and rapid prototyping of scaffolds and implants.

PubMed

Gepp, Michael M; Ehrhart, Friederike; Shirley, Stephen G; Howitz, Steffen; Zimmermann, Heiko

2009-01-01

We present a tool for dispensing very low volumes (20 nL or more) of ultra high viscosity (UHV) medical-grade alginate hydrogels. It uses a modified piezo-driven micrometering valve, integrated into a versatile system that allows fast prototyping of encapsulation procedures and scaffold production. Valves show excellent dispensing properties for UHV alginate in concentrations of 0.4% and 0.7% and also for aqueous liquids. An optimized process flow provides excellent handling of biological samples under sterile conditions. This technique allows the encapsulation of adherent cells and structuring of substrates for biotechnology and regenerative medicine. A variety of cell lines showed at least 70% viability after encapsulation (including cell lines that are relevant in regenerative medicine like Hep G2), and time-lapse analysis revealed cells proliferating and showing limited motility under alginate spots. Cells show metabolic activity, gene product expression, and physiological function. Encapsulated cells have contact with the substrate and can exchange metabolites while being isolated from macromolecules in the environment. Contactless dispensing allows structuring of substrates with alginate, isolation and transfer of cell-alginate complexes, and the dispensing of biological active hydrogels like extracellular matrix-derived gels.

Development of a simple, low cost, indirect ion beam fluence measurement system for ion implanters, accelerators

NASA Astrophysics Data System (ADS)

Suresh, K.; Balaji, S.; Saravanan, K.; Navas, J.; David, C.; Panigrahi, B. K.

2018-02-01

We developed a simple, low cost user-friendly automated indirect ion beam fluence measurement system for ion irradiation and analysis experiments requiring indirect beam fluence measurements unperturbed by sample conditions like low temperature, high temperature, sample biasing as well as in regular ion implantation experiments in the ion implanters and electrostatic accelerators with continuous beam. The system, which uses simple, low cost, off-the-shelf components/systems and two distinct layers of in-house built softwarenot only eliminates the need for costly data acquisition systems but also overcomes difficulties in using properietry software. The hardware of the system is centered around a personal computer, a PIC16F887 based embedded system, a Faraday cup drive cum monitor circuit, a pair of Faraday Cups and a beam current integrator and the in-house developed software include C based microcontroller firmware and LABVIEW based virtual instrument automation software. The automatic fluence measurement involves two important phases, a current sampling phase lasting over 20-30 seconds during which the ion beam current is continuously measured by intercepting the ion beam and the averaged beam current value is computed. A subsequent charge computation phase lasting 700-900 seconds is executed making the ion beam to irradiate the samples and the incremental fluence received by the sampleis estimated usingthe latest averaged beam current value from the ion beam current sampling phase. The cycle of current sampling-charge computation is repeated till the required fluence is reached. Besides simplicity and cost-effectiveness, other important advantages of the developed system include easy reconfiguration of the system to suit customisation of experiments, scalability, easy debug and maintenance of the hardware/software, ability to work as a standalone system. The system was tested with different set of samples and ion fluences and the results were verified using Rutherford backscattering technique which showed the satisfactory functioning of the system. The accuracy of the fluence measurements is found to be less than 2% which meets the demands of the irradiation experiments undertaken using the developed set up. The system was incorporated for regular use at the existing ultra high vacuum (UHV) ion irradiation chamber of 1.7 MV Tandem accelerator and several ion implantation experiments on a variety of samples like SS304, D9, ODS alloys have been successfully carried out.

Automated soil gas monitoring chamber

DOEpatents

Edwards, Nelson T.; Riggs, Jeffery S.

2003-07-29

A chamber for trapping soil gases as they evolve from the soil without disturbance to the soil and to the natural microclimate within the chamber has been invented. The chamber opens between measurements and therefore does not alter the metabolic processes that influence soil gas efflux rates. A multiple chamber system provides for repetitive multi-point sampling, undisturbed metabolic soil processes between sampling, and an essentially airtight sampling chamber operating at ambient pressure.

Surface characterization of tin-based inorganic EUV resists

NASA Astrophysics Data System (ADS)

Frederick, Ryan T.; Diulus, J. Trey; Lyubinetsky, Igor; Hutchison, Danielle C.; Olsen, Morgan R.; Nyman, May; Herman, Gregory S.

2018-03-01

Metal oxide nanomaterials have shown promise for use as EUV resists. Recently, significant efforts have focused on tinoxo clusters that have high absorption coefficient Sn centers and radiation sensitive organic ligands. In our studies, we have investigated a β-Keggin butyl-Sn cluster (β-NaSn13), which is charge-neutral and allows studying radiation induced chemistries without interference from counterions. We have used ambient pressure X-ray photoelectron spectroscopy (APXPS) to investigate the contrast properties of the β-NaSn13 in ultrahigh vacuum (UHV) and in the presence of ambient oxygen. These contrast studies indicate that ambient oxygen reduces the dose requirements for the solubility transition of the β-NaSn13 photoresists. APXPS spectra collected before and after the solubility transition shows that ambient oxygen causes a greater loss of butyl ligands from the samples and the formation of more tin oxide for larger doses, suggesting the presence of reactive oxygen species. APXPS was also used to study processes during the post exposure bake, where we compared the differences in film chemistries in ambient oxygen or in UHV. There were only very small differences in the APXPS spectra before exposure and after exposure and the post exposure bake. However, ambient oxygen resulted in some changes for unexposed regions during the post exposure bake; there was a greater ratio of tin oxide to other oxygen species (alkoxy ligands, hydroxyls) for samples annealed in oxygen. These results have significance for EUV and e-beam lithography processing parameters, as well as implications for cluster design and ligand chemistries.

Computational fluid dynamic (CFD) investigation of thermal uniformity in a thermal cycling based calibration chamber for MEMS

NASA Astrophysics Data System (ADS)

Gui, Xulong; Luo, Xiaobing; Wang, Xiaoping; Liu, Sheng

2015-12-01

Micro-electrical-mechanical system (MEMS) has become important for many industries such as automotive, home appliance, portable electronics, especially with the emergence of Internet of Things. Volume testing with temperature compensation has been essential in order to provide MEMS based sensors with repeatability, consistency, reliability, and durability, but low cost. Particularly, in the temperature calibration test, temperature uniformity of thermal cycling based calibration chamber becomes more important for obtaining precision sensors, as each sensor is different before the calibration. When sensor samples are loaded into the chamber, we usually open the door of the chamber, then place fixtures into chamber and mount the samples on the fixtures. These operations may affect temperature uniformity in the chamber. In order to study the influencing factors of sample-loading on the temperature uniformity in the chamber during calibration testing, numerical simulation work was conducted first. Temperature field and flow field were simulated in empty chamber, chamber with open door, chamber with samples, and chamber with fixtures, respectively. By simulation, it was found that opening chamber door, sample size and number of fixture layers all have effects on flow field and temperature field. By experimental validation, it was found that the measured temperature value was consistent with the simulated temperature value.

UHV-TEM/TED observation of Ag islands grown on Si( 1 1 1 ) 3× 3-Ag surface

NASA Astrophysics Data System (ADS)

Oshima, Yoshifumi; Nakade, Hiroyuki; Shigeki, Sinya; Hirayama, Hiroyuki; Takayanagi, Kunio

2001-11-01

Growths of Ag islands on Si(1 1 1)3×3-Ag surface at room temperature were observed by UHV transmission electron microscopy and diffraction. The Ag islands grown after six monolayer deposition had neither (1 0 0) nor (1 1 0) orientation, but had two complex epitaxial orientations dominantly. One was striped islands which gave rise to a diffraction pattern commensurate with the 3×3 lattice of the Si(1 1 1) surface. The other was the coagulated islands whose diffraction pattern indicated the Ag(1 -3 4) sheet grown parallel to the Si(1 1 1) surface.

Surface science approach to Pt/carbon model catalysts: XPS, STM and microreactor studies

NASA Astrophysics Data System (ADS)

Motin, Abdul Md.; Haunold, Thomas; Bukhtiyarov, Andrey V.; Bera, Abhijit; Rameshan, Christoph; Rupprechter, Günther

2018-05-01

Pt nanoparticles supported on carbon are an important technological catalyst. A corresponding model catalyst was prepared by physical vapor deposition (PVD) of Pt on sputtered HOPG (highly oriented pyrolytic graphite). The carbon substrate before and after sputtering as well as the Pt/HOPG system before and after Pt deposition and annealing were examined by XPS and STM. This yielded information on the surface density of defects, which serve as nucleation centres for Pt, and on the size distribution (mean size/height) of the Pt nanoparticles. Two different model catalysts were prepared with mean sizes of 2.0 and 3.6 nm, both turned out to be stable upon UHV-annealing to 300 °C. After transfer into a UHV-compatible flow microreactor and subsequent cleaning in UHV and under mbar pressure, the catalytic activity of the Pt/HOPG model system for ethylene hydrogenation was examined under atmospheric pressure flow conditions. This enabled to determine temperature-dependent conversion rates, turnover frequencies (TOFs) and activation energies. The catalytic results obtained are in line with the characteristics of technological Pt/C, demonstrating the validity of the current surface science based model catalyst approach.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Posch, J.

Systems and philosophies perceived on a grand scale, encompassing new ideas, are often characterized as a dream. But in fact, such dreams often lead to the first step to fruitful development. This article is based on a preliminary study of the existing electrical high-tension networks of Western Europe, Eastern Europe and the Soviet Union - which, as explained herein, may be merged into a multinational energy supply system. Such a system would constitute a completely interconnected Eurasian Power Grid. The idea of a Eurasian super grid, spanning from the Atlantic to the Ural and Siberia, is not new. Various studiesmore » have been conducted by both western Europe and the Soviet Union on this topic. Our world is currently in an era of extra high voltage (EHV) and ultra high voltage (UHV) electrical systems. This translates into existing UHV lines of 1150 kV which have already been proven in successful operation. Such UHV systems are capable of transmitting thousands of megawatts over a distance of a 1000 miles. Furthermore, national boundaries are not more a hindrance than the challenge of interconnecting complete networks into an overall synchronized working system with load exchange capabilities in all directions.« less

NC-AFM observation of atomic scale structure of rutile-type TiO2(110) surface prepared by wet chemical process.

PubMed

Namai, Yoshimichi; Matsuoka, Osamu

2006-04-06

We succeeded in observing the atomic scale structure of a rutile-type TiO2(110) single-crystal surface prepared by the wet chemical method of chemical etching in an acid solution and surface annealing in air. Ultrahigh vacuum noncontact atomic force microscopy (UHV-NC-AFM) was used for observing the atomic scale structures of the surface. The UHV-NC-AFM measurements at 450 K, which is above a desorption temperature of molecularly adsorbed water on the TiO2(110) surface, enabled us to observe the atomic scale structure of the TiO2(110) surface prepared by the wet chemical method. In the UHV-NC-AFM measurements at room temperature (RT), however, the atomic scale structure of the TiO2(110) surface was not observed. The TiO2(110) surface may be covered with molecularly adsorbed water after the surface was prepared by the wet chemical method. The structure of the TiO2(110) surface that was prepared by the wet chemical method was consistent with the (1 x 1) bulk-terminated model of the TiO2(110) surface.

Unexpected mechanical properties of very dry Berea sandstone near 45°C

NASA Astrophysics Data System (ADS)

Miller, R. A.; Darling, T. W.; TenCate, J. A.; Johnson, P. A.

2011-12-01

An understanding of the nonlinear and hysteretic behavior of porous rocks is important for seismic studies and geologic carbon sequestration applications. However, the fundamental processes responsible for such behavior are poorly understood, including interactions involving adsorbed water and bulk carbon dioxide. Water has been shown to affect the nonlinear mechanical properties of porous rocks, both in high humidity conditions and in low pressure conditions where only a monolayer of water is present on rock grain surfaces [1, 2]. To study the impact of small quantities of adsorbed water on the nonlinear behavior of sandstone, we compare nonlinear resonant ultrasound spectroscopy (NRUS) and time-of-flight modulation (TOFM) measurements [3] on a Berea sandstone core before and after removing bulk water from the sample. Water is removed through extended exposure to ultra high vacuum (UHV) conditions. At the sample's driest state, we achieve a partial pressure of water below 10-8 Torr at room temperature. Periodic measurements record acoustic data as the rock is slowly heated from room temperature to 55°C in UHV. Measurements made after several months of exposure to UHV conditions show behavior we have not previously observed. We report an unexpected sharp increase in Q-1 above 45°C, suggesting we have reduced the concentration of water to a low enough level to affect the sample's mechanical properties. Nonlinear effects are still present when the sample is at its driest state below 45°C, in agreement with previous work [4], which indicates water is not the sole contributor to nonlinearity in porous rock. We are also studying the effect of adding carbon dioxide or argon gas to the dry specimen. We present our acoustic data and propose a model for the impact of adsorbed water on the attenuation of porous rock. [We gratefully acknowledge support from the Nevada Terawatt Facility at the University of Nevada, Reno, and from the Geosciences Research Program of the DOE Office of Basic Energy Sciences]. [1] B. R. Tittmann, L. Ahlberg, and J. Curnow, "Internal friction and velocity measurements," Proc. of 7th Lunar Science Conference , pp. 3123-3132, 1997. [2] K. E.-A. Van Den Abeele, J. Carmeliet, P. A. Johnson, and B. Zinszner, "Influence of water saturation on the nonlinear elastic mesoscopic response in Earth materials and the implications to the mechanism of nonlinearity," Journal of Geophysical Research 107, p. 2121, June 2002. [3] "Dynamic Measures of Elastic Nonlinear (Anelastic) Behavior: Dynamic Acousto-Elasticity Testing (DAET)," G. Renaud, P-Y Le Bas, J. A. TenCate, T. J. Ulrich, J. W. Carey, J. Han, T.W. Darling and P. A. Johnson, AGU Fall Meeting, Dec. 2011. [4] "Water and CO2 chemistry influences on the mechanical integrity of rocks," T.W. Darling, P-Y Le Bas, J. W. Carey, P. A. Johnson and R. A. Miller, AGU Fall Meeting, Dec. 2010.

Apparatus for preparing a sample for mass spectrometry

DOEpatents

Villa-Aleman, Eliel

1994-01-01

An apparatus for preparing a sample for analysis by a mass spectrometer system. The apparatus has an entry chamber and an ionization chamber separated by a skimmer. A capacitor having two space-apart electrodes followed by one or more ion-imaging lenses is disposed in the ionization chamber. The chamber is evacuated and the capacitor is charged. A valve injects a sample gas in the form of sample pulses into the entry chamber. The pulse is collimated by the skimmer and enters the ionization chamber. When the sample pulse passes through the gap between the electrodes, it discharges the capacitor and is thereby ionized. The ions are focused by the imaging lenses and enter the mass analyzer, where their mass and charge are analyzed.

Device and method for automated separation of a sample of whole blood into aliquots

DOEpatents

Burtis, Carl A.; Johnson, Wayne F.

1989-01-01

A device and a method for automated processing and separation of an unmeasured sample of whole blood into multiple aliquots of plasma. Capillaries are radially oriented on a rotor, with the rotor defining a sample chamber, transfer channels, overflow chamber, overflow channel, vent channel, cell chambers, and processing chambers. A sample of whole blood is placed in the sample chamber, and when the rotor is rotated, the blood moves outward through the transfer channels to the processing chambers where the blood is centrifugally separated into a solid cellular component and a liquid plasma component. When the rotor speed is decreased, the plasma component backfills the capillaries resulting in uniform aliquots of plasma which may be used for subsequent analytical procedures.

Effect of headspace mixing in static chambers and sampling protocol on calculated CH4 fluxes from soils

NASA Astrophysics Data System (ADS)

Juszczak, R.; Pihlatie, M.; Christiansen, J. R.; Giebels, M.; Schreiber, P.; Aaltonen, H.; Korhonen, J.; Rasilo, T.; Chojnicki, B. H.; Urbaniak, M.

2009-04-01

Closed static chambers are often used for greenhouse gas flux measurements from soils. The type of chamber, chamber handling and sampling protocol can influence the measurements. In most cases the calculated fluxes are suspected to be underestimated mainly because of reduction of gas diffusion from the soil to chamber headspace due to changed trace gas concentration gradient. Thus, fans are often applied to obtain better mixing of the air inside the chamber headspace and in turn reduce the negative effect of decreased concentration gradient. The open question is, however, to which extent the fluxes are changed by fans and whether they still remain underestimated or may even be overestimated? On the other hand, different sampling protocols are used assuming that they do not affect the flux measurements. To test different types of static chambers and different sampling procedures applied for measurement of greenhouse gas (CH4 and N2O) fluxes a chamber calibration campaign was organized at Hyytiälä Forestry Field Station in Southern Finland during August-October 2008. The main aim of the campaign was to quantitatively assess the uncertaintities and errors related to static chamber measurements. During this campaign static chambers were tested for 5 different CH4 and N2O flux levels with 3 different soil conditions (moisture and porosity) in a calibration tank described by Pumpanen et al. (2004). Among the different experiments, several special tests were carried out with the closed static chambers. Here, results of two special tests are presented to document whether 1) the air mixing inside the chamber headspace, 2) different sampling procedures influence the CH4 fluxes, and 3) how different calculation methods lead to varying results. Two static chambers of different volumes (65.5 and 195 liters) but with the same circular shape and surface area were connected to a LOS GATOS fats methane analyzer. The CH4 concentration inside the chamber headspace was monitored continuously with 1Hz frequency. Additionally, two different manual samplings procedures were tested and gas samples from chamber headspace were taken for gas chromatograph (GC) and analysed in two different laboratories. Gas concentrations in the calibration tank were monitored with a GC and an automatic gas analyzer (INNOVA). The preliminary results showed that air mixing inside the chamber headspace, the way of chamber handling and sampling procedures could have pronounced influence on the trace gas concentration detection inside a chamber, and as a consequence the calculated chamber fluxes. The moment of chamber enclosure can lead to a rapid increase in CH4 concentration due to a pressure effect in the chambers without a vent tube. Thus, it is essential to critically estimate the time of the first sampling so that it is early enough after chamber enclosure, but not disturbed by the initial chamber handling. It was also observed that manual sampling of gas can change the CH4 concentration in the chamber headspace. When mixing the chamber headspace air by a syringe, the subsequent gas sampling in the syringe may affect the diffusion of gas between the soil and the chamber headspace, and hence affect the calculated fluxes. It was observed that mixing the chamber headspace with a fan instead of syringes, reduced this effect during the chamber enclosure. Overall, fluxes measured with chamber equipped with a fan always gave higher fluxes (up to 40%) as compared to fluxes measured from chambers without a fan. Results of our experiment lead to the assumption that these differences were generally larger the higher the chamber was, the less porous the soil was, and the higher the fluxes were. We conclude from our experiment that static chambers used for greenhouse gas flux measurements should be equipped with at least one fan and a vent tube to increase mixing and reduce pressure propagation in the chamber-soil system, and that special attention should be paid to the handling of the chamber and to the timing of the gas sampling. References: Pumpanen, J., Kolari, P., Ilvesniemi, H., Minkkinen, K., Vesala, T., Niinistö, S., Lohila, A., Larmola, T., Morero, M., Pihlatie, M., Janssens, I., Curiel Yuste, J., Grünzweig, J. M., Reth, S., Subke, J.-A., Savage, K., Kutsch, W., Østreng, G., Ziegler, W., Anthoni, P., Lindroth, A. & Hari, P. 2004. Comparison of different chamber techniques for measuring soil CO2 efflux. Agricultural and Forest Meteorology 123, 159-176.

Combined optical gain and degradation measurements in DCM2 doped Tris-(8-hydroxyquinoline)aluminum thin-films

NASA Astrophysics Data System (ADS)

Čehovski, Marko; Döring, Sebastian; Rabe, Torsten; Caspary, Reinhard; Kowalsky, Wolfgang

2016-04-01

Organic laser sources offer the opportunity to integrate flexible and widely tunable lasers in polymer waveguide circuits, e.g. for Lab-on-Foil applications. Therefore, it is necessary to understand gain and degradation processes for long-term operation. In this paper we address the challenge of life-time (degradation) measurements of photoluminescence (PL) and optical gain in thin-film lasers. The well known guest-host system of aluminum-chelate Alq3 (Tris-(8-hydroxyquinoline)aluminum) as host material and the laser dye DCM2 (4-(Dicyanomethylene)-2- methyl-6-julolidyl-9-enyl-4H-pyran) as guest material is employed as laser active material. Sample layers have been built up by co-evaporation in an ultrahigh (UHV) vacuum chamber. 200nm thick films of Alq3:DCM2 with different doping concentrations have been processed onto glass and thermally oxidized silicon substrates. The gain measurements have been performed by the variable stripe length (VSL) method. This measurement technique allows to determine the thin-film waveguide gain and loss, respectively. For the measurements the samples were excited with UV irradiation (ƛ = 355nm) under nitrogen atmosphere by a passively Q-switched laser source. PL degradation measurements with regard to the optical gain have been done at laser threshold (approximately 3 μJ/cm2), five times above laser threshold and 10 times above laser threshold. A t50-PL lifetime of > 107 pulses could be measured at a maximum excitation energy density of 32 μJ/cm2. This allows for a detailed analysis of the gain degradation mechanism and therefore of the stimulated cross section. Depending on the DCM2 doping concentration C the stimulated cross section was reduced by 35 %. Nevertheless, the results emphasizes the necessity of the investigation of degradation processes in organic laser sources for long-term applications.

A new generation of x-ray spectrometry UHV instruments at the SR facilities BESSY II, ELETTRA and SOLEIL

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lubeck, J., E-mail: janin.lubeck@ptb.de; Fliegauf, R.; Holfelder, I.

A novel type of ultra-high vacuum instrument for X-ray reflectometry and spectrometry-related techniques for nanoanalytics by means of synchrotron radiation (SR) has been constructed and commissioned at BESSY II. This versa-tile instrument was developed by the PTB, Germany’s national metrology institute, and includes a 9-axis manipulator that allows for an independent alignment of the samples with respect to all degrees of freedom. In addition, it integrates a rotational and translational movement of several photodiodes as well as a translational movement of a beam-geometry-defining aperture system. Thus, the new instrument enables various analytical techniques based on energy dispersive X-ray detectors suchmore » as reference-free X-Ray Fluorescence (XRF) analysis, total-reflection XRF, grazing-incidence XRF, in addition to optional X-Ray Reflectometry (XRR) measurements or polarization-dependent X-ray absorption fine structure analyses (XAFS). Samples having a size of up to (100 × 100) mm{sup 2}; can be analyzed with respect to their mass deposition, elemental, spatial or species composition. Surface contamination, nanolayer composition and thickness, depth pro-file of matrix elements or implants, nanoparticles or buried interfaces as well as molecular orientation of bonds can be accessed. Three technology transfer projects of adapted instruments have enhanced X-Ray Spectrometry (XRS) research activities within Europe at the synchrotron radiation facilities ELETTRA (IAEA) and SOLEIL (CEA/LNE-LNHB) as well as at the X-ray innovation laboratory BLiX (TU Berlin) where different laboratory sources are used. Here, smaller chamber requirements led PTB in cooperation with TU Berlin to develop a modified instrument equipped with a 7-axis manipulator: reduced freedom in the choice of experimental geometry modifications (absence of out-of-SR-plane and reference-free XRS options) has been compensated by encoder-enhanced angular accuracy for GIXRF and XRR.« less

Technical note: Headspace analysis of explosive compounds using a novel sampling chamber.

PubMed

DeGreeff, Lauryn; Rogers, Duane A; Katilie, Christopher; Johnson, Kevin; Rose-Pehrsson, Susan

2015-03-01

The development of instruments and methods for explosive vapor detection is a continually evolving field of interest. A thorough understanding of the characteristic vapor signatures of explosive material is imperative for the development and testing of new and current detectors. In this research a headspace sampling chamber was designed to contain explosive materials for the controlled, reproducible sampling and characterization of vapors associated with these materials. In a detonation test, the chamber was shown to contain an explosion equivalent to three grams of trinitrotoluene (TNT) without damage to the chamber. The efficacy of the chamber in controlled headspace sampling was evaluated in laboratory tests with bulk explosive materials. Small quantities of TNT, triacetone triperoxide (TATP) and hexamethylene triperoxide diamine (HMTD) were separately placed in the sampling chamber, and the headspace of each material was analyzed by gas chromatography/mass spectrometry (GC/MS) with online cryogenic trapping to yield characteristic vapor signatures for each explosive compound. Chamber sampling conditions, temperature and sampling time, were varied to demonstrate suitability for precise headspace analysis. Published by Elsevier Ireland Ltd.

Apparatus for preparing a sample for mass spectrometry

DOEpatents

Villa-Aleman, E.

1994-05-10

An apparatus is described for preparing a sample for analysis by a mass spectrometer system. The apparatus has an entry chamber and an ionization chamber separated by a skimmer. A capacitor having two space-apart electrodes followed by one or more ion-imaging lenses is disposed in the ionization chamber. The chamber is evacuated and the capacitor is charged. A valve injects a sample gas in the form of sample pulses into the entry chamber. The pulse is collimated by the skimmer and enters the ionization chamber. When the sample pulse passes through the gap between the electrodes, it discharges the capacitor and is thereby ionized. The ions are focused by the imaging lenses and enter the mass analyzer, where their mass and charge are analyzed. 1 figures.

Portable automation of static chamber sample collection for quantifying soil gas flux

USDA-ARS?s Scientific Manuscript database

The collection of soil gas flux using the static chamber method is labor intensive. The number of chambers that can be sampled in a given time period is limited by the spacing between chambers and the availability of trained research technicians. However, the static chamber method can limit spatial ...

Portable Automation of Static Chamber Sample Collection for Quantifying Soil Gas Flux

DOE Office of Scientific and Technical Information (OSTI.GOV)

Davis, Morgan P.; Groh, Tyler A.; Parkin, Timothy B.

Quantification of soil gas flux using the static chamber method is labor intensive. The number of chambers that can be sampled is limited by the spacing between chambers and the availability of trained research technicians. An automated system for collecting gas samples from chambers in the field would eliminate the need for personnel to return to the chamber during a flux measurement period and would allow a single technician to sample multiple chambers simultaneously. This study describes Chamber Automated Sampling Equipment (FluxCASE) to collect and store chamber headspace gas samples at assigned time points for the measurement of soil gasmore » flux. The FluxCASE design and operation is described, and the accuracy and precision of the FluxCASE system is evaluated. In laboratory measurements of nitrous oxide (N2O), carbon dioxide (CO2), and methane (CH4) concentrations of a standardized gas mixture, coefficients of variation associated with automated and manual sample collection were comparable, indicating no loss of precision. In the field, soil gas fluxes measured from FluxCASEs were in agreement with manual sampling for both N2O and CO2. Slopes of regression equations were 1.01 for CO2 and 0.97 for N2O. The 95% confidence limits of the slopes of the regression lines included the value of one, indicating no bias. Additionally, an expense analysis found a cost recovery ranging from 0.6 to 2.2 yr. Implementing the FluxCASE system is an alternative to improve the efficiency of the static chamber method for measuring soil gas flux while maintaining the accuracy and precision of manual sampling.« less

Apparatus for transporting hazardous materials

DOEpatents

Osterman, Robert A.; Cox, Robert

1992-01-01

An apparatus and method are provided for selectively receiving, transporting, and releasing one or more radioactive or other hazardous samples for analysis on a differential thermal analysis (DTA) apparatus. The apparatus includes a portable sample transporting apparatus for storing and transporting the samples and includes a support assembly for supporting the transporting apparatus when a sample is transferred to the DTA apparatus. The transporting apparatus includes a storage member which includes a plurality of storage chambers arrayed circumferentially with respect to a central axis. An adjustable top door is located on the top side of the storage member, and the top door includes a channel capable of being selectively placed in registration with the respective storage chambers thereby permitting the samples to selectively enter the respective storage chambers. The top door, when closed, isolates the respective samples within the storage chambers. A plurality of spring-biased bottom doors are located on the bottom sides of the respective storage chambers. The bottom doors isolate the samples in the respective storage chambers when the bottom doors are in the closed position. The bottom doors permit the samples to leave the respective storage chambers from the bottom side when the respective bottom doors are in respective open positions. The bottom doors permit the samples to be loaded into the respective storage chambers after the analysis for storage and transport to a permanent storage location.

Ambient atomic resolution atomic force microscopy with qPlus sensors: Part 1.

PubMed

Wastl, Daniel S

2017-01-01

Atomic force microscopy (AFM) is an enormous tool to observe nature in highest resolution and understand fundamental processes like friction and tribology on the nanoscale. Atomic resolution in highest quality was possible only in well-controlled environments like ultrahigh vacuum (UHV) or controlled buffer environments (liquid conditions) and more specified for long-term high-resolution analysis at low temperatures (∼4 K) in UHV where drift is nearly completely absent. Atomic resolution in these environments is possible and is widely used. However, in uncontrolled environments like air, with all its pollutants and aerosols, unspecified thin liquid films as thin as a single molecular water-layer of 200 pm or thicker condensation films with thicknesses up to hundred nanometer, have been a problem for highest resolution since the invention of the AFM. The goal of true atomic resolution on hydrophilic as well as hydrophobic samples was reached recently. In this manuscript we want to review the concept of ambient AFM with atomic resolution. The reader will be introduced to the phenomenology in ambient conditions and the problems will be explained and analyzed while a method for scan parameter optimization will be explained. Recently developed concepts and techniques how to reach atomic resolution in air and ultra-thin liquid films will be shown and explained in detail, using several examples. Microsc. Res. Tech. 80:50-65, 2017. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

Rain sampling device

DOEpatents

Nelson, D.A.; Tomich, S.D.; Glover, D.W.; Allen, E.V.; Hales, J.M.; Dana, M.T.

1991-05-14

The present invention constitutes a rain sampling device adapted for independent operation at locations remote from the user which allows rainfall to be sampled in accordance with any schedule desired by the user. The rain sampling device includes a mechanism for directing wet precipitation into a chamber, a chamber for temporarily holding the precipitation during the process of collection, a valve mechanism for controllably releasing samples of the precipitation from the chamber, a means for distributing the samples released from the holding chamber into vessels adapted for permanently retaining these samples, and an electrical mechanism for regulating the operation of the device. 11 figures.

Rain sampling device

DOEpatents

Nelson, Danny A.; Tomich, Stanley D.; Glover, Donald W.; Allen, Errol V.; Hales, Jeremy M.; Dana, Marshall T.

1991-01-01

The present invention constitutes a rain sampling device adapted for independent operation at locations remote from the user which allows rainfall to be sampled in accordance with any schedule desired by the user. The rain sampling device includes a mechanism for directing wet precipitation into a chamber, a chamber for temporarily holding the precipitation during the process of collection, a valve mechanism for controllably releasing samples of said precipitation from said chamber, a means for distributing the samples released from the holding chamber into vessels adapted for permanently retaining these samples, and an electrical mechanism for regulating the operation of the device.

Rotating drum variable depth sampler

DOEpatents

Nance, Thomas A [Aiken, SC; Steeper, Timothy J [Trenton, SC

2008-07-01

A sampling device for collecting depth-specific samples in silt, sludge and granular media has three chambers separated by a pair of iris valves. Rotation of the middle chamber closes the valves and isolates a sample in a middle chamber.

Note: Small anaerobic chamber for optical spectroscopy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chauvet, Adrien A. P., E-mail: adrien.chauvet@gmail.com; Chergui, Majed; Agarwal, Rachna

2015-10-15

The study of oxygen-sensitive biological samples requires an effective control of the atmosphere in which they are housed. In this aim however, no commercial anaerobic chamber is adequate to solely enclose the sample and small enough to fit in a compact spectroscopic system with which analysis can be performed. Furthermore, spectroscopic analysis requires the probe beam to pass through the whole chamber, introducing a requirement for adequate windows. In response to these challenges, we present a 1 l anaerobic chamber that is suitable for broad-band spectroscopic analysis. This chamber has the advantage of (1) providing access, via a septum, tomore » the sample and (2) allows the sample position to be adjusted while keeping the chamber fixed and hermetic during the experiment.« less

Remote water monitoring system

NASA Technical Reports Server (NTRS)

Grana, D. C.; Haynes, D. P. (Inventor)

1978-01-01

A remote water monitoring system is described that integrates the functions of sampling, sample preservation, sample analysis, data transmission and remote operation. The system employs a floating buoy carrying an antenna connected by lines to one or more sampling units containing several sample chambers. Receipt of a command signal actuates a solenoid to open an intake valve outward from the sampling unit and communicates the water sample to an identifiable sample chamber. Such response to each signal receipt is repeated until all sample chambers are filled in a sample unit. Each sample taken is analyzed by an electrochemical sensor for a specific property and the data obtained is transmitted to a remote sending and receiving station. Thereafter, the samples remain isolated in the sample chambers until the sampling unit is recovered and the samples removed for further laboratory analysis.

The behavior of N2 and O2 in pure, mixed or layered CO ices

NASA Astrophysics Data System (ADS)

Bisschop, Suzanne E.; Fraser, Helen J.; Fuchs, Guido; Öberg, Karin I.; Acharyya, Kinsuk; van Broekhuizen, Fleur; Schlemmer, Stephan; van Dishoeck, Ewine F.

N2 and O2 are molecules that are predicted to be abundant in dense molecular clouds. Both molecules are difficult to detect as neither has a dipole moment. The chemical abundance of N2 is mostly inferred from its daughter species N2H+, but was recently detected in the ISM for the first time, with an abundance of 3.3 × 10-7 (Knauth et al 2004). Searches for the submillimeter lines of O2 have given upper limits for the abundance of ≤ 2.6 10-7 for star forming clouds and ≤ 3 10-6 for cold dark clouds (Goldsmith et al. 2000). Pontoppidan et al. (2003) deduced from the CO line profile that CO is present in both H2O poor and H2O rich ice layers, so it follows that N2 is likely to be present in a H2O poor ice layer. In many cold and protostellar cores N2H+ is found to anti-correlate with HCO+ and CO (Bergin et al. 2001; Jørgensen et al. 2004). Models by, for example Bergin & Langer (1997), assume this is due to the balance between freeze-out and evaporation, where ratios for the binding energy for N2 compared to CO of 0.50-0.70 are used. To model these processes, and reproduce the observed abundances of each species it is important to determine empirically the binding energies, sticking probabilities and desorption kinetics of model ice systems containing CO, N2 and O2. It seems that these quantities depend on the degree to which N2 and O2 mix with CO. Therefore, CO and N2 ices were studied extensively in a Ultra High Vacuum (UHV) experiment (P ~ 1 × 10-10 Torr) (Oberg et al. 2005; Bisschop et al submitted)). Ice samples were deposited at 14 K on a polycrystalline gold sample, mounted in the UHV chamber, covering morphologies from pure CO and N2, and 1:1 mixtures, to 1/1 layers of both CO over N2 and N2 over CO, and layers of 40 L of CO (1 L ≈ 1 monolayer) covered with 5 to 50 L of N2. The ices were studied using a combination of Reflection Absorption Infrared Spectroscopy (RAIRS) and Temperature Programmed Desorption (TPD), at a ramp-rate of 0.1 K min-1. The TPD data were modeled to accurately determine the binding energies and desorption kinetics o each system, using information from the RAIR spectra to develop the model. Sticking probabilities were calculated from a comparison between the molecular load at the mass spectrometer during dosing onto a hot and cold sample surface. The experiments show that N2 desorption from pure N2 ice gives a slightly lower binding energy for N2-N2 than CO-CO, 790 ± 25 K and 855 ± 25 K respectively, resulting in a ratio RBE = 0.923 ± 0.003. The TPD data for the mixtures and layers (see Figure 1) show that N2 can also completely mix in with the CO ice. A fraction of the N2 molecules that have mixed into the CO-ice, desorb with CO, giving them an effective binding energy of 855 ± 25 K (RBE=1). In either case, this ratio is much closer to unity than that used in models by (for example) Bergin & Langer (1997).

The profile of the bending mode band in solid CO2

NASA Astrophysics Data System (ADS)

Baratta, G. A.; Palumbo, M. E.

2017-12-01

Context. Solid carbon dioxide (CO2) is one of the most abundant species detected in icy grain mantles in dense molecular clouds. Its identification is based on the comparison between astronomical and laboratory spectra. In the past 30 yr the profile of solid CO2 infrared absorption bands has been extensively studied experimentally, however, the debate on the structure (amorphous versus crystalline) of CO2 samples obtained in laboratory by the thin-film technique is still open. Aims: The aim of this work is to investigate if the presence of the double peak feature in the profile of the CO2 bending mode band is related to the crystalline or amorphous structure of the sample. Methods: We performed new laboratory experiments depositing CO2 under ultra high vacuum (UHV) conditions at 17 K. We investigated, using infrared transmission spectroscopy, the influence of various experimental parameters on the profile of the CO2 bands, namely deposition rate, sample thickness, annealing, and presence of H2O, CH3OH or CO co-deposited with CO2. Results: We found that, within experimental uncertainties, under UHV conditions the profile of the CO2 bands in pure solid samples does not depend on the deposition rate or the sample thickness in the ranges investigated. In all cases the bending mode band profile shows a double peak (at 660 and 655 cm-1). The spectra also show the Fermi resonance features that cannot be active in crystalline samples. On the other hand, when a small fraction of H2O or CH3OH is co-deposited with CO2 the double peak is not observed while it is observed when a CO2:CO mixture is considered. Furthermore, we measured the density of solid CO2 and the refractive index (at 543.5 nm) at 17 K and at 70 K: ρ(17 K)= 1.17 g cm-3, ρ(70K)= 1.49 g cm-3, n(17K)= 1.285, and n(70K)= 1.372. Conclusions: Our experimental results indicate that the presence of the double peak in the profile of the bending mode band is not an indication of a crystalline structure of the sample and they do not exclude the presence of amorphous solid CO2 in space.

Apparatus for Measuring Total Emissivity of Small, Low-Emissivity Samples

NASA Technical Reports Server (NTRS)

Tuttle, James; DiPirro, Michael J.

2011-01-01

An apparatus was developed for measuring total emissivity of small, lightweight, low-emissivity samples at low temperatures. The entire apparatus fits inside a small laboratory cryostat. Sample installation and removal are relatively quick, allowing for faster testing. The small chamber surrounding the sample is lined with black-painted aluminum honeycomb, which simplifies data analysis. This results in the sample viewing a very high-emissivity surface on all sides, an effect which would normally require a much larger chamber volume. The sample and chamber temperatures are individually controlled using off-the-shelf PID (proportional integral derivative) controllers, allowing flexibility in the test conditions. The chamber can be controlled at a higher temperature than the sample, allowing a direct absorptivity measurement. The lightweight sample is suspended by its heater and thermometer leads from an isothermal bar external to the chamber. The wires run out of the chamber through small holes in its corners, and the wires do not contact the chamber itself. During a steady-state measurement, the thermometer and bar are individually controlled at the same temperature, so there is zero heat flow through the wires. Thus, all of sample-temperature-control heater power is radiated to the chamber. Double-aluminized Kapton (DAK) emissivity was studied down to 10 K, which was about 25 K colder than any previously reported measurements. This verified a minimum in the emissivity at about 35 K and a rise as the temperature dropped to lower values.

AES, EELS and TRIM simulation method study of InP(100) subjected to Ar+, He+ and H+ ions bombardment.

NASA Astrophysics Data System (ADS)

Ghaffour, M.; Abdellaoui, A.; Bouslama, M.; Ouerdane, A.; Abidri, B.

2012-06-01

Auger Electron Spectroscopy (AES) and Electron Energy Loss Spectroscopy (EELS) have been performed in order to investigate the InP(100) surface subjected to ions bombardment. The InP(100) surface is always contaminated by carbon and oxygen revealed by C-KLL and O-KLL AES spectra recorded just after introduction of the sample in the UHV spectrometer chamber. The usually cleaning process of the surface is the bombardment by argon ions. However, even at low energy of ions beam (300 eV) indium clusters and phosphorus vacancies are usually formed on the surface. The aim of our study is to compare the behaviour of the surface when submitted to He+ or H+ ions bombardment. The helium ions accelerated at 500V voltage and for 45 mn allow removing contaminants but induces damaged and no stoichiometric surface. The proton ions were accelerated at low energy of 500 eV to bombard the InP surface at room temperature. The proton ions broke the In-P chemical bonds to induce the formation of In metal islands. Such a chemical reactivity between hydrogen and phosphorus led to form chemical species such as PH and PH3, which desorbed from the surface. The chemical susceptibly and the small size of H+ advantaged their diffusion into bulk. Since the experimental methods alone were not able to give us with accuracy the disturbed depth of the target by these ions. We associate to the AES and EELS spectroscopies, the TRIM (Transport and Range of Ions in Matter) simulation method in order to show the mechanism of interaction between Ar+, He+ or H+ ions and InP and determine the disturbed depth of the target by argon, helium or proton ions.

Method of retrieving a liquid sample, a suction lysimeter, a portable suction lysimeter, a lysimeter system, and a deep lysimeter

DOEpatents

Hubbell, Joel M.; Sisson, James B.

2003-08-26

A method of retrieving a liquid sample comprises providing a portable lysimeter including a semi-permeable membrane and a chamber in fluid communication with the semi-permeable membrane; making a hole at a site from which a liquid sample is desired; evacuating the chamber by applying a vacuum to the chamber; lowering the portable lysimeter into the hole; obtaining a sample in the chamber; and retrieving the lysimeter from the bore; wherein it is not necessary to backfill the bore. A portable lysimeter includes a semi-permeable member and a chamber in fluid communication with the semi-permeable membrane.

In situ surface/interface x-ray diffractometer for oxide molecular beam epitaxy

DOE PAGES

Lee, J. H.; Tung, I. C.; Chang, S. -H.; ...

2016-01-05

In situ studies of oxide molecular beam epitaxy by synchrotron x-ray scattering has been made possible by upgrading an existing UHV/molecular beam epitaxy (MBE) six-circle diffractometer system. For oxide MBE growth, pure ozone delivery to the chamber has been made available, and several new deposition sources have been made available on a new 12 in. CF (ConFlat, a registered trademark of Varian, Inc.) flange. X-ray diffraction has been used as a major probe for film growth and structures for the system. In the original design, electron diffraction was intended for the secondary diagnostics available without the necessity of the x-raymore » and located at separate positions. Deposition of films was made possible at the two diagnostic positions. And, the aiming of the evaporation sources is fixed to the point between two locations. Ozone can be supplied through two separate nozzles for each location. Also two separate thickness monitors are installed. Finally, additional features of the equipment are also presented together with the data taken during typical oxide film growth to illustrate the depth of information available via in situ x-ray techniques.« less

EMAT enhanced dispersion of particles in liquid

DOEpatents

Kisner, Roger A.; Rios, Orlando; Melin, Alexander M.; Ludtka, Gerard Michael; Ludtka, Gail Mackiewicz; Wilgen, John B.

2016-11-29

Particulate matter is dispersed in a fluid material. A sample including a first material in a fluid state and second material comprising particulate matter are placed into a chamber. The second material is spatially dispersed in the first material utilizing EMAT force. The dispersion process continues until spatial distribution of the second material enables the sample to meet a specified criterion. The chamber and/or the sample is electrically conductive. The EMAT force is generated by placing the chamber coaxially within an induction coil driven by an applied alternating current and placing the chamber and induction coil coaxially within a high field magnetic. The EMAT force is coupled to the sample without physical contact to the sample or to the chamber, by another physical object. Batch and continuous processing are utilized. The chamber may be folded within the bore of the magnet. Acoustic force frequency and/or temperature may be controlled.

High-temperature strain cell for tomographic imaging

DOEpatents

MacDowell, Alastair A.; Nasiatka, James; Haboub, Abdel; Ritchie, Robert O.; Bale, Hrishikesh A.

2015-06-16

This disclosure provides systems, methods, and apparatus related to the high temperature mechanical testing of materials. In one aspect, a method includes providing an apparatus. The apparatus may include a chamber. The chamber may comprise a top portion and a bottom portion, with the top portion and the bottom portion each joined to a window material. A first cooled fixture and a second cooled fixture may be mounted to the chamber and configured to hold the sample in the chamber. A plurality of heating lamps may be mounted to the chamber and positioned to heat the sample. The sample may be placed in the first and the second cooled fixtures. The sample may be heated to a specific temperature using the heating lamps. Radiation may be directed though the window material, the radiation thereafter interacting with the sample and exiting the chamber through the window material.

Synthesis, Properties, and Two-Dimensional Adsorption Characteristics of 5-Amino[6]hexahelicene.

PubMed

van der Meijden, Maarten W; Gelens, Edith; Quirós, Natalia Murillo; Fuhr, Javier D; Gayone, J Esteban; Ascolani, Hugo; Wurst, Klaus; Lingenfelder, Magalí; Kellogg, Richard M

2016-01-22

A convergent synthesis of racemic 5-amino[6]hexahelicene is described. Cross-coupling reactions are used to assemble a pentacyclic framework, and a metal-catalyzed ring-closure comprises the final step. The enantiomers were separated by means of chromatography and the absolute configurations were assigned by comparison of the CD spectra with hexahelicene. The t1/2  value for racemization at 210 °C was approximately 1 hour. Scanning tunneling microscopy (STM) measurements were carried out on enantiopure and racemic samples of aminohelicene on Au(111) under ultrahigh vacuum (UHV) conditions. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Design of an exposure chamber to test samplers used in the evaluation of personal exposure to nanoparticles

NASA Astrophysics Data System (ADS)

Amin, R.; Izadi, H.; Quémerais, B.

2015-05-01

The aim of this study was to design a laboratory size exposure chamber for the testing of samplers used to collect personal exposure samples for nanoparticles. A polyethylene cylindrical container with a diameter of 42 cm and height of 60 cm was used as the testing chamber. The chamber was divided into 2 parts by an aluminium honey comb. Particles generated using a 1 jet Collison nebulizer (BGI) operating at a flow rate of 4L/min were inserted into the chamber via a tube located near to the top of the chamber. A heater was inserted just after the nebulizer to avoid condensation of water in the tubing, and dilution air, running at 10L/min was inserted just after the heater. As particle charge can dramatically affect sampling a particle neutralizer was attached to the generation system so as to neutralize the particles before they enter the chamber. A diffusion dryer was used to remove any water from the air stream prior to enter the chamber. A fan was used to mix and distribute the generated particles. After generation and mixing, the particles passed through the aluminium honeycomb which is essential to eliminate any turbulent or unwanted air flow. Six sampling ports along with a pressure gauge were placed on the walls 15 cm from the bottom of the chamber. The pressure gauge was added to ensure the desired pressure is achieved during sampling. The sampling ports allowed for the connection of five samplers and sampling pumps as well as the connection of an ultrafine particle counter. The exposure chamber was developed to assess various samplers for carbon nanotubes and cellulose nanocrystals. Results showed that the chamber was working properly and that mixing was sufficiently uniform to test samplers.

Apparatus and method for the characterization of respirable aerosols

DOEpatents

Clark, Douglas K.; Hodges, Bradley W.; Bush, Jesse D.; Mishima, Jofu

2016-05-31

An apparatus for the characterization of respirable aerosols, including: a burn chamber configured to selectively contain a sample that is selectively heated to generate an aerosol; a heating assembly disposed within the burn chamber adjacent to the sample; and a sampling segment coupled to the burn chamber and configured to collect the aerosol such that it may be analyzed. The apparatus also includes an optional sight window disposed in a wall of the burn chamber such that the sample may be viewed during heating. Optionally, the sample includes one of a Lanthanide, an Actinide, and a Transition metal.

Electrophoresis device

NASA Technical Reports Server (NTRS)

Rhodes, P. H.; Snyder, R. S. (Inventor)

1982-01-01

A device for separating cellular particles of a sample substance into fractionated streams of different cellular species includes a casing having a distribution chamber, a separation chamber, and a collection chamber. The electrode chambers are separated from the separation chamber interior by means of passages such that flow variations and membrane variations around the slotted portion of the electrode chamber do not enduce flow perturbations into the laminar buffer curtain flowing in the separation chamber. The cellular particles of the sample are separated under the influence of the electrical field and the separation chamber into streams of different cellular species. The streams of separated cells enter a partition array in the collection chamber where they are fractionated and collected.

Note: Mechanical in situ exfoliation of van der Waals materials

NASA Astrophysics Data System (ADS)

Pásztor, Á.; Scarfato, A.; Renner, Ch.

2017-07-01

Exfoliation, namely, the peeling of layered materials down to a single unit-cell thin foil, opens promising avenues to fabricate novel electronic materials. New properties and original functionalities emerge in the single and few layer configurations of a number of layered compounds, in particular in transition metal dichalcogenides. However, many of these thin exfoliated materials are very sensitive to ambient conditions impeding the exploration of this new and fascinating parameter space. Here we describe a method of mechanical exfoliation in ultra-high vacuum (UHV). This technique is easily adaptable to any UHV system and allows preparing and studying air sensitive nanoflakes in situ. We present the basic design and proof-of-concept scanning tunneling microscopy imaging of VSe2 nanoflakes.

Annual Net Ecosystem Productivity of Wetlands: A Comparison of Automated and Manual Chamber Methods

NASA Astrophysics Data System (ADS)

Burrows, E. H.; Bubier, J. L.; Mosedale, A.; Crill, P. M.

2001-05-01

Net Ecosystem Exchange (NEE) of carbon dioxide (CO2) was measured in a minerotrophic poor fen in southeastern New Hampshire during the 2000 growing season using two types of chamber methods. Instantaneous CO2 flux was measured with transparent lexan and teflon static climate controlled chambers by calculating the change in headspace CO2 concentration in the chamber over time. Once per week the flux was sampled from ten manually operated chambers using a LI-COR 6200 portable photosynthesis system, which included a LI-6250 infrared gas analyzer, connected to the chambers. Ten automated chambers were installed in May of 2000, sampling CO2 flux every three hours over the diurnal cycle using a LI-COR 6262 infrared gas analyzer. The chambers and collars were placed throughout the fen in order to sample the range of plant communities. The manual sampling was done during the middle of the day, but the rate of photosynthesis changes depending on the amount of photosynthetically active radiation (PAR). In order to simulate varying light levels, shrouds blocking different amounts of light were placed over each manual chamber. An opaque shroud was used to measure respiration. NEE ranged from -13.0 to 12.5 μ mol CO2/m2/s in the manual chambers and -16.2 to 11.8 μ mol CO2/m2/s in the automated chambers for the mid-summer growing season. Manual respiration fluxes were measured under higher temperature regimes and the response of respiration to temperature will be factored in when comparing the two chamber techniques. Research during the summer of 2001 will also include diurnal measurements. Growing season net ecosystem productivity (NEP) will be estimated and compared for the two chamber systems. Several models will be used to estimate the flux when the manual chambers were not being sampled. The models will be based on biomass and dominant species in each chamber, and various environmental factors including water table, pH, relative humidity, PAR, air and peat temperature. These factors will also be used to compare differences in NEP among the chambers. Manual chambers provide greater spatial variability, but are more labor intensive. Automated chambers provide higher temporal resolution and sample more uniformly, but are more expensive and not feasible in isolated wetlands with no access to electricity. These complementary chamber techniques offer a unique opportunity to assess the variability and uncertainty in CO2 flux measurements.

Molecular-beam gas-sampling system

NASA Technical Reports Server (NTRS)

Young, W. S.; Knuth, E. L.

