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Sample records for chemical oxygen-iodine laser

  1. Applications of the chemical oxygen-iodine laser

    NASA Astrophysics Data System (ADS)

    Latham, W. Pete; Kendrick, Kip R.; Quillen, Brian

    2000-01-01

    The Chemical Oxygen-Iodine Laser (COIL) has been developed at the Air Force Research Laboratory for military applications. For example, the COIL is to be use as the laser device for the ABL. A high power laser is useful for applications that require the delivery of a substantial amount of energy to a very small focused laser spot. The COIL is a member of the class of high power lasers that are also useful for industrial applications, including the materials processing task of high speed cutting and drilling. COIL technology has received considerable interest over the last several years due to its short, fiber- deliverable wavelength, scalability to very high powers, and demonstrated nearly diffraction-limited optical quality. These unique abilities make it an ideal candidate for nuclear reactor decommissioning and nuclear warhead dismantlement. Japanese researchers envision using a COIL for disaster cleanup and survivor rescue. It is also being studied by the oil and gas industry for well drilling. Any commercial or industrial application that requires very rapid, precise, and noninvasive cutting or drilling, could be readily accomplished with a COIL. Because of the substantial power levels available with a COIL, the laser could also be used for broad area applications such as paint stripping. This paper includes a collection of experiments accomplished at the Air Force Research Laboratory Chemical Laser Facility, including metal cutting, hole drilling, high power fiber optic transmission, and rock crushing.

  2. Chemical oxygen iodine laser (COIL) technology and development

    NASA Astrophysics Data System (ADS)

    Duff, Edward A.; Truesdell, Keith A.

    2004-09-01

    In the late 1960's researchers realized that producing a population inversion in a moving medium could be used to generate high-energy laser beams. The first lasers to scale to the 10 kW size with good beam quality were supersonic flows of N2 - CO2, emitting radiation from the CO2 at 10.6 microns. In the 1970's gas dynamic CO2 lasers were scaled to hundreds of kilowatts and engineered into a KC-135 aircraft. This aircraft (The Airborne Laser Laboratory) was used to shoot down Sidewinder AIM-9B missiles in the early 1980"s. During this same time period (1970-1990) hydrogen fluoride and deuterium fluoride lasers were scaled to the MW scale in ground-based facilities. In 1978, the Iodine laser was invented at the Air Force Research Laboratory and scaled to the 100 kW level by the early 1990"s. Since the 60s, the DOD Chemical Laser development efforts have included CO2, CO, DF, HF, and Iodine. Currently, the DOD is developing DF, HF, and Iodine lasers, since CO2 and CO have wavelengths and diffraction limitations which make them less attractive for high energy weapons applications. The current military vision is to use chemical lasers to prove the principles and field ground and air mounted laser systems while attempting to develop weight efficient solid-state lasers at the high power levels for use in future Strategic and Tactical situations. This paper describes the evolution of Chemical Oxygen Iodine Lasers, their selection for use in the Airborne Laser (ABL), and the Advanced Tactical Laser (ATL). COIL was selected for these early applications because of its power scalability, its short wavelength, its atmospheric transmittance, and its excellent beam quality. The advantages and challenges are described, as well as some of the activities to improve magazine depth and logistics supportability. COIL lasers are also potentially applicable to mobile ground based applications, and future space based applications, but challenges exist. In addition, COIL is being

  3. Development of a chemical oxygen - iodine laser with production of atomic iodine in a chemical reaction

    SciTech Connect

    Censky, M; Spalek, O; Jirasek, V; Kodymova, J; Jakubec, I

    2009-11-30

    The alternative method of atomic iodine generation for a chemical oxygen - iodine laser (COIL) in chemical reactions with gaseous reactants is investigated experimentally. The influence of the configuration of iodine atom injection into the laser cavity on the efficiency of the atomic iodine generation and small-signal gain is studied. (lasers)

  4. Chemical oxygen-iodine laser power generation with an off-axis hybrid resonator.

    PubMed

    Handke, Jürgen; Schall, Wolfgang O; Hall, Thomas; Duschek, Frank; Grünewald, Karin M

    2006-06-01

    A rectangular negative branch off-axis hybrid resonator was coupled to a 10 kW class chemical oxygen-iodine laser. Resonator setup and alignment turned out to be straightforward. The extracted power was 6.6 kW and reached approximately 70% of the power for an optimized stable resonator. The divergence of the emitted laser beam in the unstable direction was lower than two times the diffraction limit. Experimentally measured margins for mirror misalignment were found in close agreement with numerical calculations. PMID:16724146

  5. Unstable resonators of high-power chemical oxygen-iodine lasers

    SciTech Connect

    Savin, A V; Strakhov, S Yu; Druzhinin, S L

    2006-09-30

    Configurations of unstable resonators are considered depending on the basic parameters of a high-power chemical oxygen-iodine laser and the design of an unstable resonator is proposed which provides the compensation of the inhomogeneity of the small-signal gain downstream of the active medium, a high energy efficiency, and stability to intracavity aberrations. The optical scheme of this resonator is presented and its properties are analysed by simulating numerically the kinetics of the active medium and resonator itself in the diffraction approximation. (laser beams and resonators)

  6. Active-medium inhomogeneities and optical quality of radiation of supersonic chemical oxygen-iodine lasers

    SciTech Connect

    Boreysho, A S; Druzhinin, S L; Lobachev, V V; Savin, A V; Strakhov, S Yu; Trilis, A V

    2007-09-30

    Optical inhomogeneities of the active medium of a supersonic chemical oxygen-iodine laser (COIL) and their effect on the radiation parameters are studied in the case when an unstable resonator is used. Classification of optical inhomogeneities and the main factors affecting the quality of COIL radiation are considered. The results of numerical simulation of a three-dimensional gas-dynamic active medium and an unstable optical resonator in the diffraction approximation are presented. The constraints in the fabrication of large-scale COILs associated with a deterioration of the optical quality of radiation are determined. (lasers)

  7. On a new method for chemical production of iodine atoms in a chemical oxygen-iodine laser

    SciTech Connect

    Andreeva, Tamara L; Kuznetsova, S V; Maslov, A I; Sorokin, Vadim N

    2004-11-30

    A new method is proposed for generating iodine atoms in a chemical oxygen-iodine laser. The method is based on a branched chain reaction of dissociation of the alkyl iodide CH{sub 3}I in a medium of singlet oxygen and chlorine. (active media)

  8. Test bed for a high throughput supersonic chemical oxygen - iodine laser

    SciTech Connect

    Singhal, Gaurav; Mainuddin; Rajesh, R; Varshney, A K; Dohare, R K; Kumar, Sanjeev; Singh, V K; Kumar, Ashwani; Verma, Avinash C; Arora, B S; Chaturvedi, M K; Tyagi, R K; Dawar, A L

    2011-05-31

    The paper reports the development of a test bed for a chemical oxygen - iodine laser based on a high throughput jet flow singlet oxygen generator (JSOG). The system provides vertical singlet oxygen extraction followed by horizontal orientation of subsequent subsystems. This design enables the study of flow complexities and engineering aspects of a distributed weight system as an input for mobile and other platform-mounted systems developed for large scale power levels. The system under consideration is modular and consists of twin SOGs, plenum and supersonic nozzle modules, with the active medium produced in the laser cavity. The maximal chlorine flow rate for the laser is {approx}1.5 mole s{sup -1} achieving a typical chemical efficiency of about 18%. (lasers)

  9. Experimental investigation of an unstable ring resonator with 90-deg beam rotation for a chemical oxygen iodine laser.

    PubMed

    Jin, Y; Yang, B; Sang, F; Zhou, D; Duo, L; Zhuang, Q

    1999-05-20

    We report the experimental results of an unstable ring resonator with 90-deg beam rotation for a kilowatt class chemical oxygen iodine laser (COIL). The distributions of near-field phase and far-field intensity were measured. A beam quality of 1.6 was achieved when the COIL average output power was approximately 5 kW. PMID:18319916

  10. COIL--Chemical Oxygen Iodine Laser: advances in development and applications

    NASA Astrophysics Data System (ADS)

    Kodymova, Jarmila

    2005-09-01

    Advantageous features of Chemical Oxygen-Iodine Laser (COIL) for laser technologies have increased considerably activities of international COIL communities during past ten years. They have been focused on the advanced concepts of hardware designs of the COIL subsystems, and testing and scaling-up of existing laser facilities. Prospective special applications of COIL technology, both civil and military, have received a significant attention and gained concrete aims. The paper is introduced by a brief description of the COIL operation mechanism and key device subsystems. It deals then with presentation of some investigated advanced concepts of singlet oxygen generators, alternative methods for atomic iodine generation, a mixing and ejector nozzle design to downsize a pressure recovery system, and optical resonators for high power COIL systems. The advanced diagnostics and computational modeling are also mentioned as very useful tools for critical insight into the laser kinetics and fluid dynamics, supporting thus the COIL research. The recent progress in the COIL development moves this laser closer to the application projects that are also briefly presented.

  11. Chemical oxygen-iodine laser for decommissioning and dismantlement of nuclear facilities

    NASA Astrophysics Data System (ADS)

    Tei, Kazuyoku; Sugimoto, Daichi; Endo, Masamori; Takeda, Shuzaburo; Fujioka, Tomoo

    2000-01-01

    Conceptual designs of a chemical oxygen-iodine laser (COIL) facility for decommissioning and dismantlement (DD) of nuclear facility is proposed. The requisite output power and beam quality was determined base don our preliminary experiments of nonmetal material processing. Assuming the laser power of 30kW, it is derived that the beam quality of M2 equals 36 required to cut a biological shield wall of a nuclear power plant at a cutting speed of 10mm/min. Then the requisite specification of an optical fiber to deliver the laser is calculated. It turned to be quite extreme, core diameter of 1.7mm and NA equals 0.018. The mass flow and heat balance of proposed facility is calculated based on our recent COIL studies. With the high-pressure subsonic mode, the vacuum pump size is minimized compared to the supersonic operation. Finally, the size of the facility is estimated assuming tow-hour continuous operation. It is revealed that such a system can be packed in five railway containers.

  12. Quantitative determination of oxygen yield in a chemical oxygen-iodine laser

    NASA Astrophysics Data System (ADS)

    Kendrick, Kip R.; Helms, Charles A.; Quillen, Brian; Copland, R. J.

    1998-05-01

    With the advent of the Airborne Laser program, the emphasis of chemical oxygen-iodine laser (COIL) research has shifted toward improving the overall efficiency. A key component of COIL is the singlet-oxygen generator (SOG). To asses the efficiency of the SOG an accurate method of determining the yield of O2((alpha) 1(Delta) g),[O2((alpha) 1(Delta) g)]/[O2(total)] where [O2(total)]equals[O2((alpha) 1(Delta) g)]+[O2(X3(Sigma) g-)], has been developed. Absorption measurements of ground-state oxygen utilizing the magnetic-dipole transition, O2(X3(Sigma) g-) at 763 nm, have been obtained using a diode laser in conjunction with a multiple-pass Herriot-cell on a 10 kW class supersonic SOIL (RADICL). When RADICL is configured with a 0.35' throat, 15' diskpack, and a medium volume transition duct, with a diluent ratio (He:O2) of 3:1, the yield of O2((alpha) 1(Delta) g) in the diagnostic duct is 0.41 +/- 0.02.

  13. Enhancement of the efficiency and control of emission parameters of an unstable-resonator chemical oxygen-iodine laser

    SciTech Connect

    Boreisho, A S; Lobachev, V V; Savin, A V; Strakhov, S Yu; Trilis, A V

    2007-07-31

    The outlook is considered for the development of a high-power supersonic flowing chemical oxygen-iodine laser operating as an amplifier and controlled by radiation from a master oscillator by using an unstable resonator with a hole-coupled mirror. The influence of the seed radiation intensity, the coupling-hole diameter, the active-medium length, and the magnification factor on the parameters of laser radiation is analysed. It is shown that the use of such resonators is most advisable in medium-power oxygen-iodine lasers for which classical unstable resonators are inefficient because of their low magnification factors. The use of unstable resonators with a hole-coupled mirror and injection provides the control of radiation parameters and a considerable increase in the output power and brightness of laser radiation. (control of laser radiation parameters)

  14. Pulsed oxygen-iodine chemical laser initiated by an electrical discharge

    SciTech Connect

    Zhang Rongyao; Chen Fang; Song Xueqin; Xu Qingzhou; Huan Changqing; Zhuang Qi; Zhang Cunhao

    1988-08-01

    This paper demonstrates for the first time the feasibility of an electrically initiated, pulsed oxygen-iodine laser which can be initiated efficiently by low energy electrons. By electrical initiation, an O/sub 2/(/sup 1/..delta..)--CH/sub 3/I--N/sub 2/ mixture has been made to lase with an output energy of 130 mJ. The efficiency of the electrical initiation is 350 times higher than that obtained with photo-initiation.

  15. Realization of an advanced nozzle concept for compact chemical oxygen iodine laser

    NASA Astrophysics Data System (ADS)

    Singhal, Gaurav; Subbarao, P. M. V.; Rajesh, R.; Mainuddin; Tyagi, R. K.; Dawar, A. L.

    2007-04-01

    Conventional supersonic chemical oxygen-iodine lasers (SCOIL) are not only low-pressure systems, with cavity pressure of 2-3 Torr and Mach number of approximately 1.5, but also are high-throughput systems with a typical laser power per unit evacuation capacity of nearly 1 J/l, thus demanding high capacity vacuum systems which mainly determine the compactness of the system. These conventional nozzle-based systems usually require a minimum of a two-stage ejector system for realization of atmospheric pressure recovery in a SCOIL. Typically for a 500 W class SCOIL, a first stage requires a motive gas flow (air) of 120 gm/s to entrain a laser gas flow of 3 g/s and is capable of achieving the pressure recovery in the range of 60-80 Torr. On the other hand, the second stage ejector requires 4.5 kg/s of motive gas (air) to achieve atmospheric pressure recovery. An advanced nozzle, also known as ejector nozzle, suitable for a 500 W-class SCOIL employing an active medium flow of nearly 12 g/s, has been developed and used instead of a conventional slit nozzle. The nozzle has been tested in both cold as well as hot run conditions of SCOIL, achieving a typical cavity pressure of nearly 10 Torr, stagnation pressure of approximately 85 Torr and a cavity Mach number of 2.5. The present study details the gas dynamic aspects of this ejector nozzle and highlights its potential as a SCOIL pressure recovery device. This nozzle in conjunction with a diffuser is capable of achieving pressure recovery equivalent to a more cumbersome first stage of the pressure recovery system used in the case of a conventional slit nozzle-based system. Thus, use of this nozzle in place of a conventional slit nozzle can achieve atmospheric discharge using a single stage ejector system, thereby making the pressure recovery system quite compact.

  16. Analysis of lasing in chemical oxygen-iodine lasers with unstable resonators using a geometric-optics model.

    PubMed

    Barmashenko, Boris D

    2009-05-01

    A simple geometric-optics model is developed that describes the power extraction in chemical oxygen-iodine lasers (COILs) with unstable resonators. The positive and negative branch unstable resonators with cylindrical mirrors that were recently used in COILs are studied theoretically. The optical extraction efficiency, spatial distributions of the intracavity radiation intensity in the flow direction, and the intensity in the far field are calculated for both kinds of resonator as a function of both the resonator and the COIL parameters. The optimal resonator magnifications that correspond to the maximum intensity in the far field are found. PMID:19412214

  17. Data acquisition and control system with a programmable logic controller (PLC) for a pulsed chemical oxygen-iodine laser

    NASA Astrophysics Data System (ADS)

    Yu, Haijun; Li, Guofu; Duo, Liping; Jin, Yuqi; Wang, Jian; Sang, Fengting; Kang, Yuanfu; Li, Liucheng; Wang, Yuanhu; Tang, Shukai; Yu, Hongliang

    2015-02-01

    A user-friendly data acquisition and control system (DACS) for a pulsed chemical oxygen -iodine laser (PCOIL) has been developed. It is implemented by an industrial control computer,a PLC, and a distributed input/output (I/O) module, as well as the valve and transmitter. The system is capable of handling 200 analogue/digital channels for performing various operations such as on-line acquisition, display, safety measures and control of various valves. These operations are controlled either by control switches configured on a PC while not running or by a pre-determined sequence or timings during the run. The system is capable of real-time acquisition and on-line estimation of important diagnostic parameters for optimization of a PCOIL. The DACS system has been programmed using software programmable logic controller (PLC). Using this DACS, more than 200 runs were given performed successfully.

  18. Mechanism of dark decomposition of iodine donor in the active medium of a pulsed chemical oxygen - iodine laser

    SciTech Connect

    Andreeva, Tamara L; Kuznetsova, S V; Maslov, A I; Sorokin, Vadim N

    2002-06-30

    A scheme is proposed that describes the dark decomposition of iodide - the donor of iodine - and the relaxation of singlet oxygen in the chlorine-containing active medium of a pulsed chemical oxygen - iodine laser (COIL). For typical compositions of the active media of pulsed COILs utilising CH{sub 3}I molecules as iodine donors, a branching chain reaction of the CH{sub 3}I decomposition accompanied by the efficient dissipation of singlet oxygen is shown to develop even at the stage of filling the active volume. In the active media with CF{sub 3}I as the donor, a similar chain reaction is retarded due to the decay of CF{sub 3} radicals upon recombination with oxygen. The validity of this mechanism is confirmed by a rather good agreement between the results of calculations and the available experimental data. The chain decomposition of alkyliodides accompanied by an avalanche production of iodine atoms represents a new way of efficient chemical production of iodine for a COIL. (active media)

  19. Gain and temperature in a slit nozzle supersonic chemical oxygen-iodine laser with transonic and supersonic injection of iodine

    NASA Astrophysics Data System (ADS)

    Rosenwaks, Salman; Barmashenko, Boris D.; Bruins, Esther; Furman, Dov; Rybalkin, Victor; Katz, Arje

    2002-05-01

    Spatial distributions of the gain and temperament across the flow were studied for transonic and supersonic schemes of the iodine injection in a slit nozzle supersonic chemical oxygen-iodine laser as a function of the iodine and secondary nitrogen flow rate, jet penetration parameter and gas pumping rate. The mixing efficiency for supersonic injection of iodine is found to be much larger than for transonic injection, the maximum values of the gain being approximately 0.65 percent/cm for both injection schemes. Measurements of the gain distribution as a function of the iodine molar flow rate nI2 were carried out. For transonic injection the optimal value of nI2 at the flow centerline is smaller than that at the off axis location. The temperature is distributed homogeneously across the flow, increasing only in the narrow boundary layers near the walls. Opening a leak downstream of the cavity in order to decease the Mach number results in a decrease of the gain and increase of the temperature. The mixing efficiency in this case is much larger than for closed leak.

  20. Kinetic-fluid dynamics modeling of I{sub 2} dissociation in supersonic chemical oxygen-iodine lasers

    SciTech Connect

    Waichman, K.; Barmashenko, B. D.; Rosenwaks, S.

    2009-09-15

    The mechanism of I{sub 2} dissociation in supersonic chemical oxygen-iodine lasers (COILs) is studied applying kinetic-fluid dynamics modeling, where pathways involving the excited species I{sub 2}(X {sup 1}SIGMA{sub g}{sup +},10<=v<25), I{sub 2}(X {sup 1}SIGMA{sub g}{sup +},25<=v<=47), I{sub 2}(A{sup '} {sup 3}PI{sub 2u}), I{sub 2}(A {sup 3}PI{sub 1u}), O{sub 2}(X {sup 3}SIGMA{sub g}{sup -},v), O{sub 2}(a {sup 1}DELTA{sub g},v), O{sub 2}(b {sup 1}SIGMA{sub g}{sup +},v), and I({sup 2}P{sub 1/2}) as intermediate reactants are included. The gist of the model is adding the first reactant and reducing the contribution of the second as compared to previous models. These changes, recently suggested by Azyazov, et al. [J. Chem. Phys. 130, 104306 (2009)], significantly improve the agreement with the measurements of the gain in a low pressure supersonic COIL for all I{sub 2} flow rates that have been tested in the experiments. In particular, the lack of agreement for high I{sub 2} flow rates, which was encountered in previous models, has been eliminated in the present model. It is suggested that future modeling of the COIL operation should take into account the proposed contribution of the above mentioned reactants.

  1. High-pressure gravity-independent singlet oxygen generator, laser nozzle, and iodine injection system for the chemical oxygen-iodine laser

    NASA Astrophysics Data System (ADS)

    Emanuel, George

    2004-09-01

    A novel approach is outlined for a singlet oxygen generator (SOG), a laser minimum length nozzle (MLN), and an iodine injector system for a chemical oxygen-iodine laser (COIL). A unified approach, referred to as a SOG/MLN/I2 system, is partly based on past experimental work. For instance, the SOG concept stems from sparger technology and a KSY fesibility experiment. A MLN with a curved sonic line is used for the laser nozzle, and slender struts are used for the injection, in the downstream direction, of iodine/helium vapor. The heated struts are located downstream of the nozzle's throat. The engineering logic behind the approach is discussed; it has a diversity of potential system benefits relative to current technology. These include a compact, scalable laser that can operate in space. The SOG operates at a significantly higher pressure with a high O2(1Δ) yield. In addition, basic hydrogen peroxide reconditioning is not required, a water vapor removal system is not required, and diluent may be unnecessary, although useful for pressure recovery. The impact on a COIL system in terms of power, efficiency, and pressure recovery is briefly assessed.

  2. Development of the electric discharge oxygen-iodine laser

    NASA Astrophysics Data System (ADS)

    Carroll, David L.; Verdeyen, Joseph T.; King, Darren M.; Palla, Andrew D.; Laystrom, Julia K.; Benavides, Gabriel F.; Zimmerman, Joseph W.; Woodard, Brian S.; Solomon, Wayne C.

    2007-05-01

    In the hybrid electric discharge Oxygen-Iodine laser (ElectricOIL), the desired O II(a1Δ) is produced using a low-to-medium pressure electric discharge. The discharge production of atomic oxygen, ozone, and other excited species adds higher levels of complexity to the post-discharge kinetics which are not encountered in a classic purely chemical O II(a1Δ) generation system. Experimental studies over the past six years using electric discharges have demonstrated O II(a) yields greater than 20%, gain, and cw laser power. Several modeling studies have also been performed for ElectricOIL and similar systems. As the development of this type of iodine laser continues, the roles of oxygen atoms and NO/NO II are found to be very significant in both the discharge region and downstream of the discharge region. A series of O II(1Δ) emission, I* emission, O-atom titrations, gain, and O II(1Δ) yield, NO II* emission, and laser power measurements have been taken to explore the complex phenomena that are being observed. As the overall system is better understood improvements are being made in laser power and efficiency.

  3. Experimental verification of the Einstein A-coefficient used for evaluation of O2(1Δg) concentration in the chemical oxygen-iodine laser

    NASA Astrophysics Data System (ADS)

    Spalek, O.; Kodymová, J.; Stopka, P.; Micek, I.

    1999-04-01

    This paper is a contribution to the current discussion on the Einstein coefficient for spontaneous emission (A-coefficient) of singlet delta oxygen, O2(1Δg), that is often used for an evaluation of O2(1Δg) concentration in a chemical oxygen-iodine laser (COIL). The published values of the A-coefficient vary in a wide range, corresponding to a radiative lifetime of O2(1Δg), τ_Δ^rad, from ~53 to ~151 min. This could make an evaluation of COIL operation questionable. In this paper, the Einstein A-coefficient is estimated, based on the comparison of O2(1Δg) concentrations determined by two independent methods: electron paramagnetic resonance and emission spectroscopy. Within the accuracy of the experimental techniques used, the value of the A-coefficient resulting from our investigation is (2.24±0.40) × 10-4 s-1, corresponding to τ_Δ^rad of ~74 min. This result is more consistent with the value of 2.58 × 10-4 s-1 of Badger et al [1] than with the value of 1.47 × 10-4 s-1 reported recently by Mlynczak and Nesbitt [2], who raised doubt about the Badger et al value.

  4. Numerical study of He/CF{sub 3}I pulsed discharge used to produce iodine atom in chemical oxygen-iodine laser

    SciTech Connect

    Zhang Jiao; Wang Yanhui; Wang Dezhen; Duo Liping; Li Guofu

    2013-04-15

    The pulsed discharge for producing iodine atoms from the alkyl and perfluoroalky iodides (CH{sub 3}I, CF{sub 3}I, etc.) is the most efficient method for achieving the pulse operating mode of a chemical oxygen-iodine laser. In this paper, a one-dimensional fluid model is developed to study the characteristics of pulsed discharge in CF{sub 3}I-He mixture. By solving continuity equation, momentum equation, Poisson equation, Boltzmann equation, and an electric circuit equation, the temporal evolution of discharge current density and various discharge products, especially the atomic iodine, are investigated. The dependence of iodine atom density on discharge parameters is also studied. The results show that iodine atom density increases with the pulsed width and pulsed voltage amplitude. The mixture ratio of CF{sub 3}I and helium plays a more significant role in iodine atom production. For a constant voltage amplitude, there exists an optimal mixture ratio under which the maximum iodine atom concentration is achieved. The bigger the applied voltage amplitude is, the higher partial pressure of CF{sub 3}I is needed to obtain the maximum iodine atom concentration.

  5. Excited states in the active media of oxygen - iodine lasers

    SciTech Connect

    Azyazov, V N

    2009-11-30

    A review of investigations of kinetic processes in active media oxygen - iodine lasers (OILs) performed in the last decade is presented. The mechanisms of pumping and quenching of electronically and vibrationally excited O{sub 2} and I{sub 2} molecules are considered, and dissociation mechanisms of I{sub 2} in the active medium of the OIL are analysed. The values of kinetic constants of processes proceeding in the active media of OILs are recommended. (review)

  6. Parameters of an electric-discharge generator of iodine atoms for a chemical oxygen-iodine laser

    SciTech Connect

    Azyazov, V N; Vorob'ev, M V; Voronov, A I; Kupryaev, Nikolai V; Mikheev, P A; Ufimtsev, N I

    2009-01-31

    Laser-induced fluorescence is used for measuring the concentration of iodine molecules at the output of an electric-discharge generator of atomic iodine. Methyl iodide CH{sub 3}I is used as the donor of atomic iodine. The fraction of iodine extracted from CH{sub 3}I in the generator is {approx}50%. The optimal operation regimes are found in which 80%-90% of iodine contained in the output flow of the generator was in the atomic state. This fraction decreased during the iodine transport due to recombination and was 20%-30% at the place where iodine was injected into the oxygen flow. The fraction of the discharge power spent for dissociation was {approx}3%. (elements of laser setups)

  7. Recent electric oxygen-iodine laser experiments and modeling

    NASA Astrophysics Data System (ADS)

    Carroll, David L.; Benavides, Gabriel F.; Zimmerman, Joseph W.; Woodard, Brian S.; Palla, Andrew D.; Day, Michael T.; Verdeyen, Joseph T.; Solomon, Wayne C.

    2011-03-01

    Experiments and modeling have led to a continuing evolution of the Electric Oxygen-Iodine Laser (ElectricOIL) system. A new concentric discharge geometry has led to improvements in O2(a) production and efficiency and permits higher pressure operation of the discharge at high flow rate. A new heat exchanger design reduces the O2(a) loss and thereby increases the O2(a) delivered into the gain region for a negligible change in flow temperature. These changes have led to an increase in laser cavity gain from 0.26% cm-1 to 0.30% cm-1. New modeling with BLAZE-V shows that an iodine pre-dissociator can have a dramatic impact upon gain and laser performance. As understanding of the ElectricOIL system continues to improve, the design of the laser systematically evolves.

  8. Evolution of the electric discharge oxygen-iodine laser

    NASA Astrophysics Data System (ADS)

    Carroll, David L.; Benavides, Gabriel F.; Zimmerman, Joseph W.; Woodard, Brian S.; Palla, Andrew D.; Day, Michael T.; Verdeyen, Joseph T.; Solomon, Wayne C.