1972-01-01

A molecular beam mass spectrometer system for rocket motor combustion chamber sampling is described. The history of the sampling system is reviewed. The problems associated with rocket motor combustion chamber sampling are reported. Several design equations are presented. The results of the experiments include the effects of cooling water flow rates, the optimum separation gap between the end plate and sampling nozzle, and preliminary data on compositions in a rocket motor combustion chamber.

Multiplexed microfluidic approach for nucleic acid enrichment

DOEpatents

VanderNoot, Victoria A.; Langevin, Stanley Alan; Bent, Zachary; Renzi, Ronald F.; Ferko, Scott M.; Van De Vreugde, James L.; Lane, Todd; Patel, Kamlesh; Branda, Steven

2016-04-26

A system for enhancing a nucleic acid sample may include a one pump, a denaturing chamber; a microfluidic hydroxyapatite chromatography device configured for performing hydroxyapatite chromatography on the nucleic acid sample, a sample collector, and tubing connecting the pump with the denaturing chamber, the hydroxyapatite chromatography device and the sample collector such that the pump may be used to move the nucleic acid sample from the denaturing chamber to the hydroxyapatite chromatography device and then to the sample collector.

Electrocapturing flow cell

DOEpatents

Morozov, Victor [Manassas, VA

2011-04-05

A flow cell for electrophoretically-assisted capturing analytes from a flow. The flow cell includes a specimen chamber, a first membrane, a second membrane, a first electrode chamber, and a second electrode chamber. The specimen chamber may have a sample inlet and a sample outlet. A first portion of the first membrane may be coupled to a first portion of the specimen chamber. A first portion of the second membrane may be coupled to a second portion of the specimen chamber. The first electrode chamber may be configured to accept a charge. A portion of the first electrode chamber may be coupled to a second portion of the first membrane. A second electrode chamber may be configured to accept an opposite charge. A portion of the second electrode chamber may be coupled to a second portion of the second membrane.

Radioiodine detector based on laser induced fluorescence

DOEpatents

McDonald, Jimmie R.; Baronavski, Andrew P.

1980-01-01

The invention involves the measurement of the concentration of the radioisotope .sup.129 I.sub.2 in the presence of a gas. The invention uses a laser to excite a sample of the .sup.129 I.sub.2 in a sample gas chamber and a reference sample of a known concentration of .sup.129 I.sub.2 in a reference gas chamber. The .sup.129 I.sub.2 in the sample and reference gas chamber each gives off fluorescence emissions which are received by photomultipliers which provide signals to a detector. The detector uses a ratioing technique to determine the concentration of .sup.129 I.sub.2 in the sample gas chamber.

Photoelectron emission yield experiments on evolution of sub-gap states in amorphous In-Ga-Zn-O thin films with post deposition hydrogen treatment

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hayashi, Kazushi, E-mail: hayashi.kazushi@kobelco.com; Hino, Aya; Tao, Hiroaki

Total photoyield emission spectroscopy (TPYS) was applied to study the evolution of sub-gap states in hydrogen-treated amorphous In-Ga-Zn-O (a-IGZO) thin films. The a-IGZO thin films were subjected to hydrogen radicals and subsequently annealed in ultra-high vacuum (UHV) conditions. A clear onset of the electron emission was observed at around 4.3 eV from the hydrogen-treated a-IGZO thin films. After successive UHV annealing at 300 °C, the onset in the TPYS spectra was shifted to 4.15 eV, and the photoelectron emission from the sub-gap states was decreased as the annealing temperature was increased. In conjunction with the results of thermal desorption spectrometer, it was deducedmore » that the hydrogen atoms incorporated in the a-IGZO thin films induced metastable sub-gap states at around 4.3 eV from vacuum level just after the hydrogenation. It was also suggested that the defect configuration was changed due to the higher temperature UHV annealing, and that the hydrogen atoms desorbed with the involvement of Zn atoms. These experiments produced direct evidence to show the formation of sub-gap states as a result of hydrogen incorporation into the a-IGZO thin films.« less

Validation of odor concentration from mechanical-biological treatment piles using static chamber and wind tunnel with different wind speed values.

PubMed

Szyłak-Szydłowski, Mirosław

2017-09-01

The basic principle of odor sampling from surface sources is based primarily on the amount of air obtained from a specific area of the ground, which acts as a source of malodorous compounds. Wind tunnels and flux chambers are often the only available, direct method of evaluating the odor fluxes from small area sources. There are currently no widely accepted chamber-based methods; thus, there is still a need for standardization of these methods to ensure accuracy and comparability. Previous research has established that there is a significant difference between the odor concentration values obtained using the Lindvall chamber and those obtained by a dynamic flow chamber. Thus, the present study compares sampling methods using a streaming chamber modeled on the Lindvall cover (using different wind speeds), a static chamber, and a direct sampling method without any screens. The volumes of chambers in the current work were similar, ~0.08 m 3 . This study was conducted at the mechanical-biological treatment plant in Poland. Samples were taken from a pile covered by the membrane. Measured odor concentration values were between 2 and 150 ou E /m 3 . Results of the study demonstrated that both chambers can be used interchangeably in the following conditions: odor concentration is below 60 ou E /m 3 , wind speed inside the Lindvall chamber is below 0.2 m/sec, and a flow value is below 0.011 m 3 /sec. Increasing the wind speed above the aforementioned value results in significant differences in the results obtained between those methods. In all experiments, the results of the concentration of odor in the samples using the static chamber were consistently higher than those from the samples measured in the Lindvall chamber. Lastly, the results of experiments were employed to determine a model function of the relationship between wind speed and odor concentration values. Several researchers wrote that there are no widely accepted chamber-based methods. Also, there is still a need for standardization to ensure full comparability of these methods. The present study compared the existing methods to improve the standardization of area source sampling. The practical usefulness of the results was proving that both examined chambers can be used interchangeably. Statistically similar results were achieved while odor concentration was below 60 ou E /m 3 and wind speed inside the Lindvall chamber was below 0.2 m/sec. Increasing wind speed over these values results in differences between these methods. A model function of relationship between wind speed and odor concentration value was determined.

Bridging the Gap: From Model Surfaces to Nanoparticle Analogs for Selective Oxidation and Steam Reforming of Methanol and Selective Hydrogenation Catalysis

NASA Astrophysics Data System (ADS)

Boucher, Matthew B.

Most industrial catalysts are very complex, comprising of non-uniform materials with varying structures, impurities, and interaction between the active metal and supporting substrate. A large portion of the ongoing research in heterogeneous catalysis focuses on understanding structure-function relationships in catalytic materials. In parallel, there is a large area of surface science research focused on studying model catalytic systems for which structural parameters can be tuned and measured with high precision. It is commonly argued, however, that these systems are oversimplified, and that observations made in model systems do not translate to robust catalysts operating in practical environments; this discontinuity is often referred to as a "gap." The focus of this thesis is to explore the mutual benefits of surface science and catalysis, or "bridge the gap," by studying two catalytic systems in both ultra-high vacuum (UHV) and near ambient-environments. The first reaction is the catalytic steam reforming of methanol (SRM) to hydrogen and carbon dioxide. The SRM reaction is a promising route for on-demand hydrogen production. For this catalytic system, the central hypothesis in this thesis is that a balance between redox capability and weak binding of reaction intermediates is necessary for high SRM activity and selectivity to carbon dioxide. As such, a new catalyst for the SRM reaction is developed which incorporates very small amounts of gold (<1 atomic %) supported on zinc oxide nanoparticles with controlled crystal structures. The performance of these catalysts was studied in a fixed-bed micro-reactor system at ambient pressures, and their structure was characterized by high-resolution microscopic and spectroscopic techniques. Pre-existing oxygen defects in zinc oxide {0001} surfaces, and those created by a perturbation of the defect equilibrium by addition of gold, provide an anchoring site for highly dispersed gold species. By utilizing shape control of zinc oxide supports, it is found that highly dispersed gold, capable of low-temperature redox behavior is most prominent on zinc oxide {0001} surfaces and leads to high SRM activity and selectivity to carbon dioxide. Like other Group IB metal catalysts the SRM over gold-zinc oxide proceeds through the formation and weak binding of formaldehyde, and subsequent coupling with methoxy to produce methyl formate. Mechanistic clarification of this point was achieved by studying the interaction methanol-water mixtures with model catalyst surfaces. Model catalysts were studied in a UHV chamber where the base pressure was maintained at 10-10 mbar. High resolutions surface science techniques show that hydrogen-bonded networks of water are capable of deprotonating methanol to methoxy on low index surfaces in the absence of atomic oxygen. These UHV studies show that adsorbates, other than oxygen, are capable of activating methanol on Group IB metal surfaces. The second reaction involves the selective hydrogenation of alkynes to alkenes. Selective hydrogenations of carbon-carbon multiple bonds are important for a wide range of industrial processes. The governing hypothesis for this reaction system is that cooperation between a minority metal with a low barrier for hydrogen dissociation, and a less-reactive host metal capable of hydrogen uptake via spillover will lead to high alkene selectivity. A strategy for the preparation of such a catalyst is developed using model catalyst studied in a UHV chamber. The model catalyst features isolated palladium atoms in a copper(111) surface, termed single atom alloy (SAA). Individual, isolated palladium atoms act as sites for hydrogen uptake, dissociation, and spillover onto an otherwise inert copper(111) host. Weak binding offered by copper provides a surface where selective hydrogenation reactions can take place. Palladium-copper SAA model catalysts are highly selective to the partial hydrogenation of acetylene, whereas surfaces containing larger palladium ensembles facilitate complete hydrogenation and decomposition. Nanoparticle analogs of palladium-copper SAAs were prepared to investigate the feasibility of this strategy for practical application. Very small amounts of palladium (<0.2 atomic %) on the surface of copper nanoparticles are highly active and selective catalysts for the partial hydrogenation of phenylacetylene to styrene. The performance of these catalysts was studied in a liquid-phase, stirred-tank batch reactor under a hydrogen head pressure of approximately 7 bar. Palladium alloyed into the surface of otherwise inactive copper nanoparticles shows a marked improvement in selectivity when compared to monometallic palladium catalysts with the same metal loading. This effect is attributed hydrogen spillover onto the copper surface. In summary, the development of new, highly active and selective catalysts for the methanol steam reforming reaction and for the partial hydrogenation of alkynes to alkenes was accomplished by the use of state-of-the-art techniques in both surface science and heterogeneous catalysis. The implications of this work can be extended to a wide variety of catalytic systems.

Immunoassay of paralytic shellfish toxins by moving magnetic particles in a stationary liquid-phase lab-on-a-chip.

PubMed

Kim, Myoung-Ho; Choi, Suk-Jung

2015-04-15

In this study, we devised a stationary liquid-phase lab-on-a-chip (SLP LOC), which was operated by moving solid-phase magnetic particles in the stationary liquid phase. The SLP LOC consisted of a sample chamber to which a sample and reactants were added, a detection chamber containing enzyme substrate solution, and a narrow channel connecting the two chambers and filled with buffer. As a model system, competitive immunoassays of saxitoxin (STX), a paralytic shellfish toxin, were conducted in the SLP LOC using protein G-coupled magnetic particles (G-MPs) as the solid phase. Anti-STX antibodies, STX-horseradish peroxidase conjugate, G-MPs, and a STX sample were added to the sample chamber and reacted by shaking. While liquids were in the stationary state, G-MPs were transported from the sample chamber to the detection chamber by moving a magnet below the LOC. After incubation to allow the enzymatic reaction to occur, the absorbance of the detection chamber solution was found to be reciprocally related to the STX concentration of the sample. Thus, the SLP LOC may represent a novel, simple format for point-of-care testing applications of enzyme-linked immunosorbent assays by eliminating complicated liquid handling steps. Copyright © 2014 Elsevier B.V. All rights reserved.

Method of plasma etching Ga-based compound semiconductors

DOEpatents

Qiu, Weibin; Goddard, Lynford L.

2012-12-25

A method of plasma etching Ga-based compound semiconductors includes providing a process chamber and a source electrode adjacent to the process chamber. The process chamber contains a sample comprising a Ga-based compound semiconductor. The sample is in contact with a platen which is electrically connected to a first power supply, and the source electrode is electrically connected to a second power supply. The method includes flowing SiCl.sub.4 gas into the chamber, flowing Ar gas into the chamber, and flowing H.sub.2 gas into the chamber. RF power is supplied independently to the source electrode and the platen. A plasma is generated based on the gases in the process chamber, and regions of a surface of the sample adjacent to one or more masked portions of the surface are etched to create a substantially smooth etched surface including features having substantially vertical walls beneath the masked portions.

Study of Residual Gas Analyser (RGA) Response towards Known Leaks

NASA Astrophysics Data System (ADS)

Pathan, Firozkhan S.; Khan, Ziauddin; Semwal, Pratibha; George, Siju; Raval, Dilip C.; Thankey, Prashant L.; Manthena, Himabindu; Yuvakiran, Paravastu; Dhanani, Kalpesh R.

2012-11-01

Helium leak testing is the most versatile form of weld qualification test for any vacuum application. Almost every ultra-high vacuum (UHV) system utilizes this technique for insuring leak tightness for the weld joints as well as demountable joints. During UHV system under operational condition with many other integrated components, in-situ developed leaks identification becomes one of the prime aspect for maintaining the health of such system and for continuing the experiments onwards. Since online utilization of leak detector (LD) has many practical limitations, residual gas analyser (RGA) can be used as a potential instrument for online leak detection. For this purpose, a co-relation for a given leak rate between Leak Detector and RGA is experimentally established. This paper describes the experimental aspect and the relationship between leak detector and RGA.

Surface spectroscopy studies of the oxidation behavior of uranium

NASA Astrophysics Data System (ADS)

Bloch, J.; Atzmony, U.; Dariel, M. P.; Mintz, M. H.; Shamir, N.

1982-02-01

Auger electron spectroscopy (AES) and X-ray photoelectron spectroscopy (XPS) techniques were utilized to study the oxidation behavior of clean uranium surfaces, at very low pressures of various atmospheres (UHV, H 2, O 2, and CO 2), at room temperature. Both for O 2 and CO 2, a precursor chemisorbed oxygen species has been identified at the very initial stage of the oxidation reaction. This chemisorbed oxygen transforms to the oxide form at a rate which depends on the pressure of the oxidizing atmosphere. Residual gaseous carbon compounds which are present even under UHV conditions result in the simultaneous formation of surface carbide which accompanies the initial stage of oxidation. This carbide however decomposes later as oxidation proceeds. Adventitious hydrocarbon adsorption occurs on the formed oxide layer.

Influence of the surface chemistry on TiO2 - TiO2 nanocontact forces as measured by an UHV-AFM

NASA Astrophysics Data System (ADS)

Kunze, Christian; Giner, Ignacio; Torun, Boray; Grundmeier, Guido

2014-03-01

Particle-wall contact forces between a TiO2 film coated AFM tip and TiO2(1 1 0) single crystal surfaces were analyzed by means of UHV-AFM. As a reference system an octadecylphosphonic acid monolayer covered TiO2(1 1 0) surface was studied. The defect chemistry of the TiO2 substrate was modified by Ar ion bombardment, water dosing at 3 × 10-6 Pa and an annealing step at 473 K which resulted in a varying density of Ti(III) states. The observed contact forces are correlated to the surface defect density and are discussed in terms of the change in the electronic structure and its influence on the Hamaker constant.

Ferromagnetic resonance in coupled permalloy double films separated by a Cu interlayer

NASA Astrophysics Data System (ADS)

Maksymowicz, A. Z.; Whiting, J. S. S.; Watson, M. L.; Chambers, A.

1991-03-01

Ferromagnetic resonance (FMR) at 16 GHz was used to study the magnetic coupling between two-layers of permalloy separated by a nonmagnetic Cu layer. Samples with the same thickness (600 Å) of both permalloy layers were deposited from e-gun sources onto glass substrates in UHV. The thickness d of the Cu interlayer was varied from 5 to 37 Å. The exchange coupling energy ( E = - KM1· M2) model was used to describe the interaction between the two magnetic layers. It was found from the ferromagnetic resonance data in the perpendicular configuration that K( d) follows an exponential law, K = K0e - d/ q, where q = 9.3 Å.

A DUST-SETTLING CHAMBER FOR SAMPLING-INSTRUMENT COMPARISON STUDIES

EPA Science Inventory

Introduction: Few methods exist that can evenly and reproducibly deposit dusts onto surfaces for surface-sampling methodological studies. A dust-deposition chamber was designed for that purpose.

Methods: A 1-m3 Rochester-type chamber was modified to produce high airborne d...

Palaeonummulites venosus: Natural growth rates and quantification by means of CT investigation

NASA Astrophysics Data System (ADS)

Kinoshita, Shunichi; Eder, Wolfgang; Woeger, Julia; Hohenegger, Johann; Briguglio, Antonino

2016-04-01

Symbiont-bearing larger benthic Foraminifera (LBF) are long-living marine (possibly >1 year), single-celled organisms with complex calcium carbonate shells. Reproduction period, longevity and chamber building rate of LBF are important for population dynamics studies. It was expected that growth experiments in laboratory cultures cannot be used for estimation of chamber building rates and longevity studies although the laboratory conditions were simulated to natural conditions. Therefore, it is necessary to study individual and population growth under natural conditions for getting natural information. Therefore, the 'natural laboratory' method was developed to calculate the averaged chamber building rate and averaged longevity of species based on monthly sampling at fixed sampling stations and to compare with laboratory cultures simulating environmental conditions as close as possible to the natural environment. Thus, in this study, samples of living individuals were collected in 16 monthly intervals at 50m depth in front of Sesoko Island, Okinawa, Japan. We used micro-computed tomography (microCT) to investigate the chamber number of every specimen from the samples immediately dried after sampling. Single non dried specimens were cultured and the time of chamber building was obtained using microphotographs counted for every specimen at 2 to 4 days time intervals. The investigation using the natural laboratory method of Palaeonummulites venosus is based on the decomposition of the monthly frequency distributions into normally distributed components. Then the shift of the component parameters mean and standard deviation was used to calculate the necessary character of maximum chamber number and the Michaelis Menten function was applied to estimate the chamber building rate under natural conditions. This resulted in two reproduction periods, the first starting in May and the second in September, both showing the same chamber building rates, where the first shows a slightly stronger increase in the initial part. Longevity seems to be round about one year. Due to the several reproduction periods, the existence of small and large specimens in the same sample and the bimodal distributions can be explained. The cultured individuals shows a much lower chamber building rate, often demonstrating a longer period with no chamber production just after sampling, the results of sampling shock. This is the first time that it can be shown that chamber building rates and longevities cannot be based on laboratory investigations.

Free-Flow Open-Chamber Electrophoresis

NASA Technical Reports Server (NTRS)

Sharnez, Rizwan; Sammons, David W.

1994-01-01

Free-flow open-chamber electrophoresis variant of free-flow electrophoresis performed in chamber with open ends and in which velocity of electro-osmotic flow adjusted equal to and opposite mean electrophoretic velocity of sample. Particles having electrophoretic mobilities greater than mean mobility of sample particles move toward cathode, those with mobilities less move toward anode. Technique applied to separation of components of mixtures of biologically important substances. Sensitivity enhanced by use of tapered chamber.

Ethylene monitoring and control system

NASA Technical Reports Server (NTRS)

Nelson, Bruce N. (Inventor); Kanc, James A. (Inventor); Richard, II, Roy V. (Inventor)

2000-01-01

A system that can accurately monitor and control low concentrations of ethylene gas includes a test chamber configured to receive sample gas potentially containing an ethylene concentration and ozone, a detector configured to receive light produced during a reaction between the ethylene and ozone and to produce signals related thereto, and a computer connected to the detector to process the signals to determine therefrom a value of the concentration of ethylene in the sample gas. The supply for the system can include a four way valve configured to receive pressurized gas at one input and a test chamber. A piston is journaled in the test chamber with a drive end disposed in a drive chamber and a reaction end defining with walls of the test chamber a variable volume reaction chamber. The drive end of the piston is pneumatically connected to two ports of the four way valve to provide motive force to the piston. A manifold is connected to the variable volume reaction chamber, and is configured to receive sample gasses from at least one of a plurality of ports connectable to degreening rooms and to supply the sample gas to the reactive chamber for reaction with ozone. The apparatus can be used to monitor and control the ethylene concentration in multiple degreening rooms.

Ethylene monitoring and control system

NASA Technical Reports Server (NTRS)

Nelson, Bruce N. (Inventor); Kane, James A. (Inventor); Richard, II, Roy V. (Inventor)

2001-01-01

A system that can accurately monitor and control low concentrations of ethylene gas includes a test chamber configured to receive sample gas potentially containing an ethylene concentration and ozone, a detector configured to receive light produced during a reaction between the ethylene and ozone and to produce signals related thereto, and a computer connected to the detector to process the signals to determine therefrom a value of the concentration of ethylene in the sample gas. The supply for the system can include a four way valve configured to receive pressurized gas at one input and a test chamber. A piston is journaled in the test chamber with a drive end disposed in a drive chamber and a reaction end defining with walls of the test chamber a variable volume reaction chamber. The drive end of the piston is pneumatically connected to two ports of the four way valve to provide motive force to the piston. A manifold is connected to the variable volume reaction chamber, and is configured to receive sample gasses from at least one of a plurality of ports connectable to degreening rooms and to supply the sample gas to the reactive chamber for reaction with ozone. The apparatus can be used to monitor and control the ethylene concentration in multiple degreening rooms.

University of Maryland MRSEC - Facilities: VTSTM

Science.gov Websites

MRSEC Templates Opportunities Search Home » Facilities » UHV-VT-STM Shared Experimental Facilities redistribute the contents without alteration is granted to educational institutions for non-profit

Study of the Decomposition and Phase Transition of Uranium Nitride under UHV Conditions via TDS, XRD, SEM, and XPS.

PubMed

Wang, Xiaofang; Long, Zhong; Bin, Ren; Yang, Ruilong; Pan, Qifa; Li, Fangfang; Luo, Lizhu; Hu, Yin; Liu, Kezhao

2016-11-07

Uranium nitrides are among the most promising fuels for Generation IV nuclear reactors, but until now, very little has been known about their thermal stability properties under nonequilibrium conditions. In this work, thermal decomposition of nitrogen-rich uranium nitride (denoted as UN 2-x ) under ultrahigh-vacuum (UHV) conditions was investigated by thermal desorption spectroscopy (TDS). It has been shown that the nitrogen TDS spectrum consists of two peaks at about 723 and 1038 K. The X-ray diffraction, scanning electron microscopy, and X-ray photoelectron microscopy results indicate that UN 2-x (UN 2 phase) decomposed into the α-U 2 N 3 phase in the first step and the α-U 2 N 3 phase decomposed into the UN phase in the second step.

Versatile, high-sensitivity faraday cup array for ion implanters

DOEpatents

Musket, Ronald G.; Patterson, Robert G.

2003-01-01

An improved Faraday cup array for determining the dose of ions delivered to a substrate during ion implantation and for monitoring the uniformity of the dose delivered to the substrate. The improved Faraday cup array incorporates a variable size ion beam aperture by changing only an insertable plate that defines the aperture without changing the position of the Faraday cups which are positioned for the operation of the largest ion beam aperture. The design enables the dose sensitivity range, typically 10.sup.11 -10.sup.18 ions/cm.sup.2 to be extended to below 10.sup.6 ions/cm.sup.2. The insertable plate/aperture arrangement is structurally simple and enables scaling to aperture areas between <1 cm.sup.2 and >750 cm.sup.2, and enables ultra-high vacuum (UHV) applications by incorporation of UHV-compatible materials.

The preparation of pure niobium for neutron dosimetry purposes

NASA Astrophysics Data System (ADS)

Schulze, Klaus; Krehl, Michael

1985-06-01

A technique is described for the preparation of high purity niobium for use in fast neutron dosimetry. Based on results of known purification processes for niobium, an optimized method has been developed, consisting of: (1) a double electrolytic refining in an eutectic lithium-, sodium-, potassium-fluoride melt, containing fluoro-potassium niobate (K 2NbF 7), (2) electron beam float zone melting (EBFZM) in ultra high vacuum (UHV) and (3) UHV treatments. Starting with EBFZM of niobium of commercial quality (140 μg/g Ta, 35 μg/g W) the tantalum and tungsten contents were reduced by a first electrolysis to approximately 4 and 4 × 10 -2 μg/g, respectively. For a second electrolytic refining using a salt bath with extremely low tantalum and tungsten contents, this material was subjected to an additional EBFZM process. The niobium metal produced by this step was three times zone melted to reduce those elements (e.g. Fe, Co, Ni, O, N) which increased during the electrolyses. Material produced by this technique has impurity concentrations below 0.4 μg/g of tantalum and 10 -2 μg/g of tungsten. The concentration of the interstitials (C, O, N except H) is below the detection limit of classical analytical methods. A further reduction of the interstitials by annealing treatments in UHV of this material resulted in an electrical residual resistivity ratio (RRR) ρ(295 K)/ ρ(4.2 K) = 24 500 indicating an impurity concentration far below 1 μg/g.

Proportional counter device for detecting electronegative species in an air sample

DOEpatents

Allman, Steve L.; Chen, Fang C.; Chen, Chung-Hsuan

1994-01-01

Apparatus for detecting an electronegative species comprises an analysis chamber, an inlet communicating with the analysis chamber for admitting a sample containing the electronegative species and an ionizable component, a radioactive source within the analysis chamber for emitting radioactive energy for ionizing a component of the sample, a proportional electron detector within the analysis chamber for detecting electrons emitted from the ionized component, and a circuit for measuring the electrons and determining the presence of the electronegative species by detecting a reduction in the number of available electrons due to capture of electrons by the electronegative species.

Proportional counter device for detecting electronegative species in an air sample

DOEpatents

Allman, S.L.; Chen, F.C.; Chen, C.H.

1994-03-08

Apparatus for detecting an electronegative species comprises an analysis chamber, an inlet communicating with the analysis chamber for admitting a sample containing the electronegative species and an ionizable component, a radioactive source within the analysis chamber for emitting radioactive energy for ionizing a component of the sample, a proportional electron detector within the analysis chamber for detecting electrons emitted from the ionized component, and a circuit for measuring the electrons and determining the presence of the electronegative species by detecting a reduction in the number of available electrons due to capture of electrons by the electronegative species. 2 figures.

Sum frequency generation spectroscopy study of hydrogenated stepped Si(111) surfaces made by molecular hydrogen exposure

NASA Astrophysics Data System (ADS)

Hien, K. T. T.; Sattar, M. A.; Miyauchi, Y.; Mizutani, G.; Rutt, H. N.

2017-09-01

Hydrogen adsorption on stepped Si(111) surfaces 9.5° miscut in the [ 1 ̅ 1 ̅ 2 ] direction has been investigated in situ in a UHV chamber with a base pressure of 10-8 Pa. The H-Si(111)1×1 surface was prepared by exposing the wafer to ultra-pure hydrogen gas at a pressure of 470 Pa. Termination of hydrogen on terraces and steps was observed by sum frequency generation (SFG) with several polarization combinations such as ppp, ssp, pps, spp, psp, sps, pss and sss. Here the 1st, 2nd and 3rd symbols indicate SFG, visible and IR polarizations, respectively. ppp and ssp-SFG clearly showed only two modes: the Si-H stretching vibration terrace mode at 2082 cm-1 (A) and the vertical step dihydride vibration mode at 2094 cm-1 (C1). Interesting points are the appearance of the C1 mode in contrast to the previous SFG spectrum of the H-Si(111)1×1 surface with the same miscut surface angle prepared by wet chemical etching. We suggest that the formation of step dihydride and its orientation on the Si(111) stepped surfaces depend strongly on the preparation method.

Linewidth studies on the the NI(4S-4P) resonance multiplet. [applicable to analysis of dayglow

NASA Technical Reports Server (NTRS)

Erdman, P. W.; Zipf, E. C.

1983-01-01

Doppler broadening of the 8691, 8212, and 1200-A multiplet lines of N I is investigated experimentally, and its implications for the interpretation of the earth's 1200-A UV dayglow are considered. A regulated 100-eV, 1-mA electron beam is passed through N2 at 300 K and about 0.0005 torr flowing through a collision chamber within a UHV system, and the radiation emitted is observed with a temperature-stabilized short-focal length monochromator with a bandpass of 0.2 A in the IR and an effective UV resolution (in second-order operation with a 3600-groove/mm plane grating) of about 0.04 A. Both the IR and VUV lines are found to be broadened to about 25 times the thermal Doppler linewidth, with the IR transitions accounting for more than half of the total N(4P) cross section at 100 eV. The kinetic energy of the N(4P) atoms produced by dissociative excitation is such that their 1200-A resonance radiation (2p2 3s4P - 2p3 4SO) would be optically thin in the upper atmosphere, contrary to what has been observed. A need to revise some aspects of current UV-dayglow models is identified.

Structural and magnetic properties of self-assembled cobalt on porous silicon; experimental and micromagnetic investigations

NASA Astrophysics Data System (ADS)

Saidani, M.; Belkacem, W.; Bessais, L.; Mliki, N.

2017-08-01

In this paper, we report on self-assembled Co nanoparticles deposited in and on porous silicon (PS) matrix by using UHV evaporation. Four samples were prepared by varying the Co deposited thickness (t = 3, 5, 7 and 10 nm). All samples have been investigated by means of Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM) and Physical Properties Measurement System (PPMS). The increase of t has induced an increase of the nanoparticle diameter from 3 nm to about 150 nm. Referring to the magnetic characterizations, this increase has been followed by a single to multi-domain transition. Therefore, this has been evidenced by a switching from superparamagnetism to purely ferromagnetism accompanied by a change in the magnetic reversal dynamics. Thus, by performing micromagnetic calculation, we have shown that a transition from the uniform rotation to vortex state occurs at a critical diameter of about 55 nm.

Multi-chamber nucleic acid amplification and detection device

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dugan, Lawrence

A nucleic acid amplification and detection device includes an amplification cartridge with a plurality of reaction chambers for containing an amplification reagent and a visual detection reagent, and a plurality of optically transparent view ports for viewing inside the reaction chambers. The cartridge also includes a sample receiving port which is adapted to receive a fluid sample and fluidically connected to distribute the fluid sample to the reaction chamber, and in one embodiment, a plunger is carried by the cartridge for occluding fluidic communication to the reaction chambers. The device also includes a heating apparatus having a heating element whichmore » is activated by controller to generate heat when a trigger event is detected. The heating apparatus includes a cartridge-mounting section which positioned a cartridge in thermal communication with the heating element so that visual changes to the contents of the reaction chambers are viewable through the view ports.« less

Design and evaluation of a restraint-free small animal inhalation dosing chamber.

PubMed

McConville, Jason T; Williams, Robert O; Carvalho, Thiago C; Iberg, Aimee N; Johnston, Keith P; Talbert, Robert L; Burgess, David; Peters, Jay I

2005-01-01

The aim of research was to design a small, restraint free, low stress animal dosing chamber for inhalation studies, and to investigate distribution of a model drug within the chamber. A small animal dosing chamber was designed that consisted of a polymethylmethacrylate (PMMA) airtight box (40.6 x 11.4 x 21.6 cm) with a hinged top, having a nominal wall thickness of 1.25 cm. The chamber was designed to hold up to 14 mice, each having a floor area of approximately 63 cm2, in accordance with Institutional Animal Care and Use Committee (IACUC) guidelines. A "rodent proof" distribution fan was attached to the center of the hinged closure lid. The chamber was divided into 1 inch2 zones (120 in total) to enable a profile of drug distribution within the chamber to be obtained. Small holes were drilled into the side of the chamber and sealed using Parafilm to allow access to the sampling zones. Syringes (5 mL) with appropriate length polytetrafluoroethylene (PTFE) tubing were inserted into the holes to reach the sampling zones (eight on either side of the chamber giving a total of 16 zones). An aqueous caffeine solution (2% w/v) in glycerol (25% w/v) was prepared and nebulized into the chamber using an Aeroneb Pro nebulizer. Caffeine containing droplets were circulated into the chamber at a flow rate of 1.5 L/min(-1), and the air was recirculated in a closed system for a total of 20 minutes to ensure a high concentration of caffeine droplets throughout. Following nebulization, air samples (5 mL) were withdrawn from the 16 sampling zones of the sealed chamber. The process was repeated in quadruplet until a total of 64 sampling zones had been sampled. The entire experiment was also repeated with the absence of the "rodent-proof" distribution fan. Drug concentrations were calculated from a calibration curve of caffeine using UV absorbance at 272 nm. An average mass of caffeine (Standard Deviation; S.D.) of 5.0 (4.2) mg was detected throughout the chamber when the distribution fan was fitted, and caffeine 12.6 (9.7) mg was detected without the fan. This indicated that presence of the fan caused impingement of the drug on both the chamber walls and fan components; effectively removing nebulized drug from circulation within the chamber. The distribution of drug was plotted using a 3D graph; this revealed a lower concentration at the periphery and a higher concentration in the center of the chamber both with and without the distribution fan in place. In conclusion, a humane, nonrestraint rodent dosing chamber was designed for the efficient delivery of nebulized drugs for up to 14 mice simultaneously. The highest levels of the model drug caffeine were detectable throughout the small animal dosing chamber without the distribution fan. A circulation flow rate of 1.5 L/min(-1) was found to be adequate to distribute drug in the chamber. Surprisingly, the results demonstrate that avoiding the use of a distribution fan altogether maximizes the drug concentration within the chamber by reducing impingement of the nebulized drug. The small animal, restraint-free dosing chamber represents an advancement in reproducible dosing via the pulmonary route in the small animal model. The dosing chamber may be adapted to present the lung with an almost unlimited array of compounds, encompassing drugs, toxic compounds, and even pathogens, while still maintaining a relatively stress-free microenvironment for the test subject and furthermore, total safety for the operator.

An Experimental Study of Upward Burning Over Long Solid Fuels: Facility Development and Comparison

NASA Technical Reports Server (NTRS)

Kleinhenz, Julie; Yuan, Zeng-Guang

2011-01-01

As NASA's mission evolves, new spacecraft and habitat environments necessitate expanded study of materials flammability. Most of the upward burning tests to date, including the NASA standard material screening method NASA-STD-6001, have been conducted in small chambers where the flame often terminates before a steady state flame is established. In real environments, the same limitations may not be present. The use of long fuel samples would allow the flames to proceed in an unhindered manner. In order to explore sample size and chamber size effects, two large chambers were developed at NASA GRC under the Flame Prevention, Detection and Suppression (FPDS) project. The first was an existing vacuum facility, VF-13, located at NASA John Glenn Research Center. This 6350 liter chamber could accommodate fuels sample lengths up to 2 m. However, operational costs and restricted accessibility limited the test program, so a second laboratory scale facility was developed in parallel. By stacking additional two chambers on top of an existing combustion chamber facility, this 81 liter Stacked-chamber facility could accommodate a 1.5 m sample length. The larger volume, more ideal environment of VF-13 was used to obtain baseline data for comparison with the stacked chamber facility. In this way, the stacked chamber facility was intended for long term testing, with VF-13 as the proving ground. Four different solid fuels (adding machine paper, poster paper, PMMA plates, and Nomex fabric) were tested with fuel sample lengths up to 2 m. For thin samples (papers) with widths up to 5 cm, the flame reached a steady state length, which demonstrates that flame length may be stabilized even when the edge effects are reduced. For the thick PMMA plates, flames reached lengths up to 70 cm but were highly energetic and restricted by oxygen depletion. Tests with the Nomex fabric confirmed that the cyclic flame phenomena, observed in small facility tests, continued over longer sample. New features were also observed at the higher oxygen/pressure conditions available in the large chamber. Comparison of flame behavior between the two facilities under identical conditions revealed disparities, both qualitative and quantitative. This suggests that, in certain ranges of controlling parameters, chamber size and shape could be one of the parameters that affect the material flammability. If this proves to be true, it may limit the applicability of existing flammability data.

High vacuum tip-enhanced Raman spectroscope based on a scanning tunneling microscope.

PubMed

Fang, Yurui; Zhang, Zhenglong; Sun, Mengtao

2016-03-01

In this paper, we present the construction of a high-vacuum tip-enhanced Raman spectroscopy (HV-TERS) system that allows in situ sample preparation and measurement. A detailed description of the prototype instrument is presented with experimental validation of its use and novel ex situ experimental results using the HV-TERS system. The HV-TERS system includes three chambers held under a 10(-7) Pa vacuum. The three chambers are an analysis chamber, a sample preparation chamber, and a fast loading chamber. The analysis chamber is the core chamber and contains a scanning tunneling microscope (STM) and a Raman detector coupled with a 50 × 0.5 numerical aperture objective. The sample preparation chamber is used to produce single-crystalline metal and sub-monolayer molecular films by molecular beam epitaxy. The fast loading chamber allows ex situ preparation of samples for HV-TERS analysis. Atomic resolution can be achieved by the STM on highly ordered pyrolytic graphite. We demonstrate the measurement of localized temperature using the Stokes and anti-Stokes TERS signals from a monolayer of 1,2-benzenedithiol on a gold film using a gold tip. Additionally, plasmonic catalysis can be monitored label-free at the nanoscale using our device. Moreover, the HV-TERS experiments show simultaneously activated infrared and Raman vibrational modes, Fermi resonance, and some other non-linear effects that are not observed in atmospheric TERS experiments. The high spatial and spectral resolution and pure environment of high vacuum are beneficial for basic surface studies.

Offline solid phase microextraction sampling system

DOEpatents

Harvey, Chris A.

2008-12-16

An offline solid phase microextraction (SPME) sampling apparatus for enabling SPME samples to be taken a number of times from a previously collected fluid sample (e.g. sample atmosphere) stored in a fused silica lined bottle which keeps volatile organics in the fluid sample stable for weeks at a time. The offline SPME sampling apparatus has a hollow body surrounding a sampling chamber, with multiple ports through which a portion of a previously collected fluid sample may be (a) released into the sampling chamber, (b) SPME sampled to collect analytes for subsequent GC analysis, and (c) flushed/purged using a fluidically connected vacuum source and purging fluid source to prepare the sampling chamber for additional SPME samplings of the same original fluid sample, such as may have been collected in situ from a headspace.

Occupational Survey Report. AFSC 4M0X1 Aerospace Physiology

DTIC Science & Technology

2002-05-01

Chamber NCOIC Job Hyperbaric Chamber Specialist Job • Perform Type 2, 4 and 1 chamber flights • Perform inside observer duties during hypobaric ...78% Hyperbaric Chamber Specialist Independent Job 4% Not Grouped 2% U2 Aerospace Physiology Cluster 10% Job Structure Sample size: 168 Aerospace...Altitude Chamber Cluster (N=130) Hypobaric Chamber Instructor/Monitor Job HAAMS Job Altitude Chamber Apprentice Job 78% UPT Parasail Job Altitude

[Development of a microenvironment test chamber for airborne microbe research].

PubMed

Zhan, Ningbo; Chen, Feng; Du, Yaohua; Cheng, Zhi; Li, Chenyu; Wu, Jinlong; Wu, Taihu

2017-10-01

One of the most important environmental cleanliness indicators is airborne microbe. However, the particularity of clean operating environment and controlled experimental environment often leads to the limitation of the airborne microbe research. This paper designed and implemented a microenvironment test chamber for airborne microbe research in normal test conditions. Numerical simulation by Fluent showed that airborne microbes were evenly dispersed in the upper part of test chamber, and had a bottom-up concentration growth distribution. According to the simulation results, the verification experiment was carried out by selecting 5 sampling points in different space positions in the test chamber. Experimental results showed that average particle concentrations of all sampling points reached 10 7 counts/m 3 after 5 minutes' distributing of Staphylococcus aureus , and all sampling points showed the accordant mapping of concentration distribution. The concentration of airborne microbe in the upper chamber was slightly higher than that in the middle chamber, and that was also slightly higher than that in the bottom chamber. It is consistent with the results of numerical simulation, and it proves that the system can be well used for airborne microbe research.

A high-efficiency acoustic chamber and the anomalous sample rotation

NASA Technical Reports Server (NTRS)

Wang, Taylor G.; Allen, J. L.

1992-01-01

A high efficiency acoustic chamber for the levitation and manipulation of liquid or molten samples in a microgravity environment has been developed. The chamber uses two acoustic drivers that are mounted at opposite corners of the chamber; by driving these at the same frequency, with 18-deg phase shifts, an increase in force of a factor of 3-4 is obtainable relative to the force of a single-driver system that is operated at the same power level. This enhancement is due to the increased coupling between the sound driver and the chamber. An anomalous rotation is noted to be associated with the chamber; this is found to be eliminated by a physically as-yet inexplicable empirical solution.

High vacuum tip-enhanced Raman spectroscope based on a scanning tunneling microscope

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fang, Yurui; Bionanophotonics, Department of Applied Physics, Chalmers University of Technology, Göteborg, SE 41296; Zhang, Zhenglong

2016-03-15

In this paper, we present the construction of a high-vacuum tip-enhanced Raman spectroscopy (HV-TERS) system that allows in situ sample preparation and measurement. A detailed description of the prototype instrument is presented with experimental validation of its use and novel ex situ experimental results using the HV-TERS system. The HV-TERS system includes three chambers held under a 10{sup −7} Pa vacuum. The three chambers are an analysis chamber, a sample preparation chamber, and a fast loading chamber. The analysis chamber is the core chamber and contains a scanning tunneling microscope (STM) and a Raman detector coupled with a 50 ×more » 0.5 numerical aperture objective. The sample preparation chamber is used to produce single-crystalline metal and sub-monolayer molecular films by molecular beam epitaxy. The fast loading chamber allows ex situ preparation of samples for HV-TERS analysis. Atomic resolution can be achieved by the STM on highly ordered pyrolytic graphite. We demonstrate the measurement of localized temperature using the Stokes and anti-Stokes TERS signals from a monolayer of 1,2-benzenedithiol on a gold film using a gold tip. Additionally, plasmonic catalysis can be monitored label-free at the nanoscale using our device. Moreover, the HV-TERS experiments show simultaneously activated infrared and Raman vibrational modes, Fermi resonance, and some other non-linear effects that are not observed in atmospheric TERS experiments. The high spatial and spectral resolution and pure environment of high vacuum are beneficial for basic surface studies.« less

Design and development of high efficiency 140W space TWT with graphite collector

NASA Astrophysics Data System (ADS)

Srivastava, V.; Purohit, G.; Sharma, R. K.; Sharma, S. M.; Bera, A.; Bhaskar, P. V.; Singh, R. R.; Prasad, K.; Kiran, V.

2008-05-01

4-stage graphite collector assembly has been designed and developed for a 140W Ku-band space TWT to achieve the collector efficiency more than 80%. The UHV compatible, high density, copper impregnated POCO graphite (DFP-1C) was used to fabricate the four collector electrodes of the 4-stage depressed collector. Copper impregnated graphite material is used for the collector electrodes because of its low secondary electron emission coefficient, high thermal and electrical conductivities, easy machining and brazing, low thermal expansion coefficient and low weight. The graphite material was characterized for the UHV compatibility. The collector electrodes were precisely fabricated by careful machining, and technology was developed for brazing of graphite electrodes with high voltage alumina insulators. Complete TWT with four-stage graphite collector was developed and 140W output power at gain more than 55 dB was achieved. The TWT was pumped from both the gun and the collector ends.

Performance analysis of microcomputer based differential protection of UHV lines under selective phase switching

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bhatti, A.A.

1990-04-01

This paper examines the effects of primary and secondary fault quantities as well s of mutual couplings of neighboring circuits on the sensitivity of operation and threshold settings of a microcomputer based differential protection of UHV lines under selective phase switching. Microcomputer based selective phase switching allows the disconnection of minimum number of phases involved in a fault and requires the autoreclosing of these phases immediately after the extinction of secondary arc. During a primary fault a heavy current contribution to the healthy phases tends to cause an unwanted tripping. Faulty phases physically disconnected constitute an isolated fault which beingmore » coupled to the system affects the current and voltage levels of the healthy phases still retained in the system and may cause an unwanted tripping. The microcomputer based differential protection, appears to have poor performance when applied to uncompensated lines employing selective pole switching.« less

Role of thermal processes in dewetting of epitaxial Ag(111) film on Si(111)

DOE PAGES

Sanders, Charlotte E.; Zhang, Chendong D.; Kellogg, Gary L.; ...

2014-08-01

Epitaxially grown silver (Ag) film on silicon (Si) is an optimal plasmonic device platform, but its technological utility has been limited by its tendency to dewet rapidly under ambient conditions (standard temperature and pressure). The mechanisms driving this dewetting have not heretofore been determined. In our study, scanning probe microscopy and low-energy electron microscopy are used to compare the morphological evolution of epitaxial Ag(111)/Si(111) under ambient conditions with that of similarly prepared films heated under ultra-high vacuum (UHV) conditions. Furthermore, dewetting is seen to be initiated with the formation of pinholes, which might function to relieve strain in the film.more » We find that in the UHV environment, dewetting is determined by thermal processes, and while under ambient conditions, thermal processes are not required. Finally, we conclude that dewetting in ambient conditions is triggered by some chemical process, most likely oxidation.« less

Uhv compatible chopper system

DOE Office of Scientific and Technical Information (OSTI.GOV)

Voss, D.E.; Cohen, S.A.

1979-11-01

A time-of-flight system utilizing a novel mechanical chopper has been developed to measure the energy spectrum of neutral deuterium atoms emitted from a tokamak plasma. The chopper system consists of a motor, a magnetically levitated shaft, and a chopper disc. The 20 g disc is rigidly attached to a 159 g shaft assembly and the set is supported against gravity in vacuum by permanent magnets and a stabilizing servo system. All components are uhv compatible to avoid contamination to the tokamak and to the detector. The 25.4 cm OD, .005 cm thick, 301 stainless steel chopper disc has 24 .025more » cm wide slots photoetched at an 11.4 cm radius. An effective aperture time of .55 ..mu..s is achieved during typical steady state operation at 22,500 rpm with a vacuum pressure of 2 x 10/sup -8/ torr.« less

Constitutional Dynamics of Metal-Organic Motifs on a Au(111) Surface.

PubMed

Kong, Huihui; Zhang, Chi; Xie, Lei; Wang, Likun; Xu, Wei

2016-06-13

Constitutional dynamic chemistry (CDC), including both dynamic covalent chemistry and dynamic noncovalent chemistry, relies on reversible formation and breakage of bonds to achieve continuous changes in constitution by reorganization of components. In this regard, CDC is considered to be an efficient and appealing strategy for selective fabrication of surface nanostructures by virtue of dynamic diversity. Although constitutional dynamics of monolayered structures has been recently demonstrated at liquid/solid interfaces, most of molecular reorganization/reaction processes were thought to be irreversible under ultrahigh vacuum (UHV) conditions where CDC is therefore a challenge to be achieved. Here, we have successfully constructed a system that presents constitutional dynamics on a solid surface based on dynamic coordination chemistry, in which selective formation of metal-organic motifs is achieved under UHV conditions. The key to making this reversible switching successful is the molecule-substrate interaction as revealed by DFT calculations. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Extracellular bioreduction

DOEpatents

Chidambaram, Devicharan [Middle Island, NY; Francis, Arokiasamy J [Middle Island, NY

2012-04-17

A method for processing environmental or industrial samples to remove, reclaim or otherwise reduce the level of chemical species present in the sample that act as redox active species. The redox active species is kept in a waste chamber and is separated from an aqueous bacterial culture that is held in a culture chamber. The waste chamber and the culture chamber are separated by a porous membrane through which electron transfer can occur but through which the aqueous bacterial culture cannot pass. The redox active species substantially remains in the waste chamber and is in non-contact with the aqueous bacterial culture during the process of removal, reduction or reclamation.

Methods and apparatus for measurement of a dimensional characteristic and methods of predictive modeling related thereto

DOEpatents

Robertson, Eric P [Idaho Falls, ID; Christiansen, Richard L [Littleton, CO

2007-05-29

A method of optically determining a change in magnitude of at least one dimensional characteristic of a sample in response to a selected chamber environment. A magnitude of at least one dimension of the at least one sample may be optically determined subsequent to altering the at least one environmental condition within the chamber. A maximum change in dimension of the at least one sample may be predicted. A dimensional measurement apparatus for indicating a change in at least one dimension of at least one sample. The dimensional measurement apparatus may include a housing with a chamber configured for accommodating pressure changes and an optical perception device for measuring a dimension of at least one sample disposed in the chamber. Methods of simulating injection of a gas into a subterranean formation, injecting gas into a subterranean formation, and producing methane from a coal bed are also disclosed.

Methods for measurement of a dimensional characteristic and methods of predictive modeling related thereto

DOEpatents

Robertson, Eric P; Christiansen, Richard L.

2007-10-23

A method of optically determining a change in magnitude of at least one dimensional characteristic of a sample in response to a selected chamber environment. A magnitude of at least one dimension of the at least one sample may be optically determined subsequent to altering the at least one environmental condition within the chamber. A maximum change in dimension of the at least one sample may be predicted. A dimensional measurement apparatus for indicating a change in at least one dimension of at least one sample. The dimensional measurement apparatus may include a housing with a chamber configured for accommodating pressure changes and an optical perception device for measuring a dimension of at least one sample disposed in the chamber. Methods of simulating injection of a gas into a subterranean formation, injecting gas into a subterranean formation, and producing methane from a coal bed are also disclosed.

Environmental chamber for in situ dynamic control of temperature and relative humidity during x-ray scattering

NASA Astrophysics Data System (ADS)

Salas-de la Cruz, David; Denis, Jeffrey G.; Griffith, Matthew D.; King, Daniel R.; Heiney, Paul A.; Winey, Karen I.

2012-02-01

We have designed, constructed, and evaluated an environmental chamber that has in situ dynamic control of temperature (25 to 90 °C) and relative humidity (0% to 95%). The compact specimen chamber is designed for x-ray scattering in transmission with an escape angle of 2θ = ±30°. The specimen chamber is compatible with a completely evacuated system such as the Rigaku PSAXS system, in which the specimen chamber is placed inside a larger evacuated chamber (flight path). It is also compatible with x-ray systems consisting of evacuated flight tubes separated by small air gaps for sample placement. When attached to a linear motor (vertical displacement), the environmental chamber can access multiple sample positions. The temperature and relative humidity inside the specimen chamber are controlled by passing a mixture of dry and saturated gas through the chamber and by heating the chamber walls. Alternatively, the chamber can be used to control the gaseous environment without humidity. To illustrate the value of this apparatus, we have probed morphology transformations in Nafion® membranes and a polymerized ionic liquid as a function of relative humidity in nitrogen.

A nanosecond pulsed laser heating system for studying liquid and supercooled liquid films in ultrahigh vacuum

DOE Office of Scientific and Technical Information (OSTI.GOV)

Xu, Yuntao; Dibble, Collin J.; Petrik, Nikolay G.