    2010-11-01

    Experiments and modeling have led to a continuing evolution of the Electric Oxygen-Iodine Laser (ElectricOIL) system. This continuous wave (cw) laser operating on the 1315 nm transition of atomic iodine is pumped by the production of O2(a) in a radio-frequency (RF) discharge in an O2/He/NO gas mixture. New discharge geometries have led to improvements in O2(a) production and efficiency. Further, size scaling is presently showing a super-linear growth in performance; a 95% enhancement in cw laser power was achieved via a 50% increase in gain length, flow rates, and discharge power. New gain recovery measurements and modeling downstream of an operating laser cavity are presented in this work for a wider range of flow conditions to help identify previously unidentified kinetic processes. Larger volume resonators that extend further downstream in the flow direction were able to extract more of the excess energy being carried by the O2(a) from the ElectricOIL gain medium; a further 87% increase in extracted laser power was obtained. As understanding of the ElectricOIL system continues to improve, the design of the laser systematically evolves. The gain has improved by more than 100-fold from the initial demonstration of 0.002% cm-1 to 0.26% cm-1, and similarly the outcoupled laser power has increased more than 600-fold from 0.16 W to 109 W.

  9. Fullerene-oxygen-iodine laser (FOIL): physical principles

    NASA Astrophysics Data System (ADS)

    Danilov, Oleg B.; Belousova, Inna M.; Mak, Artur A.; Belousov, Vlidilen P.; Grenishin, A. S.; Kiselev, V. M.; Krys'ko, A. V.; Murav'eva, T. D.; Ponomarev, Alexander N.; Sosnov, Eugene N.

    2004-09-01

    The paper considers the physical principles of developing the fullerene-oxygen-iodine laser (FOIL) with optical (sunlight in particular) pumping. Kinetic scheme of such a laser is considered. It is shown that the utmost efficiency of FOIL may exceed 40% of the energy, absorbed by fullerenes. Presented are the experimental results of singlet oxygen generation in liquid media (solutions and suspensions) and in solid-state structures, containing either fullerenes or fullerene-like nanoparticles (FNP). In experiment was shown the possibility of the singlet oxygen transfer to the gaseous phase by means of organizing of the solution (suspension) the boiling as well as of the gasodynamic wave of desorption from the solid-state structures, containing fullerenes or FNP. We present the preliminary experimental results of pulsed generation in optically pumped FOIL with the use of primary photodissociation of iodide for preparation of the atomic iodine in the generation zone. In the experiments on FOIL generation was implemented the principle of spectral separation of optical pumping.

  10. Fullurene-oxygen-iodine laser (FOIL): physical principles

    NASA Astrophysics Data System (ADS)

    Danilov, Oleg B.; Belousova, Inna M.; Mak, Artur A.; Belousov, Vlidilen P.; Grenishin, A. S.; Kiselev, V. M.; Krys'ko, A. V.; Murav'eva, T. D.; Ponomarev, Alexander N.; Sosnov, Eugene N.

    2005-03-01

    The paper considers the physical principles of developing the fullerene - oxygen - iodine laser (FOIL) with optical (sunlight in particular) pumping. Kinetic scheme of such a laser is considered. It is shown that the utmost efficiency of FOIL may exceed 40% of the energy, absorbed by fullerenes. Presented are the experimental results of singlet oxygen generation in liquid media (solutions and suspensions) and in solid-state structures, containing either fullerenes or fullerene-like nanopartickles (FNP). In experiment was shown the possibility of the singlet oxygen transfer to the gaseous phase by means of organizing of the solution (suspension) the boiling as well as of the gasodynamic wave of desorption from the solid-state structures, containing fullerenes or FNP. We present the preliminary experimental results of pulsed generation in optically pumped FOIL with the use of primary photodissociation of iodide for preparation of the atomic iodine in the generation zone. In the experiments on FOIL generation was implemented the principle of spectral separation of optical pumping.

  11. Fullerene-oxygen-iodine laser (FOIL): physical principles

    NASA Astrophysics Data System (ADS)

    Danilov, Oleg B.; Belousova, Inna M.; Mak, Artur A.; Belousov, Vlidilen P.; Grenishin, A. S.; Kiselev, V. M.; Krys'ko, A. V.; Murav'eva, T. D.; Ponomarev, Alexander N.; Sosnov, Eugene N.

    2004-06-01

    The paper considers the physical principles of developing the fullerene-oxygen-iodine laser (FOIL) with optical (sunlight in particular) pumping. Kinetic scheme of such a laser is considered. It is shown that the utmost efficiency of FOIL may exceed 40% of the energy, absorbed by fullerenes. Presented are the experimental results of singlet oxygen generation in liquid media (solutions and suspensions) and in solid-state structures, containing either fullerenes or fullerene-like nanoparticles (FNP). In experiment was shown the possibility of the singlet oxygen transfer to the gaseous phase by means of organizing of the solution (suspension) the boiling as well as of the gasodynamic wave of desorption from the solid-state structures, containing fullerenes or FNP. We present the preliminary experimental results of pulsed generation in optically pumped FOIL with the use of primary photodissociation of iodide for preparation of the atomic iodine in the generation zone. In the experiments on FOIL generation was implemented the principle of spectral separation of optical pumping.

  12. Analytic study of the chain dark decomposition reaction of iodides - atomic iodine donors - in the active medium of a pulsed chemical oxygen-iodine laser: 1. Criteria for the development of the branching chain dark decomposition reaction of iodides

    SciTech Connect

    Andreeva, Tamara L; Kuznetsova, S V; Maslov, Aleksandr I; Sorokin, Vadim N

    2009-02-28

    The scheme of chemical processes proceeding in the active medium of a pulsed chemical oxygen-iodine laser (COIL) is analysed. Based on the analysis performed, the complete system of differential equations corresponding to this scheme is replaced by a simplified system of equations describing in dimensionless variables the chain dark decomposition of iodides - atomic iodine donors, in the COIL active medium. The procedure solving this system is described, the basic parameters determining the development of the chain reaction are found and its specific time intervals are determined. The initial stage of the reaction is analysed and criteria for the development of the branching chain decomposition reaction of iodide in the COIL active medium are determined. (active media)

  13. Super-linear enhancement of the electric oxygen-iodine laser

    NASA Astrophysics Data System (ADS)

    Carroll, David L.; Woodard, Brian S.; Benavides, Gabriel F.; Zimmerman, Joseph W.; Palla, Andrew D.; Verdeyen, Joseph T.; Solomon, Wayne C.

    2012-01-01

    Continuing experiments with Electric Oxygen-Iodine Laser (EOIL) technology have significantly increased laser power output by increasing the product of gain and gain-length, g0L. Increasing the system size by a factor of 3 resulted in a 5-fold increase in laser output on the 1315-nm transition of atomic iodine. The peak output power observed was 538 W.

  14. Chemical oxygen-iodine laser (COIL) beam quality predictions using 3D Navier-Stokes (MINT) and wave optics (OCELOT) codes

    NASA Astrophysics Data System (ADS)

    Lampson, Alan I.; Plummer, David N.; Erkkila, John H.; Crowell, Peter G.; Helms, Charles A.

    1998-05-01

    This paper describes a series of analyses using the 3-d MINT Navier-Stokes and OCELOT wave optics codes to calculate beam quality in a COIL laser cavity. To make this analysis tractable, the problem was broken into two contributions to the medium quality; that associated with microscale disturbances primarily from the transverse iodine injectors, and that associated with the macroscale including boundary layers and shock-like effects. Results for both microscale and macroscale medium quality are presented for the baseline layer operating point in terms of single pass wavefront error. These results show that the microscale optical path difference effects are 1D in nature and of low spatial order. The COIL medium quality is shown to be dominated by macroscale effects; primarily pressure waves generated from flow/boundary layer interactions on the cavity shrouds.

  15. Similarity criteria in calculations of the energy characteristics of a cw oxygen - iodine laser

    SciTech Connect

    Mezhenin, A V; Azyazov, V N

    2012-12-31

    The calculated and experimental data on the energy efficiency of a cw oxygen - iodine laser (OIL) are analysed based on two similarity criteria, namely, on the ratio of the residence time of the gas mixture in the resonator to the characteristic time of extraction of the energy stored in singlet oxygen td and on the gain-to-loss ratio {Pi}. It is shown that the simplified two-level laser model satisfactorily predicts the output characteristics of OILs with a stable resonator at {tau}{sub d} {<=} 7. Efficient energy extraction from the OIL active medium is achieved in the case of {tau}{sub d} = 5 - 7, {Pi} = 4 - 8. (lasers)

  16. Feasibility of the Solar-Pumped Fullerene-Oxygen-Iodine Laser (Sun-Light FOIL)

    NASA Astrophysics Data System (ADS)

    Belousova, I. M.; Danilov, O. B.; Mak, A. A.; Belousov, V. P.; Zalesskii, V. Yu.; Grigor'ev, V. A.; Kris'ko, A. V.; Sosnov, E. N.

    2001-05-01

    The feasibility of the optically pumped (in particular, solar-pumped) fullerene-oxygen-iodine laser (FOIL) is considered. The singlet oxygen is assumed to be formed through the interaction of molecular oxygen with a mixture of (both lower and higher) fullerenes in a photogenerated triplet metastable state. The estimates based on a photokinetic model show that the solar-pumped FOIL efficiency can reach several tens of percent. The singlet-oxygen yield resulting from the interaction of optical pumping radiation with fullerenes in solutions is studied both theoretically and experimentally. As the optical pumping, we used laser radiation at 532 nm and broad-band emission of a lamp with a solarlike spectrum.

  17. Possibility of realizing fullerene-oxygen-iodine laser with solar pumping (sun-light FOIL)

    NASA Astrophysics Data System (ADS)

    Danilov, Oleg B.; Belousova, Inna M.; Mak, Artur A.; Zalessky, V. Y.; Grigor'ev, Vladimir A.; Kris'ko, A. V.; Sosnov, Eugene N.; Belousov, Vlidilen P.

    2001-05-01

    We consider the possibility to design the fullerene-oxygen- iodine laser with optical pumping (solar, particularly). It is assumed that singlet oxygen is formed at pass of molecular oxygen through (and interaction with) mixture of lower and higher fullerenes in the triplet metastable state obtained at illumination of fullerenes. The presented results of estimates by a photokinetic model show the opportunity to reach the efficiency of the FOIL with solar pumping at the level of several tens of percents. We present the results of experimental and theoretical studies of singlet oxygen yield at interaction of optical pumping with fullerene in solutions. Laser radiation with wavelength of 532 nm and wideband lamp radiation for imitation of solar radiation were used as pumping. The paper presents the first experimental results on the yield of singlet oxygen, produced in vacuum chamber via interaction of gas-phase molecular oxygen with fullerene devices, irradiated by solar-like lamp emission.

  18. Possibility of realizing fullerene-oxygen-iodine laser with solar pumping (Sun-Light FOIL)

    NASA Astrophysics Data System (ADS)

    Danilov, Oleg B.; Belousova, Inna M.; Mak, Artur A.; Zalessky, V. Y.; Grigor'ev, Vladimir A.; Kris'ko, A. V.; Sosnov, Eugene N.; Belousov, Vlidilen P.

    2001-03-01

    We consider the possibility to design the fullerene-oxygen- iodine laser with optical pumping (solar, particularly). It is assumed that singlet oxygen is formed at pass of molecular oxygen through (and interaction with) mixture of lower and higher fullerenes in the triplet metastable state obtained at illumination of fullerenes. The presented results of estimates by a photokinetic model show the opportunity to reach the efficiency of the FOIL with solar pumping at the level of several tens of percents. We present the results of experimental and theoretical studies of singlet oxygen yield at interaction of optical pumping with fullerene in solutions. Laser radiation with wavelength of 532 nm and wideband lamp radiation for imitation of solar radiation were used as pumping.

  19. Oxygen atom density and thermal energy control in an electric-oxygen iodine laser

    NASA Astrophysics Data System (ADS)

    Benavides, G. F.; Palla, A. D.; Zimmerman, J. W.; Woodard, B. S.; Carroll, D. L.; Solomon, W. C.

    2014-02-01

    Experiments[1] with Electric Oxygen-Iodine Laser (ElectricOIL) heat exchanger technology have demonstrated improved control of oxygen atom density and thermal energy, with minimal quenching of O2(a1Δ), and increasing small signal gain from 0.26% cm-1 to 0.30% cm-1. Heat exchanger technological improvements were achieved through both experimental and modeling studies, including estimation of O2(a1Δ) surface quenching coefficients for select ElectricOIL materials downstream of a radio-frequency discharge-driven singlet oxygen generator. Estimation of O2(a1Δ) quenching coefficients is differentiated from previous studies by inclusion of oxygen atoms, historically scrubbed using HgO[2-4] or AgO[5]. High-fidelity, time-dependent and steady-state simulations are presented using the new BLAZE-VI multi-physics simulation suite[6] and compared to data.

  20. Oxygen discharge and post-discharge kinetics experiments and modeling for the electric oxygen-iodine laser system.

    PubMed

    Palla, A D; Zimmerman, J W; Woodard, B S; Carroll, D L; Verdeyen, J T; Lim, T C; Solomon, W C

    2007-07-26

    Laser oscillation at 1315 nm on the I(2P1/2)-->I(2P3/2) transition of atomic iodine has been obtained by a near resonant energy transfer from O2(a1Delta) produced using a low-pressure oxygen/helium/nitric oxide discharge. In the electric discharge oxygen-iodine laser (ElectricOIL) the discharge production of atomic oxygen, ozone, and other excited species adds levels of complexity to the singlet oxygen generator (SOG) kinetics which are not encountered in a classic purely chemical O2(a1Delta) generation system. The advanced model BLAZE-IV has been introduced to study the energy-transfer laser system dynamics and kinetics. Levels of singlet oxygen, oxygen atoms, and ozone are measured experimentally and compared with calculations. The new BLAZE-IV model is in reasonable agreement with O3, O atom, and gas temperature measurements but is under-predicting the increase in O2(a1Delta) concentration resulting from the presence of NO in the discharge and under-predicting the O2(b1Sigma) concentrations. A key conclusion is that the removal of oxygen atoms by NOX species leads to a significant increase in O2(a1Delta) concentrations downstream of the discharge in part via a recycling process; however, there are still some important processes related to the NOX discharge kinetics that are missing from the present modeling. Further, the removal of oxygen atoms dramatically inhibits the production of ozone in the downstream kinetics.

  1. Oxygen discharge and post-discharge kinetics experiments and modeling for the electric oxygen-iodine laser system.

    PubMed

    Palla, A D; Zimmerman, J W; Woodard, B S; Carroll, D L; Verdeyen, J T; Lim, T C; Solomon, W C

    2007-07-26

    Laser oscillation at 1315 nm on the I(2P1/2)-->I(2P3/2) transition of atomic iodine has been obtained by a near resonant energy transfer from O2(a1Delta) produced using a low-pressure oxygen/helium/nitric oxide discharge. In the electric discharge oxygen-iodine laser (ElectricOIL) the discharge production of atomic oxygen, ozone, and other excited species adds levels of complexity to the singlet oxygen generator (SOG) kinetics which are not encountered in a classic purely chemical O2(a1Delta) generation system. The advanced model BLAZE-IV has been introduced to study the energy-transfer laser system dynamics and kinetics. Levels of singlet oxygen, oxygen atoms, and ozone are measured experimentally and compared with calculations. The new BLAZE-IV model is in reasonable agreement with O3, O atom, and gas temperature measurements but is under-predicting the increase in O2(a1Delta) concentration resulting from the presence of NO in the discharge and under-predicting the O2(b1Sigma) concentrations. A key conclusion is that the removal of oxygen atoms by NOX species leads to a significant increase in O2(a1Delta) concentrations downstream of the discharge in part via a recycling process; however, there are still some important processes related to the NOX discharge kinetics that are missing from the present modeling. Further, the removal of oxygen atoms dramatically inhibits the production of ozone in the downstream kinetics. PMID:17461557

  2. Three-block model of the kinetics of vibrationally excited I{sub 2}(X) molecules in the active media of oxygen - iodine lasers

    SciTech Connect

    Pichugin, S Yu

    2012-09-30

    A three-block model of the kinetics of vibrationally excited I{sub 2}(X) molecules in the active media of chemical oxygen - iodine lasers is developed. Instead of the system of equations describing a change in the concentrations of I{sub 2}(X, u) (u=0 - 47) molecules, this model uses equations for the total concentrations of iodine molecules belonging to the blocks of vibrational levels with u {<=} 10, u = 11 - 24, and u {>=} 25. Effective deactivation rate constants of I{sub 2}(X, 11 {<=} u {<=} 24) molecules are found for laser media of different compositions. The results of calculations performed using the proposed model agree with experimental data and are close to the parameters calculated previously by using the total system of equations for populations of individual vibrational levels of I{sub 2}(X, u). (laser applications and other topics in quantum electronics)

  3. Kinetics and scaling of gain and lasing in a 1-5 kW microwave discharge oxygen iodine laser

    NASA Astrophysics Data System (ADS)

    Rawlins, Wilson T.; Lee, Seonkyung; Hicks, Adam J.; Konen, Ian M.; Plumb, Emily P.; Oakes, David B.; Davis, Steven J.

    2010-02-01

    Scaling of Electric Oxygen-Iodine Laser (EOIL) systems to higher powers requires extension of electric discharge powers into the kW range and beyond, with high efficiency and singlet oxygen yield. This paper describes the implementation of a moderate-power (1 to 5 kW) microwave discharge at 30 to 70 Torr pressure in a supersonic flow reactor designed for systematic investigations of the scaling of gain and lasing with power and flow conditions. The 2450 MHz microwave discharge is confined near the flow axis by a swirl flow. The discharge effluent, containing active species including O2(a1▵), O(3P), and O3, passes through a 2-D flow duct equipped with a supersonic nozzle and cavity. I2 is injected upstream of the supersonic nozzle. The apparatus is water-cooled, and is modular to permit a variety of inlet, nozzle, and optical configurations. A comprehensive suite of optical emission and absorption diagnostics monitors the absolute concentrations of O2(a), O(3P), O3, I2, I(2P3/2), I(2P1/2), small-signal gain, and temperature in both the subsonic and supersonic flow streams. The experimental results include numerous observations of positive gain and lasing in supersonic flow, and the scaling of gain with a variety of flow and reaction rate conditions. The results are compared with kinetics modeling predictions to highlight key discrepancies as well as areas of agreement. The observed gains are generally lower than the predicted values, due in part to chemical kinetics effects and also due to mixing limitations specific to the reagent injection design. We discuss in detail the observed effects related to O-atom chemistry, and their import for scaling the gain to higher levels. We also will present initial beam quality measurements.

  4. Electrode system for electric-discharge generation of atomic iodine in a repetitively pulsed oxygen - iodine laser with a large active volume

    SciTech Connect

    Kazantsev, S Yu; Kononov, I G; Podlesnykh, S V; Firsov, K N

    2010-08-03

    Possibilities for increasing the active medium volume of a chemical oxygen - iodine laser (CCOIL) with a pulsed electric-discharge generation of atomic iodine are studied. The reasons are analysed of the low stability of the transverse self-sustained volume discharge in electrode systems with metal cathodes under the conditions of the electric energy input into gas-discharge plasma that are typical for CCOILs: low pressure of mixtures containing a strongly electronegative component, low voltage of discharge burning, low specific energy depositions, and long duration of the current pulse. An efficient electrode system is elaborated with the cathode based on an anisotropically-resistive material, which resulted in a stable discharge in the mixtures of iodide (CH{sub 3}I, n-C{sub 3}H{sub 7}I, C{sub 2}H{sub 5}I) with oxygen and nitrogen at the specific energy depositions of {approx}5 J L{sup -1}, pressures of 10 - 25 Torr, and mixture volume of 2.5 L. (lasers)

  5. 2D gasdynamic simulation of the kinetics of an oxygen-iodine laser with electric-discharge generation of singlet oxygen

    SciTech Connect

    Chukalovsky, A. A.; Rakhimova, T. V.; Klopovsky, K. S.; Mankelevich, Yu. A.; Proshina, O. V.

    2011-03-15

    The kinetic processes occurring in an electric-discharge oxygen-iodine laser are analyzed with the help of a 2D (r, z) gasdynamic model taking into account transport of excited oxygen, singlet oxygen, and radicals from the electric discharge and their mixing with the iodine-containing gas. The main processes affecting the dynamics of the gas temperature and gain are revealed. The simulation results obtained using the 2D model agree well with the experimental data on the mixture gain. A subsonic oxygen-iodine laser in which singlet oxygen is generated by a 350 W transverse RF discharge excited in an oxygen flow at a pressure P = 10 Torr and the discharge tube wall is covered with mercury oxide is simulated. The simulated mixing system is optimized in terms of the flow rate and the degree of preliminary dissociation of the iodine flow. The optimal regime of continuous operation of a subsonic electric-discharge oxygen-iodine laser is found.

  6. Effect of the solution temperature in a singlet-oxygen generator on the formation of active medium in an ejector oxygen - iodine laser

    SciTech Connect

    Zagidullin, M V; Nikolaev, V D; Svistun, M I; Khvatov, N A; Palina, N Yu

    2002-02-28

    The influence of the solution temperature in a singlet-oxygen generator on the formation of the active medium in the ejector oxygen - iodine laser is investigated. The following parameters of the active medium at the solution temperature -20{sup 0}C are obtained: the gain is 7.2 x 10{sup -3} cm{sup -1}, the Mach number is M=2, the temperature is 205 K, and the static pressure is 9.3 mmHg. As the solution temperature is increased to -4{sup 0}C, the gain decreases to 5 x 10{sup 3} cm{sup -1}, the Mach number decreases to 1.78, while the temperature and the static pressure increase to 241 K and 10.7 mmHg, respectively. As the solution temperature increases from -20 to -4{sup 0}C, the losses in O{sub 2}({sup 1}{Delta}) increase by less than 20%, while the dissociation efficiency of molecular iodine decreases by less than 21%. (lasers, active media)

  7. Electrochemical regeneration of basic hydrogen peroxide for chemical oxygen iodine laser

    NASA Astrophysics Data System (ADS)

    Endo, Masamori; Hano, Masami; Wakita, Syuhei; Uno, Masaharu; Takeda, Shuzaburo

    2005-03-01

    A 3.6M basic hydrogen peroxide solution is electrochemically regenerated. The apparatus was originally developed for electrolytic H2O2 production, generating dilute (<0.2M) BHP for paper manufacturing. To suppress decomposition by various mechanisms, they are identified and quantified. Both caffeine and peracetic acid are found effective to suppress autodecomposition. Theoretical prediction of the current efficiency is made to find an optimum operational condition. A BHP of 3.614M is regenerated to 3.657M with a current efficiency of 67%.

  8. An experimental research on the mixing process of supersonic oxygen-iodine parallel streams

    NASA Astrophysics Data System (ADS)

    Wang, Zengqiang; Sang, Fengting; Zhang, Yuelong; Hui, Xiaokang; Xu, Mingxiu; Zhang, Peng; Zhao, Weili; Fang, Benjie; Duo, Liping; Jin, Yuqi

    2014-12-01

    The O2(1Δ)/I2 mixing process is one of the most important steps in chemical oxygen-iodine laser (COIL). Based on the chemical fluorescence method (CFM), a diagnostic system was set up to image electronically excited fluorescent I2(B3П0) by means of a high speed camera. An optimized data analysis approach was proposed to analyze the mixing process of supersonic oxygen-iodine parallel streams, employing a set of qualitative and quantitative parameters and a proper percentage boundary threshold of the fluorescence zone. A slit nozzle bank with supersonic parallel streams and a trip tab set for enhancing the mixing process were designed and fabricated. With the diagnostic system and the data analysis approach, the performance of the trip tab set was examined and is demonstrated in this work. With the mixing enhancement, the fluorescence zone area was enlarged 3.75 times. We have studied the mixing process under different flow conditions and demonstrated the mixing properties with different iodine buffer gases, including N2, Ar, He and CO2. It was found that, among the four tested gases, Ar had the best penetration ability, whilst He showed the best free diffusion ability, and both of them could be well used as the buffer gas in our experiments. These experimental results can be useful for designing and optimizing COIL systems.

  9. Excimer laser chemical problems

    SciTech Connect

    Tennant, R.; Peterson, N.

    1982-01-01

    Techniques need to be developed to maintain XeF and XeCl laser performance over long periods of time without degradation resulting from chemical processes occurring within the laser. The dominant chemical issues include optical damage, corrosions of laser materials, gas contamination, and control of halogen concentration. Each of these issues are discussed and summarized. The methods of minimizing or controlling the chemical processes involved are presented.

  10. Lasers in chemical processing

    SciTech Connect

    Davis, J.I.

    1982-04-15

    The high cost of laser energy is the crucial issue in any potential laser-processing application. It is expensive relative to other forms of energy and to most bulk chemicals. We show those factors that have previously frustrated attempts to find commercially viable laser-induced processes for the production of materials. Having identified the general criteria to be satisfied by an economically successful laser process and shown how these imply the laser-system requirements, we present a status report on the uranium laser isotope separation (LIS) program at the Lawrence Livermore National Laboratory (LLNL).

  11. Proposal of a defense application for a chemical oxygen laser

    NASA Astrophysics Data System (ADS)

    Takehisa, K.

    2015-05-01

    Defense application for a chemical oxygen laser (COL) is explained. Although a COL has not yet been successful in lasing, the oscillator was estimated to produce a giant pulse with the full width at half maximum (FWHM) of ~0.05ms which makes the damage threshold for the mirrors several-order higher than that for a typical solid-state laser with a ~10ns pulse width. Therefore it has a potential to produce MJ class output considering the simple scalability of being a chemical laser. Since within 0.05ms a supersonic aircraft can move only a few centimeters which is roughly equal to the spot size of the focused beam at ~10km away using a large-diameter focusing mirror, a COL has a potential to make a damage to an enemy aircraft by a single shot without beam tracking. But since the extracted beam can propagate up to a few kilometers due to the absorption in the air, it may be suitable to use in space. While a chemical oxygen-iodine laser (COIL) can give a pulsed output with a width of ~2 ms using a high-pressure singlet oxygen generator (SOG). Therefore a pulsed COIL may also not require beam tracking if a target aircraft is approaching. Another advantage for these pulsed high-energy lasers (HELs) is that, in case of propagating in cloud or fog, much less energy is required for a laser for aerosol vaporization (LAV) than that of a LAV for a CW HEL. Considerations to use a COL as a directed energy weapon (DEW) in a point defense system are shown.

  12. Kinetics of an oxygen - iodine active medium with iodine atoms optically pumped on the 2P1/2 - 2P3/2 transition

    NASA Astrophysics Data System (ADS)

    Zagidullin, M. V.; Malyshev, M. S.; Azyazov, V. N.

    2015-08-01

    The kinetics of the processes occurring in an O2 - I2 - He - H2O gas flow in which photodissociation of molecular iodine at a wavelength close to 500 nm and excitation of atomic iodine on the 2P1/2 - 2P3/2 transition by narrow-band radiation near 1315 nm are implemented successively has been analysed. It is shown that implementation of these processes allows one to form an oxygen - iodine medium with a high degree of dissociation of molecular iodine and a relative content of singlet oxygen O2(a1Δ) exceeding 10%. Having formed a supersonic gas flow with a temperature ~100 K from this medium, one can reach a small-signal gain of about 10-2 cm-1 on the 2P1/2 - 2P3/2 transition in iodine atoms. The specific power per unit flow cross section in the oxygen - iodine laser with this active medium may reach ~100 W cm-2.

  13. Laser Chemical Analysis.

    ERIC Educational Resources Information Center

    Zare, Richard N.

    1984-01-01

    Reviews applications of laser methods to analytical problems, selecting examples from multiphoton ionization and fluorescence analysis. Indicates that laser methodologies promise to improve dramatically the detection of trace substances embedded in "real" matrices, giving the analyst a most powerful means for determining the composition of…

  14. High energy chemical laser system

    DOEpatents

    Gregg, D.W.; Pearson, R.K.

    1975-12-23

    A high energy chemical laser system is described wherein explosive gaseous mixtures of a reducing agent providing hydrogen isotopes and interhalogen compounds are uniformly ignited by means of an electrical discharge, flash- photolysis or an electron beam. The resulting chemical explosion pumps a lasing chemical species, hydrogen fluoride or deuterium fluoride which is formed in the chemical reaction. The generated lasing pulse has light frequencies in the 3- micron range. Suitable interhalogen compounds include bromine trifluoride (BrF$sub 3$), bromine pentafluoride (BrF$sub 5$), chlorine monofluoride (ClF), chlorine trifluoride (ClF$sub 3$), chlorine pentafluoride (ClF$sub 5$), iodine pentafluoride (IF$sub 5$), and iodine heptafluoride (IF$sub 7$); and suitable reducing agents include hydrogen (H$sub 2$), hydrocarbons such as methane (CH$sub 4$), deuterium (D$sub 2$), and diborane (B$sub 2$H$sub 6$), as well as combinations of the gaseous compound and/or molecular mixtures of the reducing agent.

  15. Chemically-Assisted Pulsed Laser-Ramjet

    SciTech Connect

    Horisawa, Hideyuki; Kaneko, Tomoki; Tamada, Kazunobu

    2010-10-13

    A preliminary study of a chemically-assisted pulsed laser-ramjet was conducted, in which chemical propellant such as a gaseous hydrogen/air mixture was utilized and detonated with a focused laser beam in order to obtain a higher impulse compared to the case only using lasers. CFD analysis of internal conical-nozzle flows and experimental measurements including impulse measurement were conducted to evaluate effects of chemical reaction on thrust performance improvement. From the results, a significant improvement in the thrust performances was confirmed with addition of a small amount of hydrogen to propellant air, or in chemically-augmented operation.

  16. Chemically-Assisted Pulsed Laser-Ramjet

    NASA Astrophysics Data System (ADS)

    Horisawa, Hideyuki; Kaneko, Tomoki; Tamada, Kazunobu

    2010-10-01

    A preliminary study of a chemically-assisted pulsed laser-ramjet was conducted, in which chemical propellant such as a gaseous hydrogen/air mixture was utilized and detonated with a focused laser beam in order to obtain a higher impulse compared to the case only using lasers. CFD analysis of internal conical-nozzle flows and experimental measurements including impulse measurement were conducted to evaluate effects of chemical reaction on thrust performance improvement. From the results, a significant improvement in the thrust performances was confirmed with addition of a small amount of hydrogen to propellant air, or in chemically-augmented operation.

  17. Laser Induced Chemical Liquid Phase Deposition (LCLD)

    SciTech Connect

    Nanai, Laszlo; Balint, Agneta M.

    2012-08-17

    Laser induced chemical deposition (LCLD) of metals onto different substrates attracts growing attention during the last decade. Deposition of metals onto the surface of dielectrics and semiconductors with help of laser beam allows the creation of conducting metal of very complex architecture even in 3D. In the processes examined the deposition occurs from solutions containing metal ions and reducing agents. The deposition happens in the region of surface irradiated by laser beam (micro reactors). Physics -chemical reactions driven by laser beam will be discussed for different metal-substrate systems. The electrical, optical, mechanical properties of created interfaces will be demonstrated also including some practical-industrial applications.

  18. Hydrogen peroxide sensor using laser grade dye Rhodamine B

    NASA Astrophysics Data System (ADS)

    Pattanaik, Amitansu; Sahare, P. D.; Nanda, Maitreyee

    2007-11-01

    Many chemical sensors based on fluorescence spectroscopy have been reported in applications, ranging from biomedical and environmental monitoring to industrial process control. In these diverse applications, the analyte can be probed directly, by measuring its intrinsic absorption, or by incorporating some transduction mechanism such as reagent chemistry to enhance sensitivity and selectivity. Hydrogen Peroxide is a colorless liquid. It is a common oxidizing and bleaching agent. It plays an important role in High Power Laser such as Chemical Oxygen Iodine Laser (COIL). As it is on the Hazardous substance list and on the special health hazard substance list, detection of Hydrogen Peroxide is of great importance. In the present study the detection of hydrogen Peroxide is by fluorescence quenching of laser grade dye Rhodamine B. Estimation of rate constant of the bimolecular quenching reaction is made.

  19. Laser-based detection of chemical contraband

    NASA Astrophysics Data System (ADS)

    Clemmer, Robert G.; Kelly, James F.; Martin, Steven W.; Mong, Gary M.; Sharpe, Steven W.

    1997-02-01

    The goal of our work is tow fold; 1) develop a portable and rapid laser based air sampler for detection of specific chemical contraband and 2) compile a spectral data base in both the near- and mid-IR of sufficiently high quality to be useful for gas phase spectroscopic identification of chemical contraband. During the synthesis or 'cooking' of many illicit chemical substances, relatively high concentrations of volatile solvents, chemical precursors and byproducts are unavoidably released to the atmosphere. In some instances, the final product may have sufficient vapor pressure to be detectable in the surrounding air. The detection of a single high-value effluent or the simultaneous detection of two or more low-value effluents can be used as reliable indicators of a nearby clandestine cooking operation. The designation of high- versus low-value effluent reflects both the commercial availability and legitimate usage of a specific chemical. This paper will describe PNNL's progress and efforts towards the development of a portable laser based air sampling system for the detection of clandestine manufacturing of methamphetamine. Although our current efforts ar focused on methamphetamine, we see no fundamental limitations on detection of other forms of chemical contraband manufacturing. This also includes the synthesis of certain classes of chemical weapons that have recently been deployed by terrorist groups.

  20. Remote Chemical Detection using Quantum Cascade Lasers

    SciTech Connect

    Hatchell, Brian K.; Harper, Warren W.; Gervais, Kevin L.

    2006-02-01

    The Infrared Technologies Program at the Pacific Northwest National Laboratory (PNNL) is focused on the science and technology of remote and in-situ chemical sensors for detecting proliferation and countering terrorism. The program is focusing on the infrared detection of gaseous species including chemical warfare agents and gases associated with the production of chemical and nuclear weapons. Several sensors under development are based on miniature infrared quantum cascade (QC) lasers constructed of semiconductor material. The QC laser is unique in that by simply changing the thickness of the semiconductor layers, the laser's wavelength can be changed to target molecular absorption features of specific chemicals. For remote sensing over long optical paths, QC lasers are applied to remote areas using the differential-absorption LIDAR technique. Using a single laser, this technique can easily monitor large areas that would require a large network of point sensors. The original remote sensing configuration, suitable for laboratory applications, consisted of an optical table, laser, beam expander, telescope, mirror, and various supporting electronic and optical components. Recently, PNNL began development of a ruggedized version to conduct experiments in real-world conditions. To reduce the effects of thermal distortion, the system had to be operated from within a large, well insulated, temperature-controlled trailer. The optical breadboard was attached to 4 shock-mounts to reduce shock and vibrational loads to the optical set-up during transport. A custom jacking system using electromechanical actuators was designed to affix the optical table directly to the ground through penetrations in the trailer floor. The jacking system allows remote sensing at longer ranges (up to 5 km) by eliminating jitter caused by wind or personnel movement within the trailer. A computer-controlled gimbal-mounted mirror was added to allow the laser beam to be accurately pointed in both the

  1. Laser Velocimetry of Chemical Vapor Deposition Flows

    NASA Technical Reports Server (NTRS)

    1993-01-01

    Laser velocimetry (LV) is being used to measure the gas flows in chemical vapor deposition (CVD) reactors. These gas flow measurements can be used to improve industrial processes in semiconductor and optical layer deposition and to validate numerical models. Visible in the center of the picture is the graphite susceptor glowing orange-hot at 600 degrees C. It is inductively heated via the copper cool surrounding the glass reactor.

  2. Intense laser beams; Proceedings of the Meeting, Los Angeles, CA, Jan. 23, 24, 1992

    NASA Technical Reports Server (NTRS)

    Wade, Richard C. (Editor); Ulrich, Peter B. (Editor)

    1992-01-01

    Various papers on intense laser beams are presented. Individual topics addressed include: novel methods of copper vapor laser excitation, UCLA IR FEL, lasing characteristics of a large-bore copper vapor laser (CVL), copper density measurement of a large-bore CVL, high-power XeCl excimer laser, solid state direct-drive circuit for pumping gas lasers, united energy model for FELs, intensity and frequency instabilities in double-mode CO2 lasers, comparison of output power stabilities of CO and CO2 lasers, increasing efficiency of sealed-off CO lasers, thermal effects in singlet delta oxygen generation, optical extraction from the chemical oxygen-iodine laser medium, generation and laser diagnostic analysis of bismuth fluoride. Also discussed are: high-Q resonator design for an HF overtone chemical lasers, improved coatings for HF overtone lasers, scaled atmospheric blooming experiment, simulation on producing conjugate field using deformable mirrors, paraxial theory of amplitude correction, potential capabilities of adaptive optical systems in the atmosphere, power beaming research at NASA, system evaluations of laser power beaming options, performance projections for laser beam power to space, independent assessment of laser power beaming options, removal of atmospheric CFCs by lasers, efficiency of vaporization cutting by CVL.

  3. Long pulse chemical laser. Final technical report

    SciTech Connect

    Bardon, R.L.; Breidenthal, R.E.; Buonadonna, V.R.

    1989-02-01

    This report covers the technical effort through February, 1989. This effort was directed towards the technology associated with the development of a large scale, long pulse DF-CO{sub 2} chemical laser. Optics damage studies performed under Task 1 assessed damage thresholds for diamond-turned salt windows. Task 2 is a multi-faceted task involving the use of PHOCL-50 for laser gain measurements, LTI experiments, and detector testing by LANL personnel. To support these latter tests, PHOCL-50 was upgraded with Boeing funding to incorporate a full aperture outcoupler that increased its energy output by over a factor of 3, to a full kilojoule. The PHOCL-50 carbon block calorimeter was also recalibrated and compared with the LANL Scientech meter. Cloud clearing studies under Task 3 initially concentrated on delivering a Boeing built Cloud Simulation Facility to LANL, and currently involves design of a Cold Cloud Simulation Facility. A Boeing IRAD funded theoretical study on cold cloud clearing revealed that ice clouds may be easier to clear then warm clouds. Task 4 involves the theoretical and experimental study of flow system design as related to laser beam quality. Present efforts on this task are concentrating on temperature gradients induced by the gas filling process. General support for the LPCL field effort is listed under Task 5, with heavy emphasis on assuring reliable operation of the Boeing built Large Slide Valve and other device related tests. The modification of the PHOCL-50 system for testing long pulse DF (4{mu}m only) chemical laser operation is being done under Task 6.

  4. Remote Chemical Sensing Using Quantum Cascade Lasers

    SciTech Connect

    Harper, Warren W.; Schultz, John F.

    2003-01-30

    Spectroscopic chemical sensing research at Pacific Northwest National Laboratory (PNNL) is focused on developing advanced sensors for detecting the production of nuclear, chemical, or biological weapons; use of chemical weapons; or the presence of explosives, firearms, narcotics, or other contraband of significance to homeland security in airports, cargo terminals, public buildings, or other sensitive locations. For most of these missions, the signature chemicals are expected to occur in very low concentrations, and in mixture with ambient air or airborne waste streams that contain large numbers of other species that may interfere with spectroscopic detection, or be mistaken for signatures of illicit activity. PNNL’s emphasis is therefore on developing remote and sampling sensors with extreme sensitivity, and resistance to interferents, or selectivity. PNNL’s research activities include: 1. Identification of signature chemicals and quantification of their spectral characteristics, 2. Identification and development of laser and other technologies that enable breakthroughs in sensitivity and selectivity, 3. Development of promising sensing techniques through experimentation and modeling the physical phenomenology and practical engineering limitations affecting their performance, and 4. Development and testing of data collection methods and analysis algorithms. Close coordination of all aspects of the research is important to ensure that all parts are focused on productive avenues of investigation. Close coordination of experimental development and numerical modeling is particularly important because the theoretical component provides understanding and predictive capability, while the experiments validate calculations and ensure that all phenomena and engineering limitations are considered.

  5. Mid-IR semiconductor lasers for chemical sensing

    NASA Technical Reports Server (NTRS)

    Hill, C. J.; Yang, R. Q.

    2003-01-01

    The development of mid-IR semiconductor diode lasers based on type-II interband cascade structures is presented. How these diode lasers can be developed to meet the requirements in chemical sensing applications is discussed.

  6. Laser-based Sensors for Chemical Detection

    SciTech Connect

    Myers, Tanya L.; Phillips, Mark C.; Taubman, Matthew S.; Bernacki, Bruce E.; Schiffern, John T.; Cannon, Bret D.

    2010-05-10

    Stand-off detection of hazardous materials ensures that the responder is located at a safe distance from the suspected source. Remote detection and identification of hazardous materials can be accomplished using a highly sensitive and portable device, at significant distances downwind from the source or the threat. Optical sensing methods, in particular infrared absorption spectroscopy combined with quantum cascade lasers (QCLs), are highly suited for the detection of chemical substances since they enable rapid detection and are amenable for autonomous operation in a compact and rugged package. This talk will discuss the sensor systems developed at Pacific Northwest National Laboratory and will discuss the progress to reduce the size and power while maintaining sensitivity to enable stand-off detection of multiple chemicals.

  7. Laser-induced destination of hazardous chemicals: A preliminary analysis

    NASA Astrophysics Data System (ADS)

    Morrison, P. F.; Wolf, K. A.

    1982-10-01

    Technical methods that might prove effective in destroying dangerous chemicals before they leave the plant environment and become subject to regulation are studied. Laser infrared multiphoton dissociation, for decomposing deleterious chemical gases is evaluated. The chlorinated ethylenes and the chlorinated ethanes are emphasized. A detailed method for decomposing chlorinated chemicals in the workplace using a relatively inexpensive CO2 laser is discussed. Results show that CO2 laser photodegradation of vinyl chloride, a chlorinated ethylene, is promising.

  8. Remote chemical sensing with quantum cascade lasers

    SciTech Connect

    Harper, Warren W.; Strasburg, Jana D.

    2004-10-15

    A trailer based sensor system has been developed for remote chemical sensing applications. The sensor uses quantum cascade lasers (QCL) that operate in the long wave infrared. The QCL is operated continuous wave, and its wavelength is both ramped over a molecular absorption feature and frequency modulated. Lock-in techniques are used to recover weak laser return signals. Field experiments have monitored ambient water vapor and small quantities of nitrous oxide, tetrafluoroethane (R134a), and hydrogen sulfide released as atmospheric plumes. Round trip path lengths up to 10 km were obtained using a retro-reflector. Atmospheric turbulence was found to be the dominating noise source. It causes intensity fluctuations in the received power, which can significantly degrade the sensor performance. Unique properties associated with QCLs enabled single beam normalization techniques to be implemented thus reducing the impact that turbulence has on experimental signal to noise. Weighted data averaging was additionally used to increase the signal to noise of data traces. Absorbance sensitivities as low as {approx}1 x 10{sup -4} could be achieved with 5 seconds of data averaging, even under high turbulence conditions.

  9. Chemically amplified laser direct-writing of aluminum

    NASA Astrophysics Data System (ADS)

    Tsao, J. Y.; Ehrlich, D. J.

    Laser microchemical direct writing has important advantages over other techniques for the deposition of thin-film patterns. Disadvantages, however, are lower throughput and the need to suppress competing processes such as gas phase nucleation of particles or substrate damage. Methods for increasing the overall speed of laser direct writing by microchemistry were investigated. A class of laser deposition techniques has emerged in which laser radiation is used only to enhance or to impede the initial nucleation of a thin film. In general, it is convenient to draw a distinction between nucleation barriers due to physical effects and those due to chemical effects. The first type of barrier is derived from surface tension. The laser deposits a pattern of heterogeneous catalyst to initiate a subsequent transformation that is chemically self-sustaining or autocatalytic. Experiments, in which the laser direct writing of patterned thin films of Al is chemically amplified by subsequent selective pyrolytic chemical vapor deposition are summarized.

  10. Laser-Beam-Absorption Chemical-Species Monitor

    NASA Technical Reports Server (NTRS)

    Gersh, Michael; Goldstein, Neil; Lee, Jamine; Bien, Fritz; Richtsmeier, Steven

    1996-01-01

    Apparatus measures concentration of chemical species in fluid medium (e.g., gaseous industrial process stream). Directs laser beam through medium, and measures intensity of beam after passage through medium. Relative amount of beam power absorbed in medium indicative of concentration of chemical species; laser wavelength chosen to be one at which species of interest absorbs.

  11. Phase control of HF chemical lasers for coherent optical recombination.

    PubMed

    Wang, C P; Smith, P L

    1979-05-01

    A servo system for phase-locking two HF chemical lasers has been designed and simulated. A steady-state phase error is achieved that is adequate for coherent optical recombination. The results are based on the measured frequency drift of a small HF chemical laser and the measured frequency response of a piezoelectric transducer (PZT) mirror driver. A major innovation is the use of rate feedback with a laser Doppler sensor to extend the useful frequency response of the PZT driver.

  12. Chemical imaging sensor and laser beacon.

    PubMed

    Carrieri, Arthur H

    2003-05-20

    Design and functional aspects of PANSPEC, a panoramic-imaging chemical vapor sensor (PANSPEC is an abbreviation for infrared panoramic-viewing spectroradiometer), were advanced and its optical system reoptimized accordingly. The PANSPEC model unites camera and fused solid-state interferometer and photopolarimeter subsystems. The camera is an eye of the open atmosphere that collects, collimates, and images ambient infrared radiance from a panoramic field of view (FOV). The passive interferometer rapidly measures an infrared-absorbing (or infrared-emitting) chemical cloud traversing the FOV by means of molecular vibrational spectroscopy. The active photopolarimeter system provides a laser beam beacon. This beam carries identification (feature spectra measured by the interferometer) and heading (detector pixels disclosing these feature spectra) information on the hazardous cloud through a binary encryption of Mueller matrix elements. Interferometer and photopolarimeter share a common configuration of photoelastic modulation optics. PANSPEC was optimized for minimum aberrations and maximum resolution of image. The optimized design was evaluated for tolerances in the shaping and mounting of the optical system, stray light, and ghost images at the focal plane given a modulation transfer function metric.

  13. Remote Chemical Sensing Using Quantum Cascade Lasers

    SciTech Connect

    Harper, Warren W.; Strasburg, Jana D.; Aker, Pam M.; Schultz, John F.

    2004-01-20

    instrument detection limit. The range of chemicals detectable by FM DIAL has also been extended. Prior to FY03 only water and nitrous oxide (N2O) had been seen. Experiments on extending the tuning range of the quantum cascade laser (QCL) currently used in the experiments demonstrate that many more species are now accessible including H2S, C2F4H2, and CH4. We additionally demonstrated that FM DIAL measurements can be made using short wave infrared (SWIR) telecommunications lasers. While measurements made using these components are noisier because turbulence and particulate matter cause more interference in this spectral region, monitoring in this region enables larger species to be detected simply because these lasers have a greater tuning range. In addition, SWIR monitoring also allows for the detection of second-row hydride species such as HF and HCl, which are important nuclear and CWA proliferation signatures.

  14. Laser cutting with chemical reaction assist

    SciTech Connect

    Gettemy, D.J.

    1991-04-08

    This invention is comprised of a method for cutting with a laser beam where an oxygen-hydrocarbon reaction is used to provide auxiliary energy to a metal workpiece to supplement the energy supplied by the laser. Oxygen is supplied to the laser focus point on the workpiece by a nozzle through which the laser beam also passes. A liquid hydrocarbon is supplied by coating the workpiece along the cutting path with the hydrocarbon prior to laser irradiation or by spraying a stream of hydrocarbon through a nozzle aimed at a point on the cutting path which is just ahead of the focus point during irradiation.

  15. Laser cutting with chemical reaction assist

    DOEpatents

    Gettemy, D.J.

    1992-11-17

    A method is described for cutting with a laser beam where an oxygen-hydrocarbon reaction is used to provide auxiliary energy to a metal workpiece to supplement the energy supplied by the laser. Oxygen is supplied to the laser focus point on the workpiece by a nozzle through which the laser beam also passes. A liquid hydrocarbon is supplied by coating the workpiece along the cutting path with the hydrocarbon prior to laser irradiation or by spraying a stream of hydrocarbon through a nozzle aimed at a point on the cutting path which is just ahead of the focus point during irradiation. 1 figure.

  16. Laser cutting with chemical reaction assist

    DOEpatents

    Gettemy, Donald J.

    1992-01-01

    A method for cutting with a laser beam where an oxygen-hydrocarbon reaction is used to provide auxiliary energy to a metal workpiece to supplement the energy supplied by the laser. Oxygen is supplied to the laser focus point on the workpiece by a nozzle through which the laser beam also passes. A liquid hydrocarbon is supplied by coating the workpiece along the cutting path with the hydrocarbon prior to laser irradiation or by spraying a stream of hydrocarbon through a nozzle aimed at a point on the cutting path which is just ahead of the focus point during irradiation.

  17. Laser micromachining of chemically altered polymers

    SciTech Connect

    Lippert, T.

    1998-08-01

    During the last decade laser processing of polymers has become an important field of applied and fundamental research. One of the most promising proposals, to use laser ablation as dry etching technique in photolithography, has not yet become an industrial application. Many disadvantages of laser ablation, compared to conventional photolithography, are the result of the use of standard polymers. These polymers are designed for totally different applications, but are compared to the highly specialized photoresist. A new approach to laser polymer ablation will be described; the development of polymers, specially designed for high resolution laser ablation. These polymers have photolabile groups in the polymer backbone, which decompose upon laser irradiation or standard polymers are modified for ablation at a specific irradiation wavelength. The absorption maximum can be tailored for specific laser emissino lines, e.g. 351, 308 and 248 nm lines of excimer lasers. The authors show that with this approach many problems associated with the application of laser ablation for photolithography can be solved. The mechanism of ablation for these photopolymers is photochemical, whereas for most of the standard polymers this mechanism is photothermal. The photochemical decomposition mechanism results in high resolution ablation with no thermal damage at the edges of the etched structures. In addition there are no redeposited ablation products or surface modifications of the polymer after ablation.

  18. Laser micromachining of chemically altered polymers

    NASA Astrophysics Data System (ADS)

    Lippert, Thomas K.

    1998-06-01

    During the last decade laser processing of polymers has become an important field of applied and fundamental research. One of the most promising proposal, to use laser ablation as dry etching technique in photolithography, has not yet become an industrial application. Many disadvantages of laser ablation, compared to conventional photolithography, are the result of the use of standard polymers. These polymers are designed for totally different applications, but are compared to the highly specialized photoresist. A new approach to laser polymer ablation will be described; the development of polymers, specially designed for high resolution laser ablation. These polymers have photolabile groups in the polymer backbone, which decompose upon laser irradiation or standard polymers are modified for ablation at a specific irradiation wavelength. The absorption maximum can be tailored for specific laser emission lines, e.g. 351, 308 and 248 nm lines of excimer lasers. We will show that with this approach many problems associated with the application of laser ablation for photolithography can be solved. The mechanism of ablation for these photopolymers is photochemical, whereas for most of the standard polymers this mechanism is photothermal. The photochemical decomposition mechanism results in high resolution ablation with no thermal damage at the edges of the etched structures. In addition there are not redeposited ablation products or surface modifications of the polymer after ablation.

  19. Chemical and Laser Sciences Division annual report 1989

    SciTech Connect

    Haines, N.

    1990-06-01

    The Chemical and Laser Sciences Division Annual Report includes articles describing representative research and development activities within the Division, as well as major programs to which the Division makes significant contributions.

  20. Problems in the development of autonomous mobile laser systems based on a cw chemical DF laser

    SciTech Connect

    Aleksandrov, B P; Bashkin, A S; Beznozdrev, V N; Parfen'ev, M V; Pirogov, N A; Semenov, S N

    2003-01-31

    The problems involved in designing autonomous mobile laser systems based on high-power cw chemical DF lasers, whose mass and size parameters would make it possible to install them on various vehicles, are discussed. The need for mobility of such lasers necessitates special attention to be paid to the quest for ways and means of reducing the mass and size of the main laser systems. The optimisation of the parameters of such lasers is studied for various methods of scaling their systems. A complex approach to analysis of the optical scheme of the laser system is developed. (special issue devoted to the 80th anniversary of academician n g basov's birth)

  1. Chemical consequences of laser-induced breakdown in molecular gases

    NASA Astrophysics Data System (ADS)

    Babánková, Dagmar; Civiš, Svatopluk; Juha, Libor

    This article gives an account of chemical reactions initiated by laser-induced dielectric breakdown (LIDB) in homogeneous molecular gases. The systematic part of the article describes the laser-plasma-chemical behavior of simple inorganic gases and their mixtures, metal carbonyls and organometallics, and organic molecular gases. Research on LIDB-initiated chemical reactions producing well-defined fine solid particles has been triggered again recently by the advent of nanotechnologies. Laser ignition of fuel mixtures is also a well researched branch of laser-plasma chemistry because of strong commercial and military interests. However, the strongest current impulses for studying laser-spark chemistry come from planetary sciences, where laser sparks have been used as a laboratory model of high-energy-density phenomena (e.g., impact of extraterrestrial bodies, lightning) in planetary atmospheres. A single pulse from a high-power laser system was used to develop an improved method for investigating this phenomenon. The particular processes responsible for the chemical action of a laser spark are identified and described in detail by the end of the article.

  2. Mid-infrared laser-spectroscopic sensing of chemical species

    PubMed Central

    Sigrist, Markus W.

    2014-01-01

    This letter reports on mid-infrared laser-based detection and analysis of chemical species. Emphasis is put on broadly tunable laser sources and sensitive detection schemes. Selected examples from our lab illustrate the performance and potential of such systems in various areas including environmental and medical sensing. PMID:26257952

  3. Application of laser Doppler velocimeter to chemical vapor laser system

    NASA Technical Reports Server (NTRS)

    Gartrell, Luther R.; Hunter, William W., Jr.; Lee, Ja H.; Fletcher, Mark T.; Tabibi, Bagher M.

    1993-01-01

    A laser Doppler velocimeter (LDV) system was used to measure iodide vapor flow fields inside two different-sized tubes. Typical velocity profiles across the laser tubes were obtained with an estimated +/-1 percent bias and +/-0.3 to 0.5 percent random uncertainty in the mean values and +/-2.5 percent random uncertainty in the turbulence-intensity values. Centerline velocities and turbulence intensities for various longitudinal locations ranged from 13 to 17.5 m/sec and 6 to 20 percent, respectively. In view of these findings, the effects of turbulence should be considered for flow field modeling. The LDV system provided calibration data for pressure and mass flow systems used routinely to monitor the research laser gas flow velocity.

  4. Project LOCOST: Laser or Chemical Hybrid Orbital Space Transport

    NASA Technical Reports Server (NTRS)

    Dixon, Alan; Kost, Alicia; Lampshire, Gregory; Larsen, Rob; Monahan, Bob; Wright, Geoff

    1990-01-01

    A potential mission in the late 1990s is the servicing of spacecraft assets located in GEO. The Geosynchronous Operations Support Center (GeoShack) will be supported by a space transfer vehicle based at the Space Station (SS). The vehicle will transport cargo between the SS and the GeoShack. A proposed unmanned, laser or chemical hybrid orbital space transfer vehicle (LOCOST) can be used to efficiently transfer cargo between the two orbits. A preliminary design shows that an unmanned, laser/chemical hybrid vehicle results in the fuel savings needed while still providing fast trip times. The LOCOST vehicle receives a 12 MW laser beam from one Earth orbiting, solar pumped, iodide Laser Power Station (LPS). Two Energy Relay Units (ERU) provide laser beam support during periods of line-of-sight blockage by the Earth. The baseline mission specifies a 13 day round trip transfer time. The ship's configuration consist of an optical train, one hydrogen laser engine, two chemical engines, a 18 m by 29 m box truss, a mission-flexible payload module, and propellant tanks. Overall vehicle dry mass is 8,000 kg. Outbound cargo mass is 20,000 kg, and inbound cargo mass is 6,000 kg. The baseline mission needs 93,000 kg of propellants to complete the scenario. Fully fueled, outbound mission mass is 121,000 kg. A regeneratively cooled, single plasma, laser engine design producing a maximum of 768 N of thrust is utilized along with two traditional chemical engines. The payload module is designed to hold 40,000 kg of cargo, though the baseline mission specifies less. A proposed design of a laser/chemical hybrid vehicle provides a trip time and propellant efficient means to transport cargo from the SS to a GeoShack. Its unique, hybrid propulsion system provides safety through redundancy, allows baseline missions to be efficiently executed, while still allowing for the possibility of larger cargo transfers.