2016-04-26

A pulsed laser heating system has been developed that enables investigations of the dynamics and kinetics of nanoscale liquid films and liquid/solid interfaces on the nanosecond timescale in ultrahigh vacuum (UHV). Details of the design, implementation and characterization of a nanosecond pulsed laser system for transiently heating nanoscale films are described. Nanosecond pulses from a Nd:YAG laser are used to rapidly heat thin films of adsorbed water or other volatile materials on a clean, well-characterized Pt(111) crystal in UHV. Heating rates of ~1010 K/s for temperature increases of ~100 – 200 K are obtained. Subsequent rapid cooling (~5 × 109more » K/s) quenches the film, permitting in-situ, post-mortem analysis using a variety of surface science techniques. Lateral variations in the laser pulse energy are ~ ± 3% leading to a temperature uncertainty of ~ ± 5 K for a temperature jump of 200 K. Initial experiments with the apparatus demonstrate that crystalline ice films initially held at 90 K can be rapidly transformed into liquid water films with T > 273 K. No discernable recrystallization occurs during the rapid cooling back to cryogenic temperatures. In contrast, amorphous solid water films heated below the melting point rapidly crystallize. The nanosecond pulsed laser heating system can prepare nanoscale liquid and supercooled liquid films that persist for nanoseconds per heat pulse in an UHV environment, enabling experimental studies of a wide range of phenomena in liquids and at liquid/solid interfaces.« less

A nanosecond pulsed laser heating system for studying liquid and supercooled liquid films in ultrahigh vacuum.

PubMed

Xu, Yuntao; Dibble, Collin J; Petrik, Nikolay G; Smith, R Scott; Joly, Alan G; Tonkyn, Russell G; Kay, Bruce D; Kimmel, Greg A

2016-04-28

A pulsed laser heating system has been developed that enables investigations of the dynamics and kinetics of nanoscale liquid films and liquid/solid interfaces on the nanosecond time scale in ultrahigh vacuum (UHV). Details of the design, implementation, and characterization of a nanosecond pulsed laser system for transiently heating nanoscale films are described. Nanosecond pulses from a Nd:YAG laser are used to rapidly heat thin films of adsorbed water or other volatile materials on a clean, well-characterized Pt(111) crystal in UHV. Heating rates of ∼10(10) K/s for temperature increases of ∼100-200 K are obtained. Subsequent rapid cooling (∼5 × 10(9) K/s) quenches the film, permitting in-situ, post-heating analysis using a variety of surface science techniques. Lateral variations in the laser pulse energy are ∼±2.7% leading to a temperature uncertainty of ∼±4.4 K for a temperature jump of 200 K. Initial experiments with the apparatus demonstrate that crystalline ice films initially held at 90 K can be rapidly transformed into liquid water films with T > 273 K. No discernable recrystallization occurs during the rapid cooling back to cryogenic temperatures. In contrast, amorphous solid water films heated below the melting point rapidly crystallize. The nanosecond pulsed laser heating system can prepare nanoscale liquid and supercooled liquid films that persist for nanoseconds per heat pulse in an UHV environment, enabling experimental studies of a wide range of phenomena in liquids and at liquid/solid interfaces.

Magic angle spinning nuclear magnetic resonance apparatus and process for high-resolution in situ investigations

DOEpatents

Hu, Jian Zhi; Sears, Jr., Jesse A.; Hoyt, David W.; Mehta, Hardeep S.; Peden, Charles H. F.

2015-11-24

A continuous-flow (CF) magic angle sample spinning (CF-MAS) NMR rotor and probe are described for investigating reaction dynamics, stable intermediates/transition states, and mechanisms of catalytic reactions in situ. The rotor includes a sample chamber of a flow-through design with a large sample volume that delivers a flow of reactants through a catalyst bed contained within the sample cell allowing in-situ investigations of reactants and products. Flow through the sample chamber improves diffusion of reactants and products through the catalyst. The large volume of the sample chamber enhances sensitivity permitting in situ .sup.13C CF-MAS studies at natural abundance.

Optical high acidity sensor

DOEpatents

Jorgensen, Betty S.; Nekimken, Howard L.; Carey, W. Patrick; O'Rourke, Patrick E.

1997-01-01

An apparatus and method for determining acid concentrations in solutions having acid concentrations of from about 0.1 Molar to about 16 Molar is disclosed. The apparatus includes a chamber for interrogation of the sample solution, a fiber optic light source for passing light transversely through the chamber, a fiber optic collector for receiving the collimated light after transmission through the chamber, a coating of an acid resistant polymeric composition upon at least one fiber end or lens, the polymeric composition in contact with the sample solution within the chamber and having a detectable response to acid concentrations within the range of from about 0.1 Molar to about 16 Molar, a measurer for the response of the polymeric composition in contact with the sample solution, and, a comparer of the measured response to predetermined standards whereby the acid molarity of the sample solution within the chamber can be determined. Preferably, a first lens is attached to the end of the fiber optic light source, the first lens adapted to collimate light from the fiber optic light source, and a second lens is attached to the end of the fiber optic collector for focusing the collimated light after transmission through the chamber.

Optical high acidity sensor

DOEpatents

Jorgensen, B.S.; Nekimken, H.L.; Carey, W.P.; O`Rourke, P.E.

1997-07-22

An apparatus and method for determining acid concentrations in solutions having acid concentrations of from about 0.1 Molar to about 16 Molar is disclosed. The apparatus includes a chamber for interrogation of the sample solution, a fiber optic light source for passing light transversely through the chamber, a fiber optic collector for receiving the collimated light after transmission through the chamber, a coating of an acid resistant polymeric composition upon at least one fiber end or lens, the polymeric composition in contact with the sample solution within the chamber and having a detectable response to acid concentrations within the range of from about 0.1 Molar to about 16 Molar, a measurer for the response of the polymeric composition in contact with the sample solution, and a comparer of the measured response to predetermined standards whereby the acid molarity of the sample solution within the chamber can be determined. Preferably, a first lens is attached to the end of the fiber optic light source, the first lens adapted to collimate light from the fiber optic light source, and a second lens is attached to the end of the fiber optic collector for focusing the collimated light after transmission through the chamber. 10 figs.

Microphysical, microchemical and adhesive properties of lunar material. 3: Gas interaction with lunar material

NASA Technical Reports Server (NTRS)

Grossman, J. J.; Mukherjee, N. R.; Ryan, J. A.

1972-01-01

Knowledge of the reactivity of lunar material surfaces is important for understanding the effects of the lunar or space environment upon this material, particularly its nature, behavior and exposure history in comparison to terrestrial materials. Adsorptive properties are one of the important techniques for such studies. Gas adsorption measurements were made on an Apollo 12 ultrahigh vacuum-stored sample and Apollo 14 and 15 N2-stored samples. Surface area measurements were made on the latter two. Adsorbate gases used were N2, A, O2 and H2O. Krypton was used for the surface area determinations. Runs were made at room and liquid nitrogen temperature in volumetric and gravimetric systems. It was found that the adsorptive/desorptive behavior was in general significantly different from that of terrestrial materials of similar type and form. Specifically (1) the UHV-stored sample exhibited very high initial adsorption indicative of high surface reactivity, and (2) the N2-stored samples at room and liquid nitrogen temperatures showed that more gas was desorbed than introduced during adsorption, indicative of gas release from the samples. The high reactivity is a scribed cosmic ray track and solar wind damage.

System and method for detecting components of a mixture including a valving scheme for competition assays

DOEpatents

Koh, Chung-Yan; Piccini, Matthew E.; Singh, Anup K.

2017-09-19

Examples are described including measurement systems for conducting competition assays. A first chamber of an assay device may be loaded with a sample containing a target antigen. The target antigen in the sample may be allowed to bind to antibody-coated beads in the first chamber. A control layer separating the first chamber from a second chamber may then be opened to allow a labeling agent loaded in a first portion of the second chamber to bind to any unoccupied sites on the antibodies. A centrifugal force may then be applied to transport the beads through a density media to a detection region for measurement by a detection unit.

System and method for detecting components of a mixture including a valving scheme for competition assays

DOEpatents

Koh, Chung-Yan; Piccini, Matthew E.; Singh, Anup K.

2017-07-11

Examples are described including measurement systems for conducting competition assays. A first chamber of an assay device may be loaded with a sample containing a target antigen. The target antigen in the sample may be allowed to bind to antibody-coated beads in the first chamber. A control layer separating the first chamber from a second chamber may then be opened to allow a labeling agent loaded in a first portion of the second chamber to bind to any unoccupied sites on the antibodies. A centrifugal force may then be applied to transport the beads through a density media to a detection region for measurement by a detection unit.

Acoustic system for material transport

NASA Technical Reports Server (NTRS)

Barmatz, M. B.; Trinh, E. H.; Wang, T. G.; Elleman, D. D.; Jacobi, N. (Inventor)

1983-01-01

An object within a chamber is acoustically moved by applying wavelengths of different modes to the chamber to move the object between pressure wells formed by the modes. In one system, the object is placed in one end of the chamber while a resonant mode, applied along the length of the chamber, produces a pressure well at the location. The frequency is then switched to a second mode that produces a pressure well at the center of the chamber, to draw the object. When the object reaches the second pressure well and is still traveling towards the second end of the chamber, the acoustic frequency is again shifted to a third mode (which may equal the first model) that has a pressure well in the second end portion of the chamber, to draw the object. A heat source may be located near the second end of the chamber to heat the sample, and after the sample is heated it can be cooled by moving it in a corresponding manner back to the first end of the chamber. The transducers for levitating and moving the object may be all located at the cool first end of the chamber.

Preparative electrophoresis for space

NASA Technical Reports Server (NTRS)

Rhodes, Percy H.; Snyder, Robert S.

1987-01-01

A premise of continuous flow electrophoresis is that removal of buoyancy-induced thermal convection caused by axial and lateral temperature gradients results in ideal performance of these instruments in space. Although these gravity dependent phenomena disturb the rectilinear flow in the separation chamber when high voltage gradients or thick chambers are used, distortion of the injected sample stream due to electrohydrodynamic effects cause major broadening of the separated bands. The electrophoresis separation process is simple, however flow local to the sample filament produced by the applied electric field have not been considered. These electrohydrodynamic flows distort the sample stream and limit the separation. Also, electroosmosis and viscous flow combine to further distort the process. A moving wall concept is being proposed for space which will eliminate and control the disturbances. The moving wall entrains the fluid to move as a rigid body and produces a constant residence time for all samples distributed across the chamber thickness. The moving wall electrophoresis chamber can only be operated in space because there is no viscous flow in the chamber to stabilize against thermal convection.

Preparative electrophoresis for space

NASA Technical Reports Server (NTRS)

Rhodes, Percy H.; Snyder, Robert S.

1988-01-01

A premise of continuous flow electrophoresis is that removal of buoyance-induced thermal convection caused by axial and lateral temperature gradients results in ideal performance of these instruments in space. Although these gravity dependent phenomena disturb the rectilinear flow in the separation chamber when high voltage gradients or thick chamber are used, distortion of the injected sample stream due to electrodynamic effects cause major broadening of the separated bands. The electrophoresis separation process is simple, however flow local to the sample filament produced by the applied electric field were not considered. These electrohydrodynamic flows distort the sample stream and limit the separation. Also, electroosmosis and viscous flow combine to further distort the process. A moving wall concept is being proposed for space which will eliminate and control the disturbances. The moving wall entrains the fluid to move as a rigid body and produces a constant residence time for all samples distributed across the chamber thickness. The moving wall electrophoresis chamber can only be operated in space because there is no viscous flow in the chamber to stabilize against thermal convection.

Spectrophotometric Attachment for the Vacuum Ultraviolet

NASA Technical Reports Server (NTRS)

Axelrod, Norman N.

1961-01-01

An absorption spectrophotometric attachment to a vacuum ultraviolet monochromator has been built and tested. With an empty sample chamber, the ratio of the radiant flux through the sample chamber to the radiant flux through the reference chamber was measured. By optimizing conditions at the entrance slit, the ratio was constant within experimental error over the region 1000-1600 A. The transmittance of thin celluloid films was measured with the attachment.

Multiple capillary biochemical analyzer

DOEpatents

Dovichi, N.J.; Zhang, J.Z.

1995-08-08

A multiple capillary analyzer allows detection of light from multiple capillaries with a reduced number of interfaces through which light must pass in detecting light emitted from a sample being analyzed, using a modified sheath flow cuvette. A linear or rectangular array of capillaries is introduced into a rectangular flow chamber. Sheath fluid draws individual sample streams through the cuvette. The capillaries are closely and evenly spaced and held by a transparent retainer in a fixed position in relation to an optical detection system. Collimated sample excitation radiation is applied simultaneously across the ends of the capillaries in the retainer. Light emitted from the excited sample is detected by the optical detection system. The retainer is provided by a transparent chamber having inward slanting end walls. The capillaries are wedged into the chamber. One sideways dimension of the chamber is equal to the diameter of the capillaries and one end to end dimension varies from, at the top of the chamber, slightly greater than the sum of the diameters of the capillaries to, at the bottom of the chamber, slightly smaller than the sum of the diameters of the capillaries. The optical system utilizes optic fibers to deliver light to individual photodetectors, one for each capillary tube. A filter or wavelength division demultiplexer may be used for isolating fluorescence at particular bands. 21 figs.

Multiple capillary biochemical analyzer

DOEpatents

Dovichi, Norman J.; Zhang, Jian Z.

1995-01-01

A multiple capillary analyzer allows detection of light from multiple capillaries with a reduced number of interfaces through which light must pass in detecting light emitted from a sample being analyzed, using a modified sheath flow cuvette. A linear or rectangular array of capillaries is introduced into a rectangular flow chamber. Sheath fluid draws individual sample streams through the cuvette. The capillaries are closely and evenly spaced and held by a transparent retainer in a fixed position in relation to an optical detection system. Collimated sample excitation radiation is applied simultaneously across the ends of the capillaries in the retainer. Light emitted from the excited sample is detected by the optical detection system. The retainer is provided by a transparent chamber having inward slanting end walls. The capillaries are wedged into the chamber. One sideways dimension of the chamber is equal to the diameter of the capillaries and one end to end dimension varies from, at the top of the chamber, slightly greater than the sum of the diameters of the capillaries to, at the bottom of the chamber, slightly smaller than the sum of the diameters of the capillaries. The optical system utilizes optic fibres to deliver light to individual photodetectors, one for each capillary tube. A filter or wavelength division demultiplexer may be used for isolating fluorescence at particular bands.

A microfluidic sub-critical water extraction instrument

NASA Astrophysics Data System (ADS)

Sherrit, Stewart; Noell, Aaron C.; Fisher, Anita; Lee, Mike C.; Takano, Nobuyuki; Bao, Xiaoqi; Kutzer, Thomas C.; Grunthaner, Frank

2017-11-01

This article discusses a microfluidic subcritical water extraction (SCWE) chip for autonomous extraction of amino acids from astrobiologically interesting samples. The microfluidic instrument is composed of three major components. These include a mixing chamber where the soil sample is mixed and agitated with the solvent (water), a subcritical water extraction chamber where the sample is sealed with a freeze valve at the chip inlet after a vapor bubble is injected into the inlet channels to ensure the pressure in the chip is in equilibrium with the vapor pressure and the slurry is then heated to ≤200 °C in the SCWE chamber, and a filter or settling chamber where the slurry is pumped to after extraction. The extraction yield of the microfluidic SCWE chip process ranged from 50% compared to acid hydrolysis and 80%-100% compared to a benchtop microwave SCWE for low biomass samples.

Growth, chamber building rate and reproduction time of Palaeonummulites venosus under natural conditions.

NASA Astrophysics Data System (ADS)

Kinoshita, Shunichi; Eder, Wolfgang; Wöger, Julia; Hohenegger, Johann; Briguglio, Antonino

2017-04-01

Investigations on Palaeonummulites venosus using the natural laboratory approach for determining chamber building rate, test diameter increase rate, reproduction time and longevity is based on the decomposition of monthly obtained frequency distributions based on chamber number and test diameter into normal-distributed components. The shift of the component parameters 'mean' and 'standard deviation' during the investigation period of 15 months was used to calculate Michaelis-Menten functions applied to estimate the averaged chamber building rate and diameter increase rate under natural conditions. The individual dates of birth were estimated using the inverse averaged chamber building rate and the inverse diameter increase rate fitted by the individual chamber number or the individual test diameter at the sampling date. Distributions of frequencies and densities (i.e. frequency divided by sediment weight) based on chamber building rate and diameter increase rate resulted both in a continuous reproduction through the year with two peaks, the stronger in May /June determined as the beginning of the summer generation (generation1) and the weaker in November determined as the beginning of the winter generation (generation 2). This reproduction scheme explains the existence of small and large specimens in the same sample. Longevity, calculated as the maximum difference in days between the individual's birth date and the sampling date seems to be round about one year, obtained by both estimations based on the chamber building rate and the diameter increase rate.

Aerosol mobility size spectrometer

DOEpatents

Wang, Jian; Kulkarni, Pramod

2007-11-20

A device for measuring aerosol size distribution within a sample containing aerosol particles. The device generally includes a spectrometer housing defining an interior chamber and a camera for recording aerosol size streams exiting the chamber. The housing includes an inlet for introducing a flow medium into the chamber in a flow direction, an aerosol injection port adjacent the inlet for introducing a charged aerosol sample into the chamber, a separation section for applying an electric field to the aerosol sample across the flow direction and an outlet opposite the inlet. In the separation section, the aerosol sample becomes entrained in the flow medium and the aerosol particles within the aerosol sample are separated by size into a plurality of aerosol flow streams under the influence of the electric field. The camera is disposed adjacent the housing outlet for optically detecting a relative position of at least one aerosol flow stream exiting the outlet and for optically detecting the number of aerosol particles within the at least one aerosol flow stream.

STM/STS study of the superconducting gap in SmFeAsO1-xFx

NASA Astrophysics Data System (ADS)

Kawashima, Yuki; Ichimura, Koichi; Katono, Kazuhiro; Kurosawa, Tohru; Oda, Migaku; Tanda, Satoshi; Kamihara, Yoichi; Hosono, Hideo

2015-02-01

We report an electron tunneling study of SmFeAsO1-xFx in the low doping region (x=0, 0.045, 0.046, 0.069) by low temperature UHV-STM/STS. Superconducting gaps are observed for each superconducting sample x=0.045 (Tc=12.9 K), x=0.046 (Tc=32.9 K) and x=0.069 (Tc=46.9 K). We obtained corresponding superconducting gap size of ΔSC = 9.5 ± 0.5 meV, 9.75±0.25 meV and 11±1 meV. While Tc increases, ΔSC is kept the same. This suggests that the effective attractive interaction is the same and that there is some mechanism that suppresses the superconductivity in the low doping region. On the other hand, similar gap structures were found in a non-superconducting sample with x=0 at 7.8 K. The obtained gap size was ΔN = 8.5 ± 1.5 meV, which is almost the same as the superconducting gap in the superconducting samples (x=0.045, 0.046, 0.069).

Interwell coupling effect in Si/SiGe quantum wells grown by ultra high vacuum chemical vapor deposition

PubMed Central

Wang, Rui; Lu, Fen; Fan, Wei Jun; Liu, Chong Yang; Loh, Ter-Hoe; Nguyen, Hoai Son; Narayanan, Balasubramanian

2007-01-01

Si/Si0.66Ge0.34coupled quantum well (CQW) structures with different barrier thickness of 40, 4 and 2 nm were grown on Si substrates using an ultra high vacuum chemical vapor deposition (UHV-CVD) system. The samples were characterized using high resolution x-ray diffraction (HRXRD), cross-sectional transmission electron microscopy (XTEM) and photoluminescence (PL) spectroscopy. Blue shift in PL peak energy due to interwell coupling was observed in the CQWs following increase in the Si barrier thickness. The Si/SiGe heterostructure growth process and theoretical band structure model was validated by comparing the energy of the no-phonon peak calculated by the 6 + 2-bandk·pmethod with experimental PL data. Close agreement between theoretical calculations and experimental data was obtained.

Fabrication and testing of an electrochemical microcell for in situ soft X-ray microspectroscopy measurements

NASA Astrophysics Data System (ADS)

Gianoncelli, A.; Kaulich, B.; Kiskinova, M.; Mele, C.; Prasciolu, M.; Sgura, I.; Bozzini, B.

2013-03-01

In this paper we report on the fabrication and testing of a novel concept of electrochemical microcell for in-situ soft X-ray microspectroscopy in transmission. The microcell, fabricated by electron-beam lithography, implements an improved electrode design, with optimal current density distribution and minimised ohmic drop, allowing the same three-electrode electrochemical control achievable with traditional cells. Moreover standard electroanalytical measurements, such as cyclic voltammetry, can be routinely performed. As far as the electrolyte is concerned, we selected a room-temperature ionic-liquid. Some of the materials belonging to this class, in addition to a broad range of outstanding electrochemical properties, feature two highlights that are crucial for in situ, soft X-ray transmission work: spinnability, enabling accurate thickness control, and stability to UHV, allowing operation of an open cell in the analysis chamber vacuum (10-6 mbar). The cell can, of course, be used also with non-vacuum stable electrolytes in the sealed version developed in previous work in our group. In this study, the microcell designed, fabricated and tested in situ by applying an anodic polarisation to a Au electrode and following the formation of a distribution of corrosion features. This specific material combination presented in this work does not limit the cell concept, that can implement any electrodic material grown by lithography, any liquid electrolyte and any spinnable solid electrolyte.

Long-term purity assessment in succinonitrile

NASA Astrophysics Data System (ADS)

Rubinstein, E. R.; Tirmizi, S. H.; Glicksman, M. E.

1990-11-01

Container materials for crystal growth chambers must be carefully selected in order to prevent sample contamination. To address the issue of contamination, high purity SCN was exposed to a variety of potential chamber construction materials, e.g., metal alloys, soldering materials, and sealants, at a temperature approximately 25 K above the melting point of SCN (58°C), over periods of up to one year. Acceptability, or lack thereof, of candidate chamber materials was determined by performing periodic melting point checks of the exposed samples. Those materials which did not measurably affect the melting point of SCN over a one-year period were considered to be chemically compatible and therefore eligible for use in constructing the flight chamber. A growth chamber constructed from compatible materials (304 SS and borosilicate glass) was filled with pure SCN. A thermistor probe placed within the chamber permitted in situ measurement of the melting point and, indirectly, of the purity of the SCN. Melting point plateaus were then determined, to assess the actual chamber performance.

Acoustic Translation of an Acoustically Levitated Sample

NASA Technical Reports Server (NTRS)

Barmatz, M. B.; Allen, J. L.

1986-01-01

Acoustic-levitation apparatus uses only one acoustic mode to move sample from one region of chamber to another. Sample heated and cooled quickly by translation between hot and cold regions of levitation chamber. Levitated sample is raised into furnace region by raising plunger. Frequency of sound produced by transducers adjusted by feedback system to maintain (102) resonant mode, which levitates sample midway between transducers and plunger regardless of plunger position.

Systems for column-based separations, methods of forming packed columns, and methods of purifying sample components

DOEpatents

Egorov, Oleg B.; O'Hara, Matthew J.; Grate, Jay W.; Chandler, Darrell P.; Brockman, Fred J.; Bruckner-Lea, Cynthia J.

2000-01-01

The invention encompasses systems for column-based separations, methods of packing and unpacking columns and methods of separating components of samples. In one aspect, the invention includes a method of packing and unpacking a column chamber, comprising: a) packing a matrix material within a column chamber to form a packed column; and b) after the packing, unpacking the matrix material from the column chamber without moving the column chamber. In another aspect, the invention includes a system for column-based separations, comprising: a) a fluid passageway, the fluid passageway comprising a column chamber and a flow path in fluid communication with the column chamber, the flow path being obstructed by a retaining material permeable to a carrier fluid and impermeable to a column matrix material suspended in the carrier fluid, the flow path extending through the column chamber and through the retaining material, the flow path being configured to form a packed column within the column chamber when a suspension of the fluid and the column matrix material is flowed along the flow path; and b) the fluid passageway extending through a valve intermediate the column chamber and the retaining material.

Systems For Column-Based Separations, Methods Of Forming Packed Columns, And Methods Of Purifying Sample Components

DOEpatents

Egorov, Oleg B.; O'Hara, Matthew J.; Grate, Jay W.; Chandler, Darrell P.; Brockman, Fred J.; Bruckner-Lea, Cynthia J.

2006-02-21

The invention encompasses systems for column-based separations, methods of packing and unpacking columns and methods of separating components of samples. In one aspect, the invention includes a method of packing and unpacking a column chamber, comprising: a) packing a matrix material within a column chamber to form a packed column; and b) after the packing, unpacking the matrix material from the column chamber without moving the column chamber. In another aspect, the invention includes a system for column-based separations, comprising: a) a fluid passageway, the fluid passageway comprising a column chamber and a flow path in fluid communication with the column chamber, the flow path being obstructed by a retaining material permeable to a carrier fluid and impermeable to a column matrix material suspended in the carrier fluid, the flow path extending through the column chamber and through the retaining material, the flow path being configured to form a packed column within the column chamber when a suspension of the fluid and the column matrix material is flowed along the flow path; and b) the fluid passageway extending through a valve intermediate the column chamber and the retaining material.

Systems For Column-Based Separations, Methods Of Forming Packed Columns, And Methods Of Purifying Sample Components.

DOEpatents

Egorov, Oleg B.; O'Hara, Matthew J.; Grate, Jay W.; Chandler, Darrell P.; Brockman, Fred J.; Bruckner-Lea, Cynthia J.

2004-08-24

The invention encompasses systems for column-based separations, methods of packing and unpacking columns and methods of separating components of samples. In one aspect, the invention includes a method of packing and unpacking a column chamber, comprising: a) packing a matrix material within a column chamber to form a packed column; and b) after the packing, unpacking the matrix material from the column chamber without moving the column chamber. In another aspect, the invention includes a system for column-based separations, comprising: a) a fluid passageway, the fluid passageway comprising a column chamber and a flow path in fluid communication with the column chamber, the flow path being obstructed by a retaining material permeable to a carrier fluid and impermeable to a column matrix material suspended in the carrier fluid, the flow path extending through the column chamber and through the retaining material, the flow path being configured to form a packed column within the column chamber when a suspension of the fluid and the column matrix material is flowed along the flow path; and b) the fluid passageway extending through a valve intermediate the column chamber and the retaining material.

New controlled environment vitrification system for preparing wet samples for cryo-SEM.

PubMed

Ge, H; Suszynski, W J; Davis, H T; Scriven, L E

2008-01-01

A new controlled environment vitrification system (CEVS) has been designed and constructed to facilitate examination by cryogenic scanning electron microscopy (Cryo-SEM) of initial suspension state and of microstructure development in latex, latex-composite and other coatings while they still contain solvent. The new system has a main chamber with provisions for coating as well as drying, and for well-controlled plunging into cryogen. An added subsidiary chamber holds samples for drying or annealing over minutes to days before they are returned to the main chamber and plunged from it. In the main chamber, samples are blade-coated on 5 x 7 mm pieces of silicon wafer and held at selected temperature and humidity for successively longer times, either there or after transfer along a rail into the subsidiary chamber. They are then placed in the sample holder mounted on the plunge rod, so as to permit adjustment of the sample's attitude when it plunges, at controlled speed, into liquid ethane at its freezing point, to a chosen depth, in order to solidify the sample without significant shear or freezing artifacts. The entries of plunging samples and related sample holders into liquid ethane were recorded with a high-speed, high-resolution Photron digital camera. The data were interpreted with a new hypothesis about the width of the band of extremely rapid cooling by deeply subcooled nucleate boiling below the line of entry. Complementary cryo-SEM images revealed that the freezing rate and surface shearing of a sample need to be balanced by adjusting the plunging attitude.

In-Situ Apatite Laser Ablation U-Th-Sm/He Dating, Methods and Challenges

NASA Astrophysics Data System (ADS)

Pickering, J. E.; Matthews, W.; Guest, B.; Hamilton, B.; Sykes, C.

2015-12-01

In-situ, laser ablation U-Th-Sm/He dating is an emerging technique in thermochronology that has been proven as a means to date zircon and monzonite1-5. In-situ U-Th-Sm/He thermochronology eliminates many of the problems and inconveniences associated with traditional, whole grain methods, including; reducing bias in grain selection based on size, shape and clarity; allowing for the use of broken grains and grains with inclusions; avoiding bad neighbour effects; and eliminating safety hazards associated with dissolution. In-situ apatite laser ablation is challenging due to low concentrations of U and Th and thus a low abundance of radiogenic He. For apatite laser ablation to be effective the ultra-high-vacuum (UHV) line must have very low and consistent background levels of He. To reduce He background, samples are mounted in a UHV stable medium. Our mounting process uses a MicroHePP (Microscope Mounted Heated Platen Press) to press samples into FEP (fluorinated ethylene propylene) bonded to an aluminum backing plate. Samples are ablated using a Resonetics 193 nm excimer laser and liberated He is measured using a quadrupole mass spectrometer on the ASI Alphachron noble gas line; collectively this system is known as the Resochron. The ablated sites are imaged using a Zygo Zescope optical profilometer and ablated pit volume measured using PitVol, a custom MatLab algorithm developed to enable precise and unbiased measurement of the ablated pit geometry. We use the well-characterized Durango apatite to demonstrate the accuracy and precision of the method. He liberated from forty-two pits, having volumes between 1700 and 9000 um3, were measured using the Resochron. The ablated sites were imaged using a Zygo Zescope optical profilometer and ablated pit volume measured using PitVol. U, Th and Sm concentrations were measured by laser ablation and the U-Th-Sm/He age calculated by standard age equation. An age of 33.8±0.31 Ma was determined and compares well with conventional U-Th/He methods, whole grain degassing and dissolution, that produced an age of 32.73±0.47 Ma for chips of the same Durango crystal. Further dating of other well characterized apatite crystals will be used to test the robustness of the method.

Surface science and model catalysis with ionic liquid-modified materials.

PubMed

Steinrück, H-P; Libuda, J; Wasserscheid, P; Cremer, T; Kolbeck, C; Laurin, M; Maier, F; Sobota, M; Schulz, P S; Stark, M

2011-06-17

Materials making use of thin ionic liquid (IL) films as support-modifying functional layer open up a variety of new possibilities in heterogeneous catalysis, which range from the tailoring of gas-surface interactions to the immobilization of molecularly defined reactive sites. The present report reviews recent progress towards an understanding of "supported ionic liquid phase (SILP)" and "solid catalysts with ionic liquid layer (SCILL)" materials at the microscopic level, using a surface science and model catalysis type of approach. Thin film IL systems can be prepared not only ex-situ, but also in-situ under ultrahigh vacuum (UHV) conditions using atomically well-defined surfaces as substrates, for example by physical vapor deposition (PVD). Due to their low vapor pressure, these systems can be studied in UHV using the full spectrum of surface science techniques. We discuss general strategies and considerations of this approach and exemplify the information available from complementary methods, specifically photoelectron spectroscopy and surface vibrational spectroscopy. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Preparation of clean surfaces and Se vacancy formation in Bi2Se3 by ion bombardment and annealing

NASA Astrophysics Data System (ADS)

Zhou, Weimin; Zhu, Haoshan; Valles, Connie M.; Yarmoff, Jory A.

2017-08-01

Bismuth Selenide (Bi2Se3) is a topological insulator (TI) with a structure consisting of stacked quintuple layers. Single crystal surfaces are commonly prepared by mechanical cleaving. This work explores the use of low energy Ar+ ion bombardment and annealing (IBA) as an alternative method to produce reproducible and stable Bi2Se3 surfaces under ultra-high vacuum (UHV). It is found that a clean and well-ordered surface can be prepared by a single cycle of 1 keV Ar+ ion bombardment and 30 min of annealing. Low energy electron diffraction (LEED) and detailed low energy ion scattering (LEIS) measurements show no differences between IBA-prepared surfaces and those prepared by in situ cleaving in UHV. Analysis of the LEED patterns shows that the optimal annealing temperature is 450 °C. Angular LEIS scans reveal the formation of surface Se vacancies when the annealing temperature exceeds 520 °C.

Stoichiometric and Oxygen-Deficient VO2 as Versatile Hole Injection Electrode for Organic Semiconductors.

PubMed

Fu, Keke; Wang, Rongbin; Katase, Takayoshi; Ohta, Hiromichi; Koch, Norbert; Duhm, Steffen

2018-03-28

Using photoemission spectroscopy, we show that the surface electronic structure of VO 2 is determined by the temperature-dependent metal-insulator phase transition and the density of oxygen vacancies, which depends on the temperature and ultrahigh vacuum (UHV) conditions. The atomically clean and stoichiometric VO 2 surface is insulating at room temperature and features an ultrahigh work function of up to 6.7 eV. Heating in UHV just above the phase transition temperature induces the expected metallic phase, which goes in hand with the formation of oxygen defects (up to 6% in this study), but a high work function >6 eV is maintained. To demonstrate the suitability of VO 2 as hole injection contact for organic semiconductors, we investigated the energy-level alignment with the prototypical organic hole transport material N, N'-di(1-naphthyl)- N, N'-diphenyl-(1,1'-biphenyl)-4,4'-diamine (NPB). Evidence for strong Fermi-level pinning and the associated energy-level bending in NPB is found, rendering an Ohmic contact for holes.

Fiber optic probe for light scattering measurements

DOEpatents

Nave, Stanley E.; Livingston, Ronald R.; Prather, William S.

1995-01-01

A fiber optic probe and a method for using the probe for light scattering analyses of a sample. The probe includes a probe body with an inlet for admitting a sample into an interior sample chamber, a first optical fiber for transmitting light from a source into the chamber, and a second optical fiber for transmitting light to a detector such as a spectrophotometer. The interior surface of the probe carries a coating that substantially prevents non-scattered light from reaching the second fiber. The probe is placed in a region where the presence and concentration of an analyte of interest are to be detected, and a sample is admitted into the chamber. Exciting light is transmitted into the sample chamber by the first fiber, where the light interacts with the sample to produce Raman-scattered light. At least some of the Raman-scattered light is received by the second fiber and transmitted to the detector for analysis. Two Raman spectra are measured, at different pressures. The first spectrum is subtracted from the second to remove background effects, and the resulting sample Raman spectrum is compared to a set of stored library spectra to determine the presence and concentration of the analyte.

Fiber optic probe for light scattering measurements

DOEpatents

Nave, S.E.; Livingston, R.R.; Prather, W.S.

1993-01-01

This invention is comprised of a fiber optic probe and a method for using the probe for light scattering analyses of a sample. The probe includes a probe body with an inlet for admitting a sample into an interior sample chamber, a first optical fiber for transmitting light from a source into the chamber, and a second optical fiber for transmitting light to a detector such as a spectrophotometer. The interior surface of the probe carries a coating that substantially prevents non-scattered light from reaching the second fiber. The probe is placed in a region where the presence and concentration of an analyte of interest are to be detected, and a sample is admitted into the chamber. Exciting light is transmitted into the sample chamber by the first fiber, where the light interacts with the sample to produce Raman-scattered light. At least some of the Raman- scattered light is received by the second fiber and transmitted to the detector for analysis. Two Raman spectra are measured, at different pressures. The first spectrum is subtracted from the second to remove background effects, and the resulting sample Raman spectrum is compared to a set of stored library spectra to determine the presence and concentration of the analyte.

DESIGN, CONSTRUCTION, AND EVALUATION OF A CHAMBER FOR AEROBIOLOGY

EPA Science Inventory

A chamber was designed and constructed for aeromicrobiology applications. An ultraviolet (UV) radiation source was incorporated to sterilize the chamber between trials. Twelve bacterial species originally isolated from air samples and obtained from the American Type Culture Colle...

Influence of counting chamber type on CASA outcomes of equine semen analysis.

PubMed

Hoogewijs, M K; de Vliegher, S P; Govaere, J L; de Schauwer, C; de Kruif, A; van Soom, A

2012-09-01

Sperm motility is considered to be one of the key features of semen analysis. Assessment of motility is frequently performed using computer-assisted sperm analysis (CASA). Nevertheless, no uniform standards are present to analyse a semen sample using CASA. We hypothesised that the type of counting chamber used might influence the results of analysis and aimed to study the effect of chamber type on estimated concentration and motility of an equine semen sample assessed using CASA. Commonly used disposable Leja chambers of different depths were compared with disposable and reusable ISAS chambers, a Makler chamber and a World Health Organization (WHO) motility slide. Motility parameters and concentrations obtained with CASA using these different chambers were analysed. The NucleoCounter was used as gold standard for determining concentration. Concentration and motility parameters were significantly influenced by the chamber type used. Using the NucleoCounter as the gold standard for determining concentration, the correlation coefficients were low for all of the various chambers evaluated, with the exception of the 12 µm deep Leja chamber. Filling a chamber by capillary forces resulted in a lower observed concentration and reduced motility parameters. All chambers evaluated in this study resulted in significant lower progressive motility than the WHO prepared slide, with the exception of the Makler chamber, which resulted in a slight, but statistically significant, increase in progressive motility estimates. Computer-assisted sperm analysis can only provide a rough estimate of sperm concentration and overestimation is likely when drop-filled slides with a coverslip are used. Motility estimates using CASA are highly influenced by the counting chamber; therefore, a complete description of the chamber type used should be provided in semen reports and in scientific articles. © 2011 EVJ Ltd.

Pulsed discharge ionization source for miniature ion mobility spectrometers

DOEpatents

Xu, Jun; Ramsey, J. Michael; Whitten, William B.

2004-11-23

A method and apparatus is disclosed for flowing a sample gas and a reactant gas (38, 43) past a corona discharge electrode (26) situated at a first location in an ion drift chamber (24), applying a pulsed voltage waveform comprising a varying pulse component and a dc bias component to the corona discharge electrode (26) to cause a corona which in turn produces ions from the sample gas and the reactant gas, applying a dc bias to the ion drift chamber (24) to cause the ions to drift to a second location (25) in the ion drift chamber (24), detecting the ions at the second location (25) in the drift chamber (24), and timing the period for the ions to drift from the corona discharge electrode to the selected location in the drift chamber.

Human portable preconcentrator system

DOEpatents

Linker, Kevin L.; Bouchier, Francis A.; Hannum, David W.; Rhykerd, Jr., Charles L.

2003-01-01

A preconcentrator system and apparatus suited to human portable use wherein sample potentially containing a target chemical substance is drawn into a chamber and through a pervious screen. The screen is adapted to capture target chemicals and then, upon heating, to release those chemicals into the chamber. Chemicals captured and then released in this fashion are then carried to a portable chemical detection device such as a portable ion mobility spectrometer. In the preferred embodiment, the means for drawing sample into the chamber comprises a reversible fan which, when operated in reverse direction, creates a backpressure that facilitates evolution of captured target chemicals into the chamber when the screen is heated.

A facility for long-term Mars simulation experiments: the Mars Environmental Simulation Chamber (MESCH).

PubMed

Jensen, Lars Liengaard; Merrison, Jonathan; Hansen, Aviaja Anna; Mikkelsen, Karina Aarup; Kristoffersen, Tommy; Nørnberg, Per; Lomstein, Bente Aagaard; Finster, Kai

2008-06-01

We describe the design, construction, and pilot operation of a Mars simulation facility comprised of a cryogenic environmental chamber, an atmospheric gas analyzer, and a xenon/mercury discharge source for UV generation. The Mars Environmental Simulation Chamber (MESCH) consists of a double-walled cylindrical chamber. The double wall provides a cooling mantle through which liquid N(2) can be circulated. A load-lock system that consists of a small pressure-exchange chamber, which can be evacuated, allows for the exchange of samples without changing the chamber environment. Fitted within the MESCH is a carousel, which holds up to 10 steel sample tubes. Rotation of the carousel is controlled by an external motor. Each sample in the carousel can be placed at any desired position. Environmental data, such as temperature, pressure, and UV exposure time, are computer logged and used in automated feedback mechanisms, enabling a wide variety of experiments that include time series. Tests of the simulation facility have successfully demonstrated its ability to produce temperature cycles and maintain low temperature (down to -140 degrees C), low atmospheric pressure (5-10 mbar), and a gas composition like that of Mars during long-term experiments.

A Facility for Long-Term Mars Simulation Experiments: The Mars Environmental Simulation Chamber (MESCH)

NASA Astrophysics Data System (ADS)

Jensen, Lars Liengaard; Merrison, Jonathan; Hansen, Aviaja Anna; Mikkelsen, Karina Aarup; Kristoffersen, Tommy; Nørnberg, Per; Lomstein, Bente Aagaard; Finster, Kai

2008-06-01

We describe the design, construction, and pilot operation of a Mars simulation facility comprised of a cryogenic environmental chamber, an atmospheric gas analyzer, and a xenon/mercury discharge source for UV generation. The Mars Environmental Simulation Chamber (MESCH) consists of a double-walled cylindrical chamber. The double wall provides a cooling mantle through which liquid N2 can be circulated. A load-lock system that consists of a small pressure-exchange chamber, which can be evacuated, allows for the exchange of samples without changing the chamber environment. Fitted within the MESCH is a carousel, which holds up to 10 steel sample tubes. Rotation of the carousel is controlled by an external motor. Each sample in the carousel can be placed at any desired position. Environmental data, such as temperature, pressure, and UV exposure time, are computer logged and used in automated feedback mechanisms, enabling a wide variety of experiments that include time series. Tests of the simulation facility have successfully demonstrated its ability to produce temperature cycles and maintain low temperature (down to -140°C), low atmospheric pressure (5 10 mbar), and a gas composition like that of Mars during long-term experiments.

RaPToRS Sample Delivery System

NASA Astrophysics Data System (ADS)

Henchen, Robert; Shibata, Kye; Krieger, Michael; Pogozelski, Edward; Padalino, Stephen; Glebov, Vladimir; Sangster, Craig

2010-11-01

At various labs (NIF, LLE, NRL), activated material samples are used to measure reaction properties. The Rapid Pneumatic Transport of Radioactive Samples (RaPToRS) system quickly and safely moves these radioactive samples through a closed PVC tube via airflow. The carrier travels from the reaction chamber to the control and analysis station, pneumatically braking at the outlet. A reversible multiplexer routes samples from various locations near the shot chamber to the analysis station. Also, the multiplexer allows users to remotely load unactivated samples without manually approaching the reaction chamber. All elements of the system (pneumatic drivers, flow control valves, optical position sensors, multiplexers, Geiger counters, and release gates at the analysis station) can be controlled manually or automatically using a custom LabVIEW interface. A prototype is currently operating at NRL in Washington DC. Prospective facilities for Raptors systems include LLE and NIF.

Chamber study of PCBemissions from caulking materials and light ballasts

EPA Science Inventory

The emissions of polychlorinated biphenyl (PCB) congeners from 13 caulk samples were tested in a micro-chamber system. Twelve samples were from PCB-contaminated buildings and one was prepared in the laboratory. Nineteen light ballasts collected from buildings that represent 13 di...

Comparative study of glass tube and mist chamber sampling techniques for the analysis of gaseous carbonyl compounds

NASA Astrophysics Data System (ADS)

François, Stéphanie; Perraud, Véronique; Pflieger, Maryline; Monod, Anne; Wortham, Henri

In this work, glass tube and mist chamber sampling techniques using 2,4-dinitrophenylhydrazine as derivative agent for the analysis of gaseous carbonyl compounds are compared. Trapping efficiencies of formaldehyde, acetaldehyde, propionaldehyde, acetone, acrolein, glyoxal, crotonaldehyde, benzaldehyde, butyraldehyde and valeraldehyde are experimentally determined using a gas-phase generator. In addition to generalise our results to all atmospheric gaseous compounds and derivative agents, theoretical trapping efficiencies and enrichment factors are expressed taking into account mechanisms involved in the two kinds of traps. Theoretical and experimental results show that, as expected, the trapping efficiencies of the glass tube depend mainly on solubility of compounds. The results provide new information and better understanding of phenomena occurring in the mist chamber and the ability of this sampler to concentrate the samples. Hence, the mist chamber is the more convenient sampling method when the trapping is associated to a fast derivatisation of the compounds and the glass tube technique must be used to trap atmospheric compounds without simultaneous derivatisation.

Polyport atmospheric gas sampler

DOEpatents

Guggenheim, S. Frederic

1995-01-01

An atmospheric gas sampler with a multi-port valve which allows for multi, sequential sampling of air through a plurality of gas sampling tubes mounted in corresponding gas inlet ports. The gas sampler comprises a flow-through housing which defines a sampling chamber and includes a gas outlet port to accommodate a flow of gases through the housing. An apertured sample support plate defining the inlet ports extends across and encloses the sampling chamber and supports gas sampling tubes which depend into the sampling chamber and are secured across each of the inlet ports of the sample support plate in a flow-through relation to the flow of gases through the housing during sampling operations. A normally closed stopper means mounted on the sample support plate and operatively associated with each of the inlet ports blocks the flow of gases through the respective gas sampling tubes. A camming mechanism mounted on the sample support plate is adapted to rotate under and selectively lift open the stopper spring to accommodate a predetermined flow of gas through the respective gas sampling tubes when air is drawn from the housing through the outlet port.

The Southwest Research Institute ultraviolet reflectance chamber (SwURC): a far ultraviolet reflectometer

NASA Astrophysics Data System (ADS)

Winters, Gregory S.; Retherford, Kurt D.; Davis, Michael W.; Escobedo, Stephen M.; Bassett, Eric C.; Patrick, Edward L.; Nagengast, Maggie E.; Fairbanks, Matthew H.; Miles, Paul F.; Parker, Joel W.; Gladstone, G. Randall; Slater, David C.; Stern, S. Alan

2012-10-01

We designed and assembled a highly capable UV reflectometer chamber and data acquisition system to provide bidirectional scattering data of various surfaces and materials. This chamber was initially conceived to create laboratory-based UV reflectance measurements of water frost on lunar soil/regolith simulants, to support interpretation of UV reflectance data from the Lyman Alpha Mapping Project ("LAMP") instrument on-board the NASA Lunar Reconnaissance Orbiter spacecraft. A deuterium lamp illuminates surfaces and materials at a fixed 45° incident beam angle over the 115 to 200 nm range via a monochromator, while a photomultiplier tube detector is scanned to cover emission angles -85° to +85° (with a gap from -60° to -30°, due to the detector blocking the incident beam). Liquid nitrogen cools the material/sample mount when desired. The chamber can be configured to test a wide range of samples and materials using sample trays and holders. Test surfaces to date include aluminum mirrors, water ice, reflectance standards, and frozen mixtures of water and lunar soil/regolith stimulant. Future UV measurements planned include Apollo lunar samples, meteorite samples, other ices, minerals, and optical surfaces. Since this chamber may well be able to provide useful research data for groups outside Southwest Research Institute, we plan to take requests from and collaborate with others in the UV and surface reflection research community.

Comparison of ammonia emissions determined using different sampling methods

USDA-ARS?s Scientific Manuscript database

Dynamic, flow-through flux chambers are sometimes used to estimate ammonia emissions from livestock operations; however, ammonia emissions from the surfaces are affected by many factors which can be affected by the chamber. Ammonia emissions estimated using environmental flow-through chambers may be...

Development of New Low Temperature Systems at Janis Research

NASA Astrophysics Data System (ADS)

Shvarts, V.; Jirmanus, M. N.; Zhao, Z.

2006-09-01

A new line of ultra low loss He-3 and He-4 superconducting magnet systems and UHV compatible He-3 systems for scanning tunneling microscopy studies have been developed during the past year. This paper discusses the details of the design and performance for the various systems.

Epitaxially Grown Films of Standing and Lying Pentacene Molecules on Cu(110) Surfaces

PubMed Central

2011-01-01

Here, it is shown that pentacene thin films (30 nm) with distinctively different crystallographic structures and molecular orientations can be grown under essentially identical growth conditions in UHV on clean Cu(110) surfaces. By X-ray diffraction, we show that the epitaxially oriented pentacene films crystallize either in the “thin film” phase with standing molecules or in the “single crystal” structure with molecules lying with their long axes parallel to the substrate. The morphology of the samples observed by atomic force microscopy shows an epitaxial alignment of pentacene crystallites, which corroborates the molecular orientation observed by X-ray diffraction pole figures. Low energy electron diffraction measurements reveal that these dissimilar growth behaviors are induced by subtle differences in the monolayer structures formed by slightly different preparation procedures. PMID:21479111

Semi-automated high-efficiency reflectivity chamber for vacuum UV measurements

NASA Astrophysics Data System (ADS)

Wiley, James; Fleming, Brian; Renninger, Nicholas; Egan, Arika

2017-08-01

This paper presents the design and theory of operation for a semi-automated reflectivity chamber for ultraviolet optimized optics. A graphical user interface designed in LabVIEW controls the stages, interfaces with the detector system, takes semi-autonomous measurements, and monitors the system in case of error. Samples and an optical photodiode sit on an optics plate mounted to a rotation stage in the middle of the vacuum chamber. The optics plate rotates the samples and diode between an incident and reflected position to measure the absolute reflectivity of the samples at wavelengths limited by the monochromator operational bandpass of 70 nm to 550 nm. A collimating parabolic mirror on a fine steering tip-tilt motor enables beam steering for detector peak-ups. This chamber is designed to take measurements rapidly and with minimal oversight, increasing lab efficiency for high cadence and high accuracy vacuum UV reflectivity measurements.

Effect of chamber characteristics, loading and analysis time on motility and kinetic variables analysed with the CASA-mot system in goat sperm.

PubMed

Del Gallego, R; Sadeghi, S; Blasco, E; Soler, C; Yániz, J L; Silvestre, M A

2017-02-01

Several factors unrelated to the semen samples could be influencing in the sperm motility analysis. The aim of the present research was to study the effect of four chambers with different characteristics, namely; slide-coverslip, Spermtrack, ISAS D4C10, and ISAS D4C20 on the sperm motility. The filling procedure (drop or capillarity) and analysis time (0, 120 and 240s), depth of chamber (10 or 20μm) and field on motility variables were analysed by use of the CASA-mot system in goat sperm. Use of the drop-filling chambers resulted in greater values than capillarity-filling chambers for all sperm motility and kinetic variables, except for LIN (64.5% compared with 56.3% of motility for drop- and capillarity-filling chambers respectively, P<0.05). There were no significant differences in total sperm motility between different chamber depths, however, use of the 20μm-chambers resulted in greater sperm progressive motility rate, VSL and LIN, and less VCL and VAP than chambers with a lesser depth. There was less sperm motility and lesser values for kinetic variables as time that elapsed increased between sample loading and sperm evaluation. For sperm motility, use of droplet-loaded chambers resulted in similar values of MOT in all microscopic fields, but sperm motility assessed in capillarity-loaded chambers was less in the central fields than in the outermost microscopic fields. For goats, it is recommended that sperm motility be analysed using the CASA-mot system with a drop-loaded chamber within 2min after filling the chamber. Copyright © 2016 Elsevier B.V. All rights reserved.

Effect of conductivity and concentration on the sample stream in the transverse axis of a continuous flow electrophoresis chamber

NASA Technical Reports Server (NTRS)

Miller, Teresa Y.; Williams, George O.; Snyder, Robert S.

1985-01-01

The resolution of continuous flow electrophoresis systems is generally measured by the spread of the sample bands in the direction of the electrophoretic migration. This paper evaluates the cross section of the sample bands in the plane perpendicular to the flow and shows that the spread in the direction perpendicular to the migration increased significantly with the applied electric field. Concentrated samples of monodisperse latex particles and vinyltoluene T-butylstyrene particles in sample buffers of different electrical conductivities were used to map the shape of the sample bands relative to the zero electric field case. As the electric field was applied, the sample band spread from an initial diameter of only one-third the chamber thickness until it approached the chamber walls where electroosmosis significantly reduced the resolution of separation. It can be shown, however, that it is possible to minimize these distortions by careful sample preparation and experiment design.

Evaluation and study of advanced optical contamination, deposition, measurement, and removal techniques. [including computer programs and ultraviolet reflection analysis

NASA Technical Reports Server (NTRS)

Linford, R. M. F.; Allen, T. H.; Dillow, C. F.

1975-01-01

A program is described to design, fabricate and install an experimental work chamber assembly (WCA) to provide a wide range of experimental capability. The WCA incorporates several techniques for studying the kinetics of contaminant films and their effect on optical surfaces. It incorporates the capability for depositing both optical and contaminant films on temperature-controlled samples, and for in-situ measurements of the vacuum ultraviolet reflectance. Ellipsometer optics are mounted on the chamber for film thickness determinations, and other features include access ports for radiation sources and instrumentation. Several supporting studies were conducted to define specific chamber requirements, to determine the sensitivity of the measurement techniques to be incorporated in the chamber, and to establish procedures for handling samples prior to their installation in the chamber. A bibliography and literature survey of contamination-related articles is included.

Modular, multi-level groundwater sampler

DOEpatents

Nichols, Ralph L.; Widdowson, Mark A.; Mullinex, Harry; Orne, William H.; Looney, Brian B.

1994-01-01

Apparatus for taking a multiple of samples of groundwater or pressure measurements from a well simultaneously. The apparatus comprises a series of chambers arranged in an axial array, each of which is dimensioned to fit into a perforated well casing and leave a small gap between the well casing and the exterior of the chamber. Seals at each end of the container define the limits to the axial portion of the well to be sampled. A submersible pump in each chamber pumps the groundwater that passes through the well casing perforations into the gap from the gap to the surface for analysis. The power lines and hoses for the chambers farther down the array pass through each chamber above them in the array. The seals are solid, water-proof, non-reactive, resilient disks supported to engage the inside surface of the well casing. Because of the modular design, the apparatus provides flexibility for use in a variety of well configurations.

An improved sample loading technique for cellular metabolic response monitoring under pressure

NASA Astrophysics Data System (ADS)

Gikunda, Millicent Nkirote

To monitor cellular metabolism under pressure, a pressure chamber designed around a simple-to-construct capillary-based spectroscopic chamber coupled to a microliter-flow perfusion system is used in the laboratory. Although cyanide-induced metabolic responses from Saccharomyces cerevisiae (baker's yeast) could be controllably induced and monitored under pressure, previously used sample loading technique was not well controlled. An improved cell-loading technique which is based on use of a secondary inner capillary into which the sample is loaded then inserted into the capillary pressure chamber, has been developed. As validation, we demonstrate the ability to measure the chemically-induced metabolic responses at pressures of up to 500 bars. This technique is shown to be less prone to sample loss due to perfusive flow than the previous techniques used.

Around Marshall

NASA Image and Video Library

2003-01-01

This is a close-up of a sample of titanium-zirconium-nickel alloy inside the Electrostatic Levitator (ESL) vacuum chamber at NASA's Marshall Space Flight Center (MSFC). The ESL uses static electricity to suspend an object (about 3-4 mm in diameter) inside a vacuum chamber allowing scientists to record a wide range of physical properties without the sample contracting the container or any instruments, conditions that would alter the readings. Once inside the chamber, a laser heats the sample until it melts. The laser is then turned off and the sample cools, changing from a liquid drop to a solid sphere. Since 1977, the ESL has been used at MSFC to study the characteristics of new metals, ceramics, and glass compounds. Materials created as a result of these tests include new optical materials, special metallic glasses, and spacecraft components.

Development of sample exchange robot PAM-HC for beamline BL-1A at the photon factory

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hiraki, Masahiko, E-mail: masahiko.hiraki@kek.jp; Department of Accelerator Science, SOKENDAI; Matsugaki, Naohiro

A macromolecular crystallography beamline, BL-1A, has been built at the Photon Factory (PF) for low energy experiments and has been operational since 2010. We have installed a sample exchange robot, PAM (PF Automated Mounting system), similar to other macromolecular crystallography beamlines. However, following the installation of a helium chamber to reduce the absorption of the diffraction signal by air, we developed a new sample exchange robot to replace PAM. The new robot, named PAM-HC (Helium Chamber), is designed with the goal of minimizing leakage of helium gas from the chamber. Here, the PAM-HC hardware and the flow of its movementmore » are described. Furthermore, measurements of temperature changes during sample exchange are presented in this paper.« less

Micro acoustic resonant chambers for heating/agitating/mixing (MARCHAM)

NASA Astrophysics Data System (ADS)

Sherrit, Stewart; Noell, Aaron C.; Fisher, Anita M.; Takano, Nobuyuki; Grunthaner, Frank

2016-04-01

A variety of applications require the mixing and/or heating of a slurry made from a powder/fluid mixture. One of these applications, Sub Critical Water Extraction (SCWE), is a process where water and an environmental powder sample (sieved soil, drill cuttings, etc.) are heated in a sealed chamber to temperatures greater than 200 degrees Celsius by allowing the pressure to increase, but without reaching the critical point of water. At these temperatures, the ability of water to extract organics from solid particulate increases drastically. This paper describes the modeling and experimentation on the use of an acoustic resonant chamber which is part of an amino acid detection instrument called Astrobionibbler [Noell et al. 2014, 2015]. In this instrument we use acoustics to excite a fluid- solid fines mixture in different frequency/amplitude regimes to accomplish a variety of sample processing tasks. Driving the acoustic resonant chamber at lower frequencies can create circulation patterns in the fluid and mixes the liquid and fines, while driving the chamber at higher frequencies one can agitate the fluid and powder and create a suspension. If one then drives the chamber at high amplitude at resonance heating of the slurry occurs. In the mixing and agitating cell the particle levitation force depends on the relative densities and compressibility's of the particulate and fluid and on the kinetic and potential energy densities associated with the velocity and pressure fields [Glynne-Jones, Boltryk and Hill 2012] in the cell. When heating, the piezoelectric transducer and chamber is driven at high power in resonance where the solid/fines region is modelled as an acoustic transmission line with a large loss component. In this regime, heat is pumped into the solution/fines mixture and rapidly heats the sample. We have modeled the piezoelectric transducer/chamber/ sample using Mason's equivalent circuit. In order to assess the validity of the model we have built and tested a variety of chambers. This paper describes the experimental results which are in general agreement with theory within the limitations of the modeling.

Process and apparatus for obtaining samples of liquid and gas from soil

DOEpatents

Rossabi, J.; May, C.P.; Pemberton, B.E.; Shinn, J.; Sprague, K.

1999-03-30

An apparatus and process for obtaining samples of liquid and gas from subsurface soil is provided having filter zone adjacent an external expander ring. The expander ring creates a void within the soil substrate which encourages the accumulation of soil-borne fluids. The fluids migrate along a pressure gradient through a plurality of filters before entering a first chamber. A one-way valve regulates the flow of fluid into a second chamber in further communication with a collection tube through which samples are collected at the surface. A second one-way valve having a reverse flow provides additional communication between the chambers for the pressurized cleaning and back-flushing of the apparatus. 8 figs.

Process and apparatus for obtaining samples of liquid and gas from soil

DOEpatents

Rossabi, Joseph; May, Christopher P.; Pemberton, Bradley E.; Shinn, Jim; Sprague, Keith

1999-01-01

An apparatus and process for obtaining samples of liquid and gas from subsurface soil is provided having filter zone adjacent an external expander ring. The expander ring creates a void within the soil substrate which encourages the accumulation of soil-borne fluids. The fluids migrate along a pressure gradient through a plurality of filters before entering a first chamber. A one-way valve regulates the flow of fluid into a second chamber in further communication with a collection tube through which samples are collected at the surface. A second one-way valve having a reverse flow provides additional communication between the chambers for the pressurized cleaning and back-flushing of the apparatus.

Characterization of reticulated vitreous carbon foam using a frisch-grid parallel-plate ionization chamber

NASA Astrophysics Data System (ADS)

Edwards, Nathaniel S.; Conley, Jerrod C.; Reichenberger, Michael A.; Nelson, Kyle A.; Tiner, Christopher N.; Hinson, Niklas J.; Ugorowski, Philip B.; Fronk, Ryan G.; McGregor, Douglas S.

2018-06-01

The propagation of electrons through several linear pore densities of reticulated vitreous carbon (RVC) foam was studied using a Frisch-grid parallel-plate ionization chamber pressurized to 1 psig of P-10 proportional gas. The operating voltages of the electrodes contained within the Frisch-grid parallel-plate ionization chamber were defined by measuring counting curves using a collimated 241Am alpha-particle source with and without a Frisch grid. RVC foam samples with linear pore densities of 5, 10, 20, 30, 45, 80, and 100 pores per linear inch were separately positioned between the cathode and anode. Pulse-height spectra and count rates from a collimated 241Am alpha-particle source positioned between the cathode and each RVC foam sample were measured and compared to a measurement without an RVC foam sample. The Frisch grid was positioned in between the RVC foam sample and the anode. The measured pulse-height spectra were indiscernible from background and resulted in negligible net count rates for all RVC foam samples. The Frisch grid parallel-plate ionization chamber measurement results indicate that electrons do not traverse the bulk of RVC foam and consequently do not produce a pulse.

Human portable preconcentrator system

DOEpatents

Linker, Kevin L.; Brusseau, Charles A.; Hannum, David W.; Puissant, James G.; Varley, Nathan R.

2003-08-12

A preconcentrator system and apparatus suited to human portable use wherein sample potentially containing a target chemical substance is drawn into a chamber and through a pervious screen. The screen is adapted to capture target chemicals and then, upon heating, to release those chemicals into the chamber. Chemicals captured and then released in this fashion are then carried to a portable chemical detection device such as a portable ion mobility spectrometer. In the preferred embodiment, the means for drawing sample into the chamber comprises a reversible fan which, when operated in reverse direction, creates a backpressure that facilitates evolution of captured target chemicals into the chamber when the screen is heated. The screen can be positioned directly in front of the detector prior to heating to improve detection capability.

Liquid helium cryostat with internal fluorescence detection for x-ray absorption studies in the 2-6 keV energy region

NASA Astrophysics Data System (ADS)

McFarlane Holman, Karen L.; Latimer, Matthew J.; Yachandra, Vittal K.

2004-06-01

X-ray absorption spectroscopy (XAS) in the intermediate x-ray region (2-6 keV) for dilute biological samples has been limited because of detector/flux limitations and inadequate cryogenic instrumentation. We have designed and constructed a new tailpiece/sample chamber for a commercially available liquid helium cooled cryostat which overcomes difficulties related to low fluorescence signals by using thin window materials and incorporating an internal photodiode detector. With the apparatus, XAS data at the Cl, S, and Ca K edges have been collected on frozen solutions and biological samples at temperatures down to 60 K. A separate chamber has been incorporated for collecting room-temperature spectra of standard compounds (for energy calibration purposes) which prevents contamination of the cryostat chamber and allows the sample to remain undisturbed, both important concerns for studying dilute and radiation-sensitive samples.

Systems and methods for analyzing liquids under vacuum

DOEpatents

Yu, Xiao-Ying; Yang, Li; Cowin, James P.; Iedema, Martin J.; Zhu, Zihua

2013-10-15

Systems and methods for supporting a liquid against a vacuum pressure in a chamber can enable analysis of the liquid surface using vacuum-based chemical analysis instruments. No electrical or fluid connections are required to pass through the chamber walls. The systems can include a reservoir, a pump, and a liquid flow path. The reservoir contains a liquid-phase sample. The pump drives flow of the sample from the reservoir, through the liquid flow path, and back to the reservoir. The flow of the sample is not substantially driven by a differential between pressures inside and outside of the liquid flow path. An aperture in the liquid flow path exposes a stable portion of the liquid-phase sample to the vacuum pressure within the chamber. The radius, or size, of the aperture is less than or equal to a critical value required to support a meniscus of the liquid-phase sample by surface tension.

Ion chamber absorbed dose calibration coefficients, N{sub D,w}, measured at ADCLs: Distribution analysis and stability

DOE Office of Scientific and Technical Information (OSTI.GOV)

Muir, B. R., E-mail: Bryan.Muir@nrc-cnrc.gc.ca

2015-04-15

Purpose: To analyze absorbed dose calibration coefficients, N{sub D,w}, measured at accredited dosimetry calibration laboratories (ADCLs) for client ionization chambers to study (i) variability among N{sub D,w} coefficients for chambers of the same type calibrated at each ADCL to investigate ion chamber volume fluctuations and chamber manufacturing tolerances; (ii) equivalency of ion chamber calibration coefficients measured at different ADCLs by intercomparing N{sub D,w} coefficients for chambers of the same type; and (iii) the long-term stability of N{sub D,w} coefficients for different chamber types by investigating repeated chamber calibrations. Methods: Large samples of N{sub D,w} coefficients for several chamber types measuredmore » over the time period between 1998 and 2014 were obtained from the three ADCLs operating in the United States. These are analyzed using various graphical and numerical statistical tests for the four chamber types with the largest samples of calibration coefficients to investigate (i) and (ii) above. Ratios of calibration coefficients for the same chamber, typically obtained two years apart, are calculated to investigate (iii) above and chambers with standard deviations of old/new ratios less than 0.3% meet stability requirements for accurate reference dosimetry recommended in dosimetry protocols. Results: It is found that N{sub D,w} coefficients for a given chamber type compared among different ADCLs may arise from differing probability distributions potentially due to slight differences in calibration procedures and/or the transfer of the primary standard. However, average N{sub D,w} coefficients from different ADCLs for given chamber types are very close with percent differences generally less than 0.2% for Farmer-type chambers and are well within reported uncertainties. Conclusions: The close agreement among calibrations performed at different ADCLs reaffirms the Calibration Laboratory Accreditation Subcommittee process of ensuring ADCL conformance with National Institute of Standards and Technology standards. This study shows that N{sub D,w} coefficients measured at different ADCLs are statistically equivalent, especially considering reasonable uncertainties. This analysis of N{sub D,w} coefficients also allows identification of chamber types that can be considered stable enough for accurate reference dosimetry.« less

Flow injection trace gas analysis method for on-site determination of organoarsenicals

DOEpatents

Aldstadt, III, Joseph H.

1997-01-01

A method for real-time determination of the concentration of Lewisite in the ambient atmosphere, the method includes separating and collecting a Lewisite sample from the atmosphere in a collection chamber, converting the collected Lewisite to an arsenite ion solution sample, pumping the arsenite ion containing sample to an electrochemical detector connected to the collection chamber, and electrochemically detecting the converted arsenite ions in the sample, whereby the concentration of arsenite ions detected is proportional to the concentration of Lewisite in the atmosphere.

High-quality EuO thin films the easy way via topotactic transformation

DOE PAGES

Mairoser, Thomas; Mundy, Julia A.; Melville, Alexander; ...

2015-07-16

Epitaxy is widely employed to create highly oriented crystalline films. A less appreciated, but nonetheless powerful means of creating such films is via topotactic transformation, in which a chemical reaction transforms a single crystal of one phase into a single crystal of a different phase, which inherits its orientation from the original crystal. Topotactic reactions may be applied to epitactic films to substitute, add or remove ions to yield epitactic films of different phases. Here we exploit a topotactic reduction reaction to provide a non-ultra-high vacuum (UHV) means of growing highly oriented single crystalline thin films of the easily over-oxidizedmore » half-metallic semiconductor europium monoxide (EuO) with a perfection rivalling that of the best films of the same material grown by molecular-beam epitaxy or UHV pulsed-laser deposition. Lastly, as the technique only requires high-vacuum deposition equipment, it has the potential to drastically improve the accessibility of high-quality single crystalline films of EuO as well as other difficult-to-synthesize compounds.« less

Scanning probe microscopy induced surface modifications of the topological insulator Bi2Te3 in different environments

NASA Astrophysics Data System (ADS)

Netsou, Asteriona-Maria; Thupakula, Umamahesh; Debehets, Jolien; Chen, Taishi; Hirsch, Brandon; Volodin, Alexander; Li, Zhe; Song, Fengqi; Seo, Jin Won; De Feyter, Steven; Schouteden, Koen; Van Haesendonck, Chris

2017-08-01

We investigated the topological insulator (TI) Bi2Te3 in four different environments (ambient, ultra-high vacuum (UHV), nitrogen gas and organic solvent environment) using scanning probe microscopy (SPM) techniques. Upon prolonged exposure to ambient conditions and organic solvent environments the cleaved surface of the pristine Bi2Te3 is observed to be strongly modified during SPM measurements, while imaging of freshly cleaved Bi2Te3 in UHV and nitrogen gas shows considerably less changes of the Bi2Te3 surface. We conclude that the reduced surface stability upon exposure to ambient conditions is triggered by adsorption of molecular species from ambient, including H2O, CO2, etc which is verified by Auger electron spectroscopy. Our findings of the drastic impact of exposure to ambient on the Bi2Te3 surface are crucial for further in-depth studies of the intrinsic properties of the TI Bi2Te3 and for potential applications that include room temperature TI based devices operated under ambient conditions.

Ricor's Nanostar water vapor compact cryopump: applications and model overview

NASA Astrophysics Data System (ADS)

Harris, Rodney S.; Nachman, Ilan; Tauber, Tomer; Kootzenko, Michael; Barak, Boris; Aminov, Eli; Gover, Dan

2017-05-01

Ricor Systems has developed a compact, single stage cryopump that fills the gap where GM and other type cryopumps can't fit in. Stirling cycle technology is highly efficient and is the primary cryogenic technology for use in IR, SWIR, HOT FPA, and other IR detector technology in military, security, and aerospace applications. Current GM based dual stage cryopumps have been the legacy type water vapor pumping system for more than 50 years. However, the typically large cryopanel head, compressor footprint, and power requirements make them not cost and use effective for small, tabletop evaporation / sputtering systems, portable analysis systems, and other systems requiring small volume vacuum creation from medium, high, and UHV levels. This single stage cryopump works well in-line with diffusion and molecular turbopumps. Studies have shown effective cooperation with non-evaporable getter technology as well for UHV levels. Further testing in this area are ongoing. Temperatures created by Stirling cycle cryogenic coolers develop a useful temperature range of 40 to 150K. Temperatures of approximately 100 K are sufficient to condense water and all hydrocarbons oil vapors.

Perspective: Chemical reactions in ionic liquids monitored through the gas (vacuum)/liquid interface.

PubMed

Maier, F; Niedermaier, I; Steinrück, H-P

2017-05-07

This perspective analyzes the potential of X-ray photoelectron spectroscopy under ultrahigh vacuum (UHV) conditions to follow chemical reactions in ionic liquids in situ. Traditionally, only reactions occurring on solid surfaces were investigated by X-ray photoelectron spectroscopy (XPS) in situ. This was due to the high vapor pressures of common liquids or solvents, which are not compatible with the required UHV conditions. It was only recently realized that the situation is very different when studying reactions in Ionic Liquids (ILs), which have an inherently low vapor pressure, and first studies have been performed within the last years. Compared to classical spectroscopy techniques used to monitor chemical reactions, the advantage of XPS is that through the analysis of their core levels all relevant elements can be quantified and their chemical state can be analyzed under well-defined (ultraclean) conditions. In this perspective, we cover six very different reactions which occur in the IL, with the IL, or at an IL/support interface, demonstrating the outstanding potential of in situ XPS to gain insights into liquid phase reactions in the near-surface region.

BOREAS TGB-1 NSA SF6 Chamber Flux Data

NASA Technical Reports Server (NTRS)

Crill, Patrick; Varner, Ruth K.; Hall, Forrest G. (Editor); Conrad, Sara K. (Editor)

2000-01-01

The BOREAS TGB-1 team made several chamber and tower measurements of trace gases at sites in the BOREAS NSA. This data set contains sulfur hexafluoride (SF6) dark chamber flux measurements at the NSA-OJP and NSA-YJP sites from 16-May through 13-Sep-1994. Gas samples were extracted approximately every 7 days from dark chambers and analyzed at the NSA lab facility. The data are provided in tabular ASCII files.

Systems and methods for separating particles and/or substances from a sample fluid

DOEpatents

Mariella, Jr., Raymond P.; Dougherty, George M.; Dzenitis, John M.; Miles, Robin R.; Clague, David S.

2016-11-01

Systems and methods for separating particles and/or toxins from a sample fluid. A method according to one embodiment comprises simultaneously passing a sample fluid and a buffer fluid through a chamber such that a fluidic interface is formed between the sample fluid and the buffer fluid as the fluids pass through the chamber, the sample fluid having particles of interest therein; applying a force to the fluids for urging the particles of interest to pass through the interface into the buffer fluid; and substantially separating the buffer fluid from the sample fluid.

A closed unventilated chamber for the measurement of transepidermal water loss.

PubMed

Nuutinen, Jouni; Alanen, Esko; Autio, Pekka; Lahtinen, Marjo-Riitta; Harvima, Ilkka; Lahtinen, Tapani

2003-05-01

Open chamber systems for measuring transepidermal water loss (TEWL) have limitations related to ambient and body-induced airflows near the probe, probe size, measurement sites and angles, and measurement range. The aim of the present investigation was to develop a closed chamber system for the TEWL measurement without significant blocking of normal evaporation through the skin. Additionally, in order to use the evaporimeter to measure evaporation rates through other biological and non-biological specimens and in the field applications, a small portable, battery-operated device was a design criteria. A closed unventilated chamber (inner volume 2.0 cm(3) was constructed. For the skin measurement, the chamber with one side open (open surface area 1.0 cm(2) is placed on the skin. The skin application time was investigated at low and high evaporation rates in order to assess the blocking effect of the chamber on normal evaporation. From the rising linear part of the relative humidity (RH) in the chamber the slope was registered. The slope was calibrated into a TEWL value by evaporating water at different temperatures and measuring the water loss of heated samples with a laboratory scale. The closed chamber evaporation technique was compared with a conventional evaporimeter based on an open chamber method (DermaLab), Cortex Technology, Hadsund, Denmark). The reproducibility of the closed chamber method was measured with the water samples and with volar forearm and palm of the hand in 10 healthy volunteers. The skin application time varied between 7 and 9 s and the linear slope region between 3 and 5 s at the evaporation rates of 3-220 g/m(2) h. A correlation coefficient between the TEWL value from the closed chamber measurements and the readings of the laboratory scale was 0.99 (P < 0.001). The reproducibility of the evaporation measurements with the water samples was 4.0% at the evaporation rate of 40 g/m(2) h. A correlation coefficient of the TEWL values between the closed chamber and open chamber measurements was 0.99 (P < 0.001) in the range where the response of a conventional evaporimeter was linear (until 120 g/m(2)h. With volar forearm and palm of the hand of 10 healthy volunteers the reproducibility of the measurements was 8.0 and 10.1%. The closed chamber technique solves the drawbacks related to open chamber evaporimeters. Especially, it extends the measurement range to high evaporation rates and TEWL measurements can be performed practically at any anatomical sites and measurement angle. By the use of a closed chamber the disturbance related to external or body-induced air flows on the measurement can be avoided.

Titanium-Zirconium-Nickel Alloy Inside Marshall's Electrostatic Levitator (ESL)

NASA Technical Reports Server (NTRS)

2003-01-01

This is a close-up of a sample of titanium-zirconium-nickel alloy inside the Electrostatic Levitator (ESL) vacuum chamber at NASA's Marshall Space Flight Center (MSFC). The ESL uses static electricity to suspend an object (about 3-4 mm in diameter) inside a vacuum chamber allowing scientists to record a wide range of physical properties without the sample contracting the container or any instruments, conditions that would alter the readings. Once inside the chamber, a laser heats the sample until it melts. The laser is then turned off and the sample cools, changing from a liquid drop to a solid sphere. Since 1977, the ESL has been used at MSFC to study the characteristics of new metals, ceramics, and glass compounds. Materials created as a result of these tests include new optical materials, special metallic glasses, and spacecraft components.

Development of a versatile user-friendly IBA experimental chamber

NASA Astrophysics Data System (ADS)

Kakuee, Omidreza; Fathollahi, Vahid; Lamehi-Rachti, Mohammad

2016-03-01

Reliable performance of the Ion Beam Analysis (IBA) techniques is based on the accurate geometry of the experimental setup, employment of the reliable nuclear data and implementation of dedicated analysis software for each of the IBA techniques. It has already been shown that geometrical imperfections lead to significant uncertainties in quantifications of IBA measurements. To minimize these uncertainties, a user-friendly experimental chamber with a heuristic sample positioning system for IBA analysis was recently developed in the Van de Graaff laboratory in Tehran. This system enhances IBA capabilities and in particular Nuclear Reaction Analysis (NRA) and Elastic Recoil Detection Analysis (ERDA) techniques. The newly developed sample manipulator provides the possibility of both controlling the tilt angle of the sample and analyzing samples with different thicknesses. Moreover, a reasonable number of samples can be loaded in the sample wheel. A comparison of the measured cross section data of the 16O(d,p1)17O reaction with the data reported in the literature confirms the performance and capability of the newly developed experimental chamber.

Reactions of NO2 with BaO/Pt(111) Model Catalysts: The Effects of BaO Film Thickness and NO2 Pressure on the Formation of Ba(NOx)2 Species

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mudiyanselage, Kumudu; Yi, Cheol-Woo; Szanyi, Janos

2011-05-31

The adsorption and reaction of NO2 on BaO (<1, ~3, and >20 monolayer equivalent (MLE))/Pt(111) model systems were studied with temperature programmed desorption (TPD), X-ray photoelectron spectroscopy (XPS), and infrared reflection absorption spectroscopy (IRAS) under ultra-high vacuum (UHV) as well as elevated pressure conditions. NO2 reacts with sub-monolayer BaO (<1 MLE) to form nitrites only, whereas the reaction of NO2 with BaO (~3 MLE)/Pt(111) produces mainly nitrites and a small amount of nitrates under UHV conditions (PNO2 ~ 1.0 × 10-9 Torr) at 300 K. In contrast, a thick BaO(>20 MLE) layer on Pt(111) reacts with NO2 to form nitrite-nitratemore » ion pairs under the same conditions. At elevated NO2 pressures (≥ 1.0 × 10-5 Torr), however, BaO layers at all these three coverages convert to amorphous barium nitrates at 300 K. Upon annealing to 500 K, these amorphous barium nitrate layers transform into crystalline phases. The thermal decomposition of the thus-formed Ba(NOx)2 species is also influenced by the coverage of BaO on the Pt(111) substrate: at low BaO coverages, these species decompose at significantly lower temperatures in comparison with those formed on thick BaO films due to the presence of Ba(NOx)2/Pt interface where the decomposition can proceed at lower temperatures. However, the thermal decomposition of the thick Ba(NO3)2 films follows that of bulk nitrates. Results obtained from these BaO/Pt(111) model systems under UHV and elevated pressure conditions clearly demonstrate that both the BaO film thickness and the applied NO2 pressure are critical in the Ba(NOx)2 formation and subsequent thermal decomposition processes.« less

Device for collecting and analyzing matrix-isolated samples

DOEpatents

Reedy, Gerald T.

1979-01-01

A gas-sample collection device is disclosed for matrix isolation of individual gas bands from a gas chromatographic separation and for presenting these distinct samples for spectrometric examination. The device includes a vacuum chamber containing a rotatably supported, specular carrousel having a number of external, reflecting surfaces around its axis of rotation for holding samples. A gas inlet is provided for depositing sample and matrix material on the individual reflecting surfaces maintained at a sufficiently low temperature to cause solidification. Two optical windows or lenses are installed in the vacuum chamber walls for transmitting a beam of electromagnetic radiation, for instance infrared light, through a selected sample. Positioned within the chamber are two concave mirrors, the first aligned to receive the light beam from one of the lenses and focus it to the sample on one of the reflecting surfaces of the carrousel. The second mirror is aligned to receive reflected light from that carrousel surface and to focus it outwardly through the second lens. The light beam transmitted from the sample is received by a spectrometer for determining absorption spectra.

Measurements of Gas-Wall Partitioning of Oxidized Species in Environmental Smog Chambers and Teflon Sampling Lines

NASA Astrophysics Data System (ADS)

Krechmer, J.; Pagonis, D.; Ziemann, P. J.; Jimenez, J. L.

2015-12-01

Environmental "smog" chambers have played an integral role in atmospheric aerosol research for decades. Recently, many works have demonstrated that the loss of gas-phase material to fluorinated ethylene propylene (FEP) chamber walls can have significant effects on secondary organic aerosol (SOA) yield results. The effects of gas-wall partitioning on highly oxidized species is still controversial, however. In this work we performed a series of experiments examining the losses of oxidized gas-phase compounds that were generated in-situ­ in an environmental chamber. The loss of species to the walls was measured using three chemical ionization mass spectrometry techniques: proton-transfer-reaction (PTR), nitrate (NO3-) ion, and iodide (I-). Many oxidized species have wall loss timescales ranging between 15 to 45 minutes and scale according to the molecule's estimated saturation concentration c* and functional groups. By comparing results of the different techniques, and in particular by the use of the "wall-less" NO3- source, we find that measuring species with high chamber wall-loss rates is complicated by the use of a standard ion-molecule reaction (IMR) region, as well as long Teflon sampling lines, which can be important sinks for gas-phase species. This effect is observed even for semi-volatile species and could have significant effects on ambient sampling techniques that make highly time-resolved measurements using long sampling lines, such as eddy covariance measurements.

Acoustical-Levitation Chamber for Metallurgy

NASA Technical Reports Server (NTRS)

Barmatz, M. B.; Trinh, E.; Wang, T. G.; Elleman, D. D.; Jacobi, N.

1983-01-01

Sample moved to different positions for heating and quenching. Acoustical levitation chamber selectively excited in fundamental and second-harmonic longitudinal modes to hold sample at one of three stable postions: A, B, or C. Levitated object quickly moved from one of these positions to another by changing modes. Object rapidly quenched at A or C after heating in furnace region at B.

Miniature thermo-electric cooled cryogenic pump

DOEpatents

Keville, R.F.

1997-11-18

A miniature thermo-electric cooled cryogenic pump is described for removing residual water molecules from an inlet sample prior to sample analysis in a mass spectroscopy system, such as ion cyclotron resonance (ICR) mass spectroscopy. The cryogenic pump is a battery operated, low power (<1.6 watts) pump with a {Delta}T=100 C characteristic. The pump operates under vacuum pressures of 5{times}10{sup {minus}4} Torr to ultra high vacuum (UHV) conditions in the range of 1{times}10{sup {minus}7} to 3{times}10{sup {minus}9} Torr and will typically remove partial pressure, 2{times}10{sup {minus}7} Torr, residual water vapor. The cryogenic pump basically consists of an inlet flange piece, a copper heat sink with a square internal bore, four two tier Peltier (TEC) chips, a copper low temperature square cross sectional tubulation, an electronic receptacle, and an exit flange piece, with the low temperature tubulation being retained in the heat sink at a bias angle of 5{degree}, and with the TECs being positioned in parallel to each other with a positive potential being applied to the top tier thereof. 2 figs.

Miniature thermo-electric cooled cryogenic pump

DOEpatents

Keville, Robert F.

1997-01-01

A miniature thermo-electric cooled cryogenic pump for removing residual water molecules from an inlet sample prior to sample analysis in a mass spectroscopy system, such as ion cyclotron resonance (ICR) mass spectroscopy. The cryogenic pump is a battery operated, low power (<1.6 watts) pump with a .DELTA.T=100.degree. C. characteristic. The pump operates under vacuum pressures of 5.times.10.sup.-4 Torr to ultra high vacuum (UHV) conditions in the range of 1.times.10.sup.-7 to 3.times.10.sup.-9 Torr and will typically remove partial pressure, 2.times.10.sup.-7 Torr, residual water vapor. The cryogenic pump basically consists of an inlet flange piece, a copper heat sink with a square internal bore, four two tier Peltier (TEC) chips, a copper low temperature square cross sectional tubulation, an electronic receptacle, and an exit flange piece, with the low temperature tubulation being retained in the heat sink at a bias angle of 5.degree., and with the TECs being positioned in parallel to each other with a positive potential being applied to the top tier thereof.

Design considerations of a thermally stabilized continuous flow electrophoresis chamber 2

NASA Technical Reports Server (NTRS)

Jandebeur, T. S.

1982-01-01

The basic adjustable parameters of a Beckman Continouous Particle Electrophoresis (CPE) Apparatus are investigated to determine the optimum conditions for ground based operation for comparison with space experiments. The possible application of electrically insulated copper/aluminum chamber walls is evaluated as a means to thermally stabilize or equilibrate lateral temperature gradients which exist on the walls of conventional plastic chambers and which distort the rectilinear base flow of buffer through the chamber, significantly affecting sample resolution.

Space Age Archaeology

NASA Technical Reports Server (NTRS)

1988-01-01

In 1985, the Egyptian Antiques Organization (EAO) asked Dr. Farouk El-Baz whether it would be possible to examine and sample the second chamber of the subterranean chamber carved in the bedrock near the Great Pyramid of Khufu in Giza, Egypt, without admitting people, air or contaminants. He felt it could by applying space technology to the task. The initial contact led to a two year project which he organized and headed a team, co-sponsored by EAO and the National Geographic Society (NGS), to apply space technology in an effort to examine and photograph the Giza Chamber. The NGS photographic division modified and tested a remotely controlled video system and a 35-millimeter camera, and developed a lighting system that would not elevate the chamber temperature. Still needed was a drill to cut through the limestone cap without using lubricants or cooling fluids that might contaminate the chamber, and an airlock that would admit the drill shaft and photo equipment but not the air. Bob Moores from Black & Decker Corporation tailored a new drill to the Giza exploration. The drill bit broke through into the chamber at a depth of 63 inches, a stainless steel tube was lowered through the airlock to take samples of the chamber air at several levels. The video camera sent images from the chamber revealing that there was a disassembled royal boat that had been there.

Technical note: drifting versus anchored flux chambers for measuring greenhouse gas emissions from running waters

NASA Astrophysics Data System (ADS)

Lorke, A.; Bodmer, P.; Noss, C.; Alshboul, Z.; Koschorreck, M.; Somlai-Haase, C.; Bastviken, D.; Flury, S.; McGinnis, D. F.; Maeck, A.; Müller, D.; Premke, K.

2015-12-01

Stream networks have recently been discovered to be major but poorly constrained natural greenhouse gas (GHG) sources. A fundamental problem is that several measurement approaches have been used without cross-comparisons. Flux chambers represent a potentially powerful methodological approach if robust and reliable ways to use chambers on running water can be defined. Here we compare the use of anchored and freely drifting chambers on various streams with different flow velocities. The study clearly shows that (1) anchored chambers enhance turbulence under the chambers and thus elevate fluxes, (2) drifting chambers have a very small impact on the water turbulence under the chamber and thus generate more reliable fluxes, (3) the bias of the anchored chambers greatly depends on chamber design and sampling conditions, and (4) there is a promising method to reduce the bias from anchored chambers by using a flexible plastic foil collar to seal the chambers to the water surface, rather than having rigid chamber walls penetrating into the water. Altogether, these results provide novel guidance on how to apply flux chambers in running water, which will have important consequences for measurements to constrain the global GHG balances.

BOREAS TGB-1/TGB-3 CH4 Chamber Flux Data over the NSA Fen

NASA Technical Reports Server (NTRS)

Bubier, Jill L.; Moore, Tim R.; Hall, Forrest G. (Editor); Conrad, Sara K. (Editor)

2000-01-01

The BOREAS TGB-3 team collected methane (CH4) chamber flux measurements at the NSA fen site during May-September 1994 and June-October 1996. Gas samples were extracted approximately every 7 days from chambers and analyzed at the NSA lab facility. The data are provided in tabular ASCII files.

Adhesion in a Vacuum Environment and its Implications for Dust Mitigation Techniques on Airless Bodies

NASA Technical Reports Server (NTRS)

Berkebile, Stephen; Gaier, James R.

2012-01-01

During the Apollo missions, the adhesion of dust to critical spacecraft systems was a greater problem than anticipated and resulted in functional degradation of thermal control surfaces, spacesuit seals, and other spacecraft components. Notably, Earth-based simulation efforts did not predict the magnitude and effects of dust adhesion in the lunar environment. Forty years later, we understand that the ultrahigh vacuum (UHV) environment, coupled with micrometeorite impacts and constant ion and photon bombardment from the sun result in atomically clean and high surface energy dust particles and spacecraft surfaces. However, both the dominant mechanism of adhesion in airless environments and the conditions for high fidelity simulation tests have still to be determined. The experiments presented in here aim to aid in the development of dust mitigation techniques for airless bodies (e.g., lunar surface, asteroids, moons of outer planets). The approach taken consists of (a) quantifying the adhesion between common polymer and metallic spacecraft materials and a synthetic noritic volcanic glass, as a function of surface cleanliness and of triboelectric charge transfer in a UHV environment, and (b) determining parameters for high fidelity tests through investigation of adhesion dependence on vacuum environment and sample treatment. Adhesion force has been measured between pins of spacecraft materials and a plate of synthetic volcanic glass by determining the pull-off force with a torsion balance. Although no significant adhesion is generally observed directly as a result of high surface energies, the adhesion due to induced electrostatic charge is observed to increase with spacecraft material cleanliness, in some cases by over a factor of 10. Furthermore, electrostatically-induced adhesion is found to decrease rapidly above pressures of 10-6 torr. It is concluded that high-fidelity tests should be conducted in high to ultrahigh vacuum and include an ionized surface cleaning process.

Modular, multi-level groundwater sampler

DOEpatents

Nichols, R.L.; Widdowson, M.A.; Mullinex, H.; Orne, W.H.; Looney, B.B.

1994-03-15

An apparatus is described for taking a multiple of samples of groundwater or pressure measurements from a well simultaneously. The apparatus comprises a series of chambers arranged in an axial array, each of which is dimensioned to fit into a perforated well casing and leave a small gap between the well casing and the exterior of the chamber. Seals at each end of the container define the limits to the axial portion of the well to be sampled. A submersible pump in each chamber pumps the groundwater that passes through the well casing perforations into the gap from the gap to the surface for analysis. The power lines and hoses for the chambers farther down the array pass through each chamber above them in the array. The seals are solid, water-proof, non-reactive, resilient disks supported to engage the inside surface of the well casing. Because of the modular design, the apparatus provides flexibility for use in a variety of well configurations. 3 figures.

Automated MALDI Matrix Coating System for Multiple Tissue Samples for Imaging Mass Spectrometry

NASA Astrophysics Data System (ADS)

Mounfield, William P.; Garrett, Timothy J.

2012-03-01

Uniform matrix deposition on tissue samples for matrix-assisted laser desorption/ionization (MALDI) is key for reproducible analyte ion signals. Current methods often result in nonhomogenous matrix deposition, and take time and effort to produce acceptable ion signals. Here we describe a fully-automated method for matrix deposition using an enclosed spray chamber and spray nozzle for matrix solution delivery. A commercial air-atomizing spray nozzle was modified and combined with solenoid controlled valves and a Programmable Logic Controller (PLC) to control and deliver the matrix solution. A spray chamber was employed to contain the nozzle, sample, and atomized matrix solution stream, and to prevent any interference from outside conditions as well as allow complete control of the sample environment. A gravity cup was filled with MALDI matrix solutions, including DHB in chloroform/methanol (50:50) at concentrations up to 60 mg/mL. Various samples (including rat brain tissue sections) were prepared using two deposition methods (spray chamber, inkjet). A linear ion trap equipped with an intermediate-pressure MALDI source was used for analyses. Optical microscopic examination showed a uniform coating of matrix crystals across the sample. Overall, the mass spectral images gathered from tissues coated using the spray chamber system were of better quality and more reproducible than from tissue specimens prepared by the inkjet deposition method.

Automated MALDI matrix coating system for multiple tissue samples for imaging mass spectrometry.

PubMed

Mounfield, William P; Garrett, Timothy J

2012-03-01

Uniform matrix deposition on tissue samples for matrix-assisted laser desorption/ionization (MALDI) is key for reproducible analyte ion signals. Current methods often result in nonhomogenous matrix deposition, and take time and effort to produce acceptable ion signals. Here we describe a fully-automated method for matrix deposition using an enclosed spray chamber and spray nozzle for matrix solution delivery. A commercial air-atomizing spray nozzle was modified and combined with solenoid controlled valves and a Programmable Logic Controller (PLC) to control and deliver the matrix solution. A spray chamber was employed to contain the nozzle, sample, and atomized matrix solution stream, and to prevent any interference from outside conditions as well as allow complete control of the sample environment. A gravity cup was filled with MALDI matrix solutions, including DHB in chloroform/methanol (50:50) at concentrations up to 60 mg/mL. Various samples (including rat brain tissue sections) were prepared using two deposition methods (spray chamber, inkjet). A linear ion trap equipped with an intermediate-pressure MALDI source was used for analyses. Optical microscopic examination showed a uniform coating of matrix crystals across the sample. Overall, the mass spectral images gathered from tissues coated using the spray chamber system were of better quality and more reproducible than from tissue specimens prepared by the inkjet deposition method.

A fast passive and planar liquid sample micromixer.

PubMed

Melin, Jessica; Gimenéz, Guillem; Roxhed, Niclas; van der Wijngaart, Wouter; Stemme, Göran

2004-06-01

A novel microdevice for passively mixing liquid samples based on surface tension and a geometrical mixing chamber is presented. Due to the laminar flow regime on the microscale, mixing becomes difficult if not impossible. We present a micromixer where a constantly changing time dependent flow pattern inside a two sample liquid plug is created as the plug simply passes through the planar mixer chamber. The device requires no actuation during mixing and is fabricated using a single etch process. The effective mixing of two coloured liquid samples is demonstrated.

Flow injection trace gas analysis method for on-site determination of organoarsenicals

DOEpatents

Aldstadt, J.H. III

1997-06-24

A method is described for real-time determination of the concentration of Lewisite in the ambient atmosphere, the method includes separating and collecting a Lewisite sample from the atmosphere in a collection chamber, converting the collected Lewisite to an arsenite ion solution sample, pumping the arsenite ion containing sample to an electrochemical detector connected to the collection chamber, and electrochemically detecting the converted arsenite ions in the sample, whereby the concentration of arsenite ions detected is proportional to the concentration of Lewisite in the atmosphere. 2 figs.

Method and Apparatus for the Collection, Storage, and Real Time Analysis of Blood and Other Bodily Fluids

NASA Technical Reports Server (NTRS)

Whiitson, Peggy A. (Inventor); Clift, Vaughan L. (Inventor)

1999-01-01

The present invention provides a method and apparatus for separating a blood sample having a volume of up to about 20 milliliters into cellular and acellular fractions. The apparatus includes a housing divided by a fibrous filter into a blood sample collection chamber having a volume of at least about 1 milliliter and a serum sample collection chamber. The fibrous filter has a pore size of less than about 3 microns, and is coated with a mixture including between about 1-40 wt/vol % mannitol and between about 0.1-15 wt/vol % of plasma fraction protein (or an animal or vegetable equivalent thereof). The coating causes the cellular fraction to be trapped by the small pores, leaving the cellular fraction intact on the fibrous filter while the acellular fraction passes through the filter for collection in unaltered form from the serum sample collection chamber.

Protective Coatings for Steel Structures: Laboratory and Field Evaluation and Development of a Model Coating Guide Specification.

DTIC Science & Technology

1980-01-01

coated with carnauba wax . Samples were exposed for 30 test cycles. The samples were cemoved from the chamber, washed with tap water, then with distil...vertically with wax -coated hooks, the bottoms of the specimens being about 12 cm from the chamber floor. The backs and edges of all specimens were

CONTINUOUS ANALYZER UTILIZING BOILING POINT DETERMINATION

DOEpatents

Pappas, W.S.

1963-03-19

A device is designed for continuously determining the boiling point of a mixture of liquids. The device comprises a distillation chamber for boiling a liquid; outlet conduit means for maintaining the liquid contents of said chamber at a constant level; a reflux condenser mounted above said distillation chamber; means for continuously introducing an incoming liquid sample into said reflux condenser and into intimate contact with vapors refluxing within said condenser; and means for measuring the temperature of the liquid flowing through said distillation chamber. (AEC)

Test and evaluation of the Argonne BPAC10 Series air chamber calorimeter designed for 20 minute measurements

DOE Office of Scientific and Technical Information (OSTI.GOV)

Perry, R.B.; Fiarman, S.; Jung, E.A.

1990-10-01

This paper is the final report on DOE-OSS Task ANLE88002 Fast Air Chamber Calorimetry.'' The task objective was to design, construct, and test an isothermal air chamber calorimeter for plutonium assay of bulk samples that would meet the following requirements for sample power measurement: average sample measurement time less than 20 minutes. Measurement of samples with power output up to 10 W. Precision of better than 1% RSD for sample power greater than 1 W. Precision better than 0.010 watt SD, for sample power less than 1 W. This report gives a description of the calorimeter hardware and software andmore » discusses the test results. The instrument operating procedure, included as an appendix, gives examples of typical input/output and explains the menu driven software. Sample measurement time of less than 20 minutes was attained by pre-equilibration of the samples in low cost precision preheaters and by prediction of equilibrium measurements. Tests at the TA55 Plutonium Facility at Los Alamos National Laboratory, on typical samples, indicates that the instrument meets all the measurement requirements.« less

Technical Note: Drifting vs. anchored flux chambers for measuring greenhouse gas emissions from running waters

NASA Astrophysics Data System (ADS)

Lorke, A.; Bodmer, P.; Noss, C.; Alshboul, Z.; Koschorreck, M.; Somlai, C.; Bastviken, D.; Flury, S.; McGinnis, D. F.; Maeck, A.; Müller, D.; Premke, K.

2015-09-01

Stream networks were recently discovered as major but poorly constrained natural greenhouse gas (GHG) sources. A fundamental problem is that several measurement approaches have been used without cross comparisons. Flux chambers represent a potentially powerful methodological approach if robust and reliable ways to use chambers on running water can be defined. Here we compare the use of anchored and freely drifting chambers on various streams having different flow velocities. The study clearly shows that (1) drifting chambers have a very small impact on the water turbulence under the chamber and thus generate more reliable fluxes, (2) anchored chambers enhance turbulence under the chambers and thus elevate fluxes, (3) the bias of the anchored chambers greatly depends on chamber design and sampling conditions, and (4) there is a promising method to reduce the bias from anchored chambers by using a flexible plastic foil seal to the water surface rather than having rigid chamber walls penetrating into the water. Altogether, these results provide novel guidance on how to apply flux chambers in running water, which will have important consequences for measurements to constrain the global GHG balances.

A method for sampling microbial aerosols using high altitude balloons.

PubMed

Bryan, N C; Stewart, M; Granger, D; Guzik, T G; Christner, B C

2014-12-01

Owing to the challenges posed to microbial aerosol sampling at high altitudes, very little is known about the abundance, diversity, and extent of microbial taxa in the Earth-atmosphere system. To directly address this knowledge gap, we designed, constructed, and tested a system that passively samples aerosols during ascent through the atmosphere while tethered to a helium-filled latex sounding balloon. The sampling payload is ~ 2.7 kg and comprised of an electronics box and three sampling chambers (one serving as a procedural control). Each chamber is sealed with retractable doors that can be commanded to open and close at designated altitudes. The payload is deployed together with radio beacons that transmit GPS coordinates (latitude, longitude and altitude) in real time for tracking and recovery. A cut mechanism separates the payload string from the balloon at any desired altitude, returning all equipment safely to the ground on a parachute. When the chambers are opened, aerosol sampling is performed using the Rotorod® collection method (40 rods per chamber), with each rod passing through 0.035 m3 per km of altitude sampled. Based on quality control measurements, the collection of ~ 100 cells rod(-1) provided a 3-sigma confidence level of detection. The payload system described can be mated with any type of balloon platform and provides a tool for characterizing the vertical distribution of microorganisms in the troposphere and stratosphere. Copyright © 2014 Elsevier B.V. All rights reserved.

Plasma current collection of Z-93 thermal control paint as measured in the Lewis Research Center's plasma interaction facility

NASA Technical Reports Server (NTRS)

Hillard, G. Barry

1993-01-01

A sample of Z-93 thermal control paint was exposed to a simulated space environment in a plasma chamber. The sample was biased through a series of voltages ranging from -100 volts to +300 volts and electron and ion currents were measured. Currents were found to be in the micro-ampere range indicating that the material remains a reasonably good insulator under plasma conditions. As a second step, the sample was left in the chamber for six days and retested. Collected currents were reduced by from two to five times from the previous values indicating a substantial loss of conductivity. As a final test, the sample was removed, exposed to room conditions for two days, and returned to the chamber. Current measurements showed that the sample had partially recovered the lost conductivity. In addition to presenting these results, this report documents all of the experimental data as well as the statistical analyses performed.

Absolute dosimetry on a dynamically scanned sample for synchrotron radiotherapy using graphite calorimetry and ionization chambers

NASA Astrophysics Data System (ADS)

Lye, J. E.; Harty, P. D.; Butler, D. J.; Crosbie, J. C.; Livingstone, J.; Poole, C. M.; Ramanathan, G.; Wright, T.; Stevenson, A. W.

2016-06-01

The absolute dose delivered to a dynamically scanned sample in the Imaging and Medical Beamline (IMBL) on the Australian Synchrotron was measured with a graphite calorimeter anticipated to be established as a primary standard for synchrotron dosimetry. The calorimetry was compared to measurements using a free-air chamber (FAC), a PTW 31 014 Pinpoint ionization chamber, and a PTW 34 001 Roos ionization chamber. The IMBL beam height is limited to approximately 2 mm. To produce clinically useful beams of a few centimetres the beam must be scanned in the vertical direction. In practice it is the patient/detector that is scanned and the scanning velocity defines the dose that is delivered. The calorimeter, FAC, and Roos chamber measure the dose area product which is then converted to central axis dose with the scanned beam area derived from Monte Carlo (MC) simulations and film measurements. The Pinpoint chamber measures the central axis dose directly and does not require beam area measurements. The calorimeter and FAC measure dose from first principles. The calorimetry requires conversion of the measured absorbed dose to graphite to absorbed dose to water using MC calculations with the EGSnrc code. Air kerma measurements from the free air chamber were converted to absorbed dose to water using the AAPM TG-61 protocol. The two ionization chambers are secondary standards requiring calibration with kilovoltage x-ray tubes. The Roos and Pinpoint chambers were calibrated against the Australian primary standard for air kerma at the Australian Radiation Protection and Nuclear Safety Agency (ARPANSA). Agreement of order 2% or better was obtained between the calorimetry and ionization chambers. The FAC measured a dose 3-5% higher than the calorimetry, within the stated uncertainties.

Detecting low levels of radionuclides in fluids

DOEpatents

Patch, Keith D.; Morgan, Dean T.

2000-01-01

An apparatus and method for detecting low levels of one or more radionuclides in a fluid sample uses a substrate that includes an ion exchange resin or other sorbent material to collect the radionuclides. A collecting apparatus includes a collecting chamber that exposes the substrate to a measured amount of the fluid sample such that radionuclides in the fluid sample are collected by the ion exchange resin. A drying apparatus, which can include a drying chamber, then dries the substrate. A measuring apparatus measures emissions from radionuclides collected on the substrate. The substrate is positioned in a measuring chamber proximate to a detector, which provides a signal in response to emissions from the radionuclides. Other analysis methods can be used to detect non-radioactive analytes, which can be collected with other types of sorbent materials.

Sample stream distortion modeled in continuous-flow electrophoresis

NASA Technical Reports Server (NTRS)

Rhodes, P. H.