  5. Molecular dispersion spectroscopy--new capabilities in laser chemical sensing.

    PubMed

    Nikodem, Michal; Wysocki, Gerard

    2012-07-01

    Laser spectroscopic techniques suitable for molecular dispersion sensing enable new applications and strategies in chemical detection. This paper discusses the current state of the art and provides an overview of recently developed chirped laser dispersion spectroscopy (CLaDS)-based techniques. CLaDS and its derivatives allow for quantitative spectroscopy of trace gases and enable new capabilities, such as extended dynamic range of concentration measurements, high immunity to photodetected intensity fluctuations, or capability of direct processing of spectroscopic signals in optical domain. Several experimental configurations based on quantum cascade lasers and examples of molecular spectroscopic data are presented to demonstrate capabilities of molecular dispersion spectroscopy in the mid-infrared spectral region.

  6. Laser studies of chemical reaction and collision processes

    SciTech Connect

    Flynn, G.

    1993-12-01

    This work has concentrated on several interrelated projects in the area of laser photochemistry and photophysics which impinge on a variety of questions in combustion chemistry and general chemical kinetics. Infrared diode laser probes of the quenching of molecules with {open_quotes}chemically significant{close_quotes} amounts of energy in which the energy transferred to the quencher has, for the first time, been separated into its vibrational, rotational, and translational components. Probes of quantum state distributions and velocity profiles for atomic fragments produced in photodissociation reactions have been explored for iodine chloride.

  7. Chemical Kinetic Modeling of HMX and TATB Laser Ignition Tests

    SciTech Connect

    Tarver, C M

    2004-03-02

    Recent laser ignition experiments on octahydro-1,3,5,7-tetranitro-1,3,5,7-terrazocine (HMX) and 1,3,5-triamino-2,4,6-trinitrobenzene (TATB) subjected to laser fluxes ranging from 10 to 800 W/cm{sup 2} produced ignition times from seconds to milliseconds. Global chemical kinetic thermal decomposition models for HMX and TATB have been developed to calculate times to thermal explosion for experiments in the seconds to days time frame. These models are applied to the laser ignition experimental data in this paper. Excellent agreement was obtained for TATB, while the calculated ignition times were longer than experiment for HMX at lower laser fluxes. At the temperatures produced in the laser experiments, HMX melts. Melting generally increases condensed phase reaction rates so faster rates were used for three of the HMX reaction rates. This improved agreement with experiments at the lower laser fluxes but yielded very fast ignition at high fluxes. The calculated times to ignition are in reasonable agreement with the laser ignition experiments, and this justifies the use of these models for estimating reaction times at impact and shock ''hot spot'' temperatures.

  8. Underwater cutting of stainless steel with the laser transmitted through optical fiber

    NASA Astrophysics Data System (ADS)

    Okado, Hideki; Sakurai, Takashi; Adachi, Junichi; Miyao, Hidehiko; Hara, Kunio

    2000-01-01

    By using a fiber-transmitted laser beam and high pressure oxygen gas, underwater laser cutting of thick stainless steel was demonstrated. In the field of decommissioning, underwater cutting of nuclear facilities is desirable. For this operation, it is very useful to apply the laser beam transmitted through optical fiber because of flexibility. We used chemical oxygen-iodine laser for fundamental experiments with laser beam power of 1-7kW. And for this experiments, we designed cutting heads with some ideas for nozzles and optics. The nozzles have various nozzle diameters and two kinds of shapes; one is conical, and the other is divergent. The latter was designed to make a supersonic gas flow by using high pressure oxygen gas. And we prepared several focusing optics with different focal lengths, which have influence on both the focal spot diameter and the depth of focus of the laser beam that incidents upon a workpiece. Cutting ability was measured by cutting a tapered workpiece. From this investigation it was clear that the nozzle-to-workpiece distance that was about 10mm had the large tolerance of deviation, and there was a suitable optics according to laser power.

  9. Molecular dispersion spectroscopy – new capabilities in laser chemical sensing

    PubMed Central

    Nikodem, Michal; Wysocki, Gerard

    2012-01-01

    Laser spectroscopic techniques suitable for molecular dispersion sensing enable new applications and strategies in chemical detection. This paper discusses the current state-of-the art and provides an overview of recently developed chirped laser dispersion spectroscopy (CLaDS) based techniques. CLaDS and its derivatives allow for quantitative spectroscopy of trace-gases and enable new capabilities such as extended dynamic range of concentration measurements, high immunity to photodetected intensity fluctuations, or capability of direct processing of spectroscopic signals in optical domain. Several experimental configurations based on quantum cascade lasers and examples of molecular spectroscopic data are presented to demonstrate capabilities of molecular dispersion spectroscopy in the mid-infrared spectral region. PMID:22809459

  10. Molecular dispersion spectroscopy--new capabilities in laser chemical sensing.

    PubMed

    Nikodem, Michal; Wysocki, Gerard

    2012-07-01

    Laser spectroscopic techniques suitable for molecular dispersion sensing enable new applications and strategies in chemical detection. This paper discusses the current state of the art and provides an overview of recently developed chirped laser dispersion spectroscopy (CLaDS)-based techniques. CLaDS and its derivatives allow for quantitative spectroscopy of trace gases and enable new capabilities, such as extended dynamic range of concentration measurements, high immunity to photodetected intensity fluctuations, or capability of direct processing of spectroscopic signals in optical domain. Several experimental configurations based on quantum cascade lasers and examples of molecular spectroscopic data are presented to demonstrate capabilities of molecular dispersion spectroscopy in the mid-infrared spectral region. PMID:22809459

  11. Mid-infrared spatial filter fabrication using laser chemical etching

    NASA Astrophysics Data System (ADS)

    Drouet D'Aubigny, Christian Y.; Walker, Christopher K.; Golish, Dathon R.

    2004-10-01

    Feedhorns like those commonly used in radio-telescope and radio communication equipment couple very efficiently (>98%) to the fundamental Gaussian mode (TEM00). High order modes are not propagated through a single-mode hollow metallic waveguides. It follows that a back to back feedhorn design joined with a small length of single-mode waveguide can be used as a very high throughput spatial filter. Laser micro machining provides a mean of scaling successful waveguide and quasi-optical components to far and mid infrared wavelengths. A laser micro machining system optimized for THz and far IR applications has been in operation at Steward Observatory for several years and produced devices designed to operate at λ=60μm. A new laser micromachining system capable of producing mid-infrared devices will soon be operational. These proceedings review metallic hollow waveguide spatial filtering theory, feedhorn designs as well as laser chemical etching and the design of a new high-NA UV laser etcher capable of sub-micron resolution to fabricate spatial filters for use in the mid-infrared.

  12. Space-Based Chemical Lasers in strategic defense

    SciTech Connect

    Wildt, D. )

    1992-07-01

    The Strategic Defense Initiative Organization (SDIO) has made significant progress in developing Space-Based chemical Laser (SBL) technologies and in studying the SBLs global defense capability. In this mission, a constellation of several orbiting laser platforms provides continuous global defense by intercepting threatening missiles in their boost phase, including short range ballistic missiles (SRBMs). An optional smaller constellation provides defense against launches from the low and midlatitude regions. In addition, SBLs have utility in other important related missions such as surveillance, air defense and discrimination. The hardware necessary to build such a system has been developed to the point where it is mature and ready for demonstration in space. Advances have been made in each of the following major areas of the SBL: laser device; optics/beam control; beam pointing; ATP (acquisition, tracking and pointing); uncooled optics; and laser lethality. Integration of the key laser and beam control technologies is now occurring in the ground-based ALI experiment, and a space demonstration experiment, Star LITE, is in the planning and concept development phase.

  13. Standoff photoacoustic sensing of trace chemicals by laser Doppler vibrometer

    NASA Astrophysics Data System (ADS)

    Fu, Y.; Hu, Q.; Liu, H.

    2016-05-01

    Photoacoustic spectroscopy (PAS) is a useful technique that suitable for trace detection of chemicals and explosives. Normally a high-sensitive microphone or a quartz tuning fork is used to detect the signal in photoacoustic cell. In recent years, laser Doppler vibrometer (LDV) is proposed to remote-sense photoacoustic signal on various substrates. It is a high-sensitivity sensor with a displacement resolution of <10pm. In this research, the photoacoustic effect of various chemicals is excited by a quantum cascade laser (QCL) with a scanning wavelength range of 6.89μm to 8.5 μm. A home-developed LDV at 1550nm wavelength is applied to detect the vibration signal. After normalize the vibration amplitude with QCL power, the photoacoustic spectrum of various chemicals can be obtained. Different factors that affect the detection accuracy and sensitivity have also been discussed. The results show the potential of the proposed technique for standoff detection of trace chemicals and explosives.

  14. Physical and Chemical Changes of Polystyrene Nanospheres Irradiated with Laser

    SciTech Connect

    Mustafa, Mohd Ubaidillah; Juremi, Nor Rashidah Md.; Mohamad, Farizan; Wibawa, Pratama Jujur; Agam, Mohd Arif; Ali, Ahmad Hadi

    2011-05-25

    It has been reported that polymer resist such as PMMA (Poly(methyl methacrylate) which is a well known and commonly used polymer resist for fabrication of electronic devices can show zwitter characteristic due to over exposure to electron beam radiation. Overexposed PMMA tend to changes their molecular structure to either become negative or positive resist corresponded to electron beam irradiation doses. These characteristic was due to crosslinking and scissors of the PMMA molecular structures, but till now the understanding of crosslinking and scissors of the polymer resist molecular structure due to electron beam exposure were still unknown to researchers. Previously we have over exposed polystyrene nanospheres to various radiation sources, such as electron beam, solar radiation and laser, which is another compound that can act as polymer resist. We investigated the physical and chemical structures of the irradiated polystyrene nanospheres with FTIR analysis. It is found that the physical and chemical changes of the irradiated polystyrene were found to be corresponded with the radiation dosages. Later, combining Laser irradiation and Reactive Ion Etching manipulation, created a facile technique that we called as LARIEA NSL (Laser and Reactive Ion Etching Assisted Nanosphere Lithography) which can be a facile technique to fabricate controllable carbonaceous nanoparticles for applications such as lithographic mask, catalysts and heavy metal absorbers.

  15. Quantum cascade laser based standoff photoacoustic chemical detection.

    PubMed

    Chen, Xing; Cheng, Liwei; Guo, Dingkai; Kostov, Yordan; Choa, Fow-Sen

    2011-10-10

    Standoff chemical detection with a distance of more than 41 feet using photoacoustic effect and quantum cascade laser (QCL) operated at relatively low power, less than 40 mW, is demonstrated for the first time. The option of using QCL provides the advantages of easy tuning and modulation besides the benefit of compact size, light weight and low power consumption. The standoff detection signal can be calibrated as a function of different parameters such as laser pulse energy, gas vapor concentration and detection distance. The results yield good agreements with theoretical model. Techniques to obtain even longer detection distance and achieve outdoor operations are in the process of implementation and their projection is discussed.

  16. Chemical analysis of surgical smoke by infrared laser spectroscopy

    NASA Astrophysics Data System (ADS)

    Gianella, Michele; Sigrist, Markus W.

    2012-11-01

    The chemical composition of surgical smoke, a gaseous by-product of some surgical devices—lasers, drills, vessel sealing devices—is of great interest due to the many toxic components that have been found to date. For the first time, surgical smoke samples collected during routine keyhole surgery were analyzed with infrared laser spectroscopy. Traces (ppm range) of methane, ethane, ethylene, carbon monoxide and sevoflurane were detected in the samples which consisted mostly of carbon dioxide and water vapor. Except for the anaesthetic sevoflurane, none of the compounds were present at dangerous concentrations. Negative effects on the health of operation room personnel can be excluded for many toxic compounds found in earlier studies, since their concentrations are below recommended exposure limits.

  17. Computation of reacting flowfield with radiation interaction in chemical lasers

    SciTech Connect

    Quan, V.; Persselin, S.F.; Yang, T.T.

    1982-01-01

    A numerical procedure has been developed to provide a rapid and stable solution of the reacting and radiating flowfield in chemical laser cavities. A marching technique, implicit in both fluid mechanics and chemistry, is employed in solving the two-dimensional mixing layer equations. The aerokinetics and radiation interaction is calculated iteratively by solving the aerokinetic equations for the gain distribution and the propagation equations for the radiation field. In the iterative solution, a linearization method which leads to enhanced numerical efficiency is employed.

  18. Innovative Laser Techniques in Chemical Kinetics: A Pedagogical Survey.

    ERIC Educational Resources Information Center

    Kovalenko, Laurie J.; Leone, Stephen R.

    1988-01-01

    Considers two types of laser applications in kinetics. Explores short laser pulses to prepare a reactant in a known state and a continuous laser as a probe to monitor specific species in a reaction. Describes how lasers work and provides several examples of kinetic reactions. (ML)

  19. Detection of chemical clouds using widely tunable quantum cascade lasers

    NASA Astrophysics Data System (ADS)

    Goyal, Anish K.; Kotidis, Petros; Deutsch, Erik R.; Zhu, Ninghui; Norman, Mark; Ye, Jim; Zafiriou, Kostas; Mazurenko, Alexander

    2015-05-01

    Widely tunable quantum cascade lasers (QCLs) spanning the long-wave infrared (LWIR) atmospheric transmission window and an HgCdTe detector were incorporated into a transceiver having a 50-mm-diameter transmit/receive aperture. The transceiver was used in combination with a 50-mm-diameter hollow retro-reflector for the open-path detection of chemical clouds. Two rapidly tunable external-cavity QCLs spanned the wavelength range of 7.5 to 12.8 m. Open-path transmission measurements were made over round-trip path-lengths of up to 562 meters. Freon-132a and other gases were sprayed into the beam path and the concentration-length (CL) product was measured as a function of time. The system exhibited a noise-equivalent concentration (NEC) of 3 ppb for Freon-132a given a round-trip path of 310 meters. Algorithms based on correlation methods were used to both identify the gases and determine their CLproducts as a function of time.

  20. Laser applications to chemical analysis: an introduction by the feature editors

    NASA Astrophysics Data System (ADS)

    Jeffries, Jay B.; Ramsey, J. Michael; Lucht, Robert P.

    1995-06-01

    This issue of Applied Optics features papers on the application of laser technology to chemical analysis. Many of the contributions, although not all, result from papers presented at the Fourth OSA Topical Meeting on Laser Applications to Chemical Analysis, which was held at Jackson Hole, Wyoming, March, 1994. This successful meeting, with nearly one hundred participants, continued the tradition of earlier LACA meetings to focus on the optical science of laser-based measurements of temperature and trace chemical assays in a wide variety of practical applications.

  1. Laser ablation of maskant used in chemical milling process for aerospace applications

    NASA Astrophysics Data System (ADS)

    Leone, C.; Lopresto, V.; Memola Capece Minutolo, F.; de Iorio, I.; Rinaldi, N.

    2010-09-01

    Chemical etching is a non-traditional machining process where a chemical solution is used to remove unwanted material by dissolution. To shape the etched area, before the process, a chemical inert paint (maskant) is applied on the surface. Then the maskant is trimmed away and the uncovered area is subject to the etching. The maskant cut could be obtained mechanically or by laser ablation. In this work, the effect of process parameters, cutting speed and beam power, on interaction phenomena and defect formation in laser cutting of polymeric maskant is studied, using a 30W CO2 laser source.

  2. Calcium fluoride windows for high-energy chemical lasers

    NASA Astrophysics Data System (ADS)

    Klein, Claude A.

    2006-10-01

    The development of high-energy lasers requires optical windows capable of handling megajoule beam energies without compromising the system's performance. Calcium fluoride (CaF2) has been identified as a prime candidate for windows operating at chemical laser wavelengths due to very low bulk absorption and exceptionally small thermal lensing coefficients; it is, however, vulnerable to structural failure owing to poor mechanical strength characteristics and a large thermal stress factor. It is, therefore, essential to properly assess the ultimate potential of this material, which we attempt to do here in the following manner: (a) We assemble reliable numbers for all pertinent properties of (111)-oriented CaF2 single crystals and polycrystalline isotropic aggregates (PIAs), such as fusion-cast CaF2, which requires addressing issues relating to the elastic properties, the stress-optic coefficients, and the flexural strength. (b) We provide correct analytical expressions for evaluating the impact of pressure- and beam-induced effects on wave-front phase distortions and mechanical failure modes, taking advantage of a previous investigation [J. Appl. Phys. 98, 043103 (2005)]. (c) We perform detailed calculations on "model" windows made of either (111)CaF2 or (PIA )CaF2 that transmit optimally truncated Gaussian beams at wavelengths of 1.15 and 3.39μm, for run times such that lateral heat conduction and surface cooling can be ignored. Our main conlusions are as follows: (a) With CaF2 windows thermal lensing, as measured in terms of the Strehl ratio and on assuming coating absorptances of no more than 3×10-5, is of no consequence in the sense that catastrophic failure may occur at fluence levels way below the threshold for optical distortion. (b) Evidence of a poor Weibull shape factor (m ≃3.5) degrades the design safety margins, which requires operating at peak intensities of no more than 100kW/cm2 to achieve optimum on-target fluences. (c) Regarding the issue of (111

  3. Fast infrared chemical imaging with a quantum cascade laser.

    PubMed

    Yeh, Kevin; Kenkel, Seth; Liu, Jui-Nung; Bhargava, Rohit

    2015-01-01

    Infrared (IR) spectroscopic imaging systems are a powerful tool for visualizing molecular microstructure of a sample without the need for dyes or stains. Table-top Fourier transform infrared (FT-IR) imaging spectrometers, the current established technology, can record broadband spectral data efficiently but requires scanning the entire spectrum with a low throughput source. The advent of high-intensity, broadly tunable quantum cascade lasers (QCL) has now accelerated IR imaging but results in a fundamentally different type of instrument and approach, namely, discrete frequency IR (DF-IR) spectral imaging. While the higher intensity of the source provides a higher signal per channel, the absence of spectral multiplexing also provides new opportunities and challenges. Here, we couple a rapidly tunable QCL with a high performance microscope equipped with a cooled focal plane array (FPA) detector. Our optical system is conceptualized to provide optimal performance based on recent theory and design rules for high-definition (HD) IR imaging. Multiple QCL units are multiplexed together to provide spectral coverage across the fingerprint region (776.9 to 1904.4 cm(-1)) in our DF-IR microscope capable of broad spectral coverage, wide-field detection, and diffraction-limited spectral imaging. We demonstrate that the spectral and spatial fidelity of this system is at least as good as the best FT-IR imaging systems. Our configuration provides a speedup for equivalent spectral signal-to-noise ratio (SNR) compared to the best spectral quality from a high-performance linear array system that has 10-fold larger pixels. Compared to the fastest available HD FT-IR imaging system, we demonstrate scanning of large tissue microarrays (TMA) in 3-orders of magnitude smaller time per essential spectral frequency. These advances offer new opportunities for high throughput IR chemical imaging, especially for the measurement of cells and tissues.

  4. Fast Infrared Chemical Imaging with a Quantum Cascade Laser

    PubMed Central

    2015-01-01

    Infrared (IR) spectroscopic imaging systems are a powerful tool for visualizing molecular microstructure of a sample without the need for dyes or stains. Table-top Fourier transform infrared (FT-IR) imaging spectrometers, the current established technology, can record broadband spectral data efficiently but requires scanning the entire spectrum with a low throughput source. The advent of high-intensity, broadly tunable quantum cascade lasers (QCL) has now accelerated IR imaging but results in a fundamentally different type of instrument and approach, namely, discrete frequency IR (DF-IR) spectral imaging. While the higher intensity of the source provides a higher signal per channel, the absence of spectral multiplexing also provides new opportunities and challenges. Here, we couple a rapidly tunable QCL with a high performance microscope equipped with a cooled focal plane array (FPA) detector. Our optical system is conceptualized to provide optimal performance based on recent theory and design rules for high-definition (HD) IR imaging. Multiple QCL units are multiplexed together to provide spectral coverage across the fingerprint region (776.9 to 1904.4 cm–1) in our DF-IR microscope capable of broad spectral coverage, wide-field detection, and diffraction-limited spectral imaging. We demonstrate that the spectral and spatial fidelity of this system is at least as good as the best FT-IR imaging systems. Our configuration provides a speedup for equivalent spectral signal-to-noise ratio (SNR) compared to the best spectral quality from a high-performance linear array system that has 10-fold larger pixels. Compared to the fastest available HD FT-IR imaging system, we demonstrate scanning of large tissue microarrays (TMA) in 3-orders of magnitude smaller time per essential spectral frequency. These advances offer new opportunities for high throughput IR chemical imaging, especially for the measurement of cells and tissues. PMID:25474546

  5. Fast infrared chemical imaging with a quantum cascade laser.

    PubMed

    Yeh, Kevin; Kenkel, Seth; Liu, Jui-Nung; Bhargava, Rohit

    2015-01-01

    Infrared (IR) spectroscopic imaging systems are a powerful tool for visualizing molecular microstructure of a sample without the need for dyes or stains. Table-top Fourier transform infrared (FT-IR) imaging spectrometers, the current established technology, can record broadband spectral data efficiently but requires scanning the entire spectrum with a low throughput source. The advent of high-intensity, broadly tunable quantum cascade lasers (QCL) has now accelerated IR imaging but results in a fundamentally different type of instrument and approach, namely, discrete frequency IR (DF-IR) spectral imaging. While the higher intensity of the source provides a higher signal per channel, the absence of spectral multiplexing also provides new opportunities and challenges. Here, we couple a rapidly tunable QCL with a high performance microscope equipped with a cooled focal plane array (FPA) detector. Our optical system is conceptualized to provide optimal performance based on recent theory and design rules for high-definition (HD) IR imaging. Multiple QCL units are multiplexed together to provide spectral coverage across the fingerprint region (776.9 to 1904.4 cm(-1)) in our DF-IR microscope capable of broad spectral coverage, wide-field detection, and diffraction-limited spectral imaging. We demonstrate that the spectral and spatial fidelity of this system is at least as good as the best FT-IR imaging systems. Our configuration provides a speedup for equivalent spectral signal-to-noise ratio (SNR) compared to the best spectral quality from a high-performance linear array system that has 10-fold larger pixels. Compared to the fastest available HD FT-IR imaging system, we demonstrate scanning of large tissue microarrays (TMA) in 3-orders of magnitude smaller time per essential spectral frequency. These advances offer new opportunities for high throughput IR chemical imaging, especially for the measurement of cells and tissues. PMID:25474546

  6. Laser Applications to Chemical, Security, and Environmental Analysis: introduction to the feature issue

    SciTech Connect

    Dreizler, Andreas; Fried, Alan; Gord, James R

    2007-07-01

    This Applied Optics feature issue on Laser Applications to Chemical, Security,and Environmental Analysis (LACSEA) highlights papers presented at theLACSEA 2006 Tenth Topical Meeting sponsored by the Optical Society ofAmerica.

  7. Optimization of an External Cavity Quantum Cascade Laser for Chemical Sensing Applications

    SciTech Connect

    Phillips, Mark C.; Bernacki, Bruce E.; Taubman, Matthew S.; Cannon, Bret D.; Schiffern, John T.; Myers, Tanya L.

    2010-03-01

    We describe and characterize an external cavity quantum cascade laser designed for detection of multiple airborne chemicals, and used with a compact astigmatic Herriott cell for sensing of acetone and hydrogen peroxide.

  8. [Effects of helium-neon laser on physico-chemical properties of the bile].

    PubMed

    Mansurov, Kh Kh; Dzhuraev, Kh Sh; Barakaev, S B; Kharina, T P; Pulatov, L I

    1990-08-01

    The influence of helium-neon laser radiation on bile physico-chemical characteristics in healthy subjects and in patients with the physico-chemical stage of gallstone disease was studied in vitro. This type of laser was found to induce positive therapeutic effects, such as: correction of hydrogen ion concentrations, surface tension and viscosity decrease and prolonged bile nucleation in patients with gallstone disease.

  9. Ultrafast laser induced breakdown spectroscopy for high spatial resolution chemical analysis

    NASA Astrophysics Data System (ADS)

    Zorba, Vassilia; Mao, Xianglei; Russo, Richard E.

    2011-02-01

    Femtosecond laser induced breakdown spectroscopy (LIBS) was used to identify the spatial resolution limitations and assess the minimal detectable mass restrictions in laser-ablation based chemical analysis. The atomic emission of sodium (Na) and potassium (K) dopants in transparent dielectric Mica matrices was studied, to find that both these elements could be detected from 450 nm diameter ablation craters, full-width-at-half-maximum (FWHM). Under optimal conditions, mass as low as 220 ag was measured, demonstrating the feasibility of using laser-ablation based chemical analysis to achieve high spatial resolution elemental analysis in real-time and at atmospheric pressure conditions.

  10. Quantum Cascade Laser Development Efforts for Implementation into Chemical and Remote Sensing Systems

    SciTech Connect

    Wojcik, Michael D.; Myers, Tanya L.; Taubman, Matthew S.; Cannon, Bret D.; Broocks, Bryan T.; Mosely, Trinesha

    2004-12-01

    Quantum cascade lasers (QCL) offer many desirable attributes as mid-infrared laser sources for chemical and remote sensing. Some key advantages are a narrow linewidth, wide bandwidth current modulation characteristics and moderate tunability (15 cm-1). Combined, these characteristics allow for applications to a wide variety of chemical and remote sensing techniques such as wavelength and frequency modulation based detection techniques, cavity enhanced point sensors as well as techniques such as LIDAR and DIAL. This paper will describe laser development efforts to enhance QCL frequency stabilization and QCL injection locking and to develop robust external cavity QCL designs.

  11. Gas dynamics of the active medium of a supersonic cw HF chemical laser

    SciTech Connect

    Fedorov, Igor' A; Rotinyan, Mikhail A; Krivitskii, A M

    2000-12-31

    Gas-dynamic characteristics of a 5-kW supersonic cw HF chemical laser with a nozzle array of size 25 cm x 2.8 cm and the nozzle - nozzle mixing scheme were experimentally studied. The distributions of Mach numbers, static pressure, total pressure behind the normal shock, and the loss of total pressure were measured in the flow of an active medium in wide ranges of variation of the flow rate of secondary fuel (hydrogen) and pressure in the atomic-fluorine generator. The energy parameters of the laser were found to be interrelated with the gas dynamics and the optical quality of the active laser medium. (lasers)

  12. Simulation of a two-frequency cw chemical HF-HBr laser

    SciTech Connect

    Aleksandrov, B P; Katorgin, B I; Stepanov, A A

    2008-10-31

    An autonomous cw chemical HF-HBr laser emitting simultaneously at {approx}2.7 {mu}m (HF molecules) and {approx}4.2 {mu}m (HBr molecules) is studied numerically by using complete Navier-Stokes equations. It is shown that the output power of the HBr laser per unit area of the nozzle array can achieve {approx}20 W cm{sup -2} for the laser region length {approx}20 cm. The relation between the radiation intensities emitted by HF and HBr molecules is controlled by diluting the secondary fuel by bromine. (lasers)

  13. Analysis of the optical extraction efficiency in gas-flow lasers with different types of resonator.

    PubMed

    Barmashenko, B D; Rosenwaks, S

    1996-12-20

    The celebrated Rigrod model [J. Appl. Phys. 34, 2602 (1963)] has recently been shown to be inadequate for calculating the output power of gas-flow lasers when the quenching of excited species is slow and the optical extraction efficiency is high [Opt. Lett. 20, 1480 (1995)]. The previous analysis of two-level systems is presented here in detail and extended to include the chemical oxygen-iodine laser (COIL). For both two-level systems and COIL's, we obtained simple analytic formulas for the output power, which should be used instead of the Rigrod model. We present the formulas for Fabry-Perot, stable, and unstable resonators. Both the saturation parameter and the extraction efficiency differ from those appearing in the Rigrod model. The highest extraction efficiency is achievable for both stable and unstable resonators with uniform intensity distribution over the resonator cross section and is greater than that calculated by the Rigrod model. A rather surprising conclusion is that the extraction efficiency of unstable resonators can be increased substantially if one increases the length of the part of the mirrors lying downstream of the optical axis. The derived formulas are applied to describe published experimental results of supersonic COIL's. The dependence of the power on the threshold gain is evaluated and from this the plenum yield of singlet oxygen is estimated. The value of the yield is in better agreement with experimental measurements than that obtained by the Rigrod model. PMID:21151313

  14. Tooth bleaching using three laser systems, halogen-light unit, and chemical action agents

    NASA Astrophysics Data System (ADS)

    Dostalova, Tatjana; Jelinkova, Helena; Housova, Devana; Sulc, Jan; Nemec, Michal; Koranda, Petr; Miyagi, Mitsunobu; Shi, Yi-Wei; Matsuura, Yuji

    2004-09-01

    μThe study describes the preclinical experience with laser-activated bleaching agent for discolored teeth. Extracted human upper central incisors were selected, and in the bleaching experiment 35% hydrogen peroxide was used. Three various laser systems and halogen-light unit for activation of the bleaching agent were applied. They were Alexandrite laser (wavelength 750 nm and 375 nm - SHG), Nd:YAG laser (wavelength 1.064 m), and Er:YAG laser (wavelength 2.94 μm). The halogen-light unit was used in a standard regime. The enamel surface was analyzed in the scanning electron microscope. The method of chemical oxidation results in a 2-3 shade change in one treatment. The halogen-light units produced the same effect with shorter time of bleaching process (from 630 s to 300 s). The Alexandrite laser (750 nm) and bleaching agent helped to reach the desired color shade after a shorter time (400 s). Alexandrite laser (375 nm) and Nd:YAG laser had no effect on the longevity of the process of bleaching. Overheating of the chemical bleaching agent was visible after Er:YAG laser activation (195 s). Slight surface modification after bleaching process was detected in SEM.

  15. Laser-machined components for microanalytical and chemical separation devices

    NASA Astrophysics Data System (ADS)

    Matson, Dean W.; Martin, Peter M.; Bennett, Wendy D.

    1998-10-01

    Excimer lasers have proven to be powerful tools for machining polymeric components used in microanalytical and microchemical separation devices. We report the use of laser machining methods to produce microfluidic channels and liquid/liquid contact membranes for a number of devices fabricated at our laboratory. Microchannels 50- to 100- micrometers -wide have been produced directly in bulk polycarbonate chips using a direct-write laser micromachining system. Wider microchannels have been produced by laser machining paths through sheets of polyimide film, then sandwiching the patterned piece between solid chips of polycarbonate stock. A comparison of direct-write and mask machining processes used to produce some of the microfluidic features is made. Examples of microanalytical devices produced using these methods are presented. Included are microdialysis units used to remove electrolytes from liquid samples and electrophoretic separation devices, both used for extremely low volume samples intended for mass spectrometric analysis. A multilayered microfluidic device designed to analyze low volume groundwater samples for hazardous metals and a fluidics motherboard are also described. Laser machining processes have also been explored for producing polymeric membranes suitable for use in liquid/liquid contactors used for removal of soluble hazardous components from waste streams. A step-and-repeat mask machining process was used to produce 0.5 X 8 cm membranes in 25- and 50-micrometers -thick polyimide. Pore diameters produced using this method were five and ten micrometers. The laser machined membranes were sputter coated with PTFE prior to use to improve fluid breakthrough characteristics.

  16. IR LASER BASED CHEMICAL SENSOR FOR THE COOPERATIVE MONITORING PROGRAM

    SciTech Connect

    Edward A Whitaker

    2005-08-08

    The purpose of this project was to investigate the device properties of the quantum cascade laser (QCL), a type of laser invented at Bell Laboratories, Lucent Technologies in the device physics research lab of Dr. Federico Capasso and more specifically to determine the remote sensing capability of this device. The PI and Stevens Institute of Technology collaborated with Dr. Capasso and Bell Laboratories to carry out this research project. The QCL is a unique laser source capable of generating laser radiation in the middle-infrared spectral region that overlaps the most important molecular absorption bands. With appropriate modulation techniques it is possible to use the laser to measure the concentration of many molecules of interest to the remote sensing community. In addition, the mid-IR emission wavelength is well suited to atmospheric transmission as mid-IR experiences much less scattering due to dust and fog. At the onset of this project little was known about several key device performance parameters of this family of lasers and the NNSA supported research enabled them to determine values of several of these characteristics.

  17. CO2 laser scribe of chemically strengthened glass with high surface compressive stress

    NASA Astrophysics Data System (ADS)

    Li, Xinghua; Vaddi, Butchi R.

    2011-03-01

    Chemically strengthened glass is finding increasing use in handheld, IT and TV cover glass applications. Chemically strengthened glass, particularly with high (>600MPa) compressive stress (CS) and deeper depth of layer (DOL), enable to retain higher strength after damage than non-strengthened glass when its surface is abraded. Corning Gorilla® Glass has particularly proven to be advantageous over competition in this attribute. However, due to high compressive stress (CS) and Central Tension (CT) cutting ion-exchanged glass is extremely difficult and often unmanageable where ever the applications require dicing the chemically strengthened mother glass into smaller parts. We at Corning have developed a CO2 laser scribe and break method (LSB) to separate a single chemically strengthened glass sheet into plurality of devices. Furthermore, CO2 laser scribe and break method enables debris-free separation of glass with high edge strength due to its mirror-like edge finish. We have investigated laser scribe and break of chemically strengthened glass with surface compressive stress greater than 600 MPa. In this paper we present the results of CO2 scribe and break method and underlying laser scribing mechanisms. We demonstrated cross-scribe repetitively on GEN 2 size chemically strengthened glass substrates. Specimens for edge strength measurements of different thickness and CS/DOL glass were prepared using the laser scribe and break technique. The specimens were tested using the standard 4-point bend method and the results are presented.

  18. Preparation of γ-Al2O3 films by laser chemical vapor deposition

    NASA Astrophysics Data System (ADS)

    Gao, Ming; Ito, Akihiko; Goto, Takashi

    2015-06-01

    γ- and α-Al2O3 films were prepared by chemical vapor deposition using CO2, Nd:YAG, and InGaAs lasers to investigate the effects of varying the laser wavelength and deposition conditions on the phase composition and microstructure. The CO2 laser was found to mostly produce α-Al2O3 films, whereas the Nd:YAG and InGaAs lasers produced γ-Al2O3 films when used at a high total pressure. γ-Al2O3 films had a cauliflower-like structure, while the α-Al2O3 films had a dense and columnar structure. Of the three lasers, it was the Nd:YAG laser that interacted most with intermediate gas species. This promoted γ-Al2O3 nucleation in the gas phase at high total pressure, which explains the cauliflower-like structure of nanoparticles observed.

  19. Chemical Bond Activation Observed with an X-ray Laser.

    PubMed

    Beye, Martin; Öberg, Henrik; Xin, Hongliang; Dakovski, Georgi L; Dell'Angela, Martina; Föhlisch, Alexander; Gladh, Jörgen; Hantschmann, Markus; Hieke, Florian; Kaya, Sarp; Kühn, Danilo; LaRue, Jerry; Mercurio, Giuseppe; Minitti, Michael P; Mitra, Ankush; Moeller, Stefan P; Ng, May Ling; Nilsson, Anders; Nordlund, Dennis; Nørskov, Jens; Öström, Henrik; Ogasawara, Hirohito; Persson, Mats; Schlotter, William F; Sellberg, Jonas A; Wolf, Martin; Abild-Pedersen, Frank; Pettersson, Lars G M; Wurth, Wilfried

    2016-09-15

    The concept of bonding and antibonding orbitals is fundamental in chemistry. The population of those orbitals and the energetic difference between the two reflect the strength of the bonding interaction. Weakening the bond is expected to reduce this energetic splitting, but the transient character of bond-activation has so far prohibited direct experimental access. Here we apply time-resolved soft X-ray spectroscopy at a free-electron laser to directly observe the decreased bonding-antibonding splitting following bond-activation using an ultrashort optical laser pulse. PMID:27584914

  20. Chemical detection and laser wavelength stabilization employing spectroscopic absorption via laser compliance voltage sensing

    DOEpatents

    Taubman, Matthew S.; Phillips, Mark C.

    2016-01-12

    Systems and methods are disclosed that provide a direct indication of the presence and concentration of an analyte within the external cavity of a laser device that employ the compliance voltage across the laser device. The systems can provide stabilization of the laser wavelength. The systems and methods can obviate the need for an external optical detector, an external gas cell, or other sensing region and reduce the complexity and size of the sensing configuration.

  1. Chemical detection and laser wavelength stabilization employing spectroscopic absorption via laser compliance voltage sensing

    DOEpatents

    Taubman, Matthew S; Phillips, Mark C

    2014-03-18

    Systems and methods are disclosed that provide a direct indication of the presence and concentration of an analyte within the external cavity of a laser device that employ the compliance voltage across the laser device. The systems can provide stabilization of the laser wavelength. The systems and methods can obviate the need for an external optical detector, an external gas cell, or other sensing region and reduce the complexity and size of the sensing configuration.

  2. About possibilities of clearing near-Earth space from dangerous debris by a spaceborne laser system with an autonomous cw chemical HF laser

    SciTech Connect

    Avdeev, A V; Bashkin, A S; Katorgin, Boris I; Parfen'ev, M V

    2011-07-31

    The possibility of clearing hazardous near-Earth space debris using a spaceborne laser station with a large autonomous cw chemical HF laser is substantiated and the requirements to its characteristics (i.e., power and divergence of laser radiation, pulse duration in the repetitively pulsed regime, repetition rate and total time of laser action on space debris, necessary to remove them from the orbits of the protected spacecrafts) are determined. The possibility of launching the proposed spaceborne laser station to the orbit with the help of a 'Proton-M' carrier rocket is considered. (laser applications)

  3. Physico-Chemical Dynamics of Nanoparticle Formation during Laser Decontamination

    SciTech Connect

    Cheng, M.D.

    2005-06-01

    Laser-ablation based decontamination is a new and effective approach for simultaneous removal and characterization of contaminants from surfaces (e.g., building interior and exterior walls, ground floors, etc.). The scientific objectives of this research are to: (1) characterize particulate matter generated during the laser-ablation based decontamination, (2) develop a technique for simultaneous cleaning and spectroscopic verification, and (3) develop an empirical model for predicting particle generation for the size range from 10 nm to tens of micrometers. This research project provides fundamental data obtained through a systematic study on the particle generation mechanism, and also provides a working model for prediction of particle generation such that an effective operational strategy can be devised to facilitate worker protection.

  4. In situ chemical composition measurements with a miniature laser ablation mass spectrometer for planetary exploration

    NASA Astrophysics Data System (ADS)

    Neuland, M. B.; Meyer, S.; Mezger, K.; Riedo, A.; Tulej, M.; Wurz, P.

    2013-09-01

    We present a miniature laser ablation mass spectrometer (LMS) for planetary and space research. For demonstrating the performance of the instrument, a sample of Allende meteorite is investigated as an analogue to a planetary surface. Investigation of a very inhomogeneous structure like the surface of a chondritic meteorite requires high spatially resolved data of chemical content, elemental and isotopic. We measure the composition of the Allende meteorite and show that by using a ns-laser for ablation, elemental analysis is accomplished with high quality allowing to study the mineralogy. The results will be compared to measurements using a fs-laser system to show improvements of the technique.

  5. Ultrasensitive standoff chemical sensing based on nonlinear multi-photon laser wave-mixing spectroscopy

    NASA Astrophysics Data System (ADS)

    Gregerson, Marc; Hetu, Marcel; Iwabuchi, Manna; Jimenez, Jorge; Warren, Ashley; Tong, William G.

    2012-10-01

    Nonlinear multi-photon laser wave mixing is presented as an ultrasensitive optical detection method for chem/bio agents in thin films and gas- and liquid-phase samples. Laser wave mixing is an unusually sensitive optical absorption-based detection method that offers significant inherent advantages including excellent sensitivity, small sample requirements, short optical path lengths, high spatial resolution, high spectral resolution and standoff remote detection capability. Wave mixing can detect trace amounts of chemicals even when using micrometer-thin samples, and hence, it can be conveniently interfaced to fibers, microarrays, microfluidic systems, lab-on-a-chip, capillary electrophoresis and other capillary- or fiber-based chemical separation systems. The wave-mixing signal is generated instantaneously as the two input laser beams intersect inside the analyte of interest. Laser excitation wavelengths can be tuned to detect multiple chemicals in their native form since wave mixing can detect both fluorescing and non-fluorescing samples at parts-pertrillion or better detection sensitivity levels. The wave-mixing signal is a laser-like coherent beam, and hence, it allows reliable and effective remote sensing of chemicals. Sensitive wave-mixing detectors offer many potential applications including sensitive detection of biomarkers, early detection of diseases, sensitive monitoring of environmental samples, and reliable detection of hazardous chem/bio agents with a standoff detection capability.

  6. LDRD final report on high power broadly tunable Mid-IR quantum cascade lasers for improved chemical species detection.

    SciTech Connect

    Wanke, Michael Clement; Hudgens, James J.; Fuller, Charles T.; Samora, Sally; Klem, John Frederick; Young, Erik W.

    2006-01-01

    The goal of our project was to examine a novel quantum cascade laser design that should inherently increase the output power of the laser while simultaneously providing a broad tuning range. Such a laser source enables multiple chemical species identification with a single laser and/or very broad frequency coverage with a small number of different lasers, thus reducing the size and cost of laser based chemical detection systems. In our design concept, the discrete states in quantum cascade lasers are replaced by minibands made of multiple closely spaced electron levels. To facilitate the arduous task of designing miniband-to-miniband quantum cascade lasers, we developed a program that works in conjunction with our existing modeling software to completely automate the design process. Laser designs were grown, characterized, and iterated. The details of the automated design program and the measurement results are summarized in this report.

  7. Initiation of the emission of chemical gas lasers by neutron fluxes

    NASA Astrophysics Data System (ADS)

    Basov, N. G.; Molchanov, A. G.; Oraevskii, A. N.

    The possibility of initiating chemical lasers through a nuclear reaction is examined, and the required threshold density of a neutron flux is determined. In particular, attention is given to the conditions of lasing using UF6-H2, UF6-H2-F2, and UF6-D2-F2-CO2 mixtures in the case of a branched chain reaction. The possibility of chemical laser initiation using UF-containing mixtures, without any external neutron source, is demonstrated for the case where the total mass of the UF6 gas containing enriched uranium exceeds the critical mass.

  8. Sub-nanometrically resolved chemical mappings of quantum-cascade laser active regions

    NASA Astrophysics Data System (ADS)

    Pantzas, Konstantinos; Beaudoin, Grégoire; Patriarche, Gilles; Largeau, Ludovic; Mauguin, Olivia; Pegolotti, Giulia; Vasanelli, Angela; Calvar, Ariane; Amanti, Maria; Sirtori, Carlo; Sagnes, Isabelle

    2016-05-01

    A procedure that produces sub-nanometrically resolved chemical mappings of MOCVD-grown InGaAs/InAlAs/InP quantum cascade lasers is presented. The chemical mappings reveal that, although the structure is lattice-matched to InP, the InAlAs barriers do not attain the nominal aluminum content—48%—and are, in fact, InGaAlAs quaternaries. This information is used to adjust the aluminum precursor flow and fine-tune the composition of the barriers, resulting in a significant improvement of the fabricated lasers.

  9. Concepts of risk assesment of complex chemical mixtures in laser pyrolysis fumes

    NASA Astrophysics Data System (ADS)

    Weber, Lothar W.; Meier, Thomas H.

    1996-01-01

    Laser-tissue interaction may generate by energy absorption a complex mixture of gaseous, volatile, semi-volatile and particular substances. At the time about 150 different components are known from IR-laser interaction with different organ tissues like liver, fat, muscle and skin. The laser-tissue interaction process thereby is dominated by heating processes, which is confirmed by the similarity of formed chemical products in comparison with conventional cooking processes for food preparation. With the identified chemical substances and relative amounts in backmind a walk along the think path of risk assessment with special reference to pyrolysis products is given. The main way of intake of pyrolysis products is the inhalative one, which results from the fine aerosols formed and the high spreading energy out of the irradiated source. The liberated amounts of irritative chemicals as (unsaturated) aldehydes, heterocycles of bad odor and possibly cancerogenic acting substances relates to some (mu) g/g of laser vaporized tissue. With regard to this exposure level in a hypothetic one cubic meter volume the occupational limit settings are far away. Even indoor air exposure levels are in nearly all cases underwent, for the content of bad smelling substances forces an effective ventilation. Up to now no laser typical chemical substance could be identified, which was not elsewhere known by frying or baking processes of meat, food or familiar. Starting with the GRAS concept of 1957 the process of risk assessment by modified food products and new ingredients is still improofing. The same process of risk assessment is governing the laser pyrolysis products of mammalian tissues. By use of sufficient suction around the laser tissue source the odor problems as well as the toxicological problems could be solved.

  10. PPLN laser-based system for chemical imaging

    NASA Astrophysics Data System (ADS)

    Ludowise, Peter D.; Ottesen, David K.; Kulp, Thomas J.; Goers, Uta-Barbara; Celina, M.; Armstrong, K.; Allendorf, Sarah W.

    1999-10-01

    An infrared-imaging instrument is being developed to provide in situ qualitative and quantitative assessment of hydrocarbon contaminants on metallic surfaces for cleaning verification. A continuous-wave infrared optical parametric oscillator (OPO), based on the quasi-phasematched material periodically poled lithium niobate (PPLN), is interfaced with an InSb focal plane array camera to perform fast, non-invasive analysis by reflectance spectroscopy. The period range of the designed fan-out PPLN crystal determines the range of the output wavelength of the light source. It is able to scan hundreds of wavenumbers positioned in the range of 2820 - 3250 cm-1, which is sufficient to detect functional groups of common organic compounds (-CH, -OH, and -NH). The capability of the instrument has been demonstrated in a preliminary investigation of reflectance measurements for hydrocarbon solvents (methanol and d-limonene) on an aluminum surface. A substantial difference in absorption is obtained for the two solvents at two different laser-illumination wavelengths, thus permitting hydrocarbon detection and molecular species differentiation. Preliminary reflectance spectra of a mixture of aliphatic hydrocarbon lubricants and drawing agents on an aluminum panel are also presented. The relative thickness of the hydrocarbon thin film is determined by the intensity ratio of images acquired at two different laser illumination frequencies.

  11. Optical far- and near-field femtosecond laser ablation of Si for nanoscale chemical analysis.

    PubMed

    Zorba, Vassilia; Mao, Xianglei; Russo, Richard E

    2010-01-01

    Extending spatial resolution in laser-based chemical analysis to the nanoscale becomes increasingly important as nanoscience and nanotechnology develop. Implementation of femtosecond laser pulses arises as a basic strategy for increasing resolution since it is associated with spatially localized material damage. In this work we study femtosecond laser far- and near-field processing of silicon (Si) at two distinct wavelengths (400 and 800 nm), for nanoscale chemical analysis. By tightly focusing femtosecond laser beams in the far-field, we were able to produce sub-micrometer craters. In order to further reduce the crater size, similar experiments were performed in the near-field through sub-wavelength apertures, resulting in the formation of sub-30-nm craters. Laser-induced breakdown spectroscopy (LIBS) was used for chemical analysis with a goal to identify the minimum crater size from which spectral emission could be measured. Emission from sub-micrometer craters (full width at half maximum) was possible, which are among the smallest ever reported for femtosecond LIBS. PMID:19787342

  12. Optical far- and near-field femtosecond laser ablation of Si for nanoscale chemical analysis

    SciTech Connect

    Zormpa, Vasileia; Mao, Xianglei; Russo, Richard E.

    2010-02-02

    Extending spatial resolution in laser-based chemical analysis to the nanoscale becomes increasingly important as nanoscience and nanotechnology develop. Implementation of femtosecond laser pulses arises as a basic strategy for increasing resolution since it is associated with spatially localized material damage. In this work we study femtosecond laser far- and near-field processing of silicon (Si) at two distinct wavelengths (400 and 800 nm), for nanoscale chemical analysis. By tightly focusing femtosecond laser beams in the far-field we were able to produce sub-micrometer craters. In order to further reduce the crater size, similar experiments were performed in the near-field through sub-wavelength apertures, resulting to the formation of sub-30 nm craters. Laser Induced Breakdown Spectroscopy (LIBS) was used for chemical analysis with a goal to identify the minimum crater size from which spectral emission could be measured. Emission from sub-micrometer craters (full-with-at-half-maximum) was possible, which are among the smallest ever reported for femtosecond LIBS.

  13. Preventing, identifying, and managing cosmetic procedure complications, part 2: lasers and chemical peels.

    PubMed

    Brown, Megan

    2016-08-01

    Part 1 of this series highlighted some of the potential complications that have been associated with soft tissue augmentation and botulinum toxin injections. In part 2, tips for how dermatology residents may prevent, identify, and manage complications from lasers and chemical peels for optimal patient outcomes are provided. PMID:27622266

  14. Laser/Plasma/Chemical-Vapor Deposition Of Diamond

    NASA Technical Reports Server (NTRS)

    Hsu, George C.

    1989-01-01

    Proposed process for deposition of diamond films includes combination of plasma induced in hydrocarbon feed gas by microwave radiation and irradiation of plasma and substrate by lasers. Deposition of graphite suppressed. Reaction chamber irradiated at wavelength favoring polymerization of CH2 radical into powders filtered out of gas. CH3 radicals, having desired sp3 configuration, remains in gas to serve as precursors for deposition. Feed gas selected to favor formation of CH3 radicals; candidates include CH4, C2H4, C2H2, and C2H6. Plasma produced by applying sufficient power at frequency of 2.45 GHz and adjusting density of gas to obtain electron kinetic energies around 100 eV in low-pressure, low-temperature regime.

  15. Generation of cavitation luminescence by laser-induced exothermic chemical reaction

    SciTech Connect

    Jung Park, Han; Diebold, Gerald J.

    2013-08-14

    Absorption of high power laser radiation by aqueous carbon suspensions is known to result in the formation of highly compressed bubbles of hydrogen and carbon monoxide through the endothermic carbon-steam reaction. The bubbles expand rapidly, overreaching their equilibrium diameter, and then collapse tens to hundreds of microseconds after formation to give a flash of radiation. Here we report on the effects of laser-initiated exothermic chemical reaction on cavitation luminescence. Experiments with hydrogen peroxide added to colloidal carbon suspensions show that both the time of the light flash following the laser pulse and the intensity of luminescence increase with hydrogen peroxide concentration, indicating that large, highly energetic gas bubbles are produced. Additional experiments with colloidal carbon suspensions show the effects of high pressure on the luminescent intensity and its time of appearance following firing of the laser.

  16. Laser Microdissection and Atmospheric Pressure Chemical Ionization Mass Spectrometry Coupled for Multimodal Imaging

    SciTech Connect

    Lorenz, Matthias; Ovchinnikova, Olga S; Kertesz, Vilmos; Van Berkel, Gary J

    2013-01-01

    This paper describes the coupling of ambient laser ablation surface sampling, accomplished using a laser capture microdissection system, with atmospheric pressure chemical ionization mass spectrometry for high spatial resolution multimodal imaging. A commercial laser capture microdissection system was placed in close proximity to a modified ion source of a mass spectrometer designed to allow for sampling of laser ablated material via a transfer tube directly into the ionization region. Rhodamine 6G dye of red sharpie ink in a laser etched pattern as well as cholesterol and phosphatidylcholine in a cerebellum mouse brain thin tissue section were identified and imaged from full scan mass spectra. A minimal spot diameter of 8 m was achieved using the 10X microscope cutting objective with a lateral oversampling pixel resolution of about 3.7 m. Distinguishing between features approximately 13 m apart in a cerebellum mouse brain thin tissue section was demonstrated in a multimodal fashion including co-registered optical and mass spectral chemical images.

  17. Duration of an intense laser pulse can determine the breakage of multiple chemical bonds.

    PubMed

    Xie, Xinhua; Lötstedt, Erik; Roither, Stefan; Schöffler, Markus; Kartashov, Daniil; Midorikawa, Katsumi; Baltuška, Andrius; Yamanouchi, Kaoru; Kitzler, Markus

    2015-08-14

    Control over the breakage of a certain chemical bond in a molecule by an ultrashort laser pulse has been considered for decades. With the availability of intense non-resonant laser fields it became possible to pre-determine femtosecond to picosecond molecular bond breakage dynamics by controlled distortions of the electronic molecular system on sub-femtosecond time scales using field-sensitive processes such as strong-field ionization or excitation. So far, all successful demonstrations in this area considered only fragmentation reactions, where only one bond is broken and the molecule is split into merely two moieties. Here, using ethylene (C2H4) as an example, we experimentally investigate whether complex fragmentation reactions that involve the breakage of more than one chemical bond can be influenced by parameters of an ultrashort intense laser pulse. We show that the dynamics of removing three electrons by strong-field ionization determines the ratio of fragmentation of the molecular trication into two respectively three moieties. We observe a relative increase of two-body fragmentations with the laser pulse duration by almost an order of magnitude. Supported by quantum chemical simulations we explain our experimental results by the interplay between the dynamics of electron removal and nuclear motion.

  18. Chemical imaging of latent fingerprints by mass spectrometry based on laser activated electron tunneling.

    PubMed

    Tang, Xuemei; Huang, Lulu; Zhang, Wenyang; Zhong, Hongying

    2015-03-01

    Identification of endogenous and exogenous chemicals contained in latent fingerprints is important for forensic science in order to acquire evidence of criminal identities and contacts with specific chemicals. Mass spectrometry has emerged as a powerful technique for such applications without any derivatization or fluorescent tags. Among these techniques, MALDI (Matrix Assisted Laser Desorption Ionization) provides small beam size but has interferences with MALDI matrix materials, which cause ion suppressions as well as limited spatial resolution resulting from uneven distribution of MALDI matrix crystals with different sizes. LAET (Laser Activated Electron Tunneling) described in this work offers capabilities for chemical imaging through electron-directed soft ionization. A special film of semiconductors has been designed for collection of fingerprints. Nanoparticles of bismuth cobalt zinc oxide were compressed on a conductive metal substrate (Al or Cu sticky tape) under 10 MPa pressure. Resultant uniform thin films provide tight and shining surfaces on which fingers are impressed. Irradiation of ultraviolet laser pulses (355 nm) on the thin film instantly generates photoelectrons that can be captured by adsorbed organic molecules and subsequently cause electron-directed ionization and fragmentation. Imaging of latent fingerprints is achieved by visualization of the spatial distribution of these molecular ions and structural information-rich fragment ions. Atomic electron emission together with finely tuned laser beam size improve spatial resolution. With the LAET technique, imaging analysis not only can identify physical shapes but also reveal endogenous metabolites present in females and males, detect contacts with prohibited substances, and resolve overlapped latent fingerprints. PMID:25647159

  19. Chemical imaging of latent fingerprints by mass spectrometry based on laser activated electron tunneling.

    PubMed

    Tang, Xuemei; Huang, Lulu; Zhang, Wenyang; Zhong, Hongying

    2015-03-01

    Identification of endogenous and exogenous chemicals contained in latent fingerprints is important for forensic science in order to acquire evidence of criminal identities and contacts with specific chemicals. Mass spectrometry has emerged as a powerful technique for such applications without any derivatization or fluorescent tags. Among these techniques, MALDI (Matrix Assisted Laser Desorption Ionization) provides small beam size but has interferences with MALDI matrix materials, which cause ion suppressions as well as limited spatial resolution resulting from uneven distribution of MALDI matrix crystals with different sizes. LAET (Laser Activated Electron Tunneling) described in this work offers capabilities for chemical imaging through electron-directed soft ionization. A special film of semiconductors has been designed for collection of fingerprints. Nanoparticles of bismuth cobalt zinc oxide were compressed on a conductive metal substrate (Al or Cu sticky tape) under 10 MPa pressure. Resultant uniform thin films provide tight and shining surfaces on which fingers are impressed. Irradiation of ultraviolet laser pulses (355 nm) on the thin film instantly generates photoelectrons that can be captured by adsorbed organic molecules and subsequently cause electron-directed ionization and fragmentation. Imaging of latent fingerprints is achieved by visualization of the spatial distribution of these molecular ions and structural information-rich fragment ions. Atomic electron emission together with finely tuned laser beam size improve spatial resolution. With the LAET technique, imaging analysis not only can identify physical shapes but also reveal endogenous metabolites present in females and males, detect contacts with prohibited substances, and resolve overlapped latent fingerprints.