1979-01-01

Buoyancy-induced disturbances in an electrophoresis-type chamber were investigated. Five tracer streams (latex) were used to visualize the flows while a nine-thermistor array sensed the temperature field. The internal heating to the chamber was provided by a 400 Hz electrical field. Cooling to the chamber was provided on the front and back faces and, in addition, on both chamber side walls. Disturbances to the symmetric base flow in the chamber occurred in the broad plane of the chamber and resulted from the formation of lateral and axial temperature gradients. The effect of these gradients was to retard or increase local flow velocities at different positions in the chamber cross section, which resulted in lateral secondary flows being induced in the broad plane of the chamber. As the adverse temperature gradients increased in magnitude, the critical Rayleigh number was approached and reverse (separated) flow became apparent, which, subsequently, led to the onset of time variant secondary flows.

Materials screening chamber for testing materials resistance to atomic oxygen

NASA Technical Reports Server (NTRS)

Pippin, H. G.; Carruth, Ralph

1989-01-01

A unique test chamber for exposing material to a known flux of oxygen atoms is described. The capabilities and operating parameters of the apparatus include production of an oxygen atom flux in excess of 5 x 10 to the 16th atoms/sq cm-sec, controlled heating of the sample specimen, RF circuitry to contain the plasma within a small volume, and long exposure times. Flux measurement capabilities include a calorimetric probe and a light titration system. Accuracy and limitations of these techniques are discussed. An extension to the main chamber to allow simultaneous ultraviolet and atomic oxygen exposure is discussed. The oxygen atoms produced are at thermal energies. Sample specimens are maintained at any selected temperature between ambient and 200 C, to within + or - 2 C. A representative example of measurements made using the chamber is presented.

Design and Applications of a Climatic Chamber for in-situ Neutron Imaging Experiments

NASA Astrophysics Data System (ADS)

Mannes, David; Schmid, Florian; Wehmann, Timon; Lehmann, Eberhard

Due to the high sensitivity for hydrogen, the detection and quantification of moisture and moisture transport processes are some of the key topics in neutron imaging. Especially when dealing with hygroscopic material, such as wood and other porous media, it is crucial for quantitative analyses to know and control the ambient conditions of the sample precisely. In this work, a neutron transparent climatic chamber is presented, which was designed and built for the imaging facilities at the Paul Scherrer Institut (PSI), Villigen (CH). The air-conditioned measuring system consists of the actual sample chamber and a moisture generator providing air with adjustable temperature and relative humidity (%RH) (up to a dew point temperature of 70 °C). The two components are connected with a flexible tube, which features insulation, a heating system and temperature sensors to prevent condensation within the tube. The sample chamber itself is equipped with neutron transparent windows, insulating double walls with three feed-through openings for the rotation stage, sensors for humidity and temperature. Thermoelectric modules allow to control the chamber temperature in the range of -20 °C to 100 °C. The chamber allows to control the climatic conditions either in a static mode (stable temperature and %RH) or in dynamic mode (humidity or temperature cycles). The envisaged areas of application are neutron radiography and tomography investigations of dynamic processes in building materials (e.g. wood, concrete), food science and any other application necessitating the control of the climatic conditions.

All-in-one 3D printed microscopy chamber for multidimensional imaging, the UniverSlide.

PubMed

Alessandri, Kevin; Andrique, Laetitia; Feyeux, Maxime; Bikfalvi, Andreas; Nassoy, Pierre; Recher, Gaëlle

2017-02-10

While live 3D high resolution microscopy techniques are developing rapidly, their use for biological applications is partially hampered by practical difficulties such as the lack of a versatile sample chamber. Here, we propose the design of a multi-usage observation chamber adapted for live 3D bio-imaging. We show the usefulness and practicality of this chamber, which we named the UniverSlide, for live imaging of two case examples, namely multicellular systems encapsulated in sub-millimeter hydrogel shells and zebrafish larvae. We also demonstrate its versatility and compatibility with all microscopy devices by using upright or inverted microscope configurations after loading the UniverSlide with fixed or living samples. Further, the device is applicable for medium/high throughput screening and automatized multi-position image acquisition, providing a constraint-free but stable and parallelized immobilization of the samples. The frame of the UniverSlide is fabricated using a stereolithography 3D printer, has the size of a microscopy slide, is autoclavable and sealed with a removable lid, which makes it suitable for use in a controlled culture environment. We describe in details how to build this chamber and we provide all the files necessary to print the different pieces in the lab.

All-in-one 3D printed microscopy chamber for multidimensional imaging, the UniverSlide

PubMed Central

Alessandri, Kevin; Andrique, Laetitia; Feyeux, Maxime; Bikfalvi, Andreas; Nassoy, Pierre; Recher, Gaëlle

2017-01-01

While live 3D high resolution microscopy techniques are developing rapidly, their use for biological applications is partially hampered by practical difficulties such as the lack of a versatile sample chamber. Here, we propose the design of a multi-usage observation chamber adapted for live 3D bio-imaging. We show the usefulness and practicality of this chamber, which we named the UniverSlide, for live imaging of two case examples, namely multicellular systems encapsulated in sub-millimeter hydrogel shells and zebrafish larvae. We also demonstrate its versatility and compatibility with all microscopy devices by using upright or inverted microscope configurations after loading the UniverSlide with fixed or living samples. Further, the device is applicable for medium/high throughput screening and automatized multi-position image acquisition, providing a constraint-free but stable and parallelized immobilization of the samples. The frame of the UniverSlide is fabricated using a stereolithography 3D printer, has the size of a microscopy slide, is autoclavable and sealed with a removable lid, which makes it suitable for use in a controlled culture environment. We describe in details how to build this chamber and we provide all the files necessary to print the different pieces in the lab. PMID:28186188

All-in-one 3D printed microscopy chamber for multidimensional imaging, the UniverSlide

NASA Astrophysics Data System (ADS)

Alessandri, Kevin; Andrique, Laetitia; Feyeux, Maxime; Bikfalvi, Andreas; Nassoy, Pierre; Recher, Gaëlle

2017-02-01

While live 3D high resolution microscopy techniques are developing rapidly, their use for biological applications is partially hampered by practical difficulties such as the lack of a versatile sample chamber. Here, we propose the design of a multi-usage observation chamber adapted for live 3D bio-imaging. We show the usefulness and practicality of this chamber, which we named the UniverSlide, for live imaging of two case examples, namely multicellular systems encapsulated in sub-millimeter hydrogel shells and zebrafish larvae. We also demonstrate its versatility and compatibility with all microscopy devices by using upright or inverted microscope configurations after loading the UniverSlide with fixed or living samples. Further, the device is applicable for medium/high throughput screening and automatized multi-position image acquisition, providing a constraint-free but stable and parallelized immobilization of the samples. The frame of the UniverSlide is fabricated using a stereolithography 3D printer, has the size of a microscopy slide, is autoclavable and sealed with a removable lid, which makes it suitable for use in a controlled culture environment. We describe in details how to build this chamber and we provide all the files necessary to print the different pieces in the lab.

Irradiation chamber and sample changer for biological samples

NASA Astrophysics Data System (ADS)

Kraft, G.; Daues, H. W.; Fischer, B.; Kopf, U.; Liebold, H. P.; Quis, D.; Stelzer, H.; Kiefer, J.; Schöpfer, F.; Schneider, E.; Weber, K.; Wulf, H.; Dertinger, H.

1980-01-01

This paper describes an irradiation system with which living cells of different origin are irradiated with heavy ion beams (18⩽ Z⩽92) at energies up to 10 MeV/amu. The system consists of a beam monitor connected to the vacuum system of the accelerator and the irradiation chamber, containing the biological samples under atmospheric pressure. The requirements and aims of the set up are discussed. The first results with saccharomyces cerevisiae and Chinese Hamster tissue cells are presented.

Results from the FIN-2 formal comparison

NASA Astrophysics Data System (ADS)

Connolly, Paul; Hoose, Corinna; Liu, Xiaohong; Moehler, Ottmar; Cziczo, Daniel; DeMott, Paul

2017-04-01

During the Fifth International Ice Nucleation Workshop (FIN-2) at the AIDA Ice Nucleation facility in Karlsruhe, Germany in March 2015, a formal comparison of ice nucleation measurement methods was conducted. During the experiments the samples of ice nucleating particles were not revealed to the instrument scientists, hence this was referred to as a "blind comparison". The two samples used were later revealed to be Arizona Test Dust and an Argentina soil sample. For these two samples seven mobile ice nucleating particle counters sampled directly from the AIDA chamber or from the aerosol preparation chamber at specified temperatures, whereas filter samples were taken for two offline deposition nucleation instruments. Wet suspension methods for determining IN concentrations were also used with 10 different methods employed. For the wet suspension methods experiments were conducted using INPs collected from the air inside the chambers (impinger sampling) and INPs taken from the bulk samples (vial sampling). Direct comparisons of the ice nucleating particle concentrations are reported as well as derived ice nucleation active site densities. The study highlights the difficulties in performing such analyses, but generally indicates that there is reasonable agreement between the wet suspension techniques. It is noted that ice nucleation efficiency derived from the AIDA chamber (quantified using the ice active surface site density approach) is higher than that for the cold stage techniques. This is both true for the Argentina soil sample and, to a lesser extent, for the Arizona Test Dust sample too. Other interesting effects were noted: for the ATD the impinger sampling demonstrated higher INP efficiency at higher temperatures (>255 K) than the vial sampling, but agreed at the lower temperatures (<255K), whereas the opposite was true for the Argentina soil sample. The results are analysed to better understand the performance of the various techniques and to address any size-sorting effects and / or sampling line loses.

Photothermal Desorption of Single-Walled Carbon Nanotubes and Coconut Shell-Activated Carbons Using a Continuous Light Source for Application in Air Sampling

PubMed Central

Floyd, Evan L.; Sapag, Karim; Oh, Jonghwa; Lungu, Claudiu T.

2014-01-01

Many techniques exist to measure airborne volatile organic compounds (VOCs), each with differing advantages; sorbent sampling is compact, versatile, has good sample stability, and is the preferred technique for collecting VOCs for hygienists. Development of a desorption technique that allows multiple analyses per sample (similar to chemical desorption) with enhanced sensitivity (similar to thermal desorption) would be helpful to field hygienists. In this study, activated carbon (AC) and single-walled carbon nanotubes (SWNT) were preloaded with toluene vapor and partially desorbed with light using a common 12-V DC, 50-W incandescent/halogen lamp. A series of experimental chamber configurations were explored starting with a 500-ml chamber under static conditions, then with low ventilation and high ventilation, finally a 75-ml high ventilation chamber was evaluated. When preloaded with toluene and irradiated at the highest lamp setting for 4min, AC desorbed 13.9, 18.5, 23.8, and 45.9% of the loaded VOC mass, in each chamber configuration, respectively; SWNT desorbed 25.2, 24.3, 37.4, and 70.5% of the loaded VOC mass, respectively. SWNT desorption was significantly greater than AC in all test conditions (P = 0.02–<0.0001) demonstrating a substantial difference in sorbent performance. When loaded with 0.435mg toluene and desorbed at the highest lamp setting for 4min in the final chamber design, the mean desorption for AC was 45.8% (39.7, 52.0) and SWNT was 72.6% (68.8, 76.4) (mean represented in terms of 95% confidence interval). All desorption measurements were obtained using a field grade photoionization detector; this demonstrates the potential of using this technique to perform infield prescreening of VOC samples for immediate exposure feedback and in the analytical lab to introduce sample to a gas chromatograph for detailed analysis of the sample. PMID:25016598

Photothermal desorption of single-walled carbon nanotubes and coconut shell-activated carbons using a continuous light source for application in air sampling.

PubMed

Floyd, Evan L; Sapag, Karim; Oh, Jonghwa; Lungu, Claudiu T

2014-08-01

Many techniques exist to measure airborne volatile organic compounds (VOCs), each with differing advantages; sorbent sampling is compact, versatile, has good sample stability, and is the preferred technique for collecting VOCs for hygienists. Development of a desorption technique that allows multiple analyses per sample (similar to chemical desorption) with enhanced sensitivity (similar to thermal desorption) would be helpful to field hygienists. In this study, activated carbon (AC) and single-walled carbon nanotubes (SWNT) were preloaded with toluene vapor and partially desorbed with light using a common 12-V DC, 50-W incandescent/halogen lamp. A series of experimental chamber configurations were explored starting with a 500-ml chamber under static conditions, then with low ventilation and high ventilation, finally a 75-ml high ventilation chamber was evaluated. When preloaded with toluene and irradiated at the highest lamp setting for 4min, AC desorbed 13.9, 18.5, 23.8, and 45.9% of the loaded VOC mass, in each chamber configuration, respectively; SWNT desorbed 25.2, 24.3, 37.4, and 70.5% of the loaded VOC mass, respectively. SWNT desorption was significantly greater than AC in all test conditions (P = 0.02-<0.0001) demonstrating a substantial difference in sorbent performance. When loaded with 0.435mg toluene and desorbed at the highest lamp setting for 4min in the final chamber design, the mean desorption for AC was 45.8% (39.7, 52.0) and SWNT was 72.6% (68.8, 76.4) (mean represented in terms of 95% confidence interval). All desorption measurements were obtained using a field grade photoionization detector; this demonstrates the potential of using this technique to perform infield prescreening of VOC samples for immediate exposure feedback and in the analytical lab to introduce sample to a gas chromatograph for detailed analysis of the sample. © The Author 2014. Published by Oxford University Press on behalf of the British Occupational Hygiene Society.

An Optimized Small Tissue Handling System for Immunohistochemistry and In Situ Hybridization

PubMed Central

Anthony, Giovanni; Lee, Ju-Ahng

2016-01-01

Recent development in 3D printing technology has opened an exciting possibility for manufacturing 3D devices on one’s desktop. We used 3D modeling programs to design 3D models of a tissue-handling system and these models were “printed” in a stereolithography (SLA) 3D printer to create precision histology devices that are particularly useful to handle multiple samples with small dimensions in parallel. Our system has been successfully tested for in situ hybridization of zebrafish embryos. Some of the notable features include: (1) A conveniently transferrable chamber with 6 mesh-bottomed wells, each of which can hold dozens of zebrafish embryos. This design allows up to 6 different samples to be treated per chamber. (2) Each chamber sits in a well of a standard 6-well tissue culture plate. Thus, up to 36 different samples can be processed in tandem using a single 6 well plate. (3) Precisely fitting lids prevent solution evaporation and condensation, even at high temperatures for an extended period of time: i.e., overnight riboprobe hybridization. (4) Flat bottom mesh maximizes the consistent treatment of individual tissue samples. (5) A magnet-based lifter was created to handle up to 6 chambers (= 36 samples) in unison. (6) The largely transparent resin aids in convenient visual inspection both with eyes and using a stereomicroscope. (7) Surface engraved labeling enables an accurate tracking of different samples. (8) The dimension of wells and chambers minimizes the required amount of precious reagents. (9) Flexible parametric modeling enables an easy redesign of the 3D models to handle larger or more numerous samples. Precise dimensions of 3D models and demonstration of how we use our devices in whole mount in situ hybridization are presented. We also provide detailed information on the modeling software, 3D printing tips, as well as 3D files that can be used with any 3D printer. PMID:27489962

Method and apparatus for scientific analysis under low temperature vacuum conditions

DOEpatents

Winefordner, James D.; Jones, Bradley T.

1990-01-01

A method and apparatus for scientific analysis of a sample under low temperature vacuum conditions uses a vacuum chamber with a conveyor belt disposed therein. One end of the conveyor belt is a cool end in thermal contact with the cold stage of a refrigerator, whereas the other end of the conveyor belt is a warm end spaced from the refrigerator. A septum allows injection of a sample into the vacuum chamber on top of the conveyor belt for spectroscopic or other analysis. The sample freezes on the conveyor belt at the cold end. One or more windows in the vacuum chamber housing allow spectroscopic analysis of the sample. Following the spectroscopic analysis, the conveyor belt may be moved such that the sample moves toward the warm end of the conveyor belt where upon it evaporates, thereby cleaning the conveyor belt. Instead of injecting the sample by way of a septum and use of a syringe and needle, the present device may be used in series with capillary-column gas chromatography or micro-bore high performance liquid chromatography.

Testing fireproof materials in a combustion chamber

NASA Astrophysics Data System (ADS)

Kulhavy, Petr; Martinec, Tomas; Novak, Ondrej; Petru, Michal; Srb, Pavel

This article deals with a prototype concept, real experiment and numerical simulation of a combustion chamber, designed for testing fire resistance some new insulating composite materials. This concept of a device used for testing various materials, providing possibility of monitoring temperatures during controlled gas combustion. As a fuel for the combustion process propane butane mixture has been used and also several kinds of burners with various conditions of inlet air (forced, free) and fuel flows were tested. The tested samples were layered sandwich materials based on various materials or foams, used as fillers in fire shutters. The temperature distribution was measured by using thermocouples. A simulation of whole concept of experimental chamber has been carried out as the non-premixed combustion process in the commercial final volume sw Pyrosim. The result was to design chamber with a construction suitable, according to the international standards, achieve the required values (temperature in time). Model of the combustion based on a stoichiometric defined mixture of gas and the tested layered samples showed good conformity with experimental results - i.e. thermal distribution inside and heat release rate that has gone through the sample.

Recovery, Transportation and Acceptance to the Curation Facility of the Hayabusa Re-Entry Capsule

NASA Technical Reports Server (NTRS)

Abe, M.; Fujimura, A.; Yano, H.; Okamoto, C.; Okada, T.; Yada, T.; Ishibashi, Y.; Shirai, K.; Nakamura, T.; Noguchi, T.;

Hyperbaric hydrothermal atomic force microscope

DOEpatents

Knauss, Kevin G.; Boro, Carl O.; Higgins, Steven R.; Eggleston, Carrick M.

2002-01-01

A hyperbaric hydrothermal atomic force microscope (AFM) is provided to image solid surfaces in fluids, either liquid or gas, at pressures greater than normal atmospheric pressure. The sample can be heated and its surface imaged in aqueous solution at temperatures greater than 100.degree. C. with less than 1 nm vertical resolution. A gas pressurized microscope base chamber houses the stepper motor and piezoelectric scanner. A chemically inert, flexible membrane separates this base chamber from the sample cell environment and constrains a high temperature, pressurized liquid or gas in the sample cell while allowing movement of the scanner. The sample cell is designed for continuous flow of liquid or gas through the sample environment.

Hyperbaric Hydrothermal Atomic Force Microscope

DOEpatents

Knauss, Kevin G.; Boro, Carl O.; Higgins, Steven R.; Eggleston, Carrick M.

2003-07-01

A hyperbaric hydrothermal atomic force microscope (AFM) is provided to image solid surfaces in fluids, either liquid or gas, at pressures greater than normal atmospheric pressure. The sample can be heated and its surface imaged in aqueous solution at temperatures greater than 100.degree. C. with less than 1 nm vertical resolution. A gas pressurized microscope base chamber houses the stepper motor and piezoelectric scanner. A chemically inert, flexible membrane separates this base chamber from the sample cell environment and constrains a high temperature, pressurized liquid or gas in the sample cell while allowing movement of the scanner. The sample cell is designed for continuous flow of liquid or gas through the sample environment.

Ultrahigh vacuum/high pressure chamber for surface x-ray diffraction experiments

NASA Astrophysics Data System (ADS)

Bernard, P.; Peters, K.; Alvarez, J.; Ferrer, S.

1999-02-01

We describe an ultrahigh vacuum chamber that can be internally pressurized to several bars and that is designed to perform surface x-ray diffraction experiments on solid-gas interfaces. The chamber has a cylindrical beryllium window that serves as the entrance and exit for the x rays. The sample surface can be ion bombarded with an ancillary ion gun and annealed to 1200 K.

A Method To Determine the Kinetics of Solute Mixing in Liquid/Liquid Formulation Dual-Chamber Syringes.

PubMed

Werk, Tobias; Mahler, Hanns-Christian; Ludwig, Imke Sonja; Luemkemann, Joerg; Huwyler, Joerg; Hafner, Mathias

Dual-chamber syringes were originally designed to separate a solid substance and its diluent. However, they can also be used to separate liquid formulations of two individual drug products, which cannot be co-formulated due to technical or regulatory issues. A liquid/liquid dual-chamber syringe can be designed to achieve homogenization and mixing of both solutions prior to administration, or it can be used to sequentially inject both solutions. While sequential injection can be easily achieved by a dual-chamber syringe with a bypass located at the needle end of the syringe barrel, mixing of the two fluids may provide more challenges. Within this study, the mixing behavior of surrogate solutions in different dual-chamber syringes is assessed. Furthermore, the influence of parameters such as injection angle, injection speed, agitation, and sample viscosity were studied. It was noted that mixing was poor for the commercial dual-chamber syringes (with a bypass designed as a longitudinal ridge) when the two liquids significantly differ in their physical properties (viscosity, density). However, an optimized dual-chamber syringe design with multiple bypass channels resulted in improved mixing of liquids. Dual-chamber syringes were originally designed to separate a solid substance and its diluent. However, they can also be used to separate liquid formulations of two individual drug products. A liquid/liquid dual-chamber syringe can be designed to achieve homogenization and mixing of both solutions prior to administration, or it can be used to sequentially inject both solutions. While sequential injection can be easily achieved by a dual-chamber syringe with a bypass located at the needle end of the syringe barrel, mixing of the two fluids may provide more challenges. Within this study, the mixing behavior of surrogate solutions in different dual-chamber syringes is assessed. Furthermore, the influence of parameters such as injection angle, injection speed, agitation, and sample viscosity were studied. It was noted that mixing was poor for the commercially available dual-chamber syringes when the two liquids significantly differ in viscosity and density. However, an optimized dual-chamber syringe design resulted in improved mixing of liquids. © PDA, Inc. 2017.

Methods of analysis by the U.S. Geological Survey National Water Quality Laboratory; use of a modified ultrasonic nebulizer for the analysis of low ionic-strength water by inductively coupled optical emission spectrometry

USGS Publications Warehouse

Harris, Carl M.; Litteral, Charles J.; Damrau, Donna L.

1997-01-01

The U.S. Geological Survey National Water Quality Laboratory has developed a method for the determination of dissolved calcium, iron, magnesium, manganese, silica, and sodium using a modified ultrasonic nebulizer sample-introduction system to an inductively coupled plasma-optical emission spectrometer. The nebulizer's spray chamber has been modified to avoid carryover and memory effects common in some conventional ultrasonic designs. The modified ultrasonic nebulizer is equipped with a high-speed rinse cycle to remove previously analyzed samples from the spray chamber without excessive flush times. This new rinse cycle decreases sample washout times by reducing carryover and memory effects from salt or analytes in previously analyzed samples by as much as 45 percent. Plasma instability has been reduced by repositioning the argon carrier gas inlet on the spray chamber and by directly pumping waste from the chamber, instead of from open drain traps, thereby maintaining constant pressure to the plasma. The ultrasonic nebulizer improves signal intensities, which are 8 to 16 times greater than for a conventional cross-flow pneumatic nebulizer, without being sensitive to clogging from salt buildup as in cross-flow nebulizers. Detection limits for the ultrasonic nebulizer are 4 to 18 times less than detection limits achievable using a cross-flow pneumatic nebulizer, with equivalent sample analysis time.

Construction ages of the Upton Stone Chamber: Preliminary findings and suggestions for future luminescence research

USGS Publications Warehouse

Mahan, Shannon; Martin, Frederick; Taylor, Cathy

2015-01-01

The Upton Chamber in Massachusetts, an earth-covered stone structure 3.4 meters (m) in diameter, with a corbelled stone dome, and a 4.3 m long entrance passageway, is studied with the aim of determining whether optically stimulated luminescence (OSL) dating methods can be used to establish the approximate construction date of the entranceway. Three samples, taken from soil behind the lowest stones in the wall of the entrance passageway, returned OSL ages between 385 and 660 years ago (or from 1625 A.D. to 1350 A.D.; using the year 2011 as the 0 year). One sample, taken below the bottom of the artifact layers in an archeological test pit in front of the chamber entrance, returned OSL ages between 650 and 880 years ago. A modern sample collected from a nearby fluvial channel returned an age between 55 and 175 years. The Upton Chamber OSL sampling results are challenging to interpret because there are mixtures in the samples of both younger and older grains that likely result from human modification, root or soil processes, animal bioturbation (i.e. ants and worms), and/or partial bleaching. The ages were determined using the lowest component of the finite mixture model as applied to a distribution of quartz grains. Further research may enable us to determine whether older components are of anthropomorphic or geological origin.

Statistical characteristics of transient enclosure voltage in ultra-high-voltage gas-insulated switchgear

NASA Astrophysics Data System (ADS)

Cai, Yuanji; Guan, Yonggang; Liu, Weidong

2017-06-01

Transient enclosure voltage (TEV), which is a phenomenon induced by the inner dielectric breakdown of SF6 during disconnector operations in a gas-insulated switchgear (GIS), may cause issues relating to shock hazard and electromagnetic interference to secondary equipment. This is a critical factor regarding the electromagnetic compatibility of ultra-high-voltage (UHV) substations. In this paper, the statistical characteristics of TEV at UHV level are collected from field experiments, and are analyzed and compared to those from a repeated strike process. The TEV waveforms during disconnector operations are recorded by a self-developed measurement system first. Then, statistical characteristics, such as the pulse number, duration of pulses, frequency components, magnitude and single pulse duration, are extracted. The transmission line theory is introduced to analyze the TEV and is validated by the experimental results. Finally, the relationship between the TEV and the repeated strike process is analyzed. This proves that the pulse voltage of the TEV is proportional to the corresponding breakdown voltage. The results contribute to the definition of the standard testing waveform of the TEV, and can aid the protection of electronic devices in substations by minimizing the threat of this phenomenon.

Industry-relevant magnetron sputtering and cathodic arc ultra-high vacuum deposition system for in situ x-ray diffraction studies of thin film growth using high energy synchrotron radiation.

PubMed

Schroeder, J L; Thomson, W; Howard, B; Schell, N; Näslund, L-Å; Rogström, L; Johansson-Jõesaar, M P; Ghafoor, N; Odén, M; Nothnagel, E; Shepard, A; Greer, J; Birch, J

2015-09-01

We present an industry-relevant, large-scale, ultra-high vacuum (UHV) magnetron sputtering and cathodic arc deposition system purposefully designed for time-resolved in situ thin film deposition/annealing studies using high-energy (>50 keV), high photon flux (>10(12) ph/s) synchrotron radiation. The high photon flux, combined with a fast-acquisition-time (<1 s) two-dimensional (2D) detector, permits time-resolved in situ structural analysis of thin film formation processes. The high-energy synchrotron-radiation based x-rays result in small scattering angles (<11°), allowing large areas of reciprocal space to be imaged with a 2D detector. The system has been designed for use on the 1-tonne, ultra-high load, high-resolution hexapod at the P07 High Energy Materials Science beamline at PETRA III at the Deutsches Elektronen-Synchrotron in Hamburg, Germany. The deposition system includes standard features of a typical UHV deposition system plus a range of special features suited for synchrotron radiation studies and industry-relevant processes. We openly encourage the materials research community to contact us for collaborative opportunities using this unique and versatile scientific instrument.

UHV AFM based colloidal probe studies of adhesive properties of VAlN hard coatings

NASA Astrophysics Data System (ADS)

Wiesing, M.; de los Arcos, T.; Grundmeier, G.

2018-01-01

The adhesion of polystyrene (PS) on V0.27Al0.29N0.44 and the related influence of the oxidation states of both surfaces was investigated using X-Ray Photoelectron Spectroscopy (XPS) and Colloidal Force Spectroscopy (CFS) in Ultra-High Vacuum (UHV). Complementary, the intimate relation between the adhesion force, the chemical structure and surface polarizability was investigated by XPS valence band spectroscopy and the calculation of non-retarded Hamaker coefficients using Lifshitz theory based on optical data as derived from Reflection Electron Energy Loss Spectroscopy (REELS) spectra. The combined electron and force spectroscopic analysis of the interaction forces disclosed quantitatively the separation of the adhesion force in van der Waals and Lewis acid-base contributions. Further, the surface polarizability of VAlN was shown to be unaffected by oxygen incorporation due to the formation of an only gradually oxidized surface comprising a range of vanadium oxidation states. In contrast, the adhesion force analysis revealed additional Lewis acid-base interactions between the oxidized and non-oxidized VAlN surfaces and carboxyl groups present in the surface of PS after an oxidative oxygen beam treatment.

Extreme pressure fluid sample transfer pump

DOEpatents

Halverson, Justin E.; Bowman, Wilfred W.

1990-01-01

A transfer pump for samples of fluids at very low or very high pressures comprising a cylinder having a piston sealed with an O-ring, the piston defining forward and back chambers, an inlet and exit port and valve arrangement for the fluid to enter and leave the forward chamber, and a port and valve arrangement in the back chamber for adjusting the pressure across the piston so that the pressure differential across the piston is essentially zero and approximately equal to the pressure of the fluid so that the O-ring seals against leakage of the fluid and the piston can be easily moved, regardless of the pressure of the fluid. The piston may be actuated by a means external to the cylinder with a piston rod extending through a hole in the cylinder sealed with a bellows attached to the piston head and the interior of the back chamber.

Se-SAD serial femtosecond crystallography datasets from selenobiotinyl-streptavidin

PubMed Central

Yoon, Chun Hong; DeMirci, Hasan; Sierra, Raymond G.; Dao, E. Han; Ahmadi, Radman; Aksit, Fulya; Aquila, Andrew L.; Batyuk, Alexander; Ciftci, Halilibrahim; Guillet, Serge; Hayes, Matt J.; Hayes, Brandon; Lane, Thomas J.; Liang, Meng; Lundström, Ulf; Koglin, Jason E.; Mgbam, Paul; Rao, Yashas; Rendahl, Theodore; Rodriguez, Evan; Zhang, Lindsey; Wakatsuki, Soichi; Boutet, Sébastien; Holton, James M.; Hunter, Mark S.

2017-01-01

We provide a detailed description of selenobiotinyl-streptavidin (Se-B SA) co-crystal datasets recorded using the Coherent X-ray Imaging (CXI) instrument at the Linac Coherent Light Source (LCLS) for selenium single-wavelength anomalous diffraction (Se-SAD) structure determination. Se-B SA was chosen as the model system for its high affinity between biotin and streptavidin where the sulfur atom in the biotin molecule (C10H16N2O3S) is substituted with selenium. The dataset was collected at three different transmissions (100, 50, and 10%) using a serial sample chamber setup which allows for two sample chambers, a front chamber and a back chamber, to operate simultaneously. Diffraction patterns from Se-B SA were recorded to a resolution of 1.9 Å. The dataset is publicly available through the Coherent X-ray Imaging Data Bank (CXIDB) and also on LCLS compute nodes as a resource for research and algorithm development. PMID:28440794

Se-SAD serial femtosecond crystallography datasets from selenobiotinyl-streptavidin

NASA Astrophysics Data System (ADS)

Yoon, Chun Hong; Demirci, Hasan; Sierra, Raymond G.; Dao, E. Han; Ahmadi, Radman; Aksit, Fulya; Aquila, Andrew L.; Batyuk, Alexander; Ciftci, Halilibrahim; Guillet, Serge; Hayes, Matt J.; Hayes, Brandon; Lane, Thomas J.; Liang, Meng; Lundström, Ulf; Koglin, Jason E.; Mgbam, Paul; Rao, Yashas; Rendahl, Theodore; Rodriguez, Evan; Zhang, Lindsey; Wakatsuki, Soichi; Boutet, Sébastien; Holton, James M.; Hunter, Mark S.

2017-04-01

We provide a detailed description of selenobiotinyl-streptavidin (Se-B SA) co-crystal datasets recorded using the Coherent X-ray Imaging (CXI) instrument at the Linac Coherent Light Source (LCLS) for selenium single-wavelength anomalous diffraction (Se-SAD) structure determination. Se-B SA was chosen as the model system for its high affinity between biotin and streptavidin where the sulfur atom in the biotin molecule (C10H16N2O3S) is substituted with selenium. The dataset was collected at three different transmissions (100, 50, and 10%) using a serial sample chamber setup which allows for two sample chambers, a front chamber and a back chamber, to operate simultaneously. Diffraction patterns from Se-B SA were recorded to a resolution of 1.9 Å. The dataset is publicly available through the Coherent X-ray Imaging Data Bank (CXIDB) and also on LCLS compute nodes as a resource for research and algorithm development.

Method and Apparatus for the Collection Storage and Real Time Analysis of Blood and Other Bodily Fluids

NASA Technical Reports Server (NTRS)

Whitson, Peggy A. (Inventor); Clift, Vaughan L. (Inventor)

1997-01-01

The present invention provides an apparatus for separating a relatively large volume of blood into cellular and acellular fractions without the need for centrifugation. The apparatus comprises a housing divided by a fibrous filter into a blood sample collection chamber having a volume of at least about 1 milliliter and a serum sample collection chamber. The fibrous filter has a pore size of less than about 3 microns, and is coated with a mixture of mannitol and plasma fraction protein (or an animal or vegetable equivalent thereof). The coating causes the cellular fraction to be trapped by the small pores, leaving the cellular fraction intact on the fibrous filter while the acellular fraction passes through the filter for collection in unaltered form from the serum sample collection chamber.

Small-Chamber Measurements of Chemical-Specific Emission Factors for Drywall

DOE Office of Scientific and Technical Information (OSTI.GOV)

Maddalena, Randy; Russell, Marion; Apte, Michael G.

2010-06-01

Imported drywall installed in U.S. homes is suspected of being a source of odorous and potentially corrosive indoor pollutants. To support an investigation of those building materials by the Consumer Products Safety Commission (CPSC), Lawrence Berkeley National Laboratory (LBNL) measured chemical-specific emission factors for 30 samples of drywall materials. Emission factors are reported for 75 chemicals and 30 different drywall samples encompassing both domestic and imported stock and incorporating natural, synthetic, or mixed gypsum core material. CPSC supplied all drywall materials. First the drywall samples were isolated and conditioned in dedicated chambers, then they were transferred to small chambers wheremore » emission testing was performed. Four sampling and analysis methods were utilized to assess (1) volatile organic compounds, (2) low molecular weight carbonyls, (3) volatile sulfur compounds, and (4) reactive sulfur gases. LBNL developed a new method that combines the use of solid phase microextraction (SPME) with small emission chambers to measure the reactive sulfur gases, then extended that technique to measure the full suite of volatile sulfur compounds. The testing procedure and analysis methods are described in detail herein. Emission factors were measured under a single set of controlled environmental conditions. The results are compared graphically for each method and in detailed tables for use in estimating indoor exposure concentrations.« less

Isothermal Dendritic Growth Experiment - Science, engineering, and hardware development for USMP space flights

NASA Technical Reports Server (NTRS)

Glicksman, M. E.; Hahn, R. C.; Koss, M. B.; Tirmizi, S. H.; Selleck, M. E.; Velosa, A.; Winsa, E.

1991-01-01

The Isothermal Dendritic Growth Experiment (IDGE) has been designed to provide microgravity data on dendritic growth for a critical test of theory. This paper updates progress on constructing a crystal growth chamber suitable for space flight. The IDGE chamber is constructed from glass and stainless steel and is hermetically sealed by electron beam welds and glass-metal seals. Initial tests of the chambers sample's melting point plateau show that the new chamber design is capable of preserving the 99.9995 percent purity of succinonitrile. Dendrite growth can be initiated in the center of the IDGE chamber by means of thermo-electric coolers and a capillary injector tube (stinger). The new IDGE chamber is ready for fully integrated tests with the prototype IDGE engineering hardware at NASA's Lewis Research Center.

Novel particle tracking algorithm based on the Random Sample Consensus Model for the Active Target Time Projection Chamber (AT-TPC)

NASA Astrophysics Data System (ADS)

Ayyad, Yassid; Mittig, Wolfgang; Bazin, Daniel; Beceiro-Novo, Saul; Cortesi, Marco

2018-02-01

The three-dimensional reconstruction of particle tracks in a time projection chamber is a challenging task that requires advanced classification and fitting algorithms. In this work, we have developed and implemented a novel algorithm based on the Random Sample Consensus Model (RANSAC). The RANSAC is used to classify tracks including pile-up, to remove uncorrelated noise hits, as well as to reconstruct the vertex of the reaction. The algorithm, developed within the Active Target Time Projection Chamber (AT-TPC) framework, was tested and validated by analyzing the 4He+4He reaction. Results, performance and quality of the proposed algorithm are presented and discussed in detail.

Note: A versatile mass spectrometer chamber for molecular beam and temperature programmed desorption experiments

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tonks, James P., E-mail: james.tonks@awe.co.uk; AWE Plc, Aldermaston, Reading, Berkshire RG7 4PR; Galloway, Ewan C., E-mail: ewan.galloway@awe.co.uk

2016-08-15

A dual purpose mass spectrometer chamber capable of performing molecular beam scattering (MBS) and temperature programmed desorption (TPD) is detailed. Two simple features of this design allow it to perform these techniques. First, the diameter of entrance aperture to the mass spectrometer can be varied to maximize signal for TPD or to maximize angular resolution for MBS. Second, the mass spectrometer chamber can be radially translated so that it can be positioned close to the sample to maximize signal or far from the sample to maximize angular resolution. The performance of this system is described and compares well with systemsmore » designed for only one of these techniques.« less

A new mass spectrometer system for investigating laser-induced vaporization phenomena

NASA Technical Reports Server (NTRS)

Lincoln, K. A.

1974-01-01

A laser has been combined with a mass spectrometer in a new configuration developed for studies of high-temperature materials. A vacuum-lock, solid-sample inlet is mounted at one end of a cylindrical, high-vacuum chamber one meter in length with a nude ion-source, time-of-flight mass spectrometer at the opposite end. The samples are positioned along the axis of the chamber at distances up to one meter from the ion source, and their surfaces are vaporized by a pulsed laser beam entering via windows on one side of the chamber. The instrumentation along with its capabilities is described, and results from laser-induced vaporization of several graphites are presented.

BOREAS TGB-1 NSA CH4 and CO2 Chamber Flux Data

NASA Technical Reports Server (NTRS)

Hall, Forrest G. (Editor); Conrad, Sara K. (Editor); Crill, Patrick; Varner, Ruth K.

2000-01-01

The BOREAS TGB-1 team made methane (CH4) and carbon dioxide (CO2) dark chamber flux measurements at the NSA-OJP, NSA-OBS, NSA-BP, and NSA-YJP sites from 16-May-1994 through 13-Sep-1994. Gas samples were extracted approximately every 7 days from dark chambers and analyzed at the NSA lab facility. The data are provided in tabular ASCII files.

Optical effect of the contamination of infrared windows by the outgassing of materials in outer space

NASA Technical Reports Server (NTRS)

Silberman, E.

1975-01-01

The products and kinetics of outgassing from S13G paint were studied by using infrared absorption measurements of the material outgassed (using an evaporation cell and vacuum chamber). Two separate long-term experimental depositions from heated samples of the S13G paint were made. Before each experiment, the vacuum chamber and sample holder were carefully cleaned and outgassed to ensure that subsequent deposits on the colled-window were due only to the products evaporated from the sample. Results of experiments are listed and discussed.

Simplified Method for the Characterization of Rectangular Straw Bales (RSB) Thermal Conductivity

NASA Astrophysics Data System (ADS)

Conti, Leonardo; Goli, Giacomo; Monti, Massimo; Pellegrini, Paolo; Rossi, Giuseppe; Barbari, Matteo

2017-10-01

This research aims to design and implement tools and methods focused at the assessment of the thermal properties of full size Rectangular Straw Bales (RSB) of various nature and origin, because their thermal behaviour is one of the key topics in market development of sustainable building materials. As a first approach a method based on a Hot-Box in agreement with the ASTM C1363 - 11 standard was adopted. This method was found to be difficult for the accurate measurement of energy flows. Instead, a method based on a constant energy input was developed. With this approach the thermal conductivity of a Rectangular Straw-Bale (RSB λ) can be determined by knowing the thermal conductivity of the materials used to build the chamber and the internal and external temperature of the samples and of the chamber. A measurement a metering chamber was built and placed inside a climate chamber, maintained at constant temperature. A known quantity of energy was introduced inside the metering chamber. A series of thermopiles detects the temperature of the internal and external surfaces of the metering chamber and of the specimens allowing to calculate the thermal conductivity of RSB in its natural shape. Different cereal samples were tested. The values were found consistent with those published in scientific literature.

Design of a Dual Waveguide Normal Incidence Tube (DWNIT) Utilizing Energy and Modal Methods

NASA Technical Reports Server (NTRS)

Betts, Juan F.; Jones, Michael G. (Technical Monitor)

2002-01-01

This report investigates the partition design of the proposed Dual Waveguide Normal Incidence Tube (DWNIT). Some advantages provided by the DWNIT are (1) Assessment of coupling relationships between resonators in close proximity, (2) Evaluation of "smart liners", (3) Experimental validation for parallel element models, and (4) Investigation of effects of simulated angles of incidence of acoustic waves. Energy models of the two chambers were developed to determine the Sound Pressure Level (SPL) drop across the two chambers, through the use of an intensity transmission function for the chamber's partition. The models allowed the chamber's lengthwise end samples to vary. The initial partition design (2" high, 16" long, 0.25" thick) was predicted to provide at least 160 dB SPL drop across the partition with a compressive model, and at least 240 dB SPL drop with a bending model using a damping loss factor of 0.01. The end chamber sample transmissions coefficients were set to 0.1. Since these results predicted more SPL drop than required, a plate thickness optimization algorithm was developed. The results of the algorithm routine indicated that a plate with the same height and length, but with a thickness of 0.1" and 0.05 structural damping loss, would provide an adequate SPL isolation between the chambers.

Effect of semen preparation on casa motility results in cryopreserved bull spermatozoa.

PubMed

Contri, Alberto; Valorz, Claudio; Faustini, Massimo; Wegher, Laura; Carluccio, Augusto

2010-08-01

Computer-assisted sperm analyzers (CASA) have become the standard tool for evaluating sperm motility and kinetic patterns because they provide objective data for thousands of sperm tracks. However, these devices are not ready-to-use and standardization of analytical practices is a fundamental requirement. In this study, we evaluated the effects of some settings, such as frame rate and frames per field, chamber and time of analysis, and samples preparations, including thawing temperature, sperm sample concentration, and media used for dilution, on the kinetic results of bovine frozen-thawed semen using a CASA. In Experiment 1, the frame rate (30-60 frame/s) significantly affected motility parameters, whereas the number of frames per field (30 or 45) did not seem to affect sperm kinetics. In Experiment 2, the thawing protocol affects sperm motility and kinetic parameters. Sperm sample concentration significantly limited the opportunity to perform the analysis and the kinetic results. A concentration of 100 and 50 x 10(6) sperm/mL limited the device's ability to perform the analysis or gave wrong results, whereas 5, 10, 20, and 30 x 10(6) sperm/mL concentrations allowed the analysis to be performed, but with different results (Experiment 3). The medium used for the dilution of the sample, which is fundamental for a correct sperm head detection, affects sperm motility results (Experiment 4). In this study, Makler and Leja chambers were used to perform the semen analysis with CASA devices. The chamber used significantly affected motility results (Experiment 5). The time between chamber loading and analysis affected sperm velocities, regardless of chamber used. Based on results recorded in this study, we propose that the CASA evaluation of motility of bovine frozen-thawed semen using Hamilton-Thorne IVOS 12.3 should be performed using a frame rate of 60 frame/s and 30 frames per field. Semen should be diluted at least at 20 x 10(6) sperm/mL using PBS. Furthermore, it is necessary to consider the type of chamber used and perform the analysis within 1 or 2 min, regardless of the chamber used. Copyright 2010 Elsevier Inc. All rights reserved.

Improved Ion Resistance for III-V Photocathodes in High Current Guns

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mulhollan, Gregory, A.

2012-11-16

The two photocathode test systems were modified, baked and recommissioned. The first system was dedicated to ion studies and the second to electron stimulated recovery (ESR) work. The demonstration system for the electron beam rejuvenation was set up, tested and demonstrated to one of the SSRL team (Dr. Kirby) during a site visit. The requisite subsystems were transferred to SSRL, installed and photoemission studies conducted on activated surfaces following electron beam exposure. Little surface chemistry change was detected in the photoemission spectra following the ESR process. The yield mapping system for the ion (and later, the electron beam rejuvenation) studiesmore » was implemented and use made routine. Ion species and flux measurements were performed for H, He, Ne, Ar, Kr and Xe ions at energies of 0.5, 1.0 and 2.0 kV. Gas induced photoyield measurements followed each ion exposure measurement. These data permit the extraction of photoyield induced change per ion (by species) at the measured energies. Electron beam induced rejuvenation was first demonstrated in the second chamber with primary electron beam energy and dependency investigations following. A Hiden quadrupole mass spectrometer for the electron stimulated desorption (ESD) measurements was procured. The UHV test systems needed for subsequent measurements were configured, baked, commissioned and utilized for their intended purposes. Measurements characterizing the desorption products from the ESD process and secondary electron (SE) yield at the surfaces of negative electron affinity GaAs photocathodes have been performed. One US Utility Patent was granted covering the ESR process.« less

Development of a nano-tesla magnetic field shielded chamber and highly precise AC-susceptibility measurement coil at μK temperatures

NASA Astrophysics Data System (ADS)

Kumar, Anil; Prakash, Om; Ramakrishanan, S.

2014-04-01

A special sample measurement chamber has been developed to perform experiments at ultralow temperatures and ultralow magnetic field. A high permeability material known as cryoperm 10 and Pb is used to shield the measurement space consisting of the signal detecting set-up and the sample. The detecting setup consists of a very sensitive susceptibility coil wound on OFHC Cu bobbin.

Thin-layer chromatography and colorimetric analysis of multi-component explosive mixtures

DOEpatents

Pagoria, Philip F.; Mitchell, Alexander R.; Whipple, Richard E.; Carman, M. Leslie

2014-08-26

A thin-layer chromatography method for detection and identification of common military and peroxide explosives in samples includes the steps of provide a reverse-phase thin-layer chromatography plate; prepare the plate by marking spots on which to deposit the samples by touching the plate with a marker; spot one micro liter of a first standard onto one of the spots, spot one micro liter of a second standard onto another of the spots, and spot samples onto other of spots producing a spotted plate; add eluent to a developing chamber; add the spotted plate to the developing chamber; remove the spotted plate from the developing chamber producing a developed plate; place the developed plate in an ultraviolet light box; add a visualization agent to a dip tank; dip the developed plate in the dip tank and remove the developed plate quickly; and detect explosives by viewing said developed plate.

Effects of humidity on sterilization of Geobacillus stearothermophilus spores with plasma-excited neutral gas

NASA Astrophysics Data System (ADS)

Matsui, Kei; Ikenaga, Noriaki; Sakudo, Noriyuki

2015-06-01

We investigate the effects of relative humidity on the sterilization process using a plasma-excited neutral gas that uniformly sterilizes both the space and inner wall of the reactor chamber at atmospheric pressure. Only reactive neutral species such as plasma-excited gas molecules and radicals were separated from the plasma and sent to the reactor chamber for chemical sterilization. The plasma source gas is nitrogen mixed with 0.1% oxygen, and the relative humidity in the source gas is controlled by changing the mixing ratio of water vapor. The relative humidity near the sample in the reactor chamber is controlled by changing the sample temperature. As a result, the relative humidity near the sample should be kept in the range from 60 to 90% for the sterilization of Geobacillus stearothermophilus spores. When the relative humidity in the source gas increases from 30 to 90%, the sterilization effect is enhanced by the same degree.

Production and distribution of dilute species in semiconducting materials

DOEpatents

James, Ralph B.; Camarda, Giuseppe; Bolotnikov, Aleksey E.; Hossain, Anwar; Yang, Ge; Kim, Kihyun

2016-09-06

Technologies are described effective to implement systems and methods of producing a material. The methods comprise receiving a tertiary semiconductor sample with a dilute species. The sample has two ends. The first end of the sample includes a first concentration of the dilute species lower than a second concentration of the dilute species in the second end of the sample. The method further comprises heating the sample in a chamber. The chamber has a first zone and a second zone. The first zone having a first temperature higher than a second temperature in the second zone. The sample is orientated such that the first end is in the first zone and the second end is in the second zone.

Optimization of a mist chamber (Cofer scrubber) for sampling water-soluble organics in air.

PubMed

Spaulding, Reggie S; Talbot, Robert W; Charles, M Judith

2002-04-15

While the atmospheric fate and transport of biogenic and anthropogenic hydrocarbons has been extensively studied, little is known about the behavior of first-, second-, and third generation photo-oxidation products that arise from OH radical oxidation of the parent species. The results of chamber experiments establish that *OH oxidation of biogenic and anthropogenic hydrocarbons yields carbonyls, dicarbonyls, hydroxycarbonyls, and keto-acids. However, little is known about the generation and fate of these products in the ambient atmospheric environment. This is changing because of the advent of methods that rely on 0-(2,3,4,5,6-pentafluorobenzyl)hydroxylamine (PFBHA) derivatization of carbonyls in concert with gas chromatography/ion trap mass spectrometry. Such methods provide the means to identify and quantify water-soluble organics, which historically have been difficult to measure. A limitation of existing sampling methods, however, is the use of devices that require low flow rates (0.5-1 L min(-1)). Accordingly, long sampling times (3-4 h) are needed to obtain pptv-ppbv detection limits. The mist chamber is an attractive device because of the high flow rates (25-70 L min(-1)) compatible with its use. Herein, we evaluate a mist chamber using a flow rate of 25-30 L min(-1) to provide short (10 min) sampling times and pptv limits of detection. The results establish a relationship between the Henry's law constant (KH) and the collection efficiency and demonstrate the suitability of the method to measure analytes with KH > or = 10(3) M atm(-1). Adjusting the pH, adding quaternary ammonium salts, or decreasing the temperature of the collecting solution in the mist chamber did not significantly affect the collection efficiency. We tested the method by sampling photooxidation products of isoprene (glyoxal, methylglyoxal, hydroxyacetone, and glycolaldehyde) in the Blodgett Forest, CA. This is the first report of a study the employs the mist chamberto sample hydroxycarbonyls. The accuracy and the reproducibility of the method were evaluated by the analysis of duplicate samples and field spikes. The mean recovery of field spikes was > or =80%, and the relative standard deviation was < or =22% between duplicate measurements. The detection limits were 48, 15, 7.7, and 2.7 pptv for glycolaldehyde, hydroxyacetone, methylglyoxal, and glyoxal, respectively. This work demonstrates the power of the mist chamber in concert with PFBHA derivatization and mass spectrometry to measure pptv concentrations of water-soluble organics with a sampling time of 10 min.

Making MUSIC: A multiple sampling ionization chamber

NASA Astrophysics Data System (ADS)

Shumard, B.; Henderson, D. J.; Rehm, K. E.; Tang, X. D.

2007-08-01

A multiple sampling ionization chamber (MUSIC) was developed for use in conjunction with the Atlas scattering chamber (ATSCAT). This chamber was developed to study the (α, p) reaction in stable and radioactive beams. The gas filled ionization chamber is used as a target and detector for both particles in the outgoing channel (p + beam particles for elastic scattering or p + residual nucleus for (α, p) reactions). The MUSIC detector is followed by a Si array to provide a trigger for anode events. The anode events are gated by a gating grid so that only (α, p) reactions where the proton reaches the Si detector result in an anode event. The MUSIC detector is a segmented ionization chamber. The active length of the chamber is 11.95 in. and is divided into 16 equal anode segments (3.5 in. × 0.70 in. with 0.3 in. spacing between pads). The dead area of the chamber was reduced by the addition of a Delrin snout that extends 0.875 in. into the chamber from the front face, to which a mylar window is affixed. 0.5 in. above the anode is a Frisch grid that is held at ground potential. 0.5 in. above the Frisch grid is a gating grid. The gating grid functions as a drift electron barrier, effectively halting the gathering of signals. Setting two sets of alternating wires at differing potentials creates a lateral electric field which traps the drift electrons, stopping the collection of anode signals. The chamber also has a reinforced mylar exit window separating the Si array from the target gas. This allows protons from the (α, p) reaction to be detected. The detection of these protons opens the gating grid to allow the drift electrons released from the ionizing gas during the (α, p) reaction to reach the anode segment below the reaction.