  20. Chemical characterization of aerosol particles by laser Raman spectroscopy. Revision

    SciTech Connect

    Fung, K.H.

    1999-12-01

    The importance of aerosol particles in many branches of science, such as atmospheric chemistry, combustion, interfacial science, and material processing, has been steadily growing during the past decades. One of the unique properties of these particles is the very high surface-to-volume ratios, thus making them readily serve as centers for gas-phase condensation and heterogeneous reactions. These particles must be characterized by size, shape, physical state, and chemical composition. Traditionally, optical elastic scattering has been applied to obtain the physical properties of these particle (e.g., particle size, size distribution, and particle density). These physical properties are particularly important in atmospheric science as they govern the distribution and transport of atmospheric aerosols.

  1. Laser-chemical modification of nucleation barriers for area-selective thin film growth

    NASA Astrophysics Data System (ADS)

    Tsao, J. Y.; Ehrlich, D. J.

    1984-09-01

    The use of laser radiation to locally modify nucleation barriers to thin film growth is discussed. Examples are described in which UV laser photodeposition is used to directly pattern surface-altering monolayer or submonolayer films. The surface-altering films can then be used to promote or both physical condensation as well as surface chmistry. A qualitative is made of two kinds of processes: those relying on physical, and those relying on chemical, barriers. A figure of merit is defined and discussed, which measures the selectivity of a given process for patterned growth.

  2. Physics of a ballistic missile defense - The chemical laser boost-phase defense

    NASA Technical Reports Server (NTRS)

    Grabbe, Crockett L.

    1988-01-01

    The basic physics involved in proposals to use a chemical laser based on satellites for a boost-phase defense are investigated. After a brief consideration of simple physical conditions for the defense, a calculation of an equation for the number of satellites needed for the defense is made along with some typical values of this for possible future conditions for the defense. Basic energy and power requirements for the defense are determined. A sumary is made of probable minimum conditions that must be achieved for laser power, targeting accuracy, number of satellites, and total sources for power needed.

  3. Preparation and analysis of chemically gradient functional bioceramic coating formed by pulsed laser deposition.

    PubMed

    Rajesh, P; Muraleedharan, C V; Sureshbabu, S; Komath, Manoj; Varma, Harikrishna

    2012-02-01

    Bioactive ceramic coatings based on calcium phosphates yield better functionality in the human body for a variety of metallic implant devices including orthopaedic and dental prostheses. In the present study chemically and hence functionally gradient bioceramic coating was obtained by pulsed laser deposition method. Calcium phosphate bioactive ceramic coatings based on hydroxyapatite (HA) and tricalcium phosphate (TCP) were deposited over titanium substrate to produce gradation in physico-chemical characteristics and in vitro dissolution behaviour. Sintered targets of HA and α-TCP were deposited in a multi target laser deposition system. The obtained deposits were characterized by X-ray diffraction, fourier transform infrared spectroscopy, scanning electron microscopy and energy dispersive X-ray analysis. Inductively coupled plasma spectroscopy was used to estimate the in vitro dissolution behaviour of coatings. The variation in mechanical property of the gradient layer was evaluated through scratch test and micro-indentation hardness. The bioactivity was examined in vitro with respect to the ability of HA layer to form on the surface as a result of contact with simulated body fluid. It could be inferred that chemically gradient functional bioceramic coating can be produced by laser deposition of multiple sintered targets with variable chemical composition.

  4. Preparation and analysis of chemically gradient functional bioceramic coating formed by pulsed laser deposition.

    PubMed

    Rajesh, P; Muraleedharan, C V; Sureshbabu, S; Komath, Manoj; Varma, Harikrishna

    2012-02-01

    Bioactive ceramic coatings based on calcium phosphates yield better functionality in the human body for a variety of metallic implant devices including orthopaedic and dental prostheses. In the present study chemically and hence functionally gradient bioceramic coating was obtained by pulsed laser deposition method. Calcium phosphate bioactive ceramic coatings based on hydroxyapatite (HA) and tricalcium phosphate (TCP) were deposited over titanium substrate to produce gradation in physico-chemical characteristics and in vitro dissolution behaviour. Sintered targets of HA and α-TCP were deposited in a multi target laser deposition system. The obtained deposits were characterized by X-ray diffraction, fourier transform infrared spectroscopy, scanning electron microscopy and energy dispersive X-ray analysis. Inductively coupled plasma spectroscopy was used to estimate the in vitro dissolution behaviour of coatings. The variation in mechanical property of the gradient layer was evaluated through scratch test and micro-indentation hardness. The bioactivity was examined in vitro with respect to the ability of HA layer to form on the surface as a result of contact with simulated body fluid. It could be inferred that chemically gradient functional bioceramic coating can be produced by laser deposition of multiple sintered targets with variable chemical composition. PMID:22105226

  5. Chemical changes accompanying facet degradation of AlGaAs quantum well lasers

    NASA Astrophysics Data System (ADS)

    Houle, F. A.; Neiman, D. L.; Tang, W. C.; Rosen, H. J.

    1992-11-01

    Detailed measurements are reported using high-resolution scanning Auger microscopy of the chemical state of uncoated quantum well (QW) laser facets after brief and intermediate operating times. Analyses or uncoated facets which have suffered catastrophic optical damage (COD) under various operating conditions are described. The data show clearly that initial facet compositions are variable and far from ideal. After operation for as little as 2-10 min, the composition of the facet regions of the active/graded index and cladding layer change markedly, but no single type of change can be linked to COD. In particular, facet oxidation is not uniform or extensive, and facets which suffer COD are not necessarily more oxidized than those which have not. Composition changes are not limited to the facet surface, indicating that elemental redistribution during laser operation is very fast. These results suggest that the process of facet degradation plays a complex role in laser degradation.

  6. Portable IR dye laser optofluidic microresonator as a temperature and chemical sensor.

    PubMed

    Lahoz, F; Martín, I R; Gil-Rostra, J; Oliva-Ramirez, M; Yubero, F; Gonzalez-Elipe, A R

    2016-06-27

    A compact and portable optofluidic microresonator has been fabricated and characterized. It is based on a Fabry-Perot microcavity consisting essentially of two tailored dichroic Bragg mirrors prepared by reactive magnetron sputtering deposition. The microresonator has been filled with an ethanol solution of Nile-Blue dye. Infrared laser emission has been measured with a pump threshold as low as 0.12 MW/cm2 and an external energy conversion efficiency of 41%. The application of the device as a temperature and a chemical sensor is demonstrated. Small temperature variations as well as small amount of water concentrations in the liquid laser medium are detected as a shift of the resonant laser modes. PMID:27410592

  7. Studies of detonations as a potential source for visible chemical lasers

    NASA Astrophysics Data System (ADS)

    Rosenwaks, S.; Ben-Porat, T.; Heflinger, D.; Tzuk, Y.; Bar, I.

    1993-07-01

    Nozzle expansion of lead azide (LA) detonation products for population control of excited species and particle size and density is examined as part of an ongoing search for visible-spectrum chemical lasers. Emission spectroscopy, laser transmission spectroscopy and laser resonant shadowgraphy (LRS) are used to visualize and characterize the detonation products; the population of excited states, the particle size, and velocity and density distributions for both free and nozzle expansion are deduced. Transmission measurements at 0.633, 0.67, 1.31, and 10.6 microns show the particle size to be around 0.9 micron under free expansion, and 0.6 micron through a nozzle. Gas and solid-particle velocity and density distributions are inferred from LRS and pressure measurements. It is shown that, under nozzle expansion, it is possible to obtain a transparent medium at the nozzle exit for a few microseconds.

  8. Chemical taggant detection and analysis by laser-induced breakdown spectroscopy

    SciTech Connect

    Wise, Steven H.; Almirall, Jose R

    2008-11-01

    A commercially available chemical identification taggant that imparts a unique elemental fingerprint to any object and can be analytically distinguished from billions of possible combinations has been developed. The liquid tag is easily applied and, once dry, can be removed and analyzed by laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) to determine the combination of elements present in the sample. The current study investigates the use of laser-induced breakdown spectroscopy (LIBS) as an alternative, and perhaps more practical, analysis scheme to LA-ICP-MS for this taggant. LIBS provides excellent discrimination potential, sensitivity, and repeatability of analysis for up to 17 rare-earth elements using a Nd:YAG 266 nm or 1064 nm laser and an intensified CCD detector.

  9. Optical properties and surface structure comparison of tooth whitening using four laser systems and chemical action agents

    NASA Astrophysics Data System (ADS)

    Dostalova, Tatjana; Jelinkova, Helena; Koranda, Pavel; Nemec, Michal; Sulc, Jan; Housova, Devana; Miyagi, Mitsunobu; Kokta, Milan R.

    2003-06-01

    The purpose of the study is to evaluate the effect of various laser techniques for bleaching teeth in office vital whitening. Hydrogen peroxide (30% concentration) and carbamide peroxide (10% solution) were used for chemical activation of bleaching process. Extracted non-carcious upper central incisors were exposed to laser radiation. Four different laser systems (Nd:YAG laser SHG, wavelength 0.53 μm, CTE:YAG laser, wavelength 2.7 μm, Nd:YAG laser, wavelength 1.06 μm, and alexandrite laser, wavelength 0.75 μm) were applied to accelerate the speed of the process. The end of chemical exposition was verified by the change of bleaching agent color. The color change was determined by stereomicroscope (Nikon SMZ 2T, Japan), the quality of surface structure was checked by scanning electron microscope Joel, Japan). The speed of bleaching rnaged from 630 s (chemical methods only) to 250-340 s (chemicals + alexandrite laser radiation). The Alexandrite laser application was considered an elective process to decrease the time of bleaching without modifying the surface.

  10. Influence of exothermic chemical reactions on laser-induced shock waves.

    PubMed

    Gottfried, Jennifer L

    2014-10-21

    Differences in the excitation of non-energetic and energetic residues with a 900 mJ, 6 ns laser pulse (1064 nm) have been investigated. Emission from the laser-induced plasma of energetic materials (e.g. triaminotrinitrobenzene [TATB], cyclotrimethylene trinitramine [RDX], and hexanitrohexaazaisowurtzitane [CL-20]) is significantly reduced compared to non-energetic materials (e.g. sugar, melamine, and l-glutamine). Expansion of the resulting laser-induced shock wave into the air above the sample surface was imaged on a microsecond timescale with a high-speed camera recording multiple frames from each laser shot; the excitation of energetic materials produces larger heat-affected zones in the surrounding atmosphere (facilitating deflagration of particles ejected from the sample surface), results in the formation of additional shock fronts, and generates faster external shock front velocities (>750 m s(-1)) compared to non-energetic materials (550-600 m s(-1)). Non-explosive materials that undergo exothermic chemical reactions in air at high temperatures such as ammonium nitrate and magnesium sulfate produce shock velocities which exceed those of the inert materials but are less than those generated by the exothermic reactions of explosive materials (650-700 m s(-1)). The most powerful explosives produced the highest shock velocities. A comparison to several existing shock models demonstrated that no single model describes the shock propagation for both non-energetic and energetic materials. The influence of the exothermic chemical reactions initiated by the pulsed laser on the velocity of the laser-induced shock waves has thus been demonstrated for the first time. PMID:25182866

  11. Influence of exothermic chemical reactions on laser-induced shock waves.

    PubMed

    Gottfried, Jennifer L

    2014-10-21

    Differences in the excitation of non-energetic and energetic residues with a 900 mJ, 6 ns laser pulse (1064 nm) have been investigated. Emission from the laser-induced plasma of energetic materials (e.g. triaminotrinitrobenzene [TATB], cyclotrimethylene trinitramine [RDX], and hexanitrohexaazaisowurtzitane [CL-20]) is significantly reduced compared to non-energetic materials (e.g. sugar, melamine, and l-glutamine). Expansion of the resulting laser-induced shock wave into the air above the sample surface was imaged on a microsecond timescale with a high-speed camera recording multiple frames from each laser shot; the excitation of energetic materials produces larger heat-affected zones in the surrounding atmosphere (facilitating deflagration of particles ejected from the sample surface), results in the formation of additional shock fronts, and generates faster external shock front velocities (>750 m s(-1)) compared to non-energetic materials (550-600 m s(-1)). Non-explosive materials that undergo exothermic chemical reactions in air at high temperatures such as ammonium nitrate and magnesium sulfate produce shock velocities which exceed those of the inert materials but are less than those generated by the exothermic reactions of explosive materials (650-700 m s(-1)). The most powerful explosives produced the highest shock velocities. A comparison to several existing shock models demonstrated that no single model describes the shock propagation for both non-energetic and energetic materials. The influence of the exothermic chemical reactions initiated by the pulsed laser on the velocity of the laser-induced shock waves has thus been demonstrated for the first time.

  12. Time evolution studies of laser induced chemical changes in InAs nanowire using Raman spectroscopy

    SciTech Connect

    Pal, Suparna; Aggarwal, R.; Kumari Gupta, Vandna; Ingale, Alka

    2014-07-07

    We report the study of time evolution of chemical changes on the surface of an InAs nanowire (NW) on laser irradiation in different power density regime, using Raman spectroscopy for a time span of 8–16 min. Mixture of metastable oxides like InAsO{sub 4,} As{sub 2}O{sub 3} are formed upon oxidation, which are reflected as sharp Raman peaks at ∼240–254 and 180–200 cm{sup −1}. Evidence of removal of arsenic layer by layer is also observed at higher power density. Position controlled laser induced chemical modification on a nanometer scale, without changing the core of the NW, can be useful for NW based device fabrication.

  13. Nanosecond laser textured superhydrophobic metallic surfaces and their chemical sensing applications

    NASA Astrophysics Data System (ADS)

    Ta, Duong V.; Dunn, Andrew; Wasley, Thomas J.; Kay, Robert W.; Stringer, Jonathan; Smith, Patrick J.; Connaughton, Colm; Shephard, Jonathan D.

    2015-12-01

    This work demonstrates superhydrophobic behavior on nanosecond laser patterned copper and brass surfaces. Compared with ultrafast laser systems previously used for such texturing, infrared nanosecond fiber lasers offer a lower cost and more robust system combined with potentially much higher processing rates. The wettability of the textured surfaces develops from hydrophilicity to superhydrophobicity over time when exposed to ambient conditions. The change in the wetting property is attributed to the partial deoxidation of oxides on the surface induced during laser texturing. Textures exhibiting steady state contact angles of up to ∼152° with contact angle hysteresis of around 3-4° have been achieved. Interestingly, the superhydrobobic surfaces have the self-cleaning ability and have potential for chemical sensing applications. The principle of these novel chemical sensors is based on the change in contact angle with the concentration of methanol in a solution. To demonstrate the principle of operation of such a sensor, it is found that the contact angle of methanol solution on the superhydrophobic surfaces exponentially decays with increasing concentration. A significant reduction, of 128°, in contact angle on superhydrophobic brass is observed, which is one order of magnitude greater than that for the untreated surface (12°), when percent composition of methanol reaches to 28%.

  14. Ultrahigh-spatial-resolution chemical and magnetic imaging by laser-based photoemission electron microscopy

    SciTech Connect

    Taniuchi, Toshiyuki Kotani, Yoshinori; Shin, Shik

    2015-02-15

    We report the first experiments carried out on a new chemical and magnetic imaging system, which combines the high spatial resolution of a photoemission electron microscope (PEEM) with a continuous-wave deep-ultraviolet laser. Threshold photoemission is sensitive to the chemical and magnetic structures of the surface of materials. The spatial resolution of PEEM is limited by space charging when using pulsed photon sources as well as aberrations in the electron optics. We show that the use of a continuous-wave laser enabled us to overcome such a limit by suppressing the space-charge effect, allowing us to obtain a resolution of approximately 2.6 nm. With this system, we demonstrated the imaging of surface reconstruction domains on Si(001) by linear dichroism with normal incidence of the laser beam. We also succeeded in magnetic imaging of thin films with the use of magnetic circular dichroism near the Fermi level. The unique features of the ultraviolet laser will give us fast switching of the incident angles and polarizations of the photon source, which will be useful for the characterization of antiferromagnetic materials as well as ferromagnetic materials.

  15. Synthesis of Cobalt Oxides Thin Films Fractal Structures by Laser Chemical Vapor Deposition

    PubMed Central

    Haniam, P.; Kunsombat, C.; Chiangga, S.; Songsasen, A.

    2014-01-01

    Thin films of cobalt oxides (CoO and Co3O4) fractal structures have been synthesized by using laser chemical vapor deposition at room temperature and atmospheric pressure. Various factors which affect the density and crystallization of cobalt oxides fractal shapes have been examined. We show that the fractal structures can be described by diffusion-limited aggregation model and discuss a new possibility to control the fractal structures. PMID:24672354

  16. Synthesis of cobalt oxides thin films fractal structures by laser chemical vapor deposition.

    PubMed

    Haniam, P; Kunsombat, C; Chiangga, S; Songsasen, A

    2014-01-01

    Thin films of cobalt oxides (CoO and Co3O4) fractal structures have been synthesized by using laser chemical vapor deposition at room temperature and atmospheric pressure. Various factors which affect the density and crystallization of cobalt oxides fractal shapes have been examined. We show that the fractal structures can be described by diffusion-limited aggregation model and discuss a new possibility to control the fractal structures. PMID:24672354

  17. Lasers.

    ERIC Educational Resources Information Center

    Schewe, Phillip F.

    1981-01-01

    Examines the nature of laser light. Topics include: (1) production and characteristics of laser light; (2) nine types of lasers; (3) five laser techniques including holography; (4) laser spectroscopy; and (5) laser fusion and other applications. (SK)

  18. Laser-based standoff detection of surface-bound explosive chemicals

    NASA Astrophysics Data System (ADS)

    Huestis, David L.; Smith, Gregory P.; Oser, Harald

    2010-04-01

    Avoiding or minimizing potential damage from improvised explosive devices (IEDs) such as suicide, roadside, or vehicle bombs requires that the explosive device be detected and neutralized outside its effective blast radius. Only a few seconds may be available to both identify the device as hazardous and implement a response. As discussed in a study by the National Research Council, current technology is still far from capable of meeting these objectives. Conventional nitrocarbon explosive chemicals have very low vapor pressures, and any vapors are easily dispersed in air. Many pointdetection approaches rely on collecting trace solid residues from dust particles or surfaces. Practical approaches for standoff detection are yet to be developed. For the past 5 years, SRI International has been working toward development of a novel scheme for standoff detection of explosive chemicals that uses infrared (IR) laser evaporation of surfacebound explosive followed by ultraviolet (UV) laser photofragmentation of the explosive chemical vapor, and then UV laser-induced fluorescence (LIF) of nitric oxide. This method offers the potential of long standoff range (up to 100 m or more), high sensitivity (vaporized solid), simplicity (no spectrometer or library of reference spectra), and selectivity (only nitrocompounds).

  19. Active coherent laser spectrometer for remote detection and identification of chemicals

    NASA Astrophysics Data System (ADS)

    MacLeod, Neil A.; Weidmann, Damien

    2012-10-01

    Currently, there exists a capability gap for the remote detection and identification of threat chemicals. We report here on the development of an Active Coherent Laser Spectrometer (ACLaS) operating in the thermal infrared and capable of multi-species stand-off detection of chemicals at sub ppm.m levels. A bench top prototype of the instrument has been developed using distributed feedback mid-infrared quantum cascade lasers as spectroscopic sources. The instrument provides active eye-safe illumination of a topographic target and subsequent spectroscopic analysis through optical heterodyne detection of the diffuse backscattered field. Chemical selectivity is provided by the combination of the narrow laser spectral bandwidth (typically < 2 MHz) and frequency tunability that allows the recording of the full absorption spectrum of any species within the instrument line of sight. Stand-off detection at distances up to 12 m has been demonstrated on light molecules such as H2O, CH4 and N2O. A physical model of the stand-off detection scenario including ro-vibrational molecular absorption parameters was used in conjunction with a fitting algorithm to retrieve quantitative mixing ratio information on multiple absorbers.

  20. Toward the realization of a compact chemical sensor platform using quantum cascade lasers

    NASA Astrophysics Data System (ADS)

    Holthoff, Ellen L.; Marcus, Logan S.; Pellegrino, Paul M.

    2015-05-01

    The Army is investigating several spectroscopic techniques (e.g., infrared spectroscopy) that could allow for an adaptable sensor platform. Traditionally, chemical sensing platforms have been hampered by the opposing concerns of increasing sensor capability while maintaining a minimal package size. Current sensors, although reasonably sized, are geared to more classical chemical threats, and the ability to expand their capabilities to a broader range of emerging threats is uncertain. Recently, photoacoustic spectroscopy, employed in a sensor format, has shown enormous potential to address these ever-changing threats, while maintaining a compact sensor design. In order to realize the advantage of photoacoustic sensor miniaturization, light sources of comparable size are required. Recent research has employed quantum cascade lasers (QCLs) in combination with MEMS-scale photoacoustic cell designs. The continuous tuning capability of QCLs over a broad wavelength range in the mid-infrared spectral region greatly expands the number of compounds that can be identified. Results have demonstrated that utilizing a tunable QCL with a MEMS-scale photoacoustic cell produces favorable detection limits (ppb levels) for chemical targets (e.g., dimethyl methyl phosphonate (DMMP), vinyl acetate, 1,4-dioxane). Although our chemical sensing research has benefitted from the broad tuning capabilities of QCLs, the limitations of these sources must be considered. Current commercially available tunable systems are still expensive and obviously geared more toward laboratory operation, not fielding. Although the laser element itself is quite small, the packaging, power supply, and controller remain logistical burdens. Additionally, operational features such as continuous wave (CW) modulation and laser output powers while maintaining wide tunability are not yet ideal for a variety of sensing applications. In this paper, we will discuss our continuing evaluation of QCL technology as it matures

  1. Development of a new laser heating system for thin film growth by chemical vapor deposition.

    PubMed

    Fujimoto, Eiji; Sumiya, Masatomo; Ohnishi, Tsuyoshi; Lippmaa, Mikk; Takeguchi, Masaki; Koinuma, Hideomi; Matsumoto, Yuji

    2012-09-01

    We have developed a new laser heating system for thin film growth by chemical vapor deposition (CVD). A collimated beam from a high-power continuous-wave 808 nm semiconductor laser was directly introduced into a CVD growth chamber without an optical fiber. The light path of the heating laser inside the chamber was isolated mechanically from the growth area by bellows to protect the optics from film coating. Three types of heat absorbers, (10 × 10 × 2 mm(3)) consisting of SiC, Ni/NiO(x), or pyrolytic graphite covered with pyrolytic BN (PG/PBN), located at the backside of the substrate, were tested for heating performance. It was confirmed that the substrate temperature could reach higher than 1500 °C in vacuum when a PG/PBN absorber was used. A wide-range temperature response between 400 °C and 1000 °C was achieved at high heating and cooling rates. Although the thermal energy loss increased in a H(2) gas ambient due to the higher thermal conductivity, temperatures up to 1000 °C were achieved even in 200 Torr H(2). We have demonstrated the capabilities of this laser heating system by growing ZnO films by metalorganic chemical vapor deposition. The growth mode of ZnO films was changed from columnar to lateral growth by repeated temperature modulation in this laser heating system, and consequently atomically smooth epitaxial ZnO films were successfully grown on an a-plane sapphire substrate.

  2. Sensing signatures mediated by chemical structure of molecular solids in laser-induced plasmas.

    PubMed

    Serrano, Jorge; Moros, Javier; Laserna, J Javier

    2015-03-01

    Laser ablation of organic compounds has been investigated for almost 30 years now, either in the framework of pulse laser deposition for the assembling of new materials or in the context of chemical sensing. Various monitoring techniques such as atomic and molecular fluorescence, time-of-flight mass spectrometry, and optical emission spectroscopy have been used for plasma diagnostics in an attempt to understand the spectral signature and potential origin of gas-phase ions and fragments from organic plasmas. Photochemical and photophysical processes occurring within these systems are generally much more complex than those suggested by observation of optical emission features. Together with laser ablation parameters, the structural and chemical-physical properties of molecules seem to be closely tied to the observed phenomena. The present manuscript, for the first time, discusses the role of molecular structure in the optical emission of organic plasmas. Factors altering the electronic distribution within the organic molecule have been found to have a direct impact on its ensuing optical emissions. The electron structure of an organic molecule, resulting from the presence, nature, and position of its atoms, governs the breakage of the molecule and, as a result, determines the extent of atomization and fragmentation that has proved to directly impact the emissions of CN radicals and C2 dimers. Particular properties of the molecule respond more positively depending on the laser irradiation wavelength, thereby redirecting the ablation process through photochemical or photothermal decomposition pathways. It is of paramount significance for chemical identification purposes how, despite the large energy stored and dissipated by the plasma and the considerable number of transient species formed, the emissions observed never lose sight of the original molecule. PMID:25668318

  3. Effect of surface topography in the generation of chemical maps by laser-induced plasma spectroscopy

    NASA Astrophysics Data System (ADS)

    Lopez-Quintas, I.; Piñon, V.; Mateo, M. P.; Nicolas, G.

    2012-09-01

    The development of technologically advanced materials is propelling the improvement of surface analytical techniques. In particular, the composition and hence the properties of most of these new materials are spatial dependent. Between the techniques able to provide chemical spatial information, laser-induced plasma spectroscopy known also as laser-induced breakdown spectroscopy (LIBS) is a very promising analytical technique. During the last decade, LIBS was successfully applied to the analysis of surfaces and the generation of chemical maps of heterogeneous materials. In the LIBS analysis, several experimental factors including surface topography must be taken into account. In this work, the influence of surface roughness in LIBS signal during the point analysis and acquisition of chemical maps was studied. For this purpose, samples of stainless steel with different surface finishes were prepared and analyzed by LIBS. In order to characterize the different surfaces, confocal microscopy images were obtained. Afterwards, both topographic and spectroscopic information were combined to show the relationship between them. Additionally, in order to reveal the effect of surface topography in the acquisition of chemical maps, a three dimensional analysis of a sample exhibiting two different finishes was carried out.

  4. Photo-vibrational spectroscopy of solid and liquid chemicals using laser Doppler vibrometer.

    PubMed

    Hu, Qi; Lim, Jacob Song Kiat; Liu, Huan; Fu, Yu

    2016-08-22

    Photoacoustic/photothermal spectroscopy is an established technique for trace detection of chemicals and explosives. However, prior sample preparation is required and the analysis is conducted in a sealed space with a high-sensitivity microphone or a piezo sensor coupled with a lock-in amplifier, limiting the technique to applications in a laboratory environment. Due to the aforementioned requirements, traditionally this technique may not be suitable for defense and security applications where the detection of explosives or hazardous chemicals is required in an open environment at a safe standoff distance. In this study, chemicals in various forms (membrane, powder and liquid) were excited by an intensity-modulated quantum cascade laser (QCL), while a laser Doppler vibrometer (LDV) based on the Mach-Zehnder interferometer was applied to detect the vibration signal resulting from the photocoustic/photothermal effect. The photo-vibrational spectrum obtained by scanning the QCL's wavelength in MIR range, coincides well with the corresponding spectrum obtained using typical FTIR equipment. The experiment demonstrated that the LDV is a capable sensor for applications in photoacoustic/photothermal spectroscopy, with potential to enable the detection of chemicals in open environment at safe standoff distance. PMID:27557194

  5. Photo-vibrational spectroscopy of solid and liquid chemicals using laser Doppler vibrometer.

    PubMed

    Hu, Qi; Lim, Jacob Song Kiat; Liu, Huan; Fu, Yu

    2016-08-22

    Photoacoustic/photothermal spectroscopy is an established technique for trace detection of chemicals and explosives. However, prior sample preparation is required and the analysis is conducted in a sealed space with a high-sensitivity microphone or a piezo sensor coupled with a lock-in amplifier, limiting the technique to applications in a laboratory environment. Due to the aforementioned requirements, traditionally this technique may not be suitable for defense and security applications where the detection of explosives or hazardous chemicals is required in an open environment at a safe standoff distance. In this study, chemicals in various forms (membrane, powder and liquid) were excited by an intensity-modulated quantum cascade laser (QCL), while a laser Doppler vibrometer (LDV) based on the Mach-Zehnder interferometer was applied to detect the vibration signal resulting from the photocoustic/photothermal effect. The photo-vibrational spectrum obtained by scanning the QCL's wavelength in MIR range, coincides well with the corresponding spectrum obtained using typical FTIR equipment. The experiment demonstrated that the LDV is a capable sensor for applications in photoacoustic/photothermal spectroscopy, with potential to enable the detection of chemicals in open environment at safe standoff distance.

  6. Laser and chemical surface modifications of titanium grade 2 for medical application

    NASA Astrophysics Data System (ADS)

    Kwaśniak, P.; Pura, J.; Zwolińska, M.; Wieciński, P.; Skarżyński, H.; Olszewski, L.; Marczak, J.; Garbacz, H.; Kurzydłowski, K. J.

    2015-05-01

    The article presents combined, chemical and physical approach to titanium surface functionalization designed for biomedical applications. The topography modification has been obtained by employing the double laser beam interference technique and chemical etching. In the outcome, clean and smooth Ti surface as well as periodic striated topography with the roughness range from nano- to micrometers were created. The obtained structures were characterized in terms of shape, roughness, chemical composition, mechanical properties and microstructures. In order to achieve all information, numerous of research methods have been used: scanning electron microscopy, atomic force microscopy, optical profilometry and microhardness measurements. Demonstrated methodology can be used as an effective tool for manufacturing controlled surface structures improving the bone-implants interactions.

  7. Latest developments toward the demonstration of a KW-class EOIL laser

    NASA Astrophysics Data System (ADS)

    Hill, Alan E.

    2008-05-01

    The electric oxygen iodine laser (EOIL) offers a vastly more practical, implementable, and safer alternative to its predecessor, the chemical oxygen iodine laser (COIL), particularly for airborne or other mobile military applications. Despite its promise and after 25 years effort, numerous laboratories around the world have not succeeded in providing the known basic physical requirements needed to electrically convert O2 into O2(a1Δ) with the fractional yields and efficiencies needed to make a practical laser. Hence, as of this date, the world record power generated from an EOIL device is only 6.5 watts. In this paper, a 30% conversion from O2 into O2(a1Δ) operating at substantial oxygen mass flow rates (0.090 moles O2/sec at 50 torr) and 40% electrical efficiency is reported. The O2(a1Δ) flow stream being produced carries 2400 watts. Gain measurements are currently in progress, to be followed shortly by power extraction. Current conditions imply that initial power extraction could push beyond 1 KW. Efforts to date have failed to generate substantial laser power because critical criteria have not been met. In order to achieve good O2(a1Δ) fractional yield, it is normally mandatory to impart on the order of 100 KJ/mole O2 while efficiently removing the waste heat energy from the generator so that less than a few hundred degrees Kelvin rise occurs due to gas heating. The generator must be excited by an electric field on the order of 10 Td. This is far below glow potential; hence, a fully externally sustained plasma generation technique is required. Ionization is supplied by means of applying short (tens of nanosecond) pulses to the O2(a1Δ) generator at 50,000 PPS, which are on the order of ten times breakdown potential. This enables a quasi-steady adjustable DC current to flow through the generator, being conducted by application of a DC, 10 to 14 Td pump E-field. This field is independently tunable. The result is that up to 180 KJ/mole O2 gets imparted to the

  8. Chemical reactions at metallic and metal/semiconductor interfaces stimulated by pulsed laser annealing

    NASA Astrophysics Data System (ADS)

    Petit, E. J.; Caudano, R.

    1992-01-01

    Multilayer Al/Sb thin films have been evaporated on GaSb single crystals in ultra-high vacuum and pulsed-laser irradiated in-situ above the energy density threshold for surface melting. Superficial and interfacial chemical reactions have been characterized in-situ by Auger electron spectroscopy; and later, by X-ray photoelectron spectroscopy profiling, Rutherford backscattering spectrometry and scanning electron microscopy. The chemical reaction between the Al and Sb films is considered as a model reaction for laser-assisted synthesis of high-purity intermetallic compounds. The observation of a strong interfacial reaction between the melted film and the substrate is also a subject of great concern for optical data recording and laser alloying of ohmic contacts on semiconductors. We show that a suitable choice of the substrate and adding a low surface tension element into the metallic film can improve its stability during melting, and prevent inhomogeneous reaction and formation of holes, cracks and particles. Finally, other solutions are suggested to improve the control of these reactions.

  9. IR and UV laser-induced chemical vapor deposition: Chemical mechanism for a-Si:H and Cr (O,C) film formation

    NASA Astrophysics Data System (ADS)

    Hess, Peter

    The characteristic features of laser-induced chemical vapor deposition in the parallel and perpendicular laser beam/surface configurations are discussed. Low temperature chemical processing with directed and spatially localized energy deposition in the system is investigated. Results obtained for the deposition of hydrogenated amorphous silicon (a-Si:H) films in the parallel configuration employing CO 2 and KrFlasers and SiH 4 and Si 2H 6 as precursors are presented. As a second example, the growth of oxygen- and carbon-containing chromium films Cr(O,C) from chromium hexacarbonyl as the precursor using cw and pulse uv lasers is discussed. The chemical pathways leasing to film formation are investigated in detail.

  10. Laser chemistry’ synthesis, physicochemical properties, and chemical processing of nanostructured carbon foams

    PubMed Central

    2013-01-01

    Laser ablation of selected coordination complexes can lead to the production of metal-carbon hybrid materials, whose composition and structure can be tailored by suitably choosing the chemical composition of the irradiated targets. This ‘laser chemistry’ approach, initially applied by our group to the synthesis of P-containing nanostructured carbon foams (NCFs) from triphenylphosphine-based Au and Cu compounds, is broadened in this study to the production of other metal-NCFs and P-free NCFs. Thus, our results show that P-free coordination compounds and commercial organic precursors can act as efficient carbon source for the growth of NCFs. Physicochemical characterization reveals that NCFs are low-density mesoporous materials with relatively low specific surface areas and thermally stable in air up to around 600°C. Moreover, NCFs disperse well in a variety of solvents and can be successfully chemically processed to enable their handling and provide NCF-containing biocomposite fibers by a wet-chemical spinning process. These promising results may open new and interesting avenues toward the use of NCFs for technological applications. PMID:23679938

  11. Laser ablation of phenylazide in an argon matrix: direct observation and chemical reactivity of ablated fragments

    NASA Astrophysics Data System (ADS)

    Niino, H.; Sato, T.; Yabe, A.

    Ablation of pentafluorophenylazide (FPA) in an Ar matrix at 8-10 K was carried out upon irradiation with ns-pulsed UV lasers in a vacuum. The plume of ablated products was monitored by a time-resolved imaging/spectroscopic technique using a gated and intensified CCD camera system. A large amount of pentafluorophenylnitrene (FPN) having a high kinetic energy ( 6 eV) was ejected as fragments from the matrix film during ablation. A quantitative formation of triplet FPN from the photolysis of the FPA was observed by spectroscopic measurements in the IR and UV-visible regions, and was confirmed by a theoretical IR spectrum calculated according to density functional theory. A FPN beam is useful for chemical surface modification of organic materials, such as aromatic polyester and alkylthiol. A surface analysis of these materials by X-ray photoelectron spectroscopy and Fourier transform infrared reflection absorption spectroscopy showed that the FPN was immobilized onto the surface through chemical bonds. This technique for the chemical surface modification of materials is made possible by a pulsed beam of reactive fragments with a high density in the laser ablation process.

  12. Microstructures and Mechanical Properties of Laser Welding Joint of a CLAM Steel with Revised Chemical Compositions

    NASA Astrophysics Data System (ADS)

    Chen, Shuhai; Huang, Jihua; Lu, Qi; Zhao, Xingke

    2016-05-01

    To suppress the tendency to form delta ferrite in weld metal (WM) of China low activation martensitic (CLAM) steel joint, a CLAM steel with revised chemical compositions was designed. Laser welding of the CLAM steel was investigated. The microstructures of the WM and heat-affected zone were analyzed. The impact toughness of the WM was evaluated by a Charpy impact test method with three V notches. The influence of temper temperature on mechanical properties was analyzed. It was found that the delta ferrite was eliminated almost completely in laser WM of CLAM steel with revised chemical compositions which has lower tendency to form delta ferrite than original chemical compositions. The joint has higher tensile strength than the parent metal. With increasing the heat input, the impact toughness of the joint is approximatively equal with that of parent metal first and then decreases obviously. Temper treatment could effectively improve mechanical property of the joint. When the temper temperature exceeds 600 °C, the impact toughness of the joint is higher than that of the parent metal.

  13. A miniature laser ablation mass spectrometer for in situ chemical composition investigation of lunar surface

    NASA Astrophysics Data System (ADS)

    Neuland, M. B.; Mezger, K.; Riedo, A.; Tulej, M.; Wurz, P.

    2015-10-01

    A miniature laser ablation mass spectrometer (LMS) is presented. The LMS is designed as a flight instrument for planetary and space research and optimised for in situ measurements of the chemical composition of rocks and soils on a planetary surface. By means of measure-ments standard reference materials of soil and a sample of the Allende meteorite we demonstrate that LMS is a suitable instrument for in situ measurements of elemental and isotopic composition with high precision and accuracy. Furthermore, it is shown that LMS data allows deriving of the material mineralogy and petrology with high spatial resolution, lateral and vertical, and the application of in situ age dating methods.

  14. Convection and mass-transport in laser-induced chemical vapor deposition

    NASA Technical Reports Server (NTRS)

    Patnaik, S.; Brown, R. A.

    1988-01-01

    Gas flow and energy and species transport in laser-induced chemical vapor deposition (LICVD) of amorphous silicon films by silane pyrolysis are analyzed by finite element analysis of a two-dimensional model for the process. Spatial nonuniformity of the deposited film is shown to result from diffusion controlled transport of products between the beam and substrate. Deposition profiles are affected by buoyancy-driven convection only at increased gas pressures. Horizontal orientation of the reactor with respect to gravity is optimal because the stagnation-like flow, that results adjacent to the substrate, enhances mixing, and smoothes the film profile.

  15. Initiation with an electron beam of chemical reactions of interest for visible wavelength lasers

    NASA Technical Reports Server (NTRS)

    Whittier, J. S.; Cool, T. A.

    1976-01-01

    A description is given of the first results obtained with a new shock tube-electron beam facility designed to provide a versatile means for the systematic search for laser operation among several candidate metal atom-oxidizer systems. According to the current experimental approach, metal atoms are obtained in the vapor phase by the dissociation of metal compounds. A shock tube is employed to provide a short duration flow through an array of 29 supersonic flow-mixing nozzles. A high energy electron accelerator is used for the rapid initiation of chemical reaction in a mixed flow of encapsulated metal and oxidizer.

  16. Hybrid chemical etching of femtosecond laser irradiated structures for engineered microfluidic devices

    NASA Astrophysics Data System (ADS)

    LoTurco, S.; Osellame, R.; Ramponi, R.; Vishnubhatla, K. C.

    2013-08-01

    We report on the fabrication of 3D buried micro-structures in fused silica glass using the selective chemical etching along femtosecond laser irradiated zones. Specifically, we have exploited a novel approach combining two different etching agents in successive steps. The widely used hydrofluoric acid solution, which provides fast volume removal, and potassium hydroxide solution, which exhibits high selectivity, are used to fabricate microfluidic structures. We demonstrate that this hybrid approach takes advantage of both of the individual etchants’ special characteristics and facilitates prototyping and fabrication of complex geometries for microfluidic devices.

  17. Analysis of lasing in gas-flow lasers with stable resonators.

    PubMed

    Barmashenko, B; Furman, D; Rosenwaks, S

    1998-08-20

    A model is developed that describes the power extraction in chemical oxygen-iodine lasers (COIL's) and CO(2) gasdynamic lasers with stable resonators when a large number of transverse Hermite-Gaussian eigenmodes oscillate. The extraction efficiency, mode intensities, and intensity distribution along the flow depend only on two parameters. The first is the ratio gamma(0) of the residence time of the gas in the resonator to the O(2)((1)D) or N(2)(v) energy extraction time and the second is the ratio of the threshold to the small-signal gain. The efficiency is maximum for gamma(0) ? infinity and decreases rapidly as gamma(0) decreases. It is found that for a range of parameters corresponding to the highest efficiencies the intensity distribution along the flow is nonuniform and has two peaks near the upstream and downstream sections of the resonator. In this case only the highest-order modes that totally fill the resonator cross section oscillate (the so-called, experimentally observed sugar scooping bimodal intensity distribution). For the range of parameters corresponding to smaller efficiencies the intensity is uniform. In this case all the modes participate in lasing; however, the intensities of the high-order modes are larger than those of the low order. The current model is compared with the plane-mirror Fabry-Perot resonator model and with the constant intraresonator intensity and rooftop models of COIL's with stable resonators. The extraction efficiency calculated with the last two models is close to that estimated from our model. However, the intensity distribution cannot be calculated correctly using the Fabry-Perot, the constant intraresonator intensity, or the rooftop model.

  18. Laser Induced Breakdown Spectroscopy applications to meteorites: Chemical analysis and composition profiles

    NASA Astrophysics Data System (ADS)

    Dell'Aglio, M.; De Giacomo, A.; Gaudiuso, R.; Pascale, O. De; Senesi, G. S.; Longo, S.

    2010-12-01

    A fast procedure for chemical analysis of different meteorites is presented, based on LIBS (Laser Induced Breakdown Spectroscopy). The technique is applied to several test cases (Dhofar 019, Dhofar 461, Sahara 98222, Toluca, Sikhote Alin and Campo del Cielo) and can be useful for rapid meteorite identification providing geologists with specific chemical information for meteorite classification. Concentration profiles of Fe, Ni and Co are simultaneously detected across the Widmanstätten structure of the iron meteorite Toluca with a view to determining cooling rates. The LIBS analysis of meteorites is also used as a laboratory test for analogous studies on the respective parent bodies (Mars, asteroids) in space exploration missions where one clear advantage of the proposed technique is that no direct contact with the sample is required.

  19. Fabrication of microchannels in single-crystal GaN by wet-chemical-assisted femtosecond-laser ablation

    NASA Astrophysics Data System (ADS)

    Nakashima, Seisuke; Sugioka, Koji; Midorikawa, Katsumi

    2009-09-01

    We investigated micro- and nano-fabrication of wide band-gap semiconductor gallium nitride (GaN) using a femtosecond (fs) laser. Nanoscale craters were successfully formed by wet-chemical-assisted fs-laser ablation, in which the laser beam is focused onto a single-crystal GaN substrate in a hydrochloric acid (HCl) solution. This allows efficient removal of ablation debris produced by chemical reactions during ablation, resulting in high-quality ablation. However, a two-step processing method involving irradiation by a fs-laser beam in air followed by wet etching, distorts the shape of the crater because of residual debris. The threshold fluence for wet-chemical-assisted fs-laser ablation is lower than that for fs-laser ablation in air, which is advantageous for improving fabrication resolution since it reduces thermal effects. We have fabricated craters as small as 510 nm by using a high numerical aperture (NA) objective lens with an NA of 0.73. Furthermore, we have formed three-dimensional hollow microchannels in GaN by fs-laser direct-writing in HCl solution.

  20. Laser-based mass spectrometry for in situ chemical composition analysis of planetary surfaces

    NASA Astrophysics Data System (ADS)

    Frey, Samira; Neuland, Maike B.; Grimaudo, Valentine; Moreno-García, Pavel; Riedo, Andreas; Tulej, Marek; Broekmann, Peter; Wurz, Peter

    2016-04-01

    Mass spectrometry is an important analytical technique in space research. The chemical composition of planetary surface material is a key scientific question on every space mission to a planet, moon or asteroid. Chemical composition measurements of rocky material on the surface are of great importance to understand the origin and evolution of the planetary body.[1] A miniature laser ablation/ionisation reflectron- type time-of-flight mass spectrometer (instrument name LMS) was designed and built at the University of Bern for planetary research.[2] Despite its small size and light weight, the LMS instrument still maintains the same capabilities as large laboratory systems, which makes it suitable for its application on planetary space missions.[3-5] The high dynamic range of about eight orders of magnitude, high lateral (μm-level) and vertical (sub-nm level) resolution and high detection sensitivity for almost all elements (10 ppb, atomic fraction) make LMS a versatile instrument for various applications. LMS is a suitable instrument for in situ measurements of elemental and isotope composition with high precision and accuracy. Measurements of Pb- isotope abundances can be used for dating of planetary material. Measurements of bio-relevant elements allow searching for past or present life on a planetary surface. The high spatial resolution, both in lateral and vertical direction, is of considerable interest, e.g. for analysis of inhomogeneous, extraterrestrial samples as well as weathering processes of planetary material. References [1] P. Wurz, D. Abplanalp, M. Tulej, M. Iakovleva, V.A. Fernandes, A. Chumikov, and G. Managadze, "Mass Spectrometric Analysis in Planetary Science: Investigation of the Surface and the Atmosphere", Sol. Sys. Res., 2012, 46, 408. [2] U. Rohner, J.A. Whitby, P. Wurz, "A miniature laser ablation time of flight mass spectrometer for in situ planetary exploration" Meas. Sci. Tch., 2003, 14, 2159. [3] M. Tulej, A. Riedo, M.B. Neuland, S

  1. Comparison of laser-ablation and hot-wall chemical vapour deposition techniques for nanowire fabrication

    NASA Astrophysics Data System (ADS)

    Stern, E.; Cheng, G.; Guthrie, S.; Turner-Evans, D.; Broomfield, E.; Lei, B.; Li, C.; Zhang, D.; Zhou, C.; Reed, M. A.

    2006-06-01

    A comparison of the transport properties of populations of single-crystal, In2O3 nanowires (NWs) grown by unassisted hot-wall chemical vapour deposition (CVD) versus NWs grown by laser-ablation-assisted chemical vapour deposition (LA-CVD) is presented. For nominally identical growth conditions across the two systems, NWs fabricated at 850 °C with laser-ablation had significantly higher average mobilities at the 99.9% confidence level, 53.3 ± 5.8 cm2 V-1 s-1 versus 10.2 ± 1.9 cm2 V-1 s-1. It is also observed that increasing growth temperature decreases mobility for LA-CVD NWs. Transmission electron microscopy studies of CVD-fabricated samples indicate the presence of an amorphous In2O3 region surrounding the single-crystal core. Further, low-temperature measurements verify the presence of ionized impurity scattering in low-mobility CVD-grown NWs.

  2. Chemical models for simulating single-walled nanotube production in arc vaporization and laser ablation processes

    NASA Technical Reports Server (NTRS)

    Scott, Carl D.

    2004-01-01

    Chemical kinetic models for the nucleation and growth of clusters and single-walled carbon nanotube (SWNT) growth are developed for numerical simulations of the production of SWNTs. Two models that involve evaporation and condensation of carbon and metal catalysts, a full model involving all carbon clusters up to C80, and a reduced model are discussed. The full model is based on a fullerene model, but nickel and carbon/nickel cluster reactions are added to form SWNTs from soot and fullerenes. The full model has a large number of species--so large that to incorporate them into a flow field computation for simulating laser ablation and arc processes requires that they be simplified. The model is reduced by defining large clusters that represent many various sized clusters. Comparisons are given between these models for cases that may be applicable to arc and laser ablation production. Solutions to the system of chemical rate equations of these models for a ramped temperature profile show that production of various species, including SWNTs, agree to within about 50% for a fast ramp, and within 10% for a slower temperature decay time.

  3. Chemical and explosive detection with long-wave infrared laser induced breakdown spectroscopy

    NASA Astrophysics Data System (ADS)

    Jin, Feng; Trivedi, Sudhir B.; Yang, Clayton S.; Brown, Ei E.; Kumi-Barimah, Eric; Hommerich, Uwe H.; Samuels, Alan C.

    2016-05-01

    Conventional laser induced breakdown spectroscopy (LIBS) mostly uses silicon-based detectors and measures the atomic emission in the UV-Vis-NIR (UVN) region of the spectrum. It can be used to detect the elements in the sample under test, such as the presence of lead in the solder for electronics during RoHS compliance verification. This wavelength region, however, does not provide sufficient information on the bonding between the elements, because the molecular vibration modes emit at longer wavelength region. Measuring long-wave infrared spectrum (LWIR) in a LIBS setup can instead reveal molecular composition of the sample, which is the information sought in applications including chemical and explosive detection and identification. This paper will present the work and results from the collaboration of several institutions to develop the methods of LWIR LIBS for chemical/explosive/pharmaceutical material detection/identification, such as DMMP and RDX, as fast as using a single excitation laser pulse. In our latest LIBS setup, both UVN and LWIR spectra can be collected at the same time, allowing more accurate detection and identification of materials.

  4. Noninvasive Facial Rejuvenation. Part 3: Physician-Directed-Lasers, Chemical Peels, and Other Noninvasive Modalities.

    PubMed

    Meaike, Jesse D; Agrawal, Nikhil; Chang, Daniel; Lee, Edward I; Nigro, Marjory G

    2016-08-01

    A proper knowledge of noninvasive facial rejuvenation is integral to the practice of a cosmetic surgeon. Noninvasive facial rejuvenation can be divided into patient- versus physician-directed modalities. Patient-directed facial rejuvenation combines the use of facial products such as sunscreen, moisturizers, retinoids, α-hydroxy acids, and various antioxidants to both maintain youthful skin and rejuvenate damaged skin. Physicians may recommend and often prescribe certain products, but patients are in control with this type of facial rejuvenation. On the other hand, physician-directed facial rejuvenation entails modalities that require direct physician involvement, such as neuromodulators, filler injections, laser resurfacing, microdermabrasion, and chemical peels. With the successful integration of each of these modalities, a complete facial regimen can be established and patient satisfaction can be maximized. This article is the last in a three-part series describing noninvasive facial rejuvenation. Here the authors review the mechanism, indications, and possible complications of lasers, chemical peels, and other commonly used noninvasive modalities. PMID:27478423

  5. Chemical-Assisted Femtosecond Laser Writing of Lab-in-Fiber Sensors

    NASA Astrophysics Data System (ADS)

    Haque, Moez

    fringe contrast and peak resolution beyond that available with FPIs and offer a significant theoretical improvement in refractometer sensitivity. The advanced laser processes optimized here may provide a new base for photonics, microfluidics, and optofluidics fabrication in a LIF platform with multiplexed functionality and rapid prototyping capabilities of fully integrable 3D optofluidic systems. The proposed LIF devices define new micro-systems for temperature, strain, pressure, refractive index, and bend strain sensing that may find application in the acoustic, aerospace, automotive, biological, chemical, civil, or medical fields.

  6. In Situ Chemical Composition Measurements of Planetary Surfaces with a Laser Ablation Mass Spectrometer

    NASA Astrophysics Data System (ADS)

    Brigitte Neuland, Maike; Riedo, Andreas; Meyer, Stefan; Mezger, Klaus; Tulej, Marek; Wurz, Peter

    2013-04-01

    The knowledge of the chemical composition of moons, comets, asteroids or other planetary bodies is of particular importance for the investigation of the origin and evolution of the Solar System. For cosmochemistry, the elemental and isotopic composition of the surface material is essential information to investigate origin, differentiation and evolution processes of the body and therefore the history of our Solar System [1]. We show that the use of laser-based mass spectrometers is essential in such research because of their high sensitivity in the ppm range and their capability for quantitative elemental and isotopic analysis. A miniaturised Laser Ablation Time-of-Flight Mass Spectrometer (LMS) was developed in our group to study the elemental composition of solid samples [2]. The instrument's small size and light weight make it suitable for an application on a space mission to determine the elemental composition of a planetary surface for example [3]. Meteorites offer the excellent possibility to study extraterrestrial material in the laboratory. To demonstrate the sensitivity and functionality of the LMS instrument, a sample of the Allende meteorite has been investigated with a high spatial resolution. The LMS measurements allowed investigations of the elemental abundances in the Allende meteorite and detailed studies of the mineralogy and volatility [4]. These approaches can be of considerable interest for in situ investigation of grains and inhomogeneous materials with high sensitivity on a planetary surface. [1] Wurz, P., Whitby, J., Managadze, G., 2009, Laser Mass Spectrometry in Planetary Science, AIP Conf. Proc. CP1144, 70-75. [2] Tulej, M., Riedo, A., Iakovleva, M., Wurz, P., 2012, Int. J. Spec., On Applicability of a Miniaturized Laser Ablation Time of Flight Mass Spectrometer for Trace Element Measurements, article ID 234949. [3] Riedo, A., Bieler, A., Neuland, M., Tulej, M., Wurz, P., 2012, Performance evaluation of a miniature laser ablation time

  7. Bioactive Ti metal analogous to human cancellous bone: Fabrication by selective laser melting and chemical treatments.

    PubMed

    Pattanayak, Deepak K; Fukuda, A; Matsushita, T; Takemoto, M; Fujibayashi, S; Sasaki, K; Nishida, N; Nakamura, T; Kokubo, T

    2011-03-01

    Selective laser melting (SLM) is a useful technique for preparing three-dimensional porous bodies with complicated internal structures directly from titanium (Ti) powders without any intermediate processing steps, with the products being expected to be useful as a bone substitute. In this study the necessary SLM processing conditions to obtain a dense product, such as the laser power, scanning speed, and hatching pattern, were investigated using a Ti powder of less than 45 μm particle size. The results show that a fully dense plate thinner than 1.8 mm was obtained when the laser power to scanning speed ratio was greater than 0.5 and the hatch spacing was less than the laser diameter, with a 30 μm thick powder layer. Porous Ti metals with structures analogous to human cancellous bone were fabricated and the compressive strength measured. The compressive strength was in the range 35-120 MPa when the porosity was in the range 75-55%. Porous Ti metals fabricated by SLM were heat-treated at 1300 °C for 1h in an argon gas atmosphere to smooth the surface. Such prepared specimens were subjected to NaOH, HCl, and heat treatment to provide bioactivity. Field emission scanning electron micrographs showed that fine networks of titanium oxide were formed over the whole surface of the porous body. These treated porous bodies formed bone-like apatite on their surfaces in a simulated body fluid within 3 days. In vivo studies showed that new bone penetrated into the pores and directly bonded to the walls within 12 weeks after implantation into the femur of Japanese white rabbits. The percentage bone affinity indices of the chemical- and heat-treated porous bodies were significantly higher than that of untreated implants.

  8. Bioactive Ti metal analogous to human cancellous bone: Fabrication by selective laser melting and chemical treatments.