Fiber optic-based regenerable biosensor

DOEpatents

Sepaniak, Michael J.; Vo-Dinh, Tuan

1993-01-01

A fiber optic-based regenerable biosensor. The biosensor is particularly suitable for use in microscale work in situ. In one embodiment, the biosensor comprises a reaction chamber disposed adjacent the distal end of a waveguide and adapted to receive therein a quantity of a sample containing an analyte. Leading into the chamber is a plurality of capillary conduits suitable for introducing into the chamber antibodies or other reagents suitable for selective interaction with a predetermined analyte. Following such interaction, the contents of the chamber may be subjected to an incident energy signal for developing fluorescence within the chamber that is detectable via the optical fiber and which is representative of the presence, i.e. concentration, of the selected analyte. Regeneration of the biosensor is accomplished by replacement of the reagents and/or the analyte, or a combination of these, at least in part via one or more of the capillary conduits. The capillary conduits extend from their respective terminal ends that are in fluid communication with the chamber, away from the chamber to respective location(s) remote from the chamber thereby permitting in situ location of the chamber and remote manipulation and/or analysis of the activity with the chamber.

Modeling and Simulation of Upset-Inducing Disturbances for Digital Systems in an Electromagnetic Reverberation Chamber

NASA Technical Reports Server (NTRS)

Torres-Pomales, Wilfredo

2014-01-01

This report describes a modeling and simulation approach for disturbance patterns representative of the environment experienced by a digital system in an electromagnetic reverberation chamber. The disturbance is modeled by a multi-variate statistical distribution based on empirical observations. Extended versions of the Rejection Samping and Inverse Transform Sampling techniques are developed to generate multi-variate random samples of the disturbance. The results show that Inverse Transform Sampling returns samples with higher fidelity relative to the empirical distribution. This work is part of an ongoing effort to develop a resilience assessment methodology for complex safety-critical distributed systems.

Development of a continuous flow thermal gradient diffusion chamber for ice nucleation studies

NASA Astrophysics Data System (ADS)

Rogers, David C.

A supercooled continuous flow, thermal gradient diffusion chamber has been developed to study the ice nucleating properties of natural or artificial aerosols. The chamber has concentric cylinder geometry with the cylinder axis alignment and airflow vertically downward. Sample airflow is 1 l min -1 and occupies the central 10% of the annular lamina; it is separated from the ice-covered walls by filtered sheath air. The wall temperatures are independently controlled over the range from about -4°C to -25°C, so that the vapor concentration at the location of the sample lamina can be set to a well defined value between ice saturation and a few percent water supersaturation. There is a range of temperature and supersaturation values across the sample region; for lamina center conditions of -15°C and +1% with respect to water, the range is -14.6 to -15.4°C and +0.53 to +1.31%. Errors in temperature control produce variations estimated as ±0.1°C and ±0.23%. Typical sample residence time is about 10 s. Ice crystals which form on active nuclei are detected optically at the outlet end of the chamber. To enhance the size difference between ice crystals and cloud droplets, the downstream 25% of the warm ice wall is covered with a thermally insulating vapor barrier which reduces the vapor concentration to ice saturation at the cold wall temperature, so cloud droplets evaporate. A mathematical model was developed to describe the temperature and vapor fields and to calculate the growth, evaporation, and sedimentation of water and ice particles. At 1% water supersaturation, the model predicts that ice particles will grow to about 5 μm diameter, and cloud droplets will achieve about 1 μm before they reach the evaporation section of the chamber. A different model was developed to describe the steady state airflow profile and location of the sample lamina. Experimental tests of the chamber were performed to characterize the airflow, to assess the ability of the technique to detect silver iodide ice nucleating aerosols and to distinguish ice crystals from water droplets.

Extraction of Thermal Performance Values from Samples in the Lunar Dust Adhesion Bell Jar

NASA Technical Reports Server (NTRS)

Gaier, James R.; Siamidis, John; Larkin, Elizabeth M. G.

2008-01-01

A simulation chamber has been developed to test the performance of thermal control surfaces under dusty lunar conditions. The lunar dust adhesion bell jar (LDAB) is a diffusion pumped vacuum chamber (10(exp -8) Torr) built to test material samples less than about 7 cm in diameter. The LDAB has the following lunar dust simulant processing capabilities: heating and cooling while stirring in order to degas and remove adsorbed water; RF air-plasma for activating the dust and for organic contaminant removal; RF H/He-plasma to simulate solar wind; dust sieving system for controlling particle sizes; and a controlled means of introducing the activated dust to the samples under study. The LDAB is also fitted with an in situ Xe arc lamp solar simulator, and a cold box that can reach 30 K. Samples of thermal control surfaces (2.5 cm diameter) are introduced into the chamber for calorimetric evaluation using thermocouple instrumentation. The object of this paper is to present a thermal model of the samples under test conditions and to outline the procedure to extract the absorptance, emittance, and thermal efficiency from the pristine and sub-monolayer dust covered samples.

Extraction of Thermal Performance Values from Samples in the Lunar Dust Adhesion Bell Jar

NASA Technical Reports Server (NTRS)

Gaier, James R.; Siamidis, John; Larkin, Elizabeth M.G.

2008-01-01

A simulation chamber has been developed to test the performance of thermal control surfaces under dusty lunar conditions. The lunar dust adhesion bell jar (LDAB) is a diffusion pumped vacuum chamber (10-8 Torr) built to test material samples less than about 7 cm in diameter. The LDAB has the following lunar dust stimulant processing capabilities: heating and cooling while stirring in order to degas and remove absorbed water; RF air-plasma for activating the dust and for organic contaminant removal; RF H/He-plasma to simulate solar wind; dust sieving system for controlling particle sizes; and a controlled means of introducing the activated dust to the samples under study. The LDAB is also fitted with an in situ Xe arc lamp solar simulator, and a cold box that can reach 30 K. Samples of thermal control surfaces (2.5 cm diameter) are introduced into the chamber for calorimetric evaluation using thermocouple instrumentation. The object of this paper is to present a thermal model of the samples under test conditions, and to outline the procedure to extract the absorptance, emittance, and thermal efficiency from the pristine and sub-monolayer dust covered samples

Extraction of Thermal Performance Values from Samples in the Lunar Dust Adhesion Bell Jar

NASA Technical Reports Server (NTRS)

Gaier, James R.; Siamidis, John; Larkin, Elizabeth M. G.

2010-01-01

A simulation chamber has been developed to test the performance of thermal control surfaces under dusty lunar conditions. The lunar dust adhesion bell jar (LDAB) is a diffusion pumped vacuum chamber (10(exp -8) Torr) built to test material samples less than about 7 cm in diameter. The LDAB has the following lunar dust simulant processing capabilities: heating and cooling while stirring in order to degas and remove adsorbed water; RF air-plasma for activating the dust and for organic contaminant removal; RF H/He-plasma to simulate solar wind; dust sieving system for controlling particle sizes; and a controlled means of introducing the activated dust to the samples under study. The LDAB is also fitted with an in situ Xe arc lamp solar simulator, and a cold box that can reach 30 K. Samples of thermal control surfaces (2.5 cm diameter) are introduced into the chamber for calorimetric evaluation using thermocouple instrumentation. The object of this paper is to present a thermal model of the samples under test conditions and to outline the procedure to extract the absorptance, emittance, and thermal efficiency from the pristine and sub-monolayer dust covered samples.

Sorption of Organophosphorus Flame-Retardants on Settled ...

EPA Pesticide Factsheets

Dust is an important sink for indoor air pollutants, such as organophosphorus flame-retardants (OPFRs) that are used as additives in industrial and consumer products including electrical and electronic products, furniture, plastics, textile, and building/construction materials. This research investigated the sorption of OPFRs, tris(2-chloroethyl) phosphate (TCEP), tris(1-chlor-2-propyl) phosphate (TCPP), and tris(1,3-dichloro-2-propyl) phosphate (TDCPP) on settled Arizona Test Dust (ATD) using a dual small chamber system. During the test, seven free film release paper dust trays covered with ATD were placed in the sink test chamber. Constant gas phase OPFRs from the source chamber were dosed into the test chamber. The dust evenly spread on each dust tray was removed from the test chamber at different exposure times to determine the amount of OPFRs absorbed by the dust. The ATD has been characterized for a nominal particle size and surface area. The mass of dust on each of seven dust trays was weighed before the dust was placed inside the sink chamber. OPFRs concentrations at the inlet and faceplate of the test chamber were monitored by collecting polyurethane foam (PUF) samples. The OPFR exposed dust and PUF samples were extracted by 1:1 ethyl acetate/methylene chloride and analyzed on GC/MS. The data were used to calculate the OPFR sorption concentration on the dust through dust/air partition. Settled dust can adsorb OPFR from air. The sorption concentration wa

Surface Science at the Solid Liquid Interface

DTIC Science & Technology

1993-10-06

prominent experimental avenue, developed originally by Hubbard et al,_ involves emersing monocrystalline elec- As for metal surfaces in ultrahigh vacuum...reliable means of both preparing and dosateizn ordered monocrystalline metal surfaces in UHV has led to ing appropriate molecular components of...surface atoms in place of bottom panel of Fig. 2, equal intensity contours are shown 23 underlying surface atoms, the compression is 24/23 - I in the

Surface Chemistry of CWAs for Decon Enabling Sciences

DTIC Science & Technology

2014-11-04

representing the formation of a hydrogen-bonded mode. Characteristic modes of the sarin molecule itself are also observed. These experimental results show...Triangle Park, NC 27709-2211 surface science, CWA, uptake, decomposition, decontamination, filtration , XPS, FTIR, TPD, MS, UHV REPORT DOCUMENTATION PAGE 11...Karwacki, Team Leader CBR Filtration Research and Technology Directorate at ECBC. Through this collaboration, we have established a facility for the study

The structure of [MnIII6 CrIII]3+ single-molecule magnets deposited in submono-layers and monolayers on surfaces studied by means of molecular resolved atomic force microscopy (AFM) and Kelvin Probe Force Microscopy in UHV

NASA Astrophysics Data System (ADS)

Heinzmann, U.; Gryzia, A.; Volkmann, T.; Brechling, A.; Hoeke, V.; Glaser, T.

2014-04-01

Single molecule magnets (SMM) deposited in submonolayers and monolayers have been analyzed with respect to their structures by means of non-contact AFM (topographic as well as damping mode) and Kelvin Probe Force Microscopy with molecular resolution.

Isothermal dendritic growth experiment: Science, engineering, and hardware development for USMP space flights

NASA Astrophysics Data System (ADS)

Glicksman, M. E.; Hahn, R. C.; Koss, M. B.; Tirmizi, S. H.; Selleck, M. E.; Velosa, A.; Winsa, E.

The Isothermal Dendritic Growth Experiment (IDGE) has been designed to provide microgravity data on dendritic growth for a critical test of theory. This paper updates our progress on constructing a crystal growth chamber suitable for space flight. The IDGE chamber is constructed from glass and stainless steel and is hermetically sealed by electron beam welds and glass-metal seals. Initial tests of the chambers sample's melting point plateau show that the new chamber design is capable of preserving the 99.9995 pct purity of succinonitrile (SCN). One can initiate dendrite growth in the center of the IDGE chamber by means of thermo-electric coolers and a capillary injector tube (stinger). The new IDGE chamber is ready for fully integrated tests with the prototype IDGE engineering hardware at NASA's Lewis Research Center.

Determination of As, Se, and Hg in fuel samples by in-chamber chemical vapor generation ICP OES using a Flow Blurring® multinebulizer.

PubMed

García, Miriam; Aguirre, Miguel Ángel; Canals, Antonio

2017-09-01

In this work, a new and simple analytical methodology based on in-chamber chemical vapor generation has been developed for the spectrochemical analysis of commercial fuel samples. A multiple nebulizer with three nebulization units has been employed for this purpose: One unit was used for sample introduction, while the other two were used for the necessary reagent introduction. In this way, the aerosols were mixed inside the spray chamber. Through this method, analyte transport and, therefore, sensitivity are improved in inductively coupled plasma-optical emission spectrometry. The factors (i.e., variables), influencing chemical vapor generation, have been optimized using a multivariate approach. Under optimum chemical vapor generation conditions ([NaBH 4 ] = 1.39%, [HCl] = 2.97 M, total liquid flow = 936 μL min -1 ), the proposed sample introduction system allowed the determination of arsenic, selenium, and mercury up to 5 μg g -1 with a limit of detection of 25, 140, and 13 μg kg -1 , respectively. Analyzing spiked commercial fuel samples, recovery values obtained were between 96 and 113%, and expanded uncertainty values ranged from 4 to 16%. The most striking practical conclusion of this investigation is that no carbon deposit appears on the plasma torch after extended periods of working. Graphical abstract A new and simple analytical methodology based on in-chamber chemical vapor generation has been developed for the spectrochemical analysis of commercial fuel samples in ICP OES.

Infrasound Sensor Calibration and Response

DTIC Science & Technology

2012-09-01

infrasound calibration chamber. Under separate funding a number of upgrades were made to the chamber. These include a Geotech Smart24 digitizer and...of upgrades were made to the chamber. These include a Geotech Smart24 digitizer and workstation, an LVDT sensor for piston phone phase measurement, a...20 samples per second on a GeoTech Instruments DL 24 digitizer. Fifty cycles of data were fit with the Matlab function NLINFIT that gave the peak

Onset of space charge effects in liquid argon ionization chambers

NASA Astrophysics Data System (ADS)

Toggerson, B.; Newcomer, A.; Rutherfoord, J.; Walker, R. B.

2009-09-01

Using a thin-gap liquid argon ionization chamber and Strontium-90 beta sources we have measured ionization currents over a wide range of gap potentials. These precision "HV plateau curves" advance the understanding of liquid argon sampling calorimeter signals, particularly at high ionization rates. The order of magnitude differences in the activities of the beta sources allow us to estimate where the ionization chamber is driven into the space-charge dominated regime.

Inherent size effects on XANES of nanometer metal clusters: Size-selected platinum clusters on silica

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dai, Yang; Gorey, Timothy J.; Anderson, Scott L.

2016-12-12

X-ray absorption near-edge structure (XANES) is commonly used to probe the oxidation state of metal-containing nanomaterials, however, as the particle size in the material drops below a few nanometers, it becomes important to consider inherent size effects on the electronic structure of the materials. In this paper, we analyze a series of size-selected Pt n/SiO 2 samples, using X-ray photoelectron spectroscopy (XPS), low energy ion scattering, grazing-incidence small angle X-ray scattering, and XANES. The oxidation state and morphology are characterized both as-deposited in UHV, and after air/O 2 exposure and annealing in H 2. Here, the clusters are found tomore » be stable during deposition and upon air exposure, but sinter if heated above ~150 °C. XANES shows shifts in the Pt L 3 edge, relative to bulk Pt, that increase with decreasing cluster size, and the cluster samples show high white line intensity. Reference to bulk standards would suggest that the clusters are oxidized, however, XPS shows that they are not. Instead, the XANES effects are attributable to development of a band gap and localization of empty state wavefunctions in small clusters.« less

Transport in ultrathin gold films decorated with magnetic Gd atoms

NASA Astrophysics Data System (ADS)

Alemani, Micol; Helgren, Erik; Hugel, Addison; Hellman, Frances

2008-03-01

We have performed four-probe transport measurements of ultrathin Au films decorated with Gd ad-atoms. The samples were prepared by quench condensation, i.e., sequential evaporation on a cryogenically cooled substrate under UHV conditions while monitoring the film thickness and resistance. Electrically continuous Au films at thickness of about 2 mono-layers of material are grown on an amorphous Ge wetting layer. The quench condensation method provides a sensitive control on the sample growth process, allowing us to tune the morphological and electrical configuration of the system. The ultrathin gold films develop from an insulating to a metallic state as a function of film thickness. The temperature dependence of the Au conductivity for different thickness is studied. It evolves from hopping transport for the insulating films, to a ln T dependence for thicker films. For gold films in the insulating regime we found a decreasing resistance by adding Gd. This is in agreement with a decreasing tunneling barrier height between metallic atoms. The Gd magnetic moments are randomly oriented for isolated atoms. This magnetic disorder leads to scattering of the charge carriers and a reduced conductivity compared to nonmagnetic materials.

Prevention of Over-Pressurization During Combustion in a Sealed Chamber

NASA Technical Reports Server (NTRS)

Gokoglu, Suleyman A.; Niehaus, Justin E.; Olson, Sandra L.; Dietrich, Daniel L.; Ruff, Gary A.; Johnston, Michael C.

2012-01-01

The combustion of flammable material in a sealed chamber invariably leads to an initial pressure rise in the volume. The pressure rise is due to the increase in the total number of gaseous moles (condensed fuel plus chamber oxygen combining to form gaseous carbon dioxide and water vapor) and, most importantly, the temperature rise of the gas in the chamber. Though the rise in temperature and pressure would reduce with time after flame extinguishment due to the absorption of heat by the walls and contents of the sealed spacecraft, the initial pressure rise from a fire, if large enough, could lead to a vehicle over-pressure and the release of gas through the pressure relief valve. This paper presents a simple lumped-parameter model of the pressure rise in a sealed chamber resulting from the heat release during combustion. The transient model considers the increase in gaseous moles due to combustion, and heat transfer to the chamber walls by convection and radiation and to the fuel-sample holder by conduction, as a function of the burning rate of the material. The results of the model are compared to the pressure rise in an experimental chamber during flame spread tests as well as to the pressure falloff after flame extinguishment. The experiments involve flame spread over thin solid fuel samples. Estimates of the heat release rate profiles for input to the model come from the assumed stoichiometric burning of the fuel along with the observed flame spread behavior. The sensitivity of the model to predict maximum chamber pressure is determined with respect to the uncertainties in input parameters. Model predictions are also presented for the pressure profile anticipated in the Fire Safety-1 experiment, a material flammability and fire safety experiment proposed for the European Space Agency (ESA) Automated Transfer Vehicle (ATV). Computations are done for a range of scenarios including various initial pressures and sample sizes. Based on these results, various mitigation approaches are suggested to prevent vehicle over-pressurization and help guide the definition of the space experiment.

Fragrance patch tests prepared in advance may give false-negative reactions.

PubMed

Mowitz, Martin; Svedman, Cecilia; Zimerson, Erik; Bruze, Magnus

2014-11-01

Several of the ingredients in fragrance mix I (FM I) have been shown to evaporate from petrolatum preparations applied in test chambers to an extent that can be suspected to affect the patch test result. To compare the reactivity towards FM I and fragrance mix II (FM II) when they are applied in test chambers in advance and immediately prior to the patch test occasion. Seven hundred and ninety-five consecutive patients were simultaneously patch tested with duplicate samples of FM I and FM II. One sample was applied in the test chamber 6 days in advance (6D sample), and the other sample was applied immediately before the patients were patch tested (fresh sample). Twenty-two (2.8%) patients reacted exclusively to the fresh sample of FM I, 6 (0.7%) reacted exclusively to the 6D sample, and 22 (2.8%) reacted to both samples. The corresponding numbers for FM II were 9 (1.1%) for the fresh sample, 6 (0.7%) for the 6D sample and 12 (1.5%) for both samples. There was a statistically significant difference between the numbers of patients reacting to the fresh and 6D samples of FM I. No corresponding difference was observed for FM II. This can probably be explained by differences in volatilities between the ingredients of FM I and FM II. © 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Matrix isolation apparatus with extended sample collection capability

DOEpatents

Reedy, Gerald T.

1987-01-01

A gas-sample collection device provides for the matrix isolation of increased amounts of a sample material for spectrographic analysis from a gas chromatographic separation. The device includes an evacuated sample collection chamber containing a disc-like specular carousel having a generally circular lateral surface upon which the sample is deposited in an inert gas matrix for infrared (IR) spectral analysis. The evacuated sample chamber is mounted in a fixed manner and is coupled to and supports a rotating cryostatic coupler which, in turn, supports the specular carousel within the collection chamber. A rotational drive system connected to the cryostatic coupler provides for its rotational displacement as well as that of the sample collecting carousel. In addition, rotation of the cryostatic coupler effects vertical displacement of the carousel to permit the collection of an extended sample band in a helical configuration on the entire lateral surface of the carousel. The various components of the carousel's angular/linear displacement drive system are located exterior to the cryostatic coupler for easy access and improved operation. The cryostatic coupler includes a 360.degree. rotary union assembly for permitting the delivery of a high pressure working fluid to the cryostatic coupler in a continuous flow manner for maintaining the specular carousel at a low temperature, e.g., 10.degree.-20.degree. K., for improved uninterrupted gas sample collection and analysis.

Method and apparatus for noble gas atom detection with isotopic selectivity

DOEpatents

Hurst, G. Samuel; Payne, Marvin G.; Chen, Chung-Hsuan; Parks, James E.

1984-01-01

Apparatus and methods of operation are described for determining, with isotopic selectivity, the number of noble gas atoms in a sample. The analysis is conducted within an evacuated chamber which can be isolated by a valve from a vacuum pumping system capable of producing a pressure of 10.sup.-8 Torr. Provision is made to pass pulses of laser beams through the chamber, these pulses having wavelengths appropriate for the resonance ionization of atoms of the noble gas under analysis. A mass filter within the chamber selects ions of a specific isotope of the noble gas, and means are provided to accelerate these selected ions sufficiently for implantation into a target. Specific types of targets are discussed. An electron measuring device produces a signal relatable to the number of ions implanted into the target and thus to the number of atoms of the selected isotope of the noble gas removed from the gas sample. The measurement can be continued until a substantial fraction, or all, of the atoms in the sample have been counted. Furthermore, additional embodiments of the apparatus are described for bunching the atoms of a noble gas for more rapid analysis, and for changing the target for repetitive cycling of the gas in the chamber. The number of repetitions of the cyclic steps depend upon the concentration of the isotope of interest, the separative efficiency of the mass filter, etc. The cycles are continued until a desired selectivity is achieved. Also described are components and a method of operation for a pre-enrichment operation for use when an introduction of a total sample would elevate the pressure within the chamber to levels in excess of those for operation of the mass filter, specifically a quadrupole mass filter. Specific examples of three noble gas isotope analyses are described.

Se-SAD serial femtosecond crystallography datasets from selenobiotinyl-streptavidin

DOE PAGES

Yoon, Chun Hong; DeMirci, Hasan; Sierra, Raymond G.; ...

2017-04-25

We provide a detailed description of selenobiotinyl-streptavidin (Se-B SA) co-crystal datasets recorded using the Coherent X-ray Imaging (CXI) instrument at the Linac Coherent Light Source (LCLS) for selenium single-wavelength anomalous diffraction (Se-SAD) structure determination. Se-B SA was chosen as the model system for its high affinity between biotin and streptavidin where the sulfur atom in the biotin molecule (C 10H 16N 2O 3S) is substituted with selenium. The dataset was collected at three different transmissions (100, 50, and 10%) using a serial sample chamber setup which allows for two sample chambers, a front chamber and a back chamber, to operatemore » simultaneously. Diffraction patterns from Se-B SA were recorded to a resolution of 1.9 Å. The dataset is publicly available through the Coherent X-ray Imaging Data Bank (CXIDB) and also on LCLS compute nodes as a resource for research and algorithm development.« less

Se-SAD serial femtosecond crystallography datasets from selenobiotinyl-streptavidin

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yoon, Chun Hong; DeMirci, Hasan; Sierra, Raymond G.

We provide a detailed description of selenobiotinyl-streptavidin (Se-B SA) co-crystal datasets recorded using the Coherent X-ray Imaging (CXI) instrument at the Linac Coherent Light Source (LCLS) for selenium single-wavelength anomalous diffraction (Se-SAD) structure determination. Se-B SA was chosen as the model system for its high affinity between biotin and streptavidin where the sulfur atom in the biotin molecule (C 10H 16N 2O 3S) is substituted with selenium. The dataset was collected at three different transmissions (100, 50, and 10%) using a serial sample chamber setup which allows for two sample chambers, a front chamber and a back chamber, to operatemore » simultaneously. Diffraction patterns from Se-B SA were recorded to a resolution of 1.9 Å. The dataset is publicly available through the Coherent X-ray Imaging Data Bank (CXIDB) and also on LCLS compute nodes as a resource for research and algorithm development.« less

Polymerase chain reaction system using magnetic beads for analyzing a sample that includes nucleic acid

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nasarabadi, Shanavaz

2011-01-11

A polymerase chain reaction system for analyzing a sample containing nucleic acid includes providing magnetic beads; providing a flow channel having a polymerase chain reaction chamber, a pre polymerase chain reaction magnet position adjacent the polymerase chain reaction chamber, and a post pre polymerase magnet position adjacent the polymerase chain reaction chamber. The nucleic acid is bound to the magnetic beads. The magnetic beads with the nucleic acid flow to the pre polymerase chain reaction magnet position in the flow channel. The magnetic beads and the nucleic acid are washed with ethanol. The nucleic acid in the polymerase chain reactionmore » chamber is amplified. The magnetic beads and the nucleic acid are separated into a waste stream containing the magnetic beads and a post polymerase chain reaction mix containing the nucleic acid. The reaction mix containing the nucleic acid flows to an analysis unit in the channel for analysis.« less

Portable instrument and method for detecting reduced sulfur compounds in a gas

DOEpatents

Gaffney, J.S.; Kelly, T.J.; Tanner, R.L.

1983-06-01

A portable real time instrument for detecting concentrations in the part per billion range of reduced sulfur compounds in a sample gas. Ozonized air or oxygen and reduced sulfur compounds in a sample gas stream react to produce chemiluminescence in a reaction chamber and the emitted light is filtered and observed by a photomultiplier to detect reduced sulfur compounds. Selective response to individual sulfur compounds is achieved by varying reaction chamber temperature and ozone and sample gas flows, and by the use of either air or oxygen as the ozone source gas.

Microgravity

NASA Image and Video Library

1998-09-30

Optical ports ring the Electrostatic Levitator (ESL) vacuum chamber to admit light from the heating laser (beam passes through the window at left), positioning lasers (one port is at center), and lamps to allow diagnostic instruments to view the sample. The ESL uses static electricity to suspend an object (about 2-3 mm in diameter) inside a vacuum chamber while a laser heats the sample until it melts. This lets scientists record a wide range of physical properties without the sample contacting the container or any instruments, conditions that would alter the readings. The Electrostatic Levitator is one of several tools used in NASA's microgravity materials science program.

New fossil remains of Homo naledi from the Lesedi Chamber, South Africa.

PubMed

Hawks, John; Elliott, Marina; Schmid, Peter; Churchill, Steven E; Ruiter, Darryl J de; Roberts, Eric M; Hilbert-Wolf, Hannah; Garvin, Heather M; Williams, Scott A; Delezene, Lucas K; Feuerriegel, Elen M; Randolph-Quinney, Patrick; Kivell, Tracy L; Laird, Myra F; Tawane, Gaokgatlhe; DeSilva, Jeremy M; Bailey, Shara E; Brophy, Juliet K; Meyer, Marc R; Skinner, Matthew M; Tocheri, Matthew W; VanSickle, Caroline; Walker, Christopher S; Campbell, Timothy L; Kuhn, Brian; Kruger, Ashley; Tucker, Steven; Gurtov, Alia; Hlophe, Nompumelelo; Hunter, Rick; Morris, Hannah; Peixotto, Becca; Ramalepa, Maropeng; Rooyen, Dirk van; Tsikoane, Mathabela; Boshoff, Pedro; Dirks, Paul Hgm; Berger, Lee R

2017-05-09

The Rising Star cave system has produced abundant fossil hominin remains within the Dinaledi Chamber, representing a minimum of 15 individuals attributed to Homo naledi . Further exploration led to the discovery of hominin material, now comprising 131 hominin specimens, within a second chamber, the Lesedi Chamber. The Lesedi Chamber is far separated from the Dinaledi Chamber within the Rising Star cave system, and represents a second depositional context for hominin remains. In each of three collection areas within the Lesedi Chamber, diagnostic skeletal material allows a clear attribution to H. naledi . Both adult and immature material is present. The hominin remains represent at least three individuals based upon duplication of elements, but more individuals are likely present based upon the spatial context. The most significant specimen is the near-complete cranium of a large individual, designated LES1, with an endocranial volume of approximately 610 ml and associated postcranial remains. The Lesedi Chamber skeletal sample extends our knowledge of the morphology and variation of H. naledi , and evidence of H. naledi from both recovery localities shows a consistent pattern of differentiation from other hominin species.

Gas chromatography/matrix-isolation apparatus

DOEpatents

Reedy, G.T.

1986-06-10

A gas-sample collection device provides matrix isolation of individual gas bands from a gas chromatographic separation and for the spectroscopic analysis of the individual sample bands. The device includes a vacuum chamber containing a rotatably supported, specular carousel having at least one reflecting surface for holding a sample deposited thereon. A gas inlet is provided for depositing a mixture of sample and matrix material on the reflecting surface which is maintained at a sufficiently low temperature to cause solidification. A first parabolic mirror directs an incident beam of electromagnetic radiation, such as in the infrared (IR) spectrum, from a source onto the sample/matrix mixture while a second parabolic mirror directs a second beam of electromagnetic radiation reflected by the specular surface to an IR spectrometer for determining the absorption spectra of the sample material deposited on the reflecting surface. The pair of off-axis parabolic mirrors having a common focal point are positioned outside of the vacuum chamber and may be displaced in combination for improved beam positioning and alignment. The carousel is provided with an aperture for each reflecting surface to facilitate accurate positioning of the incident beam relative to the gas-samples under analysis. Improved gas-sample deposition is insured by the use of a long focal length stereomicroscope positioned outside of the vacuum chamber for monitoring sample formation through a window, while the sample collector is positioned outside of the zone bounded by the incident and reflected electromagnetic beams for improved sample access and monitoring. 10 figs.

Gas chromatography/matrix-isolation apparatus

DOEpatents

Reedy, Gerald T.

1986-01-01

A gas-sample collection device provides matrix isolation of individual gas bands from a gas chromatographic separation and for the spectroscopic analysis of the individual sample bands. The device includes a vacuum chamber containing a rotatably supported, specular carousel having at least one reflecting surface for holding a sample deposited thereon. A gas inlet is provided for depositing a mixture of sample and matrix material on the reflecting surface which is maintained at a sufficiently low temperature to cause solidification. A first parabolic mirror directs an incident beam of electromagnetic radiation, such as in the infrared (IR) spectrum, from a source onto the sample/matrix mixture while a second parabolic mirror directs a second beam of electromagnetic radiation reflected by the specular surface to an IR spectrometer for determining the absorption spectra of the sample material deposited on the reflecting surface. The pair of off-axis parabolic mirrors having a common focal point are positioned outside of the vacuum chamber and may be displaced in combination for improved beam positioning and alignment. The carousel is provided with an aperture for each reflecting surface to facilitate accurate positioning of the incident beam relative to the gas-samples under analysis. Improved gas-sample deposition is insured by the use of a long focal length stereomicroscope positioned outside of the vacuum chamber for monitoring sample formation through a window, while the sample collector is positioned outside of the zone bounded by the incident and reflected electromagnetic beams for improved sample access and monitoring.

Containment of fluid samples in the hydrothermal diamond-anvil cell without the use of metal gaskets: Performance and advantages for in situ analysis

NASA Astrophysics Data System (ADS)

Chou, I.-Ming; Bassett, William A.; Anderson, Alan J.; Mayanovic, Robert A.; Shang, Linbo

2008-11-01

Metal gaskets (Re, Ir, Inconel, or stainless steel) normally used to contain fluid samples in the hydrothermal diamond-anvil cell (HDAC) are sometimes undesirable due to possible contamination and to gasket deformation at high pressures and temperatures resulting in nonisochoric behavior. Furthermore, in x-ray spectroscopic experiments, metal gaskets may attenuate the incident x-ray beam and emitted fluorescence x-rays, and the interaction of scattered radiation with the gasket may produce fluorescence that interferes with the x-ray spectrum of the sample. New arrangements and procedures were tested for the operation of the HDAC without using the metal gaskets. Distilled, de-ionized water was loaded into the sample chamber, a laser-milled recess 300 μm in diameter and ˜50 μm deep centered in the 1.0 mm face of the lower diamond anvil, and sealed by pressing the top diamond anvil face directly against the lower one without a metal gasket in between. A maximum sample pressure of 202 MPa at 617 °C was maintained for a duration of 10 min without evidence of leakage. A small change in fluid density was observed in one experiment where the sample was held at 266 MPa at 708 °C for 10 min. The gasketless HDAC was also employed in x-ray absorption spectroscopy experiments, where, in addition to the sample chamber in the lower diamond, two grooves were milled at a 90° angle to each other around the sample chamber to minimize the attenuation of incident and fluorescent x rays. With a minimum distance between the sample chamber and the grooves of 80 μm, a pressure of 76 MPa at 500 °C was maintained for 2 h with no change in the original fluid density.

Containment of fluid samples in the hydrothermal diamond-anvil cell without the use of metal gaskets: Performance and advantages for in situ analysis

USGS Publications Warehouse

Chou, I.-Ming; Bassett, William A.; Anderson, Alan J.; Mayanovic, Robert A.; Shang, L.

2008-01-01

Metal gaskets (Re, Ir, Inconel, or stainless steel) normally used to contain fluid samples in the hydrothermal diamond-anvil cell (HDAC) are sometimes undesirable due to possible contamination and to gasket deformation at high pressures and temperatures resulting in nonisochoric behavior. Furthermore, in x-ray spectroscopic experiments, metal gaskets may attenuate the incident x-ray beam and emitted fluorescence x-rays, and the interaction of scattered radiation with the gasket may produce fluorescence that interferes with the x-ray spectrum of the sample. New arrangements and procedures were tested for the operation of the HDAC without using the metal gaskets. Distilled, de-ionized water was loaded into the sample chamber, a laser-milled recess 300 ??m in diameter and ???50 ??m deep centered in the 1.0 mm face of the lower diamond anvil, and sealed by pressing the top diamond anvil face directly against the lower one without a metal gasket in between. A maximum sample pressure of 202 MPa at 617 ??C was maintained for a duration of 10 min without evidence of leakage. A small change in fluid density was observed in one experiment where the sample was held at 266 MPa at 708 ??C for 10 min. The gasketless HDAC was also employed in x-ray absorption spectroscopy experiments, where, in addition to the sample chamber in the lower diamond, two grooves were milled at a 90?? angle to each other around the sample chamber to minimize the attenuation of incident and fluorescent x rays. With a minimum distance between the sample chamber and the grooves of 80 ??m, a pressure of 76 MPa at 500 ??C was maintained for 2 h with no change in the original fluid density. ?? 2008 American Institute of Physics.

Containment of fluid samples in the hydrothermal diamond-anvil cell without the use of metal gaskets: performance and advantages for in situ analysis.

PubMed

Chou, I-Ming; Bassett, William A; Anderson, Alan J; Mayanovic, Robert A; Shang, Linbo

2008-11-01

Metal gaskets (Re, Ir, Inconel, or stainless steel) normally used to contain fluid samples in the hydrothermal diamond-anvil cell (HDAC) are sometimes undesirable due to possible contamination and to gasket deformation at high pressures and temperatures resulting in nonisochoric behavior. Furthermore, in x-ray spectroscopic experiments, metal gaskets may attenuate the incident x-ray beam and emitted fluorescence x-rays, and the interaction of scattered radiation with the gasket may produce fluorescence that interferes with the x-ray spectrum of the sample. New arrangements and procedures were tested for the operation of the HDAC without using the metal gaskets. Distilled, de-ionized water was loaded into the sample chamber, a laser-milled recess 300 microm in diameter and approximately 50 microm deep centered in the 1.0 mm face of the lower diamond anvil, and sealed by pressing the top diamond anvil face directly against the lower one without a metal gasket in between. A maximum sample pressure of 202 MPa at 617 degrees C was maintained for a duration of 10 min without evidence of leakage. A small change in fluid density was observed in one experiment where the sample was held at 266 MPa at 708 degrees C for 10 min. The gasketless HDAC was also employed in x-ray absorption spectroscopy experiments, where, in addition to the sample chamber in the lower diamond, two grooves were milled at a 90 degrees angle to each other around the sample chamber to minimize the attenuation of incident and fluorescent x rays. With a minimum distance between the sample chamber and the grooves of 80 microm, a pressure of 76 MPa at 500 degrees C was maintained for 2 h with no change in the original fluid density.

Addressing surface-induced loss and decoherence in superconducting quantum circuits

NASA Astrophysics Data System (ADS)

Fuhrer, Andreas; Mueller, Peter; Kuhlmann, Andreas; Filipp, Stefan; Deshpande, Veeresh; Drechsler, Ute

Many of the advances in coherence and fidelity of superconducting qubits have been made possible by clever engineering of the coupling to the environment and operation at noise-insensitive sweet spots. However, this leads to a compromise in experimental flexibility and device tunability, which can become inhibitive as the system size is scaled up. Material and interface related degrees of freedoms are harder to mitigate and are expected to become increasingly important in more complex systems. They impose limits both on coherence (flux-noise) and lifetimes (surface loss) of superconducting qubits. To study and eliminate these effects we have constructed a reusable UHV-compatible sample enclosure that enables us to perform various surface passivation steps before cooling superconducting devices to cryogenic temperatures. The enclosure can accommodate large chips with up to 18 microwave ports and can be vacuum sealed at pressures below 8e-10 mbar. We discuss its operation principle and present first measurement results of superconducting CPW resonators and qubit devices with and without prior surface treatments.

SnTe microcrystals: Surface cleaning of a topological crystalline insulator

DOE Office of Scientific and Technical Information (OSTI.GOV)

Saghir, M., E-mail: M.Saghir@warwick.ac.uk, E-mail: G.Balakrishnan@warwick.ac.uk; Walker, M.; McConville, C. F.

Investigating nanometer and micron sized materials thought to exhibit topological surface properties that can present a challenge, as clean surfaces are a pre-requisite for band structure measurements when using nano-ARPES or laser-ARPES in ultra-high vacuum. This issue is exacerbated when dealing with nanometer or micron sized materials, which have been prepared ex-situ and so have been exposed to atmosphere. We present the findings of an XPS study where various cleaning methods have been employed to reduce the surface contamination and preserve the surface quality for surface sensitive measurements. Microcrystals of the topological crystalline insulator SnTe were grown ex-situ and transferredmore » into ultra high vacuum (UHV) before being treated with either atomic hydrogen, argon sputtering, annealing, or a combination of treatments. The samples were also characterised using the scanning electron microscopy, both before and after treatment. It was found that atomic hydrogen cleaning with an anneal cycle (200 °C) gave the best clean surface results.« less

XPS study of graphene oxide reduction induced by (100) and (111)-oriented Si substrates

NASA Astrophysics Data System (ADS)

Priante, F.; Salim, M.; Ottaviano, L.; Perrozzi, F.

2018-02-01

The reduction of graphene oxide (GO) has been extensively studied in literature in order to let GO partially recover the properties of graphene. Most of the techniques proposed to reduce GO are based on high temperature annealing or chemical reduction. A new procedure, based on the direct reduction of GO by etched Si substrate, was recently proposed in literature. In the present work, we accurately investigated the Si-GO interaction with x-ray photoelectron spectroscopy. In order to avoid external substrate oxidation factors we used EtOH as the GO solvent instead of water, and thermal annealing was carried out in UHV. We investigated the effect of Si(100), Si(111) and Au substrates on GO, to probe the role played by both the substrate composition and substrate orientation during the reduction process. A similar degree of GO reduction was observed for all samples but only after thermal annealing, ruling out the direct reduction effect of the substrate.

Secondary Electron Emission Yields

NASA Technical Reports Server (NTRS)

Krainsky, I.; Lundin, W.; Gordon, W. L.; Hoffman, R. W.

1981-01-01

The secondary electron emission (SEE) characteristics for a variety of spacecraft materials were determined under UHV conditions using a commercial double pass CMA which permits sequential Auger electron electron spectroscopic analysis of the surface. The transparent conductive coating indium tin oxide (ITO) was examined on Kapton and borosilicate glass and indium oxide on FED Teflon. The total SEE coefficient ranges from 2.5 to 2.6 on as-received surfaces and from 1.5 to 1.6 on Ar(+) sputtered surfaces with 5 nm removed. A cylindrical sample carousel provides normal incidence of the primary beam as well as a multiple Faraday cup measurement of the approximately nA beam currents. Total and true secondary yields are obtained from target current measurements with biasing of the carousel. A primary beam pulsed mode to reduce electron beam dosage and minimize charging of insulating coatings was applied to Mg/F2 coated solar cell covers. Electron beam effects on ITO were found quite important at the current densities necessary to do Auger studies.

Sensitivity, specificity and predictive values of anterior chamber tap in cases of bacterial endophthalmitis.

PubMed

Sjoholm-Gomez de Liano, Carl; Soberon-Ventura, Vidal F; Salcedo-Villanueva, Guillermo; Santos-Palacios, Abril; Guerrero-Naranjo, Jose Luis; Fromow-Guerra, Jans; García-Aguirre, Gerardo; Morales-Canton, Virgilio; Velez-Montoya, Raul

2017-01-01

To assess the sensitivity, specificity, positive predictive value and negative predictive value of anterior chamber tap for the diagnosis of bacterial endophthalmitis on a population with high prevalence. Retrospective, single centre, case series study. We reviewed all medical records with clinical diagnosis of bacterial endophthalmitis in our hospital from January 1st, 2000 to December 31st 2014. From each record, we documented general demographic data, best corrected visual acuity and vitreous and aqueous tap microbiological results. All cases were further divided according to the endophthalmitis aetiology to perform individual calculations of sensitivity, specificity, positive predictive value, negative predictive value, accuracy and prevalence. We used the results of the vitreous tap as the gold standard for diagnosis of bacterial endophthalmitis. We excluded those records in which the aqueous and vitreous samples were not taken simultaneously or had an incomplete microbiological report. Significance were assessed with chi squared statistics, with an alpha value of 0.05 for statistical significance. A total of 190 cases fulfilled the inclusion/exclusion criteria. Positive culture rate from vitreous samples was 64.74%. Positive culture rate from aqueous sample was 32.11%. Bacteria isolated from aqueous samples matched those isolated from vitreous samples 78.68% of the time. The overall sensitivity was 38.21%, specificity: 75.51%, positive predictive value: 79.66%, negative predictive value: 32.74% ( p  = 0.08). Subgroup analysis showed that anterior chamber taps in cases of post-surgical endophthalmitis had a moderate to low sensitivity (37.73%), high specificity (93%) and high positive predictive value (95%) ( p  < 0.04). The sensitivity and specificity of anterior chamber tap are low and should not be used for critical therapeutic decisions in patients with suspected bacterial endophthalmitis. In cases of post-surgical endophthalmitis, the result of an anterior chamber tap could be used for therapeutic guidance, but only in conjunction with clinical presentation and in the absence of a better method for diagnosis.

Hot Jet Ignition Delay Characterization of Methane and Hydrogen at Elevated Temperatures

NASA Astrophysics Data System (ADS)

Tarraf Kojok, Ali

This study contributes to a better understanding of ignition by hot combustion gases which finds application in internal combustion chambers with pre-chamber ignition as well as in wave rotor engine applications. The experimental apparatus consists of two combustion chambers: a pre chamber that generates the transient hot jet of gas and a main chamber which contains the main fuel air blend under study. Variables considered are three fuel mixtures (Hydrogen, Methane, 50% Hydrogen-Methane), initial pressure in the pre-chamber ranging from 1 to 2 atm, equivalence ratio of the fuel air mixture in the main combustion chamber ranging from 0.4 to 1.5, and initial temperature of the main combustion chamber mixture ranging from 297 K to 500 K. Experimental data makes use of 4 pressure sensors with a recorded sampling rate up to 300 kHz, as well as high speed Schlieren imaging with a recorded frame rate up to 20,833 frame per seconds. Results shows an overall increase in ignition delay with increasing equivalence ratio. High temperature of the main chamber blend was found not to affect hot jet ignition delay considerably. Physical mixing effects, and density of the main chamber mixture have a greater effect on hot jet ignition delay.

A new HF-resistant tandem spray chamber for improved determination of trace elements and Pb isotopes using inductively coupled plasma-mass spectrometry

NASA Astrophysics Data System (ADS)

Krachler, Michael; Rausch, Nicole; Feuerbacher, Helmut; Klemens, Patrick

2005-07-01

The use of a new HF-resistant tandem spray chamber arrangement consisting of a cyclonic spray chamber and a Scott-type spray chamber made from PFA and PEEK provides a straightforward approach for improving the performance of inductively coupled-mass spectrometry (ICP-MS). The characteristics of the tandem spray chamber were critically evaluated against a PEEK cyclonic and a PFA Scott-type spray chamber, respectively. Sensitivity across the entire mass range was increased by about three times compared to the conventional setup utilizing only one spray chamber. Precision of the results, especially at low signal intensities, improved by 160% and 31% compared to the cyclonic and Scott-type spray chamber, respectively. Using the tandem spray chamber, the oxide formation rate was lowered by about 50%. Signals as low as 30 counts could be determined under routine measurement conditions with a RSD of 2.4% thus allowing to precisely quantify small concentration differences at the ng l - 1 concentration level. The excellent precision (0.02-0.07%) of 206Pb / 207Pb and 206Pb / 208Pb ratios determined in pore water samples was rather limited by the instrumental capabilities of the single collector ICP-MS instrument than by the performance of the tandem spray chamber.

Advanced Photon Source accelerator ultrahigh vacuum guide

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liu, C.; Noonan, J.

1994-03-01

In this document the authors summarize the following: (1) an overview of basic concepts of ultrahigh vacuum needed for the APS project, (2) a description of vacuum design and calculations for major parts of APS, including linac, linac waveguide, low energy undulator test line, positron accumulator ring (PAR), booster synchrotron ring, storage ring, and insertion devices, and (3) cleaning procedures of ultrahigh vacuum (UHV) components presently used at APS.

A Systematic Cathode Study-Activation of a Thermionic Cathode, and Measuring Cesium Evaporation from a Dispenser Photocathode

DTIC Science & Technology

2010-06-01

QCM Quartz Crystal Deposition Monitor SEM Scanning Electron Microscope SRF Superconducting Radio Frequency T Torr Ti Titanium UHV Ultra...High Vacuum ( ᝺-7 Torr) UM University of Maryland QCM Quartz Crystal Deposition Monitor V Volt VAC Voltage-Alternating Current xvii...event. The two originally had problems with their tungsten filaments crystallizing and breaking. Being experimentalists, they added thorium in an

Stimulated Electron Desorption Studies from Microwave Vacuum Electronics / High Power Microwave Materials

DTIC Science & Technology

2010-02-11

purchase a new gun. Mr. Mike Ackeret ( Transfer Engineering Inc.) Transfer Engineering’s expertise in specialty UHV work and machining propelled...modifications they helped design for the test stand. With UNLV guidance, Transfer Engineering designed and built the original UNLV SEE Test Stand...Staib electron gun, an isolated beam drift tube, a hexanode delay line with a chevron microchannel plate (MCP) stack, an isolated grid, an isolated

MarsVac: Pneumatic Sampling System for Planetary Exploration

NASA Astrophysics Data System (ADS)

Zacny, K.; Mungas, G.; Chu, P.; Craft, J.; Davis, K.

2008-12-01

We are proposing a Mars Sample Return scheme whereby a sample of regolith is acquired directly into a Mars Ascent Vehicle using a pneumatic system. Unlike prior developments that used suction to collect fines, the proposed system uses positive pressure to move the regolith. We envisage 3 pneumatic tubes to be embedded inside the 3 legs of the lander. Upon landing, the legs will burry themselves into the regolith and the tubes will fill up with regolith. With one puff of gas, the regolith can be lifted into a sampling chamber onboard of the Mars Ascent Vehicle. An additional chamber can be opened to acquire atmospheric gas and dust. The entire MSR will require 1) an actuator to open/close sampling chamber and 2) a valve to open gas cylinder. In the most recent study related to lunar excavation and funded under the NASA SBIR program we have shown that it is possible lift over 3000 grams of soil with only 1 gram of gas at 1atm. Tests conducted under Mars atmospheric pressure conditions (5 torr). In September of 2008, we will be performing tests at 1/6thg (Moon) and 1/3g (Mars) to determine mass lifting efficiencies in reduced gravities.

Estimation of interaction energy and contact stiffness in atomic-scale sliding on a model sodium chloride surface in ethanol.

PubMed

Agmon, Liron; Shahar, Itai; Yosufov, Danny; Pimentel, Carlos; Pina, Carlos M; Gnecco, Enrico; Berkovich, Ronen

2018-03-16

Friction force microscopy (FFM) in aqueous environments has recently proven to be a very effective method for lattice-resolution imaging of crystal surfaces. Here we demonstrate the use of ethanol for similar measurements on water-soluble materials. Lattice resolved frictional stick-slip traces of a cleaved NaCl(100) surface submerged in ethanol are compared with previous obtained FFM results in ultrahigh vacuum (UHV). We use the Prandtl-Tomlinson framework to estimate the amplitude of the corrugation potential and the contact stiffness. The surface potential amplitude scales with the applied normal loads are in good agreement with data obtained for NaCl measured under UHV conditions, but demonstrates deviations from the ideal periodic potential given by the Prandtl-Tomlinson model. An additional finding is that the use of ethanol allows us to explore higher load ranges without detectable evidence of surface wear. The contact stiffness does not vary significantly with the normal load up to 38 nN, while above it a sudden increase by almost one order of magnitude was observed. Comparing this to previous results suggests that considerable atom rearrangements may occur in the contact region, although the (100) surface structure is preserved by ethanol-assisted diffusion of Na and Cl ions.

Electron-spectroscopy and -diffraction study of the conductivity of CVD diamond ( 0 0 1 )2×1 surface

NASA Astrophysics Data System (ADS)

Kono, S.; Takano, T.; Shimomura, M.; Goto, T.; Sato, K.; Abukawa, T.; Tachiki, M.; Kawarada, H.

2003-04-01

A chemical vapor deposition as-grown diamond (0 0 1) single-domain 2 × 1 surface was studied by electron-spectroscopy and electron-diffraction in ultrahigh vacuum (UHV). In order to change the surface conductivity (SC) of the diamond in UHV, three annealing stages were used; without annealing, annealing at 300 °C and annealing at 550 °C. From low energy electron diffraction and X-ray photoelectron spectroscopic (XPS) studies, an existence of SC was suggested for the first two stages of annealing and an absence of SC was suggested for the last stage of annealing. Changes in C KVV Auger electron spectroscopic spectra, C KVV Auger electron diffraction (AED) patterns and C 1s XPS peak positions were noticed between the annealing stages at 300 and 550 °C. These changes are interpreted as such that the state of hydrogen involvement in a subsurface of diamond (0 0 1)2 × 1 changes as SC changes. In particular, the presence of local disorder in diamond configuration in SC subsurface is pointed out from C KVV AED. From C 1s XPS peak shifts, a lower bound for the Fermi-level for SC layers from the valence band top is presented to be ˜0.5 eV.

Oxidation of palladium on Au(111) and ZnO(0001) supports

DOE PAGES

Lallo, J.; Tenney, S. A.; Kramer, A.; ...

2014-10-21

The oxidation of supported Pd-deposits on Au(111) and ZnO(0001) single crystals has been studied by x- ray photoemission spectroscopy (XPS). Oxidation has been carried out ex-situ in a high-pressure cell with subsequent vacuum-transfer and characterization by XPS in ultrahigh vacuum (UHV), as well as using in-situ characterization by synchrotron based near-ambient pressure XPS. On Au(111) alloying of Pd with the substrate competes with oxidation and only sufficiently thick Pd films have been found to oxidize. For Pd on ZnO the oxidation conditions depend on the amount of deposited Pd. Thicker Pd deposits behave similar to bulk Pd, while thinner filmsmore » oxidize already at lower temperatures. Interestingly, for very small amounts of Pd, in-situ XPS shows full oxidation at room temperature and at less than 0.6 mbar O₂ pressure. This indicates a lowering of the kinetic barriers for oxidation of very small supported Pd-clusters. The formed oxide is, however, not stable in UHV and a slow reduction is observed. The instability of this oxide indicates that the Pd-oxide formed at the interface to ZnO may have different chemical properties compared to bulk PdO or surface oxides on Pd.« less

Sonogashira cross-coupling over Au(1 1 1): from UHV to ambient pressure

NASA Astrophysics Data System (ADS)

Johansson, N.; Sisodiya, S.; Shayesteh, P.; Chaudhary, S.; Andersen, J. N.; Knudsen, J.; Wendt, O. F.; Schnadt, J.

2017-11-01

We have studied the reaction of phenylacetylene (PA) with chloro-, bromo-, and iodobenzene on the Au(1 1 1) surface as a model system for the gold-catalysed Sonogashira cross-coupling. Both ultrahigh vacuum-based and ambient pressure x-ray photoelectron spectroscopy show that iodo- and chlorobenzene (IB and CB) undergo the cross-coupling reaction towards diphenylacetylene. Bromobenzene (BB), in contrast, does not react in the UHV experiments. Further, at ambient pressure signs are found for poisoning of the Au(1 1 1) surface by a carbon species formed in the reaction. The understanding obtained in the reaction experiments are based on a thorough investigation of the adsorption of PA, IB, CB, and BB on the Au(1 1 1) surface by soft x-ray absorption spectroscopy and temperature-dependent x-ray photoelectron spectroscopy. In particular, the experiments provide the orientation of the intact adsorbates with respect to the surfaces at liquid nitrogen temperature. Dissociation in the temperature regime between  -80 and  -15 °C is observed for iodo- and chlorobenzene, but not for BB, in agreement with that only IB and CB, but not BB, react with PA to form diphenylacetylene. The difference is tentatively attributed to a difference in surface orientation of the different halobenzenes.

Design and qualification of an UHV system for operation on sounding rockets

DOE Office of Scientific and Technical Information (OSTI.GOV)

Grosse, Jens, E-mail: jens.grosse@dlr.de; Braxmaier, Claus; Seidel, Stephan Tobias

The sounding rocket mission MAIUS-1 has the objective to create the first Bose–Einstein condensate in space; therefore, its scientific payload is a complete cold atom experiment built to be launched on a VSB-30 sounding rocket. An essential part of the setup is an ultrahigh vacuum system needed in order to sufficiently suppress interactions of the cooled atoms with the residual background gas. Contrary to vacuum systems on missions aboard satellites or the international space station, the required vacuum environment has to be reached within 47 s after motor burn-out. This paper contains a detailed description of the MAIUS-1 vacuum system, asmore » well as a description of its qualification process for the operation under vibrational loads of up to 8.1 g{sub RMS} (where RMS is root mean square). Even though a pressure rise dependent on the level of vibration was observed, the design presented herein is capable of regaining a pressure of below 5 × 10{sup −10} mbar in less than 40 s when tested at 5.4 g{sub RMS}. To the authors' best knowledge, it is the first UHV system qualified for operation on a sounding rocket.« less

Interactions of gaseous molecules with X-ray photons and photoelectrons in AP-XPS study of solid surface in gas phase.

PubMed

Tao, Franklin Feng; Nguyen, Luan

2018-04-18

Studies of the surface of a catalyst in the gas phase via photoelectron spectroscopy is an important approach to establish a correlation between the surface of a catalyst under reaction conditions or during catalysis and its corresponding catalytic performance. Unlike the well understood interactions between photoelectrons and the atomic layers of a surface in ultrahigh vacuum (UHV) and the well-developed method of quantitative analysis of a solid surface in UHV, a fundamental understanding of the interactions between X-ray photons and gaseous molecules and between photoelectrons and molecules of the gas phase in ambient pressure X-ray photoelectron spectroscopy (AP-XPS) is lacking. Through well designed experiments, here the impact of the interactions between photoelectrons and gaseous molecules and interactions between X-ray photons and gaseous molecules on the intensity of the collected photoelectrons have been explored. How the changes in photoelectron intensity resulting from these interactions influence measurement of the authentic atomic ratio of element M to A of a solid surface has been discussed herein, and methods to correct the measured nominal atomic ratio of two elements of a solid surface upon travelling through a gas phase to its authentic atomic ratio have been developed.

SSCE, Rominger works with middeck experiment

NASA Image and Video Library

1997-08-29

STS085-339-006 (7 - 19 August 1997) --- Astronaut Kent V. Rominger, pilot, checks on the Solid Surface Combustion Experiment (SSCE) on the mid-deck of the Space Shuttle Discovery. The experiment, which occupies the space of four lockers, consists of a Polymethyl Methacrylate (PMMA) fuel sample internally mounted in the center of a pressurized chamber. Two windows orthogonal to each other in the chamber wall allow viewing by a 16mm camera of the side edge and top of the PMMA sample.

A Laboratory Investigation of Aerosol and Extinction Characteristics for SALTY DOG, NWC 29 and NWC 78 Pyrotechnics

DTIC Science & Technology

1980-10-01

The artificial fogs are produced by 1’SALTY DOC,14 and phosphorus pentoxide smokeS~in Calspan’s 590 cubic meter chamber at controlled relative...the chamber experiments, an isokinetic sampling inlet was employed for minimizing aerosol losses during sampling. Instrumentation used to monitor...with a 1 cfm critical orifice and vacuum pump. Additionally, a flow meter , placed behind the filter, was monitored to assure that filter loading did

Trace level detection of analytes using artificial olfactometry

NASA Technical Reports Server (NTRS)

Lewis, Nathan S. (Inventor); Severin, Erik J. (Inventor); Wong, Bernard (Inventor)

2002-01-01

The present invention provides a device for detecting the presence of an analyte, such as for example, a lightweight device, including: a sample chamber having a fluid inlet port for the influx of the analyte; a fluid concentrator in flow communication with the sample chamber wherein the fluid concentrator has an absorbent material capable of absorbing the analyte and capable of desorbing a concentrated analyte; and an array of sensors in fluid communication with the concentrated analyte to be released from the fluid concentrator.

A centrifugal direct recombinase polymerase amplification (direct-RPA) microdevice for multiplex and real-time identification of food poisoning bacteria.

PubMed

Choi, Goro; Jung, Jae Hwan; Park, Byung Hyun; Oh, Seung Jun; Seo, Ji Hyun; Choi, Jong Seob; Kim, Do Hyun; Seo, Tae Seok

2016-06-21

In this study, we developed a centrifugal direct recombinase polymerase amplification (direct-RPA) microdevice for multiplex and real-time identification of food poisoning bacteria contaminated milk samples. The microdevice was designed to contain identical triplicate functional units and each unit has four reaction chambers, thereby making it possible to perform twelve direct-RPA reactions simultaneously. The integrated microdevice consisted of two layers: RPA reagents were injected in the top layer, while spiked milk samples with food poisoning bacteria were loaded into sample reservoirs in the bottom layer. For multiplex bacterial detection, the target gene-specific primers and probes were dried in each reaction chamber. The introduced samples and reagents could be equally aliquoted and dispensed into each reaction chamber by centrifugal force, and then the multiplex direct-RPA reaction was executed. The target genes of bacteria spiked in milk could be amplified at 39 °C without a DNA extraction step by using the direct-RPA cocktails, which were a combination of a direct PCR buffer and RPA enzymes. As the target gene amplification proceeded, the increased fluorescence signals coming from the reaction chambers were recorded in real-time at an interval of 2 min. The entire process, including the sample distribution, the direct-RPA reaction, and the real-time analysis, was accomplished with a custom-made portable genetic analyzer and a miniaturized optical detector. Monoplex, duplex, and triplex food poisoning bacteria (Salmonella enterica, Escherichia coli O157:H7, and Vibrio parahaemolyticus) detection was successfully performed with a detection sensitivity of 4 cells per 3.2 μL of milk samples within 30 min. By implementing the direct-PRA on the miniaturized centrifugal microsystem, the on-site food poisoning bacteria analysis would be feasible with high speed, sensitivity, and multiplicity.

Environmental chamber measurements of mercury flux from coal utilization by-products

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pekney, Natalie J.; Martello, Donald; Schroeder, Karl

2009-05-01

An environmental chamber was constructed to measure the mercury flux from coal utilization by-product (CUB) samples. Samples of fly ash, FGD gypsum, and wallboard made from FGD gypsum were tested under both dark and illuminated conditions with or without the addition of water to the sample. Mercury releases varied widely, with 7- day experiment averages ranging from -6.8 to 73 ng/m(2) h for the fly ash samples and -5.2 to 335 ng/m(2) h for the FGD/wallboard samples. Initial mercury content, fly ash type, and light exposure had no observable consistent effects on the mercury flux. For the fly ash samples,more » the effect of a mercury control technology was to decrease the emission. For three of the four pairs of FGD gypsum and wallboard samples, the wallboard sample released less (or absorbed more) mercury than the gypsum.« less

Environmental chamber measurements of mercury flux from coal utilization by-products

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pekney, N.J.; Martello, D.V.; Schroeder, K.T.

2009-05-01

An environmental chamber was constructed to measure the mercury flux from coal utilization by-product (CUB) samples. Samples of fly ash, FGD gypsum, and wallboard made from FGD gypsum were tested under both dark and illuminated conditions with or without the addition of water to the sample. Mercury releases varied widely, with 7-day experiment averages ranging from -6.8 to 73 ng/m2 h for the fly ash samples and -5.2 to 335 ng/m2 h for the FGD/wallboard samples. Initial mercury content, fly ash type, and light exposure had no observable consistent effects on the mercury flux. For the fly ash samples, themore » effect of a mercury control technology was to decrease the emission. For three of the four pairs of FGD gypsum and wallboard samples, the wallboard sample released less (or absorbed more) mercury than the gypsum.« less

Compensation to Presidents, Senior Executives, and Technical Staff at Federally Funded Research and Development Centers

DTIC Science & Technology

1995-05-01

principally surveys from Wyatt Data Services and the U.S. Chamber of Commerce ) to evaluate the reasonableness of compensation. The Wyatt surveys provided...better matches to similar industries, but the sample sizes often were too small to ensure stability in the data. Both the Wyatt survey and Chamber of Commerce survey...came from the U.S Chamber of Commerce Employee Benefits survey and included both defined benefit and 25 (P) Data removed for proprietary reasons

Charged particle mobility refrigerant analyzer

DOEpatents

Allman, S.L.; Chunghsuan Chen; Chen, F.C.

1993-02-02

A method for analyzing a gaseous electronegative species comprises the steps of providing an analysis chamber; providing an electric field of known potential within the analysis chamber; admitting into the analysis chamber a gaseous sample containing the gaseous electronegative species; providing a pulse of free electrons within the electric field so that the pulse of free electrons interacts with the gaseous electronegative species so that a swarm of electrically charged particles is produced within the electric field; and, measuring the mobility of the electrically charged particles within the electric field.

Charged particle mobility refrigerant analyzer

DOEpatents

Allman, Steve L.; Chen, Chung-Hsuan; Chen, Fang C.

1993-01-01

A method for analyzing a gaseous electronegative species comprises the steps of providing an analysis chamber; providing an electric field of known potential within the analysis chamber; admitting into the analysis chamber a gaseous sample containing the gaseous electronegative species; providing a pulse of free electrons within the electric field so that the pulse of free electrons interacts with the gaseous electronegative species so that a swarm of electrically charged particles is produced within the electric field; and, measuring the mobility of the electrically charged particles within the electric field.

Double window viewing chamber assembly

NASA Technical Reports Server (NTRS)

Keller, V. W. (Inventor); Owen, R. B. (Inventor); Elkins, B. R. (Inventor); White, W. T. (Inventor)

1986-01-01

A viewing chamber which permits observation of a sample retained therein includes a pair of double window assemblies mounted in opposed openings in the walls thereof so that a light beam can directly enter and exit from the chamber. A flexible mounting arrangement for the outer windows of the window assemblies enables the windows to be brought into proper alignment. An electrical heating arrangement prevents fogging of the outer windows whereas desiccated air in the volume between the outer and inner windows prevents fogging of the latter.

NEUTRON MEASURING METHOD AND APPARATUS

DOEpatents

Seaborg, G.T.; Friedlander, G.; Gofman, J.W.

1958-07-29

A fast neutron fission detecting apparatus is described consisting of a source of fast neutrons, an ion chamber containing air, two electrodes within the ion chamber in confronting spaced relationship, a high voltage potential placed across the electrodes, a shield placed about the source, and a suitable pulse annplifier and recording system in the electrode circuit to record the impulse due to fissions in a sannple material. The sample material is coated onto the active surface of the disc electrode and shielding means of a material having high neutron capture capabilities for thermal neutrons are provided in the vicinity of the electrodes and about the ion chamber so as to absorb slow neutrons of thermal energy to effectively prevent their diffusing back to the sample and causing an error in the measurement of fast neutron fissions.

Electromagnetic Characterization of Materials Using a Dual Chambered High Temperature Waveguide

DTIC Science & Technology

to just one day through simultaneous measurement of the sample and the empty second chamber. A vector network analyzer (VNA) will be used to run X-band...calculated from the Nicolson-Ross-Weir inversion algorithm for computing permittivity and permeability using VNA measured S-parameters at increasing temperatures.

Stability of selected volatile contact allergens in different patch test chambers under different storage conditions.

PubMed

Mose, Kristian F; Andersen, Klaus E; Christensen, Lars Porskjaer

2012-04-01

Patch test preparations of volatile substances may evaporate during storage, thereby giving rise to reduced patch test concentrations. To investigate the stability of selected acrylates/methacrylates and fragrance allergens in three different test chambers under different storage conditions. Petrolatum samples of methyl methacrylate (MMA), 2-hydroxyethyl methacrylate (2-HEMA), 2-hydroxypropyl acrylate (2-HPA), cinnamal and eugenol in patch test concentrations were stored in three different test chambers (IQ chamber™, IQ Ultimate™, and Van der Bend® transport container) at room temperature and in a refrigerator. The samples were analysed in triplicate with high-performance liquid chromatography. The decrease in concentration was substantial for all five allergens under both storage conditions in IQ chamber™ and IQ Ultimate™, with the exception of 2-HEMA during storage in the refrigerator. For these two chamber systems, the contact allergen concentration dropped below the stability limit in the following order: MMA, cinnamal, 2-HPA, eugenol, and 2-HEMA. In the Van der Bend® transport container, the contact allergens exhibited acceptable stability under both storage conditions, whereas MMA and 2-HPA required cool storage for maintenance of the limit. The Van der Bend® transport container was the best device for storage of samples of volatile contact allergens. © 2012 John Wiley & Sons A/S.

Design of a novel system for spectroscopy measurements of the aqueous humor

NASA Astrophysics Data System (ADS)

Miller, Joe; Uttamchandani, Deepak G.

2001-06-01

The authors report on the design of a system which will enable real time measurements of (therapeutic) drug concentrations in the anterior chamber of the eye. Currently the concentration of therapeutic drugs in the anterior chamber is determined by analyzing samples which have been removed from the aqueous humor of laboratory animal eyes. This sampling via paracentesis can be painful and does not provide a continuous measurement. Our system will be far less invasive, removing the need for sampling via paracentesis, and also providing a continuous measurement, enabling a more complete understanding of the kinetics of ophthalmic drugs. A key component in our novel system is a specially constructed contact lens. We report on the design, optimization and manufacture of such a contact lens system capable of directing UV/VIS light in, across and out of the anterior chamber of the eye, thereby enabling absorption spectroscopy measurements of the aqueous humor to be undertaken. Design of the one piece contact lens/mirror system was achieved using the Zemax optical design software package and the lens was fabricated from synthetic fused silica. Results from modeling of the lens and experimental measurements on light propagation across the anterior chamber of animal eyes assisted by the lens will be reported.

Portable apparatus for the measurement of environmental radon and thoron

DOEpatents

Negro, Vincent C.

2001-01-01

The radometer is a portable instrument for the measurement of the concentration of atmospheric radon/thoron in a test area. A constant velocity pump pulls the air from the outside at a constant flow rate. If the air is too moist, some or all of the sample is passed through a desiccant filter prior to encountering an electrostatic filter. The electrostatic filter prevents any charged particles from entering the sampling chamber. Once the sample has entered the chamber, the progeny of the decay of radon/thoron are collected on a detector and measured. The measured data is compiled by a computer and displayed.

Microgravity

NASA Image and Video Library

1998-09-30

Optical prots ring the Electrostatic Levitator (ESL) vacuum chamber to admit light from the heating laser (the beam passes through the window at left), poisitioning lasers (one port is at center), and lamps (such as the deuterium arc lamp at right), and to allow diagnostic instruments to view the sample. The ESL uses static electricity to suspend an object (about 2-3 mm in diameter) inside a vacuum chamber while a laser heats the sample until it melts. This lets scientists record a wide range of physical properties without the sample contacting the container or any instruments, conditions that would alter the readings. The Electrostatic Levitator is one of several tools used in NASA's microgravity materials science program.

Microgravity

NASA Image and Video Library

1998-09-30

Optical prots ring the Electrostatic Levitator (ESL) vacuum chamber to admit light from the heating laser (the beam passes through the window at left), poisitioning lasers (one port is at center), and lamps (arc lamp at right), and to allow diagnostic instruments to view the sample. The ESL uses static electricity to suspend an object (about 2-3 mm in diameter) inside a vacuum chamber while a laser heats the sample until it melts. This lets scientists record a wide range of physical properties without the sample contacting the container or any instruments, conditions that would alter the readings. The Electrostatic Levitator is one of several tools used in NASA's microgravity materials science program.

Lattice Matched Iii-V IV Semiconductor Heterostructures: Metalorganic Chemical Vapor Deposition and Remote Plasma Enhanced Chemical Vapor Deposition.

NASA Astrophysics Data System (ADS)

Choi, Sungwoo

1992-01-01

This thesis describes the growth and characterization of wide gap III-V compound semiconductors such as aluminum gallium arsenide (Al_{rm x} Ga_{rm 1-x}As), gallium nitride (GaN), and gallium phosphide (GaP), deposited by the metalorganic chemical vapor deposition (MOCVD) and remote plasma enhanced chemical vapor deposition (Remote PECVD). In the first part of the thesis, the optimization of GaAs and Al_{rm x}Ga _{rm 1-x}As hetero -epitaxial layers on Ge substrates is described in the context of the application in the construction of cascade solar cells. The emphasis on this study is on the trade-offs in the choice of the temperature related to increasing interdiffusion/autodoping and increasing perfection of the epilayer with increasing temperature. The structural, chemical, optical, and electrical properties of the heterostructures are characterized by x-ray rocking curve measurement, scanning electron microscopy (SEM), electron beam induced current (EBIC), cross-sectional transmission electron microscopy (X-TEM), Raman spectroscopy, secondary ion mass spectrometry (SIMS), and steady-state and time-resolved photoluminescence (PL). Based on the results of this work the optimum growth temperature is 720^circC. The second part of the thesis describes the growth of GaN and GaP layers on silicon and sapphire substrates and the homoepitaxy of GaP by remote PECVD. I have designed and built an ultra high vacuum (UHV) deposition system which includes: the gas supply system, the pumping system, the deposition chamber, the load-lock chamber, and the waste disposal system. The work on the deposition of GaN on Si and sapphire focuses onto the understanding of the growth kinetics. In addition, Auger electron spectroscopy (AES) for surface analysis, x-ray diffraction methods and microscopic analyses using SEM and TEM for structural characterization, infrared (IR) and ultraviolet (UV) absorption measurements for optical characterization, and electrical characterization results on the GaN films are presented. In the deposition GaP thin films by remote PECVD, trimethylgallium and in-situ generated phosphine precursors are employed as source gases which permits homo- and heteroepitaxial growth as substrate temperature of 590-620^ circC. Also, the growth kinetics of gallium phosphide is discussed. As in the case of GaN, the surface, structural, chemical, optical, and electrical properties are characterized and the results are discussed.

Intraocular concentrations of gatifloxacin and moxifloxacin in the anterior chamber via diffusion through the cornea using collagen shields.

PubMed

Kleinmann, Guy; Larson, Scott; Neuhann, Irmingard M; Hunold, Anne C; LeBoyer, Russell; Hickman, Scott; Mamalis, Nick; Olson, Randall J

2006-02-01

To evaluate the penetration of gatifloxacin and moxifloxacin into the anterior chamber, and any adverse reaction to the cornea, using collagen shields presoaked in oversaturated solutions of the antibiotics. Collagen shields, presoaked for 10 minutes in an oversaturated solution of gatifloxacin or moxifloxacin, were placed on the surface of each of the corneas of 15 rabbits for a total of 30 eyes (15 in each group). The antibiotics were prepared by dissolving the powder form of the antibiotics in a solution until no further particulate could be further dissolved. Aqueous humor samples were taken 3.5 and 6 hours later. The initial concentrations of gatifloxacin and moxifloxacin were 5.43 +/- 0.16 mg/mL and 3.14 +/- 0.22 mg/mL, respectively. The average concentration of gatifloxacin in the anterior chamber was higher than that of moxifloxacin at the 3.5-hour sample (6.32 +/- 2.67 microg/mL versus 3.55 +/- 3.5 microg/mL, P = 0.0034). The concentrations of both antibiotics, although decreased, remained relatively high at the 6-hour sample (1.39 +/- 1.13 microg/mL versus 0.816 +/- 0.6 microg/mL at 6 hours, respectively, P = 0.22). No obvious clinical or histologic signs of toxicity were noticed in either group. Gatifloxacin and moxifloxacin showed good penetration into the anterior chamber with no obvious adverse reaction to the cornea. The concentrations in the anterior chamber exceeded the minimal inhibitory concentration (MIC) 90 of most organisms responsible for postoperative endophthalmitis (POE).

The "Flexi-Chamber": A Novel Cost-Effective In Situ Respirometry Chamber for Coral Physiological Measurements.

PubMed

Camp, Emma F; Krause, Sophie-Louise; Santos, Lourianne M F; Naumann, Malik S; Kikuchi, Ruy K P; Smith, David J; Wild, Christian; Suggett, David J

2015-01-01

Coral reefs are threatened worldwide, with environmental stressors increasingly affecting the ability of reef-building corals to sustain growth from calcification (G), photosynthesis (P) and respiration (R). These processes support the foundation of coral reefs by directly influencing biogeochemical nutrient cycles and complex ecological interactions and therefore represent key knowledge required for effective reef management. However, metabolic rates are not trivial to quantify and typically rely on the use of cumbersome in situ respirometry chambers and/or the need to remove material and examine ex situ, thereby fundamentally limiting the scale, resolution and possibly the accuracy of the rate data. Here we describe a novel low-cost in situ respirometry bag that mitigates many constraints of traditional glass and plexi-glass incubation chambers. We subsequently demonstrate the effectiveness of our novel "Flexi-Chamber" approach via two case studies: 1) the Flexi-Chamber provides values of P, R and G for the reef-building coral Siderastrea cf. stellata collected from reefs close to Salvador, Brazil, which were statistically similar to values collected from a traditional glass respirometry vessel; and 2) wide-scale application of obtaining P, R and G rates for different species across different habitats to obtain inter- and intra-species differences. Our novel cost-effective design allows us to increase sampling scale of metabolic rate measurements in situ without the need for destructive sampling and thus significantly expands on existing research potential, not only for corals as we have demonstrated here, but also other important benthic groups.

New fossil remains of Homo naledi from the Lesedi Chamber, South Africa

PubMed Central

Hawks, John; Elliott, Marina; Schmid, Peter; Churchill, Steven E; de Ruiter, Darryl J; Roberts, Eric M; Hilbert-Wolf, Hannah; Garvin, Heather M; Williams, Scott A; Delezene, Lucas K; Feuerriegel, Elen M; Randolph-Quinney, Patrick; Kivell, Tracy L; Laird, Myra F; Tawane, Gaokgatlhe; DeSilva, Jeremy M; Bailey, Shara E; Brophy, Juliet K; Meyer, Marc R; Skinner, Matthew M; Tocheri, Matthew W; VanSickle, Caroline; Walker, Christopher S; Campbell, Timothy L; Kuhn, Brian; Kruger, Ashley; Tucker, Steven; Gurtov, Alia; Hlophe, Nompumelelo; Hunter, Rick; Morris, Hannah; Peixotto, Becca; Ramalepa, Maropeng; van Rooyen, Dirk; Tsikoane, Mathabela; Boshoff, Pedro; Dirks, Paul HGM; Berger, Lee R

2017-01-01

The Rising Star cave system has produced abundant fossil hominin remains within the Dinaledi Chamber, representing a minimum of 15 individuals attributed to Homo naledi. Further exploration led to the discovery of hominin material, now comprising 131 hominin specimens, within a second chamber, the Lesedi Chamber. The Lesedi Chamber is far separated from the Dinaledi Chamber within the Rising Star cave system, and represents a second depositional context for hominin remains. In each of three collection areas within the Lesedi Chamber, diagnostic skeletal material allows a clear attribution to H. naledi. Both adult and immature material is present. The hominin remains represent at least three individuals based upon duplication of elements, but more individuals are likely present based upon the spatial context. The most significant specimen is the near-complete cranium of a large individual, designated LES1, with an endocranial volume of approximately 610 ml and associated postcranial remains. The Lesedi Chamber skeletal sample extends our knowledge of the morphology and variation of H. naledi, and evidence of H. naledi from both recovery localities shows a consistent pattern of differentiation from other hominin species. DOI: http://dx.doi.org/10.7554/eLife.24232.001 PMID:28483039

Evaluation of Two Surface Sampling Methods for Detection of Erwinia herbicola on a Variety of Materials by Culture and Quantitative PCR▿

PubMed Central

Buttner, Mark P.; Cruz, Patricia; Stetzenbach, Linda D.; Cronin, Tracy

2007-01-01

This research was designed to evaluate surface sampling protocols for use with culture and quantitative PCR (QPCR) amplification assay for detection of the gram-negative bacterial biothreat simulant Erwinia herbicola on a variety of surface materials. Surfaces selected for evaluation were wood laminate, glass and computer monitor screens, metal file cabinets, plastic arena seats, nylon seat cushions, finished concrete flooring, and vinyl tile flooring. Laboratory and test chamber studies were performed to evaluate two sampling methods, a sponge and a macrofoam swab, for detection of E. herbicola on surface materials. In laboratory trials, seven materials were inoculated with a known concentration of E. herbicola cells and samples were collected from the surfaces of the materials to determine sampling efficiencies. Culture analysis was ineffective for assessing E. herbicola collection efficiency because very few culturable cells were obtained from surface samples. QPCR demonstrated that E. herbicola DNA was present in high concentrations on all of the surface samples, and sampling efficiencies ranged from 0.7 to 52.2%, depending on the sampling method and the surface material. The swab was generally more efficient than the sponge for collection of E. herbicola from surfaces. Test chamber trials were also performed in which E. herbicola was aerosolized into the chamber and allowed to settle onto test materials. Surface sampling results supported those obtained in laboratory trials. The results of this study demonstrate the capabilities of QPCR to enhance the detection and enumeration of biocontaminants on surface materials and provide information on the comparability of sampling methods. PMID:17416685

Evaluation of two surface sampling methods for detection of Erwinia herbicola on a variety of materials by culture and quantitative PCR.

PubMed

Buttner, Mark P; Cruz, Patricia; Stetzenbach, Linda D; Cronin, Tracy

2007-06-01

This research was designed to evaluate surface sampling protocols for use with culture and quantitative PCR (QPCR) amplification assay for detection of the gram-negative bacterial biothreat simulant Erwinia herbicola on a variety of surface materials. Surfaces selected for evaluation were wood laminate, glass and computer monitor screens, metal file cabinets, plastic arena seats, nylon seat cushions, finished concrete flooring, and vinyl tile flooring. Laboratory and test chamber studies were performed to evaluate two sampling methods, a sponge and a macrofoam swab, for detection of E. herbicola on surface materials. In laboratory trials, seven materials were inoculated with a known concentration of E. herbicola cells and samples were collected from the surfaces of the materials to determine sampling efficiencies. Culture analysis was ineffective for assessing E. herbicola collection efficiency because very few culturable cells were obtained from surface samples. QPCR demonstrated that E. herbicola DNA was present in high concentrations on all of the surface samples, and sampling efficiencies ranged from 0.7 to 52.2%, depending on the sampling method and the surface material. The swab was generally more efficient than the sponge for collection of E. herbicola from surfaces. Test chamber trials were also performed in which E. herbicola was aerosolized into the chamber and allowed to settle onto test materials. Surface sampling results supported those obtained in laboratory trials. The results of this study demonstrate the capabilities of QPCR to enhance the detection and enumeration of biocontaminants on surface materials and provide information on the comparability of sampling methods.

Detection system for a gas chromatograph

DOEpatents

Hayes, John M.; Small, Gerald J.

1984-01-01

A method and apparatus are described for the quantitative analysis of vaporizable compounds, and in particular of polycyclic aromatic hydrocarbons which may be induced to fluoresce. The sample to be analyzed is injected into a gas chromatography column and is eluted through a narrow orifice into a vacuum chamber. The free expansion of the eluted sample into the vacuum chamber creates a supersonic molecular beam in which the sample molecules are cooled to the extent that the excited vibrational and rotational levels are substantially depopulated. The cooled molecules, when induced to fluoresce by laser excitation, give greatly simplified spectra suitable for analytical purposes. The laser induced fluorimetry provides great selectivity, and the gas chromatograph provides quantitative transfer of the sample to the molecular beam.

Nonevaporable getter coating chambers for extreme high vacuum

DOE PAGES

Stutzman, Marcy L.; Adderley, Philip A.; Mamun, Md Abdullah Al; ...

2018-03-01

Techniques for NEG coating a large diameter chamber are presented along with vacuum measurements in the chamber using several pumping configurations, with base pressure as low as 1.56x10^-12 Torr (N2 equivalent) with only a NEG coating and small ion pump. We then describe modifications to the NEG coating process to coat complex geometry chambers for ultra-cold atom trap experiments. Surface analysis of NEG coated samples are used to measure composition and morphology of the thin films. Finally, pressure measurements are compared for two NEG coated polarized electron source chambers: the 130 kV polarized electron source at Jefferson Lab and themore » upgraded 350 kV polarized 2 electron source, both of which are approaching or within the extreme high vacuum (XHV) range, defined as P<7.5x10^-13 Torr.« less

Nonevaporable getter coating chambers for extreme high vacuum

DOE Office of Scientific and Technical Information (OSTI.GOV)

Stutzman, Marcy L.; Adderley, Philip A.; Mamun, Md Abdullah Al

Techniques for NEG coating a large diameter chamber are presented along with vacuum measurements in the chamber using several pumping configurations, with base pressure as low as 1.56x10^-12 Torr (N2 equivalent) with only a NEG coating and small ion pump. We then describe modifications to the NEG coating process to coat complex geometry chambers for ultra-cold atom trap experiments. Surface analysis of NEG coated samples are used to measure composition and morphology of the thin films. Finally, pressure measurements are compared for two NEG coated polarized electron source chambers: the 130 kV polarized electron source at Jefferson Lab and themore » upgraded 350 kV polarized 2 electron source, both of which are approaching or within the extreme high vacuum (XHV) range, defined as P<7.5x10^-13 Torr.« less

Evaluation of a disposable plastic Neubauer counting chamber for semen analysis.

PubMed

Kirkman-Brown, Jackson; Björndahl, Lars

2009-02-01

To evaluate whether disposable plastic counting chambers effectively could replace nondisposable, time-consuming, and potentially dangerous glass hemocytometers. Evaluation of equipment in modern laboratory andrology. Comparison of results obtained with plastic chambers with results obtained with "gold-standard" glass hemocytometer counts. Diagnostic laboratory for andrology. Twenty-one patients undergoing investigation for infertility problems. No interventions with patients; sperm in diluted semen samples were used when patients had allowed the use for research and training. Sperm concentration, difference from results obtained with standard equipment. In the first three experimental series, with use of standard routine phase-contrast microscopy, significantly lower count results were obtained consistently from the plastic chambers than from standard chambers. In the fourth series, with use of specialized equipment, equivalent results were obtained but with a considerably greater time commitment because of difficulties in distinguishing sperm adjacent to the gridlines in the plastic chambers. The plastic disposable chamber type was not suitable for routine semen analysis because results are variable depending on the microscope used, and increased time is necessary to do the assessment accurately.

Upright Imaging of Drosophila Egg Chambers

PubMed Central

Manning, Lathiena; Starz-Gaiano, Michelle

2015-01-01

Drosophila melanogaster oogenesis provides an ideal context for studying varied developmental processes since the ovary is relatively simple in architecture, is well-characterized, and is amenable to genetic analysis. Each egg chamber consists of germ-line cells surrounded by a single epithelial layer of somatic follicle cells. Subsets of follicle cells undergo differentiation during specific stages to become several different cell types. Standard techniques primarily allow for a lateral view of egg chambers, and therefore a limited view of follicle cell organization and identity. The upright imaging protocol describes a mounting technique that enables a novel, vertical view of egg chambers with a standard confocal microscope. Samples are first mounted between two layers of glycerin jelly in a lateral (horizontal) position on a glass microscope slide. The jelly with encased egg chambers is then cut into blocks, transferred to a coverslip, and flipped to position egg chambers upright. Mounted egg chambers can be imaged on either an upright or an inverted confocal microscope. This technique enables the study of follicle cell specification, organization, molecular markers, and egg development with new detail and from a new perspective. PMID:25867882

Multifunctional Ultra-high Vacuum Apparatus for Studies of the Interactions of Chemical Warfare Agents on Complex Surfaces

DTIC Science & Technology

2014-01-02

of the formation of a hydrogen-bonded hydroxyl. Characteristic modes of the sarin molecule itself are also ob- served. These experimental results show...chemical warfare agent, surface science, uptake, decontamination, filtration , UHV, XPS, FTIR, TPD REPORT DOCUMENTATION PAGE 11. SPONSOR/MONITOR’S...challenges that accompany the research of these toxic, often very low vapor pressure, compounds. While results of vacuum-based surface science

CO oxidation studies over supported noble metal catalysts and single crystals: A review

NASA Technical Reports Server (NTRS)

Boecker, Dirk; Gonzalez, Richard D.

1987-01-01

The catalytic oxidation of CO over noble metal catalysts is reviewed. Results obtained on supported noble metal catalysts and single crystals both at high pressures and under UHV conditions are compared. The underlying causes which result in surface instabilities and multiple steady-state oscillations are considered, in particular, the occurrence of hot spots. CO islands of reactivity, surface oxide formation and phase transformations under oscillatory conditions are discussed.

Apollo Experiment Report: Lunar-Sample Processing in the Lunar Receiving Laboratory High-Vacuum Complex

NASA Technical Reports Server (NTRS)

White, D. R.

1976-01-01

A high-vacuum complex composed of an atmospheric decontamination system, sample-processing chambers, storage chambers, and a transfer system was built to process and examine lunar material while maintaining quarantine status. Problems identified, equipment modifications, and procedure changes made for Apollo 11 and 12 sample processing are presented. The sample processing experiences indicate that only a few operating personnel are required to process the sample efficiently, safely, and rapidly in the high-vacuum complex. The high-vacuum complex was designed to handle the many contingencies, both quarantine and scientific, associated with handling an unknown entity such as the lunar sample. Lunar sample handling necessitated a complex system that could not respond rapidly to changing scientific requirements as the characteristics of the lunar sample were better defined. Although the complex successfully handled the processing of Apollo 11 and 12 lunar samples, the scientific requirement for vacuum samples was deleted after the Apollo 12 mission just as the vacuum system was reaching its full potential.

A novel design for a dual stable isotope continuous labeling chamber: results on labeling efficiency and C and N allocation in Andropogon gerardii

NASA Astrophysics Data System (ADS)

Soong, J.; Stewart, C.; Reuss, D.; Pinney, C.; Cotrufo, F. M.

2010-12-01

The use of stable isotope enriched plant material can provide an unobstructed method of studying ecosystem nutrient dynamics between plants, soil, and atmosphere. However, the production of uniformly labeled perennial plant material is challenging due to plant physiological constraints and the mechanics of building and operating an isotope labeling system. In this study we present the design of a novel dual 13C and 15N continuous isotope labeling chamber located at Colorado State University. The chamber is equipped with automatic controls for CO2 concentration, temperature, and humidity, and has successfully been used to grow and label the tallgrass perennial Andropogon gerardii in pots from rhizomes. Three different nitrogen fertilization levels were applied to assess how substrate availability may alter growth and overall performance in the system. The efficiency of the 13C and 15N labeling chamber, its design and overall performance, as well as a full C, N, 13C, and 15N budget of the aboveground biomass, belowground biomass, and soil will be presented. Solid samples were analyzed on an EA-IRMS, while air samples from the chamber were analyzed using a precon-GC-IRMS system. The dual stable isotope labeled A. gerardii produced from this chamber will be used in a decomposition experiment to quantify the relative contribution of aboveground litter derived C to soil respiration, dissolved organic carbon, and various soil organic matter pools. Based on the results of our A. gerardii 13C and 15N labeling experiment we believe that this chamber design can be used to successfully produce dual stable isotope labeled plants for a wide variety of terrestrial nutrient flux experiments.

Characterization of a Head-Only Aerosol Exposure System for Nonhuman Primates

DTIC Science & Technology

2010-01-01

Alicat Scientific). The flow used provided isokinetic sampling, assuming the presence of laminar flow at the filter inlet, so that the chamber...airflow measured at the chamber inlet using a Gilibrator flow meter (Sensidyne LP) was 29.79±0.88L/min (n= 10; CV=2.97%). With both the aerosol

Microbial volatile organic compounds in moldy interiors: a long-term climate chamber study.

PubMed

Schuchardt, Sven; Strube, Andrea

2013-06-01

The present study simulated large-scale indoor mold damage in order to test the efficiency of air sampling for the detection of microbial volatile organic compounds (MVOCs). To do this, a wallpaper damaged by condensation was stored in a climate chamber (representing a hypothetical test room of 40 m(3) volume) and was inoculated with 14 typical indoor fungal strains. The chamber ventilation conditions were adjusted to common values found in moldy homes, and the mold growth was allowed to continue to higher than average values. The MVOC content of the chamber air was analyzed daily for a period of 105 days using coupled gas chromatography/mass spectrometry (GC-MS). This procedure guarantees MVOC profiling without external factors such as outdoor air, building materials, furniture, and occupants. However, only nine MVOCs could be detected during the sampling period, which indicates that the very low concentrated MVOCs are hardly accessible, even under these favorable conditions. Furthermore, most of the MVOCs that were detected cannot be considered as reliable indicators of mold growth in indoor environments. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Mimicking Mars: a vacuum simulation chamber for testing environmental instrumentation for Mars exploration.

PubMed

Sobrado, J M; Martín-Soler, J; Martín-Gago, J A

2014-03-01

We have built a Mars environmental simulation chamber, designed to test new electromechanical devices and instruments that could be used in space missions. We have developed this environmental system aiming at validating the meteorological station Rover Environment Monitoring Station of NASA's Mars Science Laboratory mission currently installed on Curiosity rover. The vacuum chamber has been built following a modular configuration and operates at pressures ranging from 1000 to 10(-6) mbars, and it is possible to control the gas composition (the atmosphere) within this pressure range. The device (or sample) under study can be irradiated by an ultraviolet source and its temperature can be controlled in the range from 108 to 423 K. As an important improvement with respect to other simulation chambers, the atmospheric gas into the experimental chamber is cooled at the walls by the use of liquid-nitrogen heat exchangers. This chamber incorporates a dust generation mechanism designed to study Martian-dust deposition while modifying the conditions of temperature, and UV irradiated.

Improved Rhenium Thrust Chambers

NASA Technical Reports Server (NTRS)

O'Dell, John Scott

2015-01-01

Radiation-cooled bipropellant thrust chambers are being considered for ascent/ descent engines and reaction control systems on various NASA missions and spacecraft, such as the Mars Sample Return and Orion Multi-Purpose Crew Vehicle (MPCV). Currently, iridium (Ir)-lined rhenium (Re) combustion chambers are the state of the art for in-space engines. NASA's Advanced Materials Bipropellant Rocket (AMBR) engine, a 150-lbf Ir-Re chamber produced by Plasma Processes and Aerojet Rocketdyne, recently set a hydrazine specific impulse record of 333.5 seconds. To withstand the high loads during terrestrial launch, Re chambers with improved mechanical properties are needed. Recent electrochemical forming (EL-Form"TM") results have shown considerable promise for improving Re's mechanical properties by producing a multilayered deposit composed of a tailored microstructure (i.e., Engineered Re). The Engineered Re processing techniques were optimized, and detailed characterization and mechanical properties tests were performed. The most promising techniques were selected and used to produce an Engineered Re AMBR-sized combustion chamber for testing at Aerojet Rocketdyne.

Design and performance of a dynaniic gas flux chamber.

PubMed

Reichman, Rivka; Rolston, Dennis E

2002-01-01

Chambers are commonly used to measure the emission of many trace gases and chemicals from soil. An aerodynamic (flow through) chamber was designed and fabricated to accurately measure the surface flux of trace gases. Flow through the chamber was controlled with a small vacuum at the outlet. Due to the design using fans, a partition plate, and aerodynamic ends, air is forced to sweep parallel and uniform over the entire soil surface. A fraction of the air flowing inside the chamber is sampled in the outlet. The air velocity inside the chamber is controlled by fan speed and outlet suction flow rate. The chamber design resulted in a uniform distribution of air velocity at the soil surface. Steady state flux was attained within 5 min when the outlet air suction rate was 20 L/min or higher. For expected flux rates, the presence of the chamber did not affect the measured fluxes at outlet suction rates of around 20 L/min, except that the chamber caused some cooling of the surface in field experiments. Sensitive measurements of the pressure deficit across the soil layer in conjunction with measured fluxes in the source box and chamber outlet show that the outflow rate must be controlled carefully to minimize errors in the flux measurements. Both over- and underestimation of the fluxes are possible if the outlet flow rate is not controlled carefully. For this design, the chamber accurately measured steady flux at outlet air suction rates of approximately 20 L/min when the pressure deficit within the chamber with respect to the ambient atmosphere ranged between 0.46 and 0.79 Pa.

Apparatus for sampling and characterizing aerosols

DOEpatents

Dunn, Patrick F.; Herceg, Joseph E.; Klocksieben, Robert H.

1986-01-01

Apparatus for sampling and characterizing aerosols having a wide particle size range at relatively low velocities may comprise a chamber having an inlet and an outlet, the chamber including: a plurality of vertically stacked, successive particle collection stages; each collection stage includes a separator plate and a channel guide mounted transverse to the separator plate, defining a labyrinthine flow path across the collection stage. An opening in each separator plate provides a path for the aerosols from one collection stage to the next. Mounted within each collection stage are one or more particle collection frames.

Oscillational instabilities in single-mode acoustic levitators

NASA Technical Reports Server (NTRS)

Rudnick, Joseph; Barmatz, M.

1990-01-01

An extension of standard results for the acoustic force on an object in a single-mode resonant chamber yields predictions for the onset of oscillational instabilities when objects are levitated or positioned in these chambers. The results are consistent with experimental investigations. The present approach accounts for the effect of time delays on the response of a cavity to the motion of an object inside it. Quantitative features of the instabilities are investigated. The experimental conditions required for sample stability, saturation of sample oscillations, hysteretic effects, and the loss of the ability to levitate are discussed.

Scanning tunneling microscopy studies of diamond films and optoelectronic materials

NASA Technical Reports Server (NTRS)

Perez, Jose M.

1993-01-01

In this report, we report on progress achieved from 12/1/92 to 10/1/93 under the grant entitled 'Scanning Tunneling Microscopy Studies of Diamond Films and Optoelectronic Materials'. We have set-up a chemical vapor deposition (CVD) diamond film growth system and a Raman spectroscopy system to study the nucleation and growth of diamond films with atomic resolution using scanning tunneling microscopy (STM). A unique feature of the diamond film growth system is that diamond films can be transferred directly to the ultrahigh vacuum (UHV) chamber of a scanning tunneling microscope without contaminating the films by exposure to air. The University of North Texas (UNT) provided $20,000 this year as matching funds for the NASA grant to purchase the diamond growth system. In addition, UNT provided a Coherent Innova 90S Argon ion laser, a Spex 1404 double spectrometer, and a Newport optical table costing $90,000 to set-up the Raman spectroscopy system. The CVD diamond growth system and Raman spectroscopy system will be used to grow and characterize diamond films with atomic resolution using STM as described in our proposal. One full-time graduate student and one full-time undergraduate student are supported under this grant. In addition, several graduate and undergraduate students were supported during the summer to assist in setting-up the diamond growth and Raman spectroscopy systems. We have obtained research results concerning STM of the structural and electronic properties of CVD grown diamond films, and STM and scanning tunneling spectroscopy of carbon nanotubes. In collaboration with the transmission electron microscopy (TEM) group at UNT, we have also obtained results concerning the optoelectronic material siloxene. These results were published in refereed scientific journals, submitted for publication, and presented as invited and contributed talks at scientific conferences.

Minimizing Artifacts and Biases in Chamber-Based Measurements of Soil Respiration

NASA Astrophysics Data System (ADS)

Davidson, E. A.; Savage, K.

2001-05-01

Soil respiration is one of the largest and most important fluxes of carbon in terrestrial ecosystems. The objectives of this paper are to review concerns about uncertainties of chamber-based measurements of CO2 emissions from soils, to evaluate the direction and magnitude of these potential errors, and to explain procedures that minimize these errors and biases. Disturbance of diffusion gradients cause underestimate of fluxes by less than 15% in most cases, and can be partially corrected for with curve fitting and/or can be minimized by using brief measurement periods. Under-pressurization or over-pressurization of the chamber caused by flow restrictions in air circulating designs can cause large errors, but can also be avoided with properly sized chamber vents and unrestricted flows. Somewhat larger pressure differentials are observed under windy conditions, and the accuracy of measurements made under such conditions needs more research. Spatial and temporal heterogeneity can be addressed with appropriate chamber sizes and numbers and frequency of sampling. For example, means of 8 randomly chosen flux measurements from a population of 36 measurements made with 300 cm2 chambers in tropical forests and pastures were within 25% of the full population mean 98% of the time and were within 10% of the full population mean 70% of the time. Comparisons of chamber-based measurements with tower-based measurements of total ecosystem respiration require analysis of the scale of variation within the purported tower footprint. In a forest at Howland, Maine, the differences in soil respiration rates among very poorly drained and well drained soils were large, but they mostly were fortuitously cancelled when evaluated for purported tower footprints of 600-2100 m length. While all of these potential sources of measurement error and sampling biases must be carefully considered, properly designed and deployed chambers provide a reliable means of accurately measuring soil respiration in terrestrial ecosystems.

Technical Review of the Laboratory Biosphere Closed Ecological System Facility

NASA Astrophysics Data System (ADS)

Dempster, W.; van Thillo, M.; Alling, A.; Allen, J.; Silverstone, S.; Nelson, M.

The "Laboratory Biosphere", a new closed ecological system facility in Santa Fe, New Mexico (USA) has been constructed and became operational in May 2002. Built and operated by the Global Ecotechnics consortium (Biosphere Technologies and Biosphere Foundation with Biospheric Design Inc., and the Institute of Ecotechnics), the research apparatus for intensive crop growth, biogeochemical cycle dynamics and recycling of inedible crop biomass comprises a sealed cylindrical steel chamber and attached variable volume chamber (lung) to prevent pressures caused by the expansion and contraction of the contained air. The cylindrical growing chamber is 3.7m (12 feet) long and 3.7m (12 foot) diameter, giving an internal volume of 34 m3 (1200 ft 3 ). The two crop growth beds cover 5.5 m2, with a soil depth of 0.3m (12 inches), with 12 x 1000 watt high-pressure sodium lights capable of variable lighting of 40-70 mol per m2 per day. A small soil bed reactor in the chamber can be activated to help with metabolism of chamber trace gases. The volume of the attached variable volume chamber (lung) can range between 0-11 m3 (0-400 ft 3 ). Evapotranspired and soil leachate water are collected, combined and recycled to water the planting beds. Sampling ports enable testing of water quality of leachate, condensate and irrigation water. Visual inspection windows provide views of the entire interior and growing beds. The chamber is also outfitted with an airlock to minimize air exchange when people enter and work in the chamber. Continuous sensors include atmospheric CO2 and oxygen, temperature, humidity, soil moisture, light level and water levels in reservoirs. Both "sniffer" (air ports) and "sipper" (water ports) will enable collection of water or air samples for detailed analysis. This paper reports on the development of this new soil-based bioregenerative life support closed system apparatus and its technical challenges and capabilities.

BOREAS TGB-3 CH4 and CO2 Chamber Flux Data over NSA Upland Sites

NASA Technical Reports Server (NTRS)

Savage, Kathleen; Hall, Forrest G. (Editor); Conrad, Sara K. (Editor); Moore, Tim R.

2000-01-01

The BOReal Ecosystem-Atmosphere Study Trace Gas Biogeochemistry (BOREAS TGB-3) team collected methane and carbon dioxide (CH4, CO2) chamber flux measurements at the Northern Study Area (NSA) Fen, Old Black Spruce (OBS), Young Jack Pine (YJP), and auxiliary sites along Gillam Road and the 1989 burn site. Gas samples were extracted from chambers and analyzed at the NSA lab facility approximately every 7 days during May to September 1994 and June to October 1996. The data are provided in tabular ASCII files.

Atmospheric sampling glow discharge ionization source

DOEpatents

McLuckey, Scott A.; Glish, Gary L.

1989-01-01

An atmospheric sampling glow discharge ionization source that can be used in combination with an analytical instrument which operates at high vacuum, such as a mass spectrometer. The atmospheric sampling glow discharge ionization source comprises a chamber with at least one pair of electrodes disposed therein, an inlet for a gaseous sample to be analyzed and an outlet communicating with an analyzer which operates at subatmospheric pressure. The ionization chamber is maintained at a pressure below atmospheric pressure, and a voltage difference is applied across the electrodes to induce a glow discharge between the electrodes, so that molecules passing through the inlet are ionized by the glow discharge and directed into the analyzer. The ionization source accepts the sample under atmospheric pressure conditions and processes it directly into the high vacuum instrument, bridging the pressure gap and drawing off unwanted atmospheric gases. The invention also includes a method for analyzing a gaseous sample using the glow discharge ionization source described above.

Parallel detecting, spectroscopic ellipsometers/polarimeters

DOEpatents

Furtak, Thomas E.

2002-01-01

The parallel detecting spectroscopic ellipsometer/polarimeter sensor has no moving parts and operates in real-time for in-situ monitoring of the thin film surface properties of a sample within a processing chamber. It includes a multi-spectral source of radiation for producing a collimated beam of radiation directed towards the surface of the sample through a polarizer. The thus polarized collimated beam of radiation impacts and is reflected from the surface of the sample, thereby changing its polarization state due to the intrinsic material properties of the sample. The light reflected from the sample is separated into four separate polarized filtered beams, each having individual spectral intensities. Data about said four individual spectral intensities is collected within the processing chamber, and is transmitted into one or more spectrometers. The data of all four individual spectral intensities is then analyzed using transformation algorithms, in real-time.

Synchrotron X-Ray Diffraction Study of Structure and Growth of Adsorbed Layers

NASA Astrophysics Data System (ADS)

Dai, Pengcheng

Synchrotron x-ray diffraction and scanning-tunneling -microscopy (STM) experiments reveal a new commensurate monolayer structure of 10CB (decylcyanobiphenyl) molecules adsorbed on the (0001) graphite surface. Our results are consistent with two generic structures for nCB monolayers on surfaces of hexagonal symmetry. The monolayer d spacing of the new phase inferred by STM is 10% layer than that obtained by x-ray diffraction on the same sample. We suggest that part of this discrepancy results from a systematic error introduced in calibration of the STM length scale against the graphite substrate. For multilayer nCB films, we find that a polycrystalline structure is formed and most of the adsorbed molecules are aligned with their long axis perpendicular to the graphite surface. Synchrotron x-ray scattering has been used to investigate the structure and growth of xenon physisorbed on the Ag(111) surface using a specially designed ultra -high vacuum (UHV) chamber. For growth under quasi-equilibrium conditions, the bulk Xe-Xe spacing is reached at monolayer completion and solid films of thickness >= 220 A are observed in which an 'ABC' stacking sequence predominates. Under kinetic growth conditions, intensity oscillations at the Xe anti-Bragg position of the specular rod are observed as a function of time, indicating layer -by-layer growth. Analysis of the specular reflectivity at different coverages yields the fractional layer occupancies and the spacing between the Ag(111) surface and first Xe layer. We have conducted a series of low-energy electron diffraction (LEED) 'kinetic isotherm' experiments on both xenon and hexane rm(C_6H_{14 }) films adsorbed on the Ag(111) surface. Our preliminary results show that under the pressure and temperature range accessible to the experiments, all of the Xe kinetic isotherms fall on a universal curve which is concave upward. However, the hexane kinetic isotherms have a qualitatively different shape (S-like) at the higher temperatures while being similar to Xe at low temperatures. From these experiments, we determine that the growth of xenon from submonolayer to 0.9 monolayer is 'zero-order'. However, the growth of hexane is more complicated. It follows the 'first-order' at low temperatures, and changes to S-like shape at high temperatures which we do not yet understand.

Effects of residual hydrogen in sputtering atmosphere on structures and properties of amorphous In-Ga-Zn-O thin films

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tang, Haochun; Ishikawa, Kyohei; Ide, Keisuke

2015-11-28

We investigated the effects of residual hydrogen in sputtering atmosphere on subgap states and carrier transport in amorphous In-Ga-Zn-O (a-IGZO) using two sputtering systems with different base pressures of ∼10{sup −4} and 10{sup −7 }Pa (standard (STD) and ultrahigh vacuum (UHV) sputtering, respectively), which produce a-IGZO films with impurity hydrogen contents at the orders of 10{sup 20} and 10{sup 19 }cm{sup −3}, respectively. Several subgap states were observed by hard X-ray photoemission spectroscopy, i.e., peak-shape near-valence band maximum (near-VBM) states, shoulder-shape near-VBM states, peak-shape near-conduction band minimum (near-CBM) states, and step-wise near-CBM states. It was confirmed that the formation of these subgapmore » states were affected strongly by the residual hydrogen (possibly H{sub 2}O). The step-wise near-CBM states were observed only in the STD films deposited without O{sub 2} gas flow and attributed to metallic In. Such step-wise near-CBM state was not detected in the other films including the UHV films even deposited without O{sub 2} flow, substantiating that the metallic In is segregated by the strong reduction effect of the hydrogen/H{sub 2}O. Similarly, the density of the near-VBM states was very high for the STD films deposited without O{sub 2}. These films had low film density and are consistent with a model that voids in the amorphous structure form a part of the near-VBM states. On the other hand, the UHV films had high film densities and much less near-VBM states, keeping the possibility that some of the near-VBM states, in particular, of the peak-shape ones, originate from –OH and weakly bonded oxygen. These results indicate that 2% of excess O{sub 2} flow is required for the STD sputtering to compensate the effects of the residual hydrogen/H{sub 2}O. The high-density near-VBM states and the metallic In segregation deteriorated the electron mobility to 0.4 cm{sup 2}/(V s)« less

Fourth-generation plasma immersion ion implantation and deposition facility for hybrid surface modification layer fabrication.

PubMed

Wang, Langping; Huang, Lei; Xie, Zhiwen; Wang, Xiaofeng; Tang, Baoyin

2008-02-01

The fourth-generation plasma immersion ion implantation and deposition (PIIID) facility for hybrid and batch treatment was built in our laboratory recently. Comparing with our previous PIIID facilities, several novel designs are utilized. Two multicathode pulsed cathodic arc plasma sources are fixed on the chamber wall symmetrically, which can increase the steady working time from 6 h (the single cathode source in our previous facilities) to about 18 h. Meanwhile, the inner diameter of the pulsed cathodic arc plasma source is increased from the previous 80 to 209 mm, thus, large area metal plasma can be obtained by the source. Instead of the simple sample holder in our previous facility, a complex revolution-rotation sample holder composed of 24 shafts, which can rotate around its axis and adjust its position through revolving around the center axis of the vacuum chamber, is fixed in the center of the vacuum chamber. In addition, one magnetron sputtering source is set on the chamber wall instead of the top cover in the previous facility. Because of the above characteristic, the PIIID hybrid process involving ion implantation, vacuum arc, and magnetron sputtering deposition can be acquired without breaking vacuum. In addition, the PIIID batch treatment of cylinderlike components can be finished by installing these components on the rotating shafts on the sample holder.

Compact, Automated Centrifugal Slide-Staining System

NASA Technical Reports Server (NTRS)

Feeback, Daniel L.; Clarke, Mark S. F.

2004-01-01

The Directional Acceleration Vector-Driven Displacement of Fluids (DAVD-DOF) system, under development at the time of reporting the information for this article, would be a relatively compact, automated, centrifugally actuated system for staining blood smears and other microbiological samples on glass microscope slides in either a microgravitational or a normal Earth gravitational environment. The DAVD-DOF concept is a successor to the centrifuge-operated slide stainer (COSS) concept, which was reported in Slide-Staining System for Microgravity or Gravity (MSC-22949), NASA Tech Briefs, Vol. 25, No. 1 (January, 2001), page 64. The COSS includes reservoirs and a staining chamber that contains a microscope slide to which a biological sample is affixed. The staining chamber is sequentially filled with and drained of staining and related liquids from the reservoirs by use of a weighted plunger to force liquid from one reservoir to another at a constant level of hypergravity maintained in a standard swing-bucket centrifuge. In the DAVD-DOF system, a staining chamber containing a sample would also be sequentially filled and emptied, but with important differences. Instead of a simple microscope slide, one would use a special microscope slide on which would be fabricated a network of very small reservoirs and narrow channels connected to a staining chamber (see figure). Unlike in the COSS, displacement of liquid would be effected by use of the weight of the liquid itself, rather than the weight of a plunger.

Growth, chamber building rate and reproduction time of Palaeonummulites venosus (Foraminifera) under natural conditions

NASA Astrophysics Data System (ADS)

Kinoshita, Shunichi; Eder, Wolfgang; Wöger, Julia; Hohenegger, Johann; Briguglio, Antonino

2017-12-01

We investigated the symbiont-bearing benthic foraminifer Palaeonummulites venosus to determine the chamber building rate (CBR), test diameter increase rate (DIR), reproduction time and longevity using the `natural laboratory' approach. This is based on the decomposition of monthly obtained frequency distributions of chamber number and test diameter into normally distributed components. Test measurements were taken using MicroCT. The shift of the mean and standard deviation of component parameters during the 15-month investigation period was used to calculate Michaelis-Menten functions applied to estimate the averaged CBR and DIR under natural conditions. The individual dates of birth were estimated using the inverse averaged CBR and the inverse DIR fitted by the individual chamber number or the individual test diameter at the sampling date. Distributions of frequencies and densities (i.e., frequency divided by sediment weight) based on both CBR and DIR revealed continuous reproduction throughout the year with two peaks, a stronger one in June determined as the onset of the summer generation (generation 1) and a weaker one in November determined as the onset of the winter generation (generation 2). This reproduction scheme explains the presence of small and large specimens in the same sample. Longevity, calculated as the maximum difference in days between the individual's birth date and the sampling date, is approximately 1.5 yr, an estimation obtained by using both CBR and DIR.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Paik, Samuel Y.; Epperson, Patrick M.; Kasper, Kenneth M.

Here, this article presents air and surface sampling data collected over the first two years since beryllium was introduced as a target material at the National Ignition Facility. Over this time, 101 experiments with beryllium-containing targets were executed. The data provides an assessment of current conditions in the facility and a baseline for future impacts as new, reduced regulatory limits for beryllium are being proposed by both the Occupational Safety and Health Administration and Department of Energy. This study also investigates how beryllium deposits onto exposed surfaces as a result of x-ray vaporization and the effectiveness of simple decontamination measuresmore » in reducing the amount of removable beryllium from a surface. Based on 1,961 surface wipe samples collected from entrant components (equipment directly exposed to target debris) and their surrounding work areas during routine reconfiguration activities, only one result was above the beryllium release limit of 0.2 µg/100 cm 2 and 27 results were above the analytical reporting limit of 0.01 µg/100 cm 2, for a beryllium detection rate of 1.4%. Surface wipe samples collected from the internal walls of the NIF target chamber, however, showed higher levels of beryllium, with beryllium detected on 73% and 87% of the samples during the first and second target chamber entries (performed annually), respectively, with 23% of the samples above the beryllium release limit during the second target chamber entry. The analysis of a target chamber wall panel exposed during the first 30 beryllium-containing experiments (cumulatively) indicated that 87% of the beryllium contamination remains fixed onto the surface after wet wiping the surface and 92% of the non-fixed contamination was removed by decontaminating the surface using a dry wipe followed by a wet wipe. Personal airborne exposures assessed during access to entrant components and during target chamber entry indicated that airborne beryllium was not present in workers' breathing zones. Finally, all the data thus far have shown that beryllium has been effectively managed to prevent exposures to workers during routine and non-routine work.« less

Assessment of personal airborne exposures and surface contamination from x-ray vaporization of beryllium targets at the National Ignition Facility.

PubMed

Paik, Samuel Y; Epperson, Patrick M; Kasper, Kenneth M

2017-06-01

This article presents air and surface sampling data collected over the first two years since beryllium was introduced as a target material at the National Ignition Facility. Over this time, 101 experiments with beryllium-containing targets were executed. The data provides an assessment of current conditions in the facility and a baseline for future impacts as new, reduced regulatory limits for beryllium are being proposed by both the Occupational Safety and Health Administration and Department of Energy. This study also investigates how beryllium deposits onto exposed surfaces as a result of x-ray vaporization and the effectiveness of simple decontamination measures in reducing the amount of removable beryllium from a surface. Based on 1,961 surface wipe samples collected from entrant components (equipment directly exposed to target debris) and their surrounding work areas during routine reconfiguration activities, only one result was above the beryllium release limit of 0.2 µg/100 cm 2 and 27 results were above the analytical reporting limit of 0.01 µg/100 cm 2 , for a beryllium detection rate of 1.4%. Surface wipe samples collected from the internal walls of the NIF target chamber, however, showed higher levels of beryllium, with beryllium detected on 73% and 87% of the samples during the first and second target chamber entries (performed annually), respectively, with 23% of the samples above the beryllium release limit during the second target chamber entry. The analysis of a target chamber wall panel exposed during the first 30 beryllium-containing experiments (cumulatively) indicated that 87% of the beryllium contamination remains fixed onto the surface after wet wiping the surface and 92% of the non-fixed contamination was removed by decontaminating the surface using a dry wipe followed by a wet wipe. Personal airborne exposures assessed during access to entrant components and during target chamber entry indicated that airborne beryllium was not present in workers' breathing zones. All the data thus far have shown that beryllium has been effectively managed to prevent exposures to workers during routine and non-routine work.

Assessment of personal airborne exposures and surface contamination from x-ray vaporization of beryllium targets at the National Ignition Facility

DOE PAGES

Paik, Samuel Y.; Epperson, Patrick M.; Kasper, Kenneth M.

2017-02-28

Here, this article presents air and surface sampling data collected over the first two years since beryllium was introduced as a target material at the National Ignition Facility. Over this time, 101 experiments with beryllium-containing targets were executed. The data provides an assessment of current conditions in the facility and a baseline for future impacts as new, reduced regulatory limits for beryllium are being proposed by both the Occupational Safety and Health Administration and Department of Energy. This study also investigates how beryllium deposits onto exposed surfaces as a result of x-ray vaporization and the effectiveness of simple decontamination measuresmore » in reducing the amount of removable beryllium from a surface. Based on 1,961 surface wipe samples collected from entrant components (equipment directly exposed to target debris) and their surrounding work areas during routine reconfiguration activities, only one result was above the beryllium release limit of 0.2 µg/100 cm 2 and 27 results were above the analytical reporting limit of 0.01 µg/100 cm 2, for a beryllium detection rate of 1.4%. Surface wipe samples collected from the internal walls of the NIF target chamber, however, showed higher levels of beryllium, with beryllium detected on 73% and 87% of the samples during the first and second target chamber entries (performed annually), respectively, with 23% of the samples above the beryllium release limit during the second target chamber entry. The analysis of a target chamber wall panel exposed during the first 30 beryllium-containing experiments (cumulatively) indicated that 87% of the beryllium contamination remains fixed onto the surface after wet wiping the surface and 92% of the non-fixed contamination was removed by decontaminating the surface using a dry wipe followed by a wet wipe. Personal airborne exposures assessed during access to entrant components and during target chamber entry indicated that airborne beryllium was not present in workers' breathing zones. Finally, all the data thus far have shown that beryllium has been effectively managed to prevent exposures to workers during routine and non-routine work.« less

[Application of laminar air flow techniques in burn treatment].

PubMed

Chen, Hua-de; Lai, Wen; Zheng, Shao-yi; Gao, Hui; Xiong, Bing; Bian, Hui-ning; Liu, Zuo-An; Wei, Li-jun

2005-12-01

To evaluate the value of laminar flow in the treatment of burns. The air in the laminar flow chamber and the wound tissues of the patients were sampled for bacterial detection. The number and stains of bacterial colony from different classes of laminar air flow chambers at different time points were inspected and compared. The bacterial number was 0 in the laminar flow chamber of 1000 grade, which was obviously different from that in the public area. The mortality was obviously decreased in the laminar air flow chamber with shorter treatment time and hospitalization. No wound infection occurred and the wounds healed smoothly in all these patients. The application of laminar air flow can be helpful for the treatment of severe burns.

High-resolution microscope for tip-enhanced optical processes in ultrahigh vacuum

NASA Astrophysics Data System (ADS)

Steidtner, Jens; Pettinger, Bruno

2007-10-01

An optical microscope based on tip-enhanced optical processes that can be used for studies on adsorbates as well as thin layers and nanostructures is presented. The microscope provides chemical and topographic informations with a resolution of a few nanometers and can be employed in ultrahigh vacuum as well as gas phase. The construction involves a number of improvements compared to conventional instruments. The central idea is to mount, within an UHV system, an optical platform with all necessary optical elements to a rigid frame that also carries the scanning tunneling microscope unit and to integrate a high numerical aperture parabolic mirror between the scanning probe microscope head and the sample. The parabolic mirror serves to focus the incident light and to collect a large fraction of the scattered light. The first experimental results of Raman measurements on silicon samples as well as brilliant cresyl blue layers on single crystalline gold and platinum surfaces in ultrahigh vacuum are presented. For dye adsorbates a Raman enhancement of ˜106 and a net signal gain of up to 4000 was observed. The focus diameter (˜λ/2) was measured by Raman imaging the focal region on a Si surface. The requirements of the parabolic mirror in terms of alignment accuracy were experimentally determined as well.

Field results of antifouling techniques for optical instruments

USGS Publications Warehouse

Strahle, W.J.; Hotchkiss, F.S.; Martini, Marinna A.

1998-01-01

An anti-fouling technique is developed for the protection of optical instruments from biofouling which leaches a bromide compound into a sample chamber and pumps new water into the chamber prior to measurement. The primary advantage of using bromide is that it is less toxic than the metal-based antifoulants. The drawback of the bromide technique is also discussed.

A portable molecular-sieve-based CO2 sampling system for radiocarbon measurements

NASA Astrophysics Data System (ADS)

Palonen, V.

2015-12-01

We have developed a field-capable sampling system for the collection of CO2 samples for radiocarbon-concentration measurements. Most target systems in environmental research are limited in volume and CO2 concentration, making conventional flask sampling hard or impossible for radiocarbon studies. The present system captures the CO2 selectively to cartridges containing 13X molecular sieve material. The sampling does not introduce significant under-pressures or significant losses of moisture to the target system, making it suitable for most environmental targets. The system also incorporates a significantly larger sieve container for the removal of CO2 from chambers prior to the CO2 build-up phase and sampling. In addition, both the CO2 and H2O content of the sample gas are measured continuously. This enables in situ estimation of the amount of collected CO2 and the determination of CO2 flux to a chamber. The portable sampling system is described in detail and tests for the reliability of the method are presented.

Construction and testing of a simple and economical soil greenhouse gas automatic sampler

USGS Publications Warehouse

Ginting, D.; Arnold, S.L.; Arnold, N.S.; Tubbs, R.S.

2007-01-01

Quantification of soil greenhouse gas emissions requires considerable sampling to account for spatial and/or temporal variation. With manual sampling, additional personnel are often not available to sample multiple sites within a narrow time interval. The objectives were to construct an automatic gas sampler and to compare the accuracy and precision of automatic versus manual sampling. The automatic sampler was tested with carbon dioxide (CO2) fluxes that mimicked the range of CO2 fluxes during a typical corn-growing season in eastern Nebraska. Gas samples were drawn from the chamber at 0, 5, and 10 min manually and with the automatic sampler. The three samples drawn with the automatic sampler were transferred to pre-vacuumed vials after 1 h; thus the samples in syringe barrels stayed connected with the increasing CO2 concentration in the chamber. The automatic sampler sustains accuracy and precision in greenhouse gas sampling while improving time efficiency and reducing labor stress. Copyright ?? Taylor & Francis Group, LLC.

A portable molecular-sieve-based CO2 sampling system for radiocarbon measurements.

PubMed

Palonen, V

2015-12-01

We have developed a field-capable sampling system for the collection of CO2 samples for radiocarbon-concentration measurements. Most target systems in environmental research are limited in volume and CO2 concentration, making conventional flask sampling hard or impossible for radiocarbon studies. The present system captures the CO2 selectively to cartridges containing 13X molecular sieve material. The sampling does not introduce significant under-pressures or significant losses of moisture to the target system, making it suitable for most environmental targets. The system also incorporates a significantly larger sieve container for the removal of CO2 from chambers prior to the CO2 build-up phase and sampling. In addition, both the CO2 and H2O content of the sample gas are measured continuously. This enables in situ estimation of the amount of collected CO2 and the determination of CO2 flux to a chamber. The portable sampling system is described in detail and tests for the reliability of the method are presented.

Studies with sample conductivity, insertion rates, and particle deflection in a continuous flow electrophoresis system

NASA Technical Reports Server (NTRS)

Williams, G., Jr.

1982-01-01

The continuous flow electrophoresis system makes electrophoresis possible in a free-flowing film of aqueous electrolyte medium. The sample continuously enters the electrolyte at the top of the chamber and is subjected to the action of a lateral dc field. This divides the sample into fractions since each component has a distinctive electrophoretic mobility. Tests were made using monodisperse polystyrene latex microspheres to determine optimum sample conductivity, insertion rates and optimum electric field applications as baseline data for future STS flight experiments. Optimum sample flow rates for the selected samples were determined to be approximately 26 micro-liters/min. Experiments with samples in deionized water yielded best results and voltages in the 20 V/cm to 30 V/cm range were optimum. Deflections of formaldehyde fixed turkey and bovine erythrocytes were determined using the continuous flow electrophoresis system. The effects of particle interactions on sample resolution and migration in the chamber was also evaluated.

Detection system for a gas chromatograph. [. cap alpha. -methylnaphthalene,. beta. -methylnapthalene

DOEpatents

Hayes, J.M.; Small, G.J.

1982-04-26

A method and apparatus are described for the quantitative analysis of vaporizable compounds, and in particular of polycyclic aromatic hydrocarbons which may be induced to fluoresce. The sample to be analyzed is injected into a gas chromatography column and is eluted through a narrow orifice into a vacuum chamber. The free expansion of the eluted sample into the vacuum chamber creates a supersonic molecular beam in which the sample molecules are cooled to the extent that the excited vibrational and rotational levels are substantially depopulated. The cooled molecules, when induced to fluoresce by laser excitation, give greatly simplified spectra suitable for analytical purposes. The laser induced fluorimetry provides great selectivity, and the gas chromatograph provides quantitative transfer of the sample to the molecular beam. 3 figures, 2 tables.

The application of "natural" growth rates of Heterostegina depressa to infer timing of reproduction events

NASA Astrophysics Data System (ADS)

Eder, Wolfgang; Julia, Woeger; Kinoshita, Shunichi; Hohenegger, Johann; Briguglio, Antonino

2017-04-01

To explore applicability of the natural laboratory approach (sensu Hohenegger) on population dynamic studies of recent larger benthic foraminifera, this relatively new experimental method has been applied on Heterostegina depressa populations from Sesoko Jima, NW Okinawa, Japan. It is used to gain an averaged chamber and diameter building rate, as well as the average longevity of H. depressa based on monthly samplings at fixed sampling stations. Samples were collected by SCUBA in 16 monthly intervals around 20 and 50 meters water depth, wherefrom live populations were dried and investigated by microCT. The specimens were measured regarding chamber number and maximum diameter. This biometric data has been tested for the presence of multiple generations of H. depressa megalospheres. In case of skewed or bimodal frequency distributions, they were decomposed into normally distributed components. Means and standard deviations of each component of every month were extracted and could be used to calculate the maximum values of chamber number and diameter for all sampling intervals. Based on these maximal values, the natural chamber/diameter growth rate was fitted by Michaelis-Menten functions. By inversion of this growth functions the birthdate of every specimen was calculated. Frequency diagrams of these dates reveal a continuous background reproduction throughout the year, yet show distinct reproduction peaks in late spring and late autumn. Further, sinusoidal regression analysis support these two main reproduction cycles, one short-term cycle 70 days and a one long-term cycles around 180 days. Surprisingly, similar cycles have been found in different studies on volumetric growth of larger benthic foraminifera.

Comparative performance study of different sample introduction techniques for rapid and precise selenium isotope ratio determination using multi-collector inductively coupled plasma mass spectrometry (MC-ICP/MS).

PubMed

Elwaer, Nagmeddin; Hintelmann, Holger

2007-11-01

The analytical performance of five sample introduction systems, a cross flow nebulizer spray chamber, two different solvent desolvation systems, a multi-mode sample introduction system (MSIS), and a hydride generation (LI2) system were compared for the determination of Se isotope ratio measurements using multi-collector inductively coupled plasma mass spectrometry (MC-ICP/MS). The optimal operating parameters for obtaining the highest Se signal-to-noise (S/N) ratios and isotope ratio precision for each sample introduction were determined. The hydride generation (LI2) system was identified as the most suitable sample introduction method yielding maximum sensitivity and precision for Se isotope ratio measurement. It provided five times higher S/N ratios for all Se isotopes compared to the MSIS, 20 times the S/N ratios of both desolvation units, and 100 times the S/N ratios produced by the conventional spray chamber sample introduction method. The internal precision achieved for the (78)Se/(82)Se ratio at 100 ng mL(-1) Se with the spray chamber, two desolvation, MSIS, and the LI2 systems coupled to MC-ICP/MS was 150, 125, 114, 13, and 7 ppm, respectively. Instrument mass bias factors (K) were calculated using an exponential law correction function. Among the five studied sample introduction systems the LI2 showed the lowest mass bias of -0.0265 and the desolvation system showed the largest bias with -0.0321.

Note: Fabrication and characterization of molybdenum tips for scanning tunneling microscopy and spectroscopy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Carrozzo, P.; Tumino, F.; Facibeni, A.

We present a method for the preparation of bulk molybdenum tips for Scanning Tunneling Microscopy and Spectroscopy and we assess their potential in performing high resolution imaging and local spectroscopy by measurements on different single crystal surfaces in UHV, namely, Au(111), Si(111)-7 × 7, and titanium oxide 2D ordered nanostructures supported on Au(111). The fabrication method is versatile and can be extended to other metals, e.g., cobalt.

A versatile substrate design for LEED and AES studies in uhv.

NASA Technical Reports Server (NTRS)

Holloway, P. H.; Hudson, J. B.

1972-01-01

A substrate design is described that incorporates a single crystal disk into an electrically isolated, electron bombardment heated mount. Electron and photon leakage from the bombarding filament are prevented, and LEED and AES may be used at elevated temperatures. A cold finger, thermally coupled to the mount, decreases the time lost between cleaning the crystal and cooling it to the desired observation temperature. The cold finger also allows observation at temperatures below ambient.

Exploiting basic principles to control the selectivity of the vapor phase catalytic oxidative cross-coupling of primary alcohols over nanoporous gold catalysts

DOE PAGES

Wang, Lu-Cun; Stowers, Kara J.; Zugic, Branko; ...

2015-05-20

It is important to achieve high selectivity for high volume chemical synthesis in order to lower energy consumption through reduction in waste. Here, we report the selective synthesis of methyl esters—methyl acetate and methyl butyrate—through catalytic O 2-assisted cross-coupling of methanol with ethanol or 1-butanol using activated, support-free nanoporous gold (npAu). Both well-controlled studies on ingots in UHV and experiments under ambient pressure catalytic conditions on both ingots and microspherical hollow shell catalysts reveal guiding principles for controlling selectivity. Under UHV conditions, the ester products of the cross-coupling of methanol with both ethanol and 1-butanol evolve near room temperature inmore » temperature-programmed reaction studies, indicating that the reactions occur facilely. Furthermore, under steady-state catalytic operation, high stable activity was observed for cross-coupling in flowing gaseous reactant mixtures at atmospheric pressure and 423 K with negligible combustion. Optimum selectivity for cross-coupling is obtained in methanol-rich mixtures due to a combination of two factors: (1) the relative coverage of the respective alkoxys and (2) the relative facility of their β-H elimination. The relative coverage of the alkoxys is governed by van der Waal’s interactions between the alkyl groups and the surface; here, we demonstrate the importance of these weak interactions in a steady-state catalytic process.« less

"Un-annealed and Annealed Pd Ultra-Thin Film on SiC Characterized by Scanning Probe Microscopy and X-ray Photoelectron Spectroscopy"

NASA Technical Reports Server (NTRS)

Lu, W. J.; Shi, D. T.; Elshot, K.; Bryant, E.; Lafate, K.; Chen, H.; Burger, A.; Collins, W. E.

1998-01-01

Pd/SiC has been used as a hydrogen and a hydrocarbon gas sensor operated at high temperature. UHV (Ultra High Vacuum)-Scanning Tunneling Microscopy (STM), Atomic Force Microscopy (AFM) and X-ray Photoelectron Spectroscopy (XPS) techniques were applied to study the relationship between the morphology and chemical compositions for Pd ultra-thin films on SiC (less than 30 angstroms) at different annealing temperatures. Pd ultra-thin film on 6H-SiC was prepared by the RF sputtering method. The morphology from UHV-STM and AFM shows that the Pd thin film was well deposited on SiC substrate, and the Pd was partially aggregated to round shaped participates at an annealing temperature of 300 C. At 400 C, the amount of surface participates decreases, and some strap shape participates appear. From XPS, Pd2Si was formed on the surface after annealing at 300 C, and all Pd reacted with SiC to form Pd2Si after annealing at 400 C. The intensity of the XPS Pd peak decreases enormously at 400 C. The Pd film diffused into SiC, and the Schottky barrier height has almost no changes. The work shows the Pd sicilides/SiC have the same electronic properties with Pd/SiC, and explains why the Pd/SiC sensor still responds to hydrogen at high operating temperatures.

X-Ray Photoelectron Spectroscopy and Ultrahigh Vacuum Contactless Capacitance-Voltage Characterization of Novel Oxide-Free InP Passivation Process Using a Silicon Surface Quantum Well

NASA Astrophysics Data System (ADS)

Takahashi, Hiroshi; Hashizume, Tamotsu; Hasegawa, Hideki

1999-02-01

In order to understand and optimize a novel oxide-free InP passivation process using a silicon surface quantum well, a detailed in situ X-ray photoelectron spectroscopy (XPS) and ultrahigh vacuum (UHV) contactless capacitance-voltage (C-V) study of the interface was carried out. Calculation of quantum levels in the silicon quantum well was performed on the basis of the band lineup of the strained Si3N4/Si/InP interface and the result indicated that the interface should become free of gap states when the silicon layer thickness is below 5 Å. Experimentally, such a delicate Si3N4/Si/InP structure was realized by partial nitridation of a molecular beam epitaxially (MBE) grown pseudomorphic silicon layer using an electron cyclotron resonance (ECR) N2 plasma. The progress of nitridation was investigated in detail by angle-resolved XPS. A newly developed UHV contactless C-V method realized in situ characterization of surface electronic properties of InP at each processing step for passivation. It was found that the interface state density decreased substantially into the 1010 cm-2 eV-1 range by optimizing the nitridation process of the silicon layer. It was concluded that both the surface bond termination and state removal by quantum confinement are responsible for the NSS reduction.

Intercomparison of OH Radical Measurements by Long-Path Absorption and Laser Induced Fluorescence in the Atmosphere Simulation Chamber SAPHIR

NASA Astrophysics Data System (ADS)

Dorn, H.-P.; Brauers, T.; Greif, J.; Häseler, R.; Hofzumahaus, A.; Holland, F.; Rupp, L.

2003-04-01

A striking advantage of the SAPHIR chamber is the availability of two spectroscopic detection instruments for OH radicals: Laser-Induced Fluorescence Spectroscopy (LIF) and Long-Path Differential Optical Laser Absorption Spectroscopy (DOAS). Both instruments have already been compared in 1994 during the field measurement campaign POPCORN. They agreed well with a correlation coefficient of r=0.90 and a weighted linear fit with a slope of 1.09 +- 0.12. However, OH measurements in the simulation chamber differ significantly from measurements in ambient air. While DOAS measures OH as an integral value along the central longitudinal axis of SAPHIR, LIF samples the air locally and close (2 cm) to the floor of the chamber. Thus, the LIF measurements might be possibly affected by local concentration gradients caused by insufficient mixing of the chamber air or by deposition to the wall. On the other hand, if turbulent mixing of the chamber air is weak and high concentrations of ozone are used in experiments, the DOAS instrument might be subject to artificial formation of OH radicals in the air volume which is illuminated by the detection laser. This interference results from laser induced photolysis of ozone and the subsequent reaction of water vapor with the excited oxygen atoms formed. Thus it is of decisive importance to compare OH measurements from both instruments in order to investigate potential disturbing effects due to the specific sampling properties of both instruments within SAPHIR. We report on OH measurements accomplished simultaneously with both instruments using different trace gas compositions and experimental conditions.

Biogenic NO emission from a spruce forest soil in the Fichtelgebirge (Germany) under the influence of different understorey vegetation cover

NASA Astrophysics Data System (ADS)

Bargsten, A.; Andreae, M. O.; Meixner, F. X.

2009-04-01

Within the framework of the EGER project (ExchanGE processes in mountainous Regions) soil samples have been taken from the spruce forest site "Weidenbrunnen" (Fichtelgebirge, Germany) in September 2008 to determine the NO exchange in the laboratory and for a series of soil analyses. The soil was sampled below different understorey vegetation covers: young Norway spruce, moss/litter, blueberries and grass. We investigated the net NO release rate from corresponding organic layers as well as from the A horizon of respective soils. Additionally we measured pH, C/N ratio, contents of ammonium, nitrate, and organic C, bulk density, the thickness of the organic layer and the quality of the organic matter. Net NO release rates (as well as the NO production and NO consumption rates) from the soil samples were determined by a fully automated laboratory incubation & fumigation system. Purified dry air passed five dynamic incubation chambers, four containing water saturated soil samples and one reference chamber. By this procedure, the soil samples dried out slowly (within 2-6 days), covering the full range of soil moisture (0-300% gravimetric soil moisture). To quantify NO production and NO consumption rates separately, soil samples were fumigated with zero-air (approx. 0 ppb NO) and air of 133 ppb NO. The chambers were placed in a thermostatted cabinet for incubation at 10 an 20˚ C. NO and H2O concentrations at the outlet of the five dynamic chambers were measured sequentially by chemiluminescence and IR-absorption based analyzers, switching corresponding valves every two minutes. Net NO release rates were determined from the NO concentration difference between soil containing and reference chambers. Corresponding measurements of H2O mixing ratio yielded the evaporation loss of the soil samples, which (referenced to the gravimetric soil water content before and after the incubation experiment) provided the individual soil moisture contents of each soil samples during the incubation experiment. Our contribution focus net NO release rates, NO production and NO consumption rates of spruce forest soils sampled under different understorey vegetation covers. Generally, organic layers show significant higher NO production and NO consumption rates than the soils from the corresponding A horizons. Soils under the understorey vegetation cover "moos/litter" revealed the lowest NO production and NO consumption rates. Net NO release rates, NO production and NO consumption rates of soil samples obtained below the four different under- storey vegetation covers will be discussed in terms of pH, C/N ratio, contents of ammonium, nitrate, and organic C, bulk density, thickness of organic layer, as well as quality of the organic matter.

A Retrieval System for Radioactive Target Materials at the NIF

NASA Astrophysics Data System (ADS)

Krieger, M.; Shibata, K.; Fallica, J.; Henchen, R.; Pogozelski, E.; Padalino, S.; Sangster, T. C.; Suny Collaboration; Laboratory Collaboration

2011-10-01

Currently, solid radioactive material collection from the NIF target chamber is performed via the DIM. The retrieval process takes several hours to complete. To decrease this time for short lived radioisotopes, the Target Materials Retrieval System (TMRS) is being designed to move a radioactive sample from the target chamber to the counting station in less than 50 seconds, using a closed-loop helium filled RaPToRS system. The TMRS consists of three components: the retrieval apparatus, RaPToRS and the counting station. Starting at 0.5 meters from TCC, the sample will move from the vacuum chamber, travel through 60 meters of 10 centimeter diameter RaPToRS tubes, reaching speeds of 10 m/s. The sample will then arrive at the counting station, where it be robotically placed in front of a gamma ray detector. The use of helium will decrease background gamma radiation produced by activated N2 normally found in a pressurized air system. This work was supported in part by the US Department of Energy through the LLE.

A load-lock compatible system for in situ electrical resistivity measurements during thin film growth.

PubMed

Colin, J J; Diot, Y; Guerin, Ph; Lamongie, B; Berneau, F; Michel, A; Jaouen, C; Abadias, G

2016-02-01

An experimental setup designed for in situ electrical resistance measurement during thin film growth is described. The custom-built sample holder with a four-point probe arrangement can be loaded into a high-vacuum magnetron sputter-deposition chamber through a load-lock transfer system, allowing measurements on series of samples without venting the main chamber. Electrical contact is ensured with circular copper tracks inserted in a Teflon plate on a mounting holder station inside the deposition chamber. This configuration creates the possibility to measure thickness-dependent electrical resistance changes with sub-monolayer resolution and is compatible with use of sample rotation during growth. Examples are presented for metallic films with high adatom mobility growing in a Volmer-Weber mode (Ag and Pd) as well as for refractory metal (Mo) with low adatom mobility. Evidence for an amorphous-to-crystalline phase transition at a film thickness of 2.6 nm is reported during growth of Mo on an amorphous Si underlayer, supporting previous findings based on in situ wafer curvature measurements.

Porous silicon structures with high surface area/specific pore size

DOEpatents

Northrup, M.A.; Yu, C.M.; Raley, N.F.

1999-03-16

Fabrication and use of porous silicon structures to increase surface area of heated reaction chambers, electrophoresis devices, and thermopneumatic sensor-actuators, chemical preconcentrates, and filtering or control flow devices. In particular, such high surface area or specific pore size porous silicon structures will be useful in significantly augmenting the adsorption, vaporization, desorption, condensation and flow of liquids and gases in applications that use such processes on a miniature scale. Examples that will benefit from a high surface area, porous silicon structure include sample preconcentrators that are designed to adsorb and subsequently desorb specific chemical species from a sample background; chemical reaction chambers with enhanced surface reaction rates; and sensor-actuator chamber devices with increased pressure for thermopneumatic actuation of integrated membranes. Examples that benefit from specific pore sized porous silicon are chemical/biological filters and thermally-activated flow devices with active or adjacent surfaces such as electrodes or heaters. 9 figs.

Process for forming a porous silicon member in a crystalline silicon member

DOEpatents

Northrup, M. Allen; Yu, Conrad M.; Raley, Norman F.

1999-01-01

Fabrication and use of porous silicon structures to increase surface area of heated reaction chambers, electrophoresis devices, and thermopneumatic sensor-actuators, chemical preconcentrates, and filtering or control flow devices. In particular, such high surface area or specific pore size porous silicon structures will be useful in significantly augmenting the adsorption, vaporization, desorption, condensation and flow of liquids and gasses in applications that use such processes on a miniature scale. Examples that will benefit from a high surface area, porous silicon structure include sample preconcentrators that are designed to adsorb and subsequently desorb specific chemical species from a sample background; chemical reaction chambers with enhanced surface reaction rates; and sensor-actuator chamber devices with increased pressure for thermopneumatic actuation of integrated membranes. Examples that benefit from specific pore sized porous silicon are chemical/biological filters and thermally-activated flow devices with active or adjacent surfaces such as electrodes or heaters.

Porous silicon structures with high surface area/specific pore size

DOEpatents

Northrup, M. Allen; Yu, Conrad M.; Raley, Norman F.

1999-01-01

Fabrication and use of porous silicon structures to increase surface area of heated reaction chambers, electrophoresis devices, and thermopneumatic sensor-actuators, chemical preconcentrates, and filtering or control flow devices. In particular, such high surface area or specific pore size porous silicon structures will be useful in significantly augmenting the adsorption, vaporization, desorption, condensation and flow of liquids and gasses in applications that use such processes on a miniature scale. Examples that will benefit from a high surface area, porous silicon structure include sample preconcentrators that are designed to adsorb and subsequently desorb specific chemical species from a sample background; chemical reaction chambers with enhanced surface reaction rates; and sensor-actuator chamber devices with increased pressure for thermopneumatic actuation of integrated membranes. Examples that benefit from specific pore sized porous silicon are chemical/biological filters and thermally-activated flow devices with active or adjacent surfaces such as electrodes or heaters.

Method of plasma etching GA-based compound semiconductors

DOEpatents

Qiu, Weibin; Goddard, Lynford L.

2013-01-01

A method of plasma etching Ga-based compound semiconductors includes providing a process chamber and a source electrode adjacent thereto. The chamber contains a Ga-based compound semiconductor sample in contact with a platen which is electrically connected to a first power supply, and the source electrode is electrically connected to a second power supply. SiCl.sub.4 and Ar gases are flowed into the chamber. RF power is supplied to the platen at a first power level, and RF power is supplied to the source electrode. A plasma is generated. Then, RF power is supplied to the platen at a second power level lower than the first power level and no greater than about 30 W. Regions of a surface of the sample adjacent to one or more masked portions of the surface are etched at a rate of no more than about 25 nm/min to create a substantially smooth etched surface.

Organic ferroelectric evaporator with substrate cooling and in situ transport capabilities.

PubMed

Foreman, K; Labedz, C; Shearer, M; Adenwalla, S

2014-04-01

We report on the design, operation, and performance of a thermal evaporation chamber capable of evaporating organic thin films. Organic thin films are employed in a diverse range of devices and can provide insight into fundamental physical phenomena. However, growing organic thin films is often challenging and requires very specific deposition parameters. The chamber presented here is capable of cooling sample substrates to temperatures below 130 K and allows for the detachment of the sample from the cooling stage and in situ transport. This permits the use of multiple deposition techniques in separate, but connected, deposition chambers without breaking vacuum and therefore provides clean, well characterized interfaces between the organic thin film and any adjoining layers. We also demonstrate a successful thin film deposition of an organic material with a demanding set of deposition parameters, showcasing the success of this design.

SEM technique for imaging and measuring electronic transport in nanocomposites based on electric field induced contrast

DOEpatents

Jesse, Stephen [Knoxville, TN; Geohegan, David B [Knoxville, TN; Guillorn, Michael [Brooktondale, NY

2009-02-17

Methods and apparatus are described for SEM imaging and measuring electronic transport in nanocomposites based on electric field induced contrast. A method includes mounting a sample onto a sample holder, the sample including a sample material; wire bonding leads from the sample holder onto the sample; placing the sample holder in a vacuum chamber of a scanning electron microscope; connecting leads from the sample holder to a power source located outside the vacuum chamber; controlling secondary electron emission from the sample by applying a predetermined voltage to the sample through the leads; and generating an image of the secondary electron emission from the sample. An apparatus includes a sample holder for a scanning electron microscope having an electrical interconnect and leads on top of the sample holder electrically connected to the electrical interconnect; a power source and a controller connected to the electrical interconnect for applying voltage to the sample holder to control the secondary electron emission from a sample mounted on the sample holder; and a computer coupled to a secondary electron detector to generate images of the secondary electron emission from the sample.

Controlling hydrogenation activity and selectivity of bimetallic surfaces and catalysts

NASA Astrophysics Data System (ADS)

Murillo, Luis E.

Studies of bimetallic systems are of great interest in catalysis due to the novel properties that they often show in comparison with the parent metals. The goals of this dissertation are: (1) to expand the studies of self-hydrogenation and hydrogenation reactions on bimetallic surfaces under ultra high vacuum conditions (UHV) using different hydrocarbon as probe molecules; (2) to attempt to correlate the surface science findings with supported catalyst studies under more realistic conditions; and (3) to investigate the competitive hydrogenation of C=C versus C=O bonds on Pt(111) modified by different 3d transition metals. Hydrogenation studies using temperature programmed desorption (TPD) on Ni/Pt(111) bimetallic surfaces have demonstrated an enhancement in the low temperature hydrogenation activity relative to that of clean Pt(111). This novel hydrogenation pathway can be achieved under UHV conditions by controlling the structures of the bimetallic surfaces. A low temperature hydrogenation activity of 1-hexene and 1-butene has been observed on a Pt-Ni-Pt(111) subsurface structure, where Ni atoms are mainly present on the second layer of the Pt(111) single crystal. These results are in agreement with previous studies of self-hydrogenation and hydrogenation of cyclohexene. However, a much higher dehydrogenation activity is observed in the reaction of cyclohexene to produce benzene, demonstrating that the hydrocarbon structure has an effect on the reaction pathways. On the other hand, self-hydrogenation of 1-butene is not observed on the Pt-Ni-Pt(111) surface, indicating that the chain length (or molecular weight) has a significant effect on the selfhydrogenation activity. The gas phase reaction of cyclohexene on Ni/Pt supported on alumina catalysts has also shown a higher self-hydrogenation activity in comparison with the same reaction performed on supported monometallic catalysts. The effects of metal loading and impregnation sequence of the metal precursors are also discussed. Chemisorption, TPD, FTIR using a batch reactor for the self-hydrogenation of cyclohexene and CO adsorbed on the bimetallic surfaces were carried out to correlate surface science findings with experiments on supported bimetallic catalysts. To expand the studies on the effect of bimetallic structures on hydrogenation reactions, molecules with multiple functional groups such as alpha,beta-unsaturated aldehydes were also investigated. Studies of selective hydrogenation of a,ss-unsaturated aldehydes toward the desired unsaturated alcohols are of interest for the production of fine chemicals and pharmaceuticals. In these compounds, competitive hydrogenation of the C=C and C=O bonds occurs. TPD and HREELS experiments of acrolein (CH2=CH-CH=O) on Pt-based bimetallic surfaces are performed to investigate their effects on the hydrogenation activity of the C-O bond. The production of the desired unsaturated alcohol, allyl alcohol, has been observed for the first time on Pt-Ni-Pt(111) under UHV conditions. However, the propionaldehyde yield is five times higher than the allyl alcohol yield. Thus, a preferential isomerization reaction of allyl alcohol to propionaldehyde is very likely to occur on the Pt-Ni-Pt(111) surface as observed on the desorption studies of allyl alcohol on this surface. The hydrogenation of acrolein is also carried out under UHV conditions on other 3d-transition metal/Pt(111) surfaces such as Co/Pt(111), Fe/Pt(111), and Cu/Pt(111). So far, the highest activity and allyl alcohol yield are found on the Pt-Ni-Pt(111) surface with pre-adsorbed hydrogen.

Oscillational instabilities in single mode acoustics levitators

NASA Technical Reports Server (NTRS)

Rudnick, J.; Barmatz, Martin

1990-01-01

An extention of standard results for the acoustic force on an object in a single-mode resonant chamber yields predictions for the onset of oscillational instabilities when objects are levitated or positioned in these chambers. The authors' results are consistent with those of experimental investigators. The present approach accounts for the effects of time delays in the response of a cavity to the motion of an object inside of it. Quantitative features of the instabilities are investigated. The experimental conditions required for sample stability, saturation of sample oscillations, hysteretic effects, and the loss of ability to levitate are discussed.

Trace level detection of analytes using artificial olfactometry

NASA Technical Reports Server (NTRS)

Wong, Bernard (Inventor); Lewis, Nathan S. (Inventor); Severin, Erik J. (Inventor)

2001-01-01

The present invention provides a device for detecting the presence of an analyte, wherein said analyte is a microorganism marker gas. The device comprises a sample chamber having a fluid inlet port for the influx of the microorganism marker gas; a fluid concentrator in flow communication with the sample chamber, wherein the fluid concentrator has an absorbent material capable of absorbing the microorganism marker gas and thereafter releasing a concentrated microorganism marker gas; and an array of sensors in fluid communication with the concentrated microorganism marker gas. The sensor array detects and identifies the marker gas upon its release from fluid concentrate.

IceBreaker: Mars Drill and Sample Delivery System

NASA Astrophysics Data System (ADS)

Mellerowicz, B. L.; Paulsen, G. L.; Zacny, K.; McKay, C.; Glass, B. J.; Dave, A.; Davila, A. F.; Marinova, M.

2012-12-01

We report on the development and testing of a one meter class prototype Mars drill and cuttings sample delivery system. The IceBreaker drill consists of a rotary-percussive drill head, a sampling auger with a bit at the end having an integrated temperature sensor, a Z-stage for advancing the auger into the ground, and a sam-pling station for moving the augered ice shavings or soil cuttings into a sample cup. The drill is deployed from a 3 Degree of Freedom (DOF) robotic arm. The drill demonstrated drilling in ice-cemented ground, ice, and rocks at the 1-1-100-100 level; that is the drill reached 1 meter in 1 hour with 100 Watts of power and 100 Newton Weight on Bit. This cor-responds to an average energy of 100 Whr. The drill has been extensively tested in the Mars chamber to a depth of 1 meter, as well as in the Antarctic and the Arctic Mars analog sites. We also tested three sample delivery systems: 1) 4 DOF arm with a custom soil scoop at the end; 2) Pneumatic based, and 3) Drill based enabled by the 3 (DOF) drill deployment boom. In all approaches there is an air-gap between the sterilized drill (which penetrates subsurface) and the sample transfer hardware (which is not going to be sterilized). The air gap satisfies the planetary protection requirements. The scoop acquires cuttings sample once they are augered to the surface, and drops them into an in-strument inlet port. The system has been tested in the Mars chamber and in the Arctic. The pneumatic sample delivery system uses compressed gas to move the sample captured inside a small chamber inte-grated with the auger, directly into the instrument. The system was tested in the Mars chamber. In the third approach the drill auger captures the sample on its flutes, the 3 DOF boom positions the tip of the auger above the instrument, and then the auger discharges the sample into an instrument. This approach was tested in the labolatory (at STP). The above drilling and sample delivery tests have shown that drilling and sample transfer on Mars, in ice cemented ground with limited power, energy and Weight on Bit, and collecting samples in dis-crete depth intervals is possible within the given mass, power, and energy levels of a Phoenix-size lander and within the duration of a Phoenix-like mission.

Cryopreservation of sperm of red abalone (Haliotis rufescens)

USGS Publications Warehouse

Salinas-Flores, L.; Paniagua-Chavez, C. G.; Jenkins, J.A.; Tiersch, T.R.

2005-01-01

Abalone culture, a developing industry in Baja California, Mexico, would benefit from genetic improvement and controlled breeding. The use of cryopreserved sperm would allow germplasm availability, and this study was designed to develop sperm cryopreservation protocols for red abalone Haliotis rufescens. The acute toxic effects of the cryoprotectants dimethyl sulfoxide (DMSO), propylene glycol (PG), and glycerol (GLY) were assessed after suspending sperm in different concentrations, whereby cryoprotectant treatments of 10% DMSO and 10% GLY equilibrated for 10 min yielded the highest range of motile sperm in preliminary freezing trials and were used for cryopreservation studies. To determine effective cooling rates, three freezing chambers were tested. Replicate samples of sperm from 4 males were placed in 0.5-mL French straws and frozen using a commercial freezing chamber (CFC) used for bull sperm, a programmable rate chamber (PRC), and a manually controlled styrofoam chamber (MCC). For the CFC, the cooling rate was 16??C/min, from 4??C to -140??C. For the PRC and MCC, it was 1??C/min, from -20??C to -30??C. The samples were held at -30??C for 5 min before being plunged into liquid nitrogen (-196??C) for storage, and each sample was thawed in a water bath at 45??C for 8 s. The quality of thawed sperm was determined by estimating percent motility, evaluating membrane integrity using a dual-staining technique and flow cytometry, and estimating fertilization rate. Statistical analyses were performed using 2-way ANOVA where chamber and treatment were the independent variables. Sperm quality parameters were independent. For motilities, a significant interaction was noted between the cryoprotective treatment and the chamber type, whereby motilities for DMSO and GLY were higher (P = 0.0055) using MCC. Membrane integrities were significantly lower after using the PRC than the CFC or the MCC (P = 0.0167). The highest post-thaw motility (48 ?? 7%) was found using sperm suspended in 10% glycerol and frozen in the MCC. The highest percent of intact membranes (56 ?? 11%) was for sperm suspended in 10% glycerol and frozen in the CFC. The highest fertilization rate (29 ?? 10%) was with samples frozen with 10% glycerol in the CFC. The use of cryopreserved sperm from red abalone provides an alternative breeding option for culture and the protocols delineated are the first developed for this species.