    PubMed

    Pattanayak, Deepak K; Fukuda, A; Matsushita, T; Takemoto, M; Fujibayashi, S; Sasaki, K; Nishida, N; Nakamura, T; Kokubo, T

    2011-03-01

    Selective laser melting (SLM) is a useful technique for preparing three-dimensional porous bodies with complicated internal structures directly from titanium (Ti) powders without any intermediate processing steps, with the products being expected to be useful as a bone substitute. In this study the necessary SLM processing conditions to obtain a dense product, such as the laser power, scanning speed, and hatching pattern, were investigated using a Ti powder of less than 45 μm particle size. The results show that a fully dense plate thinner than 1.8 mm was obtained when the laser power to scanning speed ratio was greater than 0.5 and the hatch spacing was less than the laser diameter, with a 30 μm thick powder layer. Porous Ti metals with structures analogous to human cancellous bone were fabricated and the compressive strength measured. The compressive strength was in the range 35-120 MPa when the porosity was in the range 75-55%. Porous Ti metals fabricated by SLM were heat-treated at 1300 °C for 1h in an argon gas atmosphere to smooth the surface. Such prepared specimens were subjected to NaOH, HCl, and heat treatment to provide bioactivity. Field emission scanning electron micrographs showed that fine networks of titanium oxide were formed over the whole surface of the porous body. These treated porous bodies formed bone-like apatite on their surfaces in a simulated body fluid within 3 days. In vivo studies showed that new bone penetrated into the pores and directly bonded to the walls within 12 weeks after implantation into the femur of Japanese white rabbits. The percentage bone affinity indices of the chemical- and heat-treated porous bodies were significantly higher than that of untreated implants. PMID:20883832

  9. An infrared free-electron laser for the Chemical Dynamics Research Laboratory

    SciTech Connect

    Vaughan, D.

    1992-04-01

    This document describes a free-electron laser (FEL) proposed as part of the Chemical Dynamics Research Laboratory (CDRL), a user facility that also incorporates several advanced lasers of conventional design and two beamlines for the ALS. The FEL itself addresses the needs of the chemical sciences community for a high-brightness, tunable source covering a broad region of the infrared spectrum -- from 3 to 50 {mu}m. All of these sources, together with a variety of sophisticated experimental stations, will be housed in a new building to be located adjacent to the ALS. The radiation sources can be synchronized to permit powerful two-color, pump-probe experiments that will further our fundamental understanding of chemical dynamics at the molecular level, especially those aspects relevant to practical issues in combustion chemistry. The technical approach adopted in this design makes use of superconducting radiofrequency (SCRF) accelerating structures. The primary motivation for adopting this approach was to meet the user requirement for wavelength stability equal to one part in 10{sup 4}. Previous studies concluded that a wavelength stability of only one part in 10{sup 3} could be achieved with currently available room-temperature technology. In addition, the superconducting design operates in a continuous-wave (cw) mode and hence offers considerably higher average optical output power. It also allows for various pulse-gating configurations that will permit simultaneous multiuser operations. A summary of the comparative performance attainable with room-temperature and superconducting designs is given. The FEL described in this report provides a continuous train of 30-ps micropulses, with 100{mu}J of optical energy per micropulse, at a repetition rate of 6.1 MHz. The device can also deliver pulses at a cw repetition rate of 12.2 MHz, with a peak power of 50 {mu}J per micropulse. 70 ref.

  10. An infrared free-electron laser for the Chemical Dynamics Research Laboratory. Design report

    SciTech Connect

    Vaughan, D.

    1992-04-01

    This document describes a free-electron laser (FEL) proposed as part of the Chemical Dynamics Research Laboratory (CDRL), a user facility that also incorporates several advanced lasers of conventional design and two beamlines for the ALS. The FEL itself addresses the needs of the chemical sciences community for a high-brightness, tunable source covering a broad region of the infrared spectrum -- from 3 to 50 {mu}m. All of these sources, together with a variety of sophisticated experimental stations, will be housed in a new building to be located adjacent to the ALS. The radiation sources can be synchronized to permit powerful two-color, pump-probe experiments that will further our fundamental understanding of chemical dynamics at the molecular level, especially those aspects relevant to practical issues in combustion chemistry. The technical approach adopted in this design makes use of superconducting radiofrequency (SCRF) accelerating structures. The primary motivation for adopting this approach was to meet the user requirement for wavelength stability equal to one part in 10{sup 4}. Previous studies concluded that a wavelength stability of only one part in 10{sup 3} could be achieved with currently available room-temperature technology. In addition, the superconducting design operates in a continuous-wave (cw) mode and hence offers considerably higher average optical output power. It also allows for various pulse-gating configurations that will permit simultaneous multiuser operations. A summary of the comparative performance attainable with room-temperature and superconducting designs is given. The FEL described in this report provides a continuous train of 30-ps micropulses, with 100{mu}J of optical energy per micropulse, at a repetition rate of 6.1 MHz. The device can also deliver pulses at a cw repetition rate of 12.2 MHz, with a peak power of 50 {mu}J per micropulse. 70 ref.

  11. High rate, large area laser-assisted chemical vapor deposition of nickel from nickel carbonyl

    NASA Astrophysics Data System (ADS)

    Paserin, Vlad

    High-power diode lasers (HPDL) are being increasingly used in industrial applications. Deposition of nickel from nickel carbonyl (Ni(CO)4 ) precursor by laser-induced chemical vapor deposition (CVD) was studied with emphasis on achieving high deposition rates. An HPDL system was used to provide a novel energy source facilitating a simple and compact design of the energy delivery system. Nickel deposits on complex, 3-dimensional polyurethane foam substrates were prepared and characterized. The resulting "nickel foam" represents a novel material of high porosity (>95% by volume) finding uses, among others, in the production of rechargeable battery and fuel cell electrodes and as a specialty high-temperature filtration medium. Deposition rates up to ˜19 mum/min were achieved by optimizing the gas precursor flow pattern and energy delivery to the substrate surface using a 480W diode laser. Factors affecting the transition from purely heterogeneous decomposition to a combined hetero- and homogeneous decomposition of nickel carbonyl were studied. High quality, uniform 3-D deposits produced at a rate more than ten times higher than in commercial processes were obtained by careful balance of mass transport (gas flow) and energy delivery (laser power). Cross-flow of the gases through the porous substrate was found to be essential in facilitating mass transport and for obtaining uniform deposits at high rates. When controlling the process in a transient regime (near the onset of homogenous decomposition), unique morphology features formed as part of the deposits, including textured surface with pyramid-shape crystallites, spherical and non-spherical particles and filaments. Operating the laser in a pulsed mode produced smooth, nano-crystalline deposits with sub-100 nm grains. The effect of H2S, a commonly used additive in nickel carbonyl CVD, was studied using both polyurethane and nickel foam substrates. H2S was shown to improve the substrate coverage and deposit

  12. A nuclear pumped laser for the Laboratory Microfusion Facility

    NASA Astrophysics Data System (ADS)

    Miley, G. H.

    1989-08-01

    The Laboratory Microfusion Facility (LMF) has been proposed to study Inertial Confinement Fusion targets with reactor-grade gains. An advanced solid-state laser is the prime candidate as the driver for the LMF. However, here, a conceptual design is presented here for an alternate approach using a Nuclear Pumped Laser (NPL). A pulsed fission reactor is used to excite an oxygen-iodine laser in this design, based on preliminary data on nuclear pumping of O2(1-Delta). Although a working NPL of this specific type has not yet been assembled, it is believed that this concept holds great potential, both as a test facility driver and as a future power reactor.

  13. Ar+ and CuBr laser-assisted chemical bleaching of teeth: estimation of whiteness degree

    NASA Astrophysics Data System (ADS)

    Dimitrov, S.; Todorovska, Roumyana; Gizbrecht, Alexander I.; Raychev, L.; Petrov, Lyubomir P.

    2003-11-01

    In this work the results of adaptation of impartial methods for color determination aimed at developing of techniques for estimation of human teeth whiteness degree, sufficiently handy for common use in clinical practice are presented. For approbation and by the way of illustration of the techniques, standards of teeth colors were used as well as model and naturally discolored human teeth treated by two bleaching chemical compositions activated by three light sources each: Ar+ and CuBr lasers, and a standard halogen photopolymerization lamp. Typical reflection and fluorescence spectra of some samples are presented; the samples colors were estimated by a standard computer processing in RGB and B coordinates. The results of the applied spectral and colorimetric techniques are in a good agreement with those of the standard computer processing of the corresponding digital photographs and complies with the visually estimated degree of the teeth whiteness judged according to the standard reference scale commonly used in the aesthetic dentistry.

  14. Chemical, morphological and chromatic behavior of mural paintings under Er:YAG laser irradiation

    NASA Astrophysics Data System (ADS)

    Striova, J.; Camaiti, M.; Castellucci, E. M.; Sansonetti, A.

    2011-08-01

    Several pigments (malachite CuCO3ṡCu(OH)2, azurite 2CuCO3ṡCu(OH)2, yellow ochre (goethite α-FeOOH, gypsum CaSO4ṡ2H2O), St. John's white CaCO3 formed from slaked lime) and respective mural paintings specimens were subjected to the free-running Er:YAG laser radiation in order to study their damage thresholds, in a broad range of laser fluences, both in dry and wet conditions. The specimens' damage thresholds were evaluated by spectroscopic methods, colorimetric measurements and microscopic observation. The pigments containing -OH groups were found to be more sensitive than St. John's white; hence the most sensitive paint layers in dry conditions are those containing malachite, azurite (both 1.3 J/cm2) and yellow ochre (2.5 J/cm2) as compared to the ones containing St. John's white (15.2 J/cm2). The presence of wetting agents (w.a.) attenuated the pigments chemical alteration. The damage thresholds of all the paint layers, in presence of w.a., were found to be around 2.5 J/cm2. The alteration was caused by thermo-mechanical damage and by binding medium ablation of a fresco and a secco prepared specimens, respectively.

  15. Laser studies of chemical dynamics at the gas-solid interface. Progress report

    SciTech Connect

    Cavanagh, R.R.; King, D.S.

    1985-10-14

    The pathways and rates of energy transfer at surfaces remain some of the key unresolved issues for understanding chemical reactions occurring at this interface region. A dedicated experimental facility incorporating both sophisticated laser probes and modern surface diagnostics is being applied to the study of the thermal desorption of molecules chemisorbed on well-characterized surfaces. The thermal desorption process was chosen for initial study because thermally activated desorption, and its reverse, trapping, are key steps for the control of heterogeneous reactions. While it is frequently assumed that the desorbed species may be described in terms of equilibration with the substrate heat bath, there have been no previous direct tests of the validity of this assumption. In fact, our earlier measurements of NO thermally desorbed from Ru(001) indicated this not to be the case. In the past year we have taken a detailed look at the thermal desorption of NO from Pt(111). Emphasis was placed on trying to uncover the relative importance of adsorbate-surface versus adsorbate-adsorbate interactions. In addition, we have assembled a high vacuum test station to investigate the effects of rapid pulsed laser heating on an adsorbate covered surface (Pt foil).

  16. Colour and chemical changes of the lime wood surface due to CO2 laser thermal modification

    NASA Astrophysics Data System (ADS)

    Kubovský, Ivan; Kačík, František

    2014-12-01

    We studied colour and main wood components changes of lime wood caused by CO2 laser beam irradiation. The dry surface of lime wood (Tilia vulgaris L.) was irradiated with the CO2 laser beam (wavelength of 10.6 μm) at different exposures (expressed as the irradiation dose). Colour changes were monitored by the spectrophotometer, chemical changes were observed by the ATR-FTIR spectroscopy and carbohydrates were analysed by the HPLC method. With the growth of the irradiation dose (from 8.1 to 28.7 J cm-2) lightness (ΔL*) decrease and increase of the total colour difference (ΔE*) were observed. Higher values of the input energy lead to accelerating the mutual reaction of the functional groups resulting in the subsequent condensation of lignin. The total decrease in saccharides at the highest irradiation dose reaches 27.39% of the initial amount of saccharides in the reference sample. We have observed degradation and loss of hemicelluloses.

  17. Temperature engineered growth of low-threshold quantum well lasers by metalorganic chemical vapor deposition

    SciTech Connect

    Dzurko, K.M.; Menu, E.P.; Beyler, C.A.; Osinski, J.S.; Dapkus, P.D.

    1989-01-09

    A new technique is demonstrated for the formation of narrow active regions in quantum well lasers. In temperature engineered growth (TEG), the substrate temperature is varied during the growth of epitaxial layers by metalorganic chemical vapor deposition (MOCVD) on nonplanar substrates, allowing two-dimensional control of device features. Buried heterostructure designs with submicron active region stripe widths are obtained without the need for fine process control of lateral dimensions. The contact area above the active region is coplanar with the surrounding surface and wide enough to allow easy contacting and heat sinking. Carrier confinement is accomplished by lateral thickness variation of the quantum well active region resulting in a local strip of minimum band gap. Lasers grown in this manner exhibit cw threshold currents as low as 3.8 mA (3.4 mA pulsed), having an as-grown active region width of 0.5 ..mu..m. The near-field optical profile indicates stable, single transverse mode operation and minimal current leakage in these devices.

  18. Standoff detection of chemical and biological threats using laser-induced breakdown spectroscopy.

    PubMed

    Gottfried, Jennifer L; De Lucia, Frank C; Munson, Chase A; Miziolek, Andrzej W

    2008-04-01

    Laser-induced breakdown spectroscopy (LIBS) is a promising technique for real-time chemical and biological warfare agent detection in the field. We have demonstrated the detection and discrimination of the biological warfare agent surrogates Bacillus subtilis (BG) (2% false negatives, 0% false positives) and ovalbumin (0% false negatives, 1% false positives) at 20 meters using standoff laser-induced breakdown spectroscopy (ST-LIBS) and linear correlation. Unknown interferent samples (not included in the model), samples on different substrates, and mixtures of BG and Arizona road dust have been classified with reasonable success using partial least squares discriminant analysis (PLS-DA). A few of the samples tested such as the soot (not included in the model) and the 25% BG:75% dust mixture resulted in a significant number of false positives or false negatives, respectively. Our preliminary results indicate that while LIBS is able to discriminate biomaterials with similar elemental compositions at standoff distances based on differences in key intensity ratios, further work is needed to reduce the number of false positives/negatives by refining the PLS-DA model to include a sufficient range of material classes and carefully selecting a detection threshold. In addition, we have demonstrated that LIBS can distinguish five different organophosphate nerve agent simulants at 20 meters, despite their similar stoichiometric formulas. Finally, a combined PLS-DA model for chemical, biological, and explosives detection using a single ST-LIBS sensor has been developed in order to demonstrate the potential of standoff LIBS for universal hazardous materials detection.

  19. Tattoo pigments are cleaved by laser light-the chemical analysis in vitro provide evidence for hazardous compounds.

    PubMed

    Vasold, Rudolf; Naarmann, Natascha; Ulrich, Heidi; Fischer, Daniela; König, Burkhard; Landthaler, Michael; Bäumler, Wolfgang

    2004-01-01

    In the western world, more than 80 million people decorate their skin with tattoos. Tattoo colorants are injected into the skin, like medical drugs. Most tattoo colorants are industrial pigments, and chemical industries have never produced them for human use but only to stain consumer goods. Up to 10% of tattooed people request removal of their tattoos because of an improved self-image or social stigmatization. In contrast to tattooing, physicians usually perform the tattoo removal. For that purpose laser light at very high intensities irradiates the skin to destroy the tattoo pigments. Based on a recent analysis of tattoo pigments, two widely used azo compounds were irradiated in suspension with laser and subsequently analyzed by using quantitative high-performance liquid chromatography and mass spectrometry. The high laser intensities cleaved the azo compounds, leading to an increase of decomposition products such as 2-methyl-5-nitroaniline, 2-5-dichloraniline and 4-nitro-toluene, which are toxic or even carcinogenic compounds. Moreover, the results of the chemical analysis show that the tattoo colorants already contain such compounds before laser irradiation. Because of a high number of patients undergoing laser treatment of tattoos and based on the results of our findings in vitro, it is an important goal to perform a risk assessment in humans regarding laser-induced decomposition products.

  20. Effects of high-repetition-rate femtosecond laser micromachining on the physical and chemical properties of polylactide (PLA).

    PubMed

    Jia, Wei; Luo, Yiming; Yu, Jian; Liu, Bowen; Hu, Minglie; Chai, Lu; Wang, Chingyue

    2015-10-19

    The effects of femtosecond laser ablation, with 115 fs pulses at 1040 nm wavelength and 57 MHz repetition-rate, on the physical and chemical properties of polylactide (PLA) were studied in air and in water. The surface of the PLA sample ablated by high-repetition-rate femtosecond laser was analysed using field emission scanning electron microscopy, infrared spectroscopy, raman spectroscopy, as well as X-ray photoelectron spectroscopy. Compared with the experiments in the air at ambient temperature, melting resolidification was negligible for the experiments conducted under water. Neither in air nor under water did oxidation and crystallization process take place in the laser ablated surface. In addition, the intensity of some oxygen related peaks increased for water experiments, probably due to the hydrolysis. Meantime, the chemical shift to higher energies appeared in C1s XPS spectrum of laser processing in water. Interestingly, a large amount of defects were observed after laser processing in air, while no significant change was shown under water experiments. This indicates that thermal and mechanical effects by high-repetition-rate femtosecond laser ablation in water are quite limited, which could be even ignored.

  1. Use of external cavity quantum cascade laser compliance voltage in real-time trace gas sensing of multiple chemicals

    SciTech Connect

    Phillips, Mark C.; Taubman, Matthew S.; Kriesel, Jason M.

    2015-02-08

    We describe a prototype trace gas sensor designed for real-time detection of multiple chemicals. The sensor uses an external cavity quantum cascade laser (ECQCL) swept over its tuning range of 940-1075 cm-1 (9.30-10.7 µm) at a 10 Hz repetition rate.

  2. A modular architecture for multi-channel external cavity quantum cascade laser-based chemical sensors: a systems approach

    SciTech Connect

    Taubman, Matthew S.; Myers, Tanya L.; Bernacki, Bruce E.; Stahl, Robert D.; Cannon, Bret D.; Schiffern, John T.; Phillips, Mark C.

    2012-04-01

    A multi-channel laser-based chemical sensor platform is presented, in which a modular architecture allows the exchange of complete sensor channels without disruption to overall operation. Each sensor channel contains custom optical and electronics packages, which can be selected to access laser wavelengths, interaction path lengths and modulation techniques optimal for a given application or mission. Although intended primarily to accommodate mid-infrared (MIR) external cavity quantum cascade lasers (ECQCLs)and astigmatic Herriott cells, channels using visible or near infrared (NIR) lasers or other gas cell architectures can also be used, making this a truly versatile platform. Analog and digital resources have been carefully chosen to facilitate small footprint, rapid spectral scanning, ow-noise signal recovery, failsafe autonomous operation, and in-situ chemometric data analysis, storage and transmission. Results from the demonstration of a two-channel version of this platform are also presented.

  3. Portable open-path chemical sensor using a quantum cascade laser

    NASA Astrophysics Data System (ADS)

    Corrigan, Paul; Lwin, Maung; Huntley, Reuven; Chhabra, Amandeep; Moshary, Fred; Gross, Barry; Ahmed, Samir

    2009-05-01

    Remote sensing of enemy installations or their movements by trace gas detection is a critical but challenging military objective. Open path measurements over ranges of a few meters to many kilometers with sensitivity in the parts per million or billion regime are crucial in anticipating the presence of a threat. Previous approaches to detect ground level chemical plumes, explosive constituents, or combustion have relied on low-resolution, short range Fourier transform infrared spectrometer (FTIR), or low-sensitivity near-infrared differential optical absorption spectroscopy (DOAS). As mid-infrared quantum cascade laser (QCL) sources have improved in cost and performance, systems based on QCL's that can be tailored to monitor multiple chemical species in real time are becoming a viable alternative. We present the design of a portable, high-resolution, multi-kilometer open path trace gas sensor based on QCL technology. Using a tunable (1045-1047cm-1) QCL, a modeled atmosphere and link-budget analysis with commercial component specifications, we show that with this approach, accuracy in parts per billion ozone or ammonia can be obtained in seconds at path lengths up to 10 km. We have assembled an open-path QCL sensor based on this theoretical approach at City College of New York, and we present preliminary results demonstrating the potential of QCLs in open-path sensing applications.

  4. Femtosecond laser pulses for chemical-free embryonic and mesenchymal stem cell differentiation

    NASA Astrophysics Data System (ADS)

    Mthunzi, Patience; Dholakia, Kishan; Gunn-Moore, Frank

    2011-10-01

    Owing to their self renewal and pluripotency properties, stem cells can efficiently advance current therapies in tissue regeneration and/or engineering. Under appropriate culture conditions in vitro, pluripotent stem cells can be primed to differentiate into any cell type some examples including neural, cardiac and blood cells. However, there still remains a pressing necessity to answer the biological questions concerning how stem cell renewal and how differentiation programs are operated and regulated at the genetic level. In stem cell research, an urgent requirement on experimental procedures allowing non-invasive, marker-free observation of growth, proliferation and stability of living stem cells under physiological conditions exists. Femtosecond (fs) laser pulses have been reported to non-invasively deliver exogenous materials, including foreign genetic species into both multipotent and pluripotent stem cells successfully. Through this multi-photon facilitated technique, directly administering fs laser pulses onto the cell plasma membrane induces transient submicrometer holes, thereby promoting cytosolic uptake of the surrounding extracellular matter. To display a chemical-free cell transfection procedure that utilises micro-litre scale volumes of reagents, we report for the first time on 70 % transfection efficiency in ES-E14TG2a cells using the enhanced green fluorescing protein (EGFP) DNA plasmid. We also show how varying the average power output during optical transfection influences cell viability, proliferation and cytotoxicity in embryonic stem cells. The impact of utilizing objective lenses of different numerical aperture (NA) on the optical transfection efficiency in ES-E14TG2a cells is presented. Finally, we report on embryonic and mesenchymal stem cell differentiation. The produced specialized cell types could thereafter be characterized and used for cell based therapies.

  5. Chemical and structural changes of quartz surfaces due to structuring by laser-induced backside wet etching.

    PubMed

    Kopitkovas, G; Deckert, V; Lippert, T; Raimondi, F; Schneider, C W; Wokaun, A

    2008-06-14

    Various physical and chemical processes which are involved in laser-induced backside wet etching are investigated. The surface of quartz etched by the laser-induced backside wet etching using a XeCl excimer laser at various fluences is analyzed by Raman microscopy, X-ray photoelectron spectroscopy and fiber-tip attenuated total-reflection Fourier-transform infrared spectroscopy. The investigations reveal the formation of a high amount of amorphous carbon deposits at low laser fluences, which strongly adhere to the quartz surface. Combining X-ray photoelectron spectroscopy and Fourier-transform infrared spectroscopy reveals that the quartz is also chemically and structurally modified due to a loss of oxygen and by a change of the quartz polymorph at intermediate and high laser fluences. These modification and their differences for different fluences are explained by the etching mechanisms itself, i.e. different magnitudes of temperature and pressure jumps. The results show clearly which conditions for etching must be applied to machine high-quality structures, e.g. micro-optical elements in quartz.

  6. In situ analytical assessment and chemical imaging of historical buildings using a man-portable laser system.

    PubMed

    Fortes, F J; Cuñat, J; Cabalín, L M; Laserna, J J

    2007-05-01

    In this work, the capability of laser-induced breakdown spectrometry for the in situ analytical assessment and chemical mapping of the façade of the cathedral of Malaga (Spain) has been demonstrated. The task required the use of a portable laser analyzer that allowed real-time spectral acquisitions in the field. A man-portable laser, based on a Q-switched Nd:YAG laser operating at its fundamental wavelength, has been utilized to generate a LIBS plasma of the sample surface. A chemical characterization of the different materials employed in the construction of this building has been performed. The purpose of this study was to use LIBS spectrochemical analysis to qualitatively discriminate between sandstone, limestone, marble, and cement mortar, which are the main components used in this class of historical monument. The field analysis was performed in two zones: the northern façade and the "girola"; the total areas of analysis of the two regions were 250 m(2) and 650 m(2), respectively. Chemical images of Si/Ca and Ca/Mg ratios from both parts of the building were generated. During the measurement campaign, a protocol of analysis was chosen so as to achieve an accurate description of the building materials with respectable spatial resolutions.

  7. Laser photoacoustic spectroscopy helps fight terrorism: High sensitivity detection of chemical Warfare Agent and explosives

    NASA Astrophysics Data System (ADS)

    Patel, C. K. N.

    2008-01-01

    Tunable laser photoacoustic spectroscopy is maturing rapidly in its applications to real world problems. One of the burning problems of the current turbulent times is the threat of terrorist acts against civilian population. This threat appears in two distinct forms. The first is the potential release of chemical warfare agents (CWA), such as the nerve agents, in a crowded environment. An example of this is the release of Sarin by Aum Shinrikyo sect in a crowded Tokyo subway in 1995. An example of the second terrorist threat is the ever-present possible suicide bomber in crowded environment such as airports, markets and large buildings. Minimizing the impact of both of these threats requires early detection of the presence of the CWAs and explosives. Photoacoustic spectroscopy is an exquisitely sensitive technique for the detection of trace gaseous species, a property that Pranalytica has extensively exploited in its CO2 laser based commercial instrumentation for the sub-ppb level detection of a number of industrially important gases including ammonia, ethylene, acrolein, sulfur hexafluoride, phosphine, arsine, boron trichloride and boron trifluoride. In this presentation, I will focus, however, on our recent use of broadly tunable single frequency high power room temperature quantum cascade lasers (QCL) for the detection of the CWAs and explosives. Using external grating cavity geometry, we have developed room temperature QCLs that produce continuously tunable single frequency CW power output in excess of 300 mW at wavelengths covering 5 μm to 12 μm. I will present data that show a CWA detection capability at ppb levels with false alarm rates below 1:108. I will also show the capability of detecting a variety of explosives at a ppb level, again with very low false alarm rates. Among the explosives, we have demonstrated the capability of detecting homemade explosives such as triacetone triperoxide and its liquid precursor, acetone which is a common household

  8. Process development for the manufacture of an integrated dispenser cathode assembly using laser chemical vapor deposition

    NASA Astrophysics Data System (ADS)

    Johnson, Ryan William

    2005-07-01

    Laser Chemical Vapor Deposition (LCVD) has been shown to have great potential for the manufacture of small, complex, two or three dimensional metal and ceramic parts. One of the most promising applications of the technology is in the fabrication of an integrated dispenser cathode assembly. This application requires the deposition of a boron nitride-molybdenum composite structure. In order to realize this structure, work was done to improve the control and understanding of the LCVD process and to determine experimental conditions conducive to the growth of the required materials. A series of carbon fiber and line deposition studies were used to characterize process-shape relationships and study the kinetics of carbon LCVD. These studies provided a foundation for the fabrication of the first high aspect ratio multi-layered LCVD wall structures. The kinetics studies enabled the formulation of an advanced computational model in the FLUENT CFD package for studying energy transport, mass and momentum transport, and species transport within a forced flow LCVD environment. The model was applied to two different material systems and used to quantify deposition rates and identify rate-limiting regimes. A computational thermal-structural model was also developed using the ANSYS software package to study the thermal stress state within an LCVD deposit during growth. Georgia Tech's LCVD system was modified and used to characterize both boron nitride and molybdenum deposition independently. The focus was on understanding the relations among process parameters and deposit shape. Boron nitride was deposited using a B3 N3H6-N2 mixture and growth was characterized by sporadic nucleation followed by rapid bulk growth. Molybdenum was deposited from the MoCl5-H2 system and showed slow, but stable growth. Each material was used to grow both fibers and lines. The fabrication of a boron nitride-molybdenum composite was also demonstrated. In sum, this work served to both advance the

  9. Laser speckle technique to study the effect of chemical pre-treatment on the quality of minimally processed apples

    NASA Astrophysics Data System (ADS)

    Minz, Preeti D.; Nirala, A. K.

    2016-04-01

    In the present study, the laser speckle technique has been used for the quality evaluation of chemically treated cut apples. Chemical pre-treatment includes 1% (w/v) solution of citric acid (CA), sodium chloride (SC), and a combination of CA and sodium chloride (CS). The variation in weight loss, respiration rate, total soluble solids (TSS), titratable acidity (TA), and absorbance of chemically treated cut apples stored at 5 °C was monitored for 11 d. The speckle grain size was calculated by an autocovariance method from the speckled images of freshly cut chemically treated apples. The effect of chemicals on TSS and the TA content variation of the cut apples were well correlated to the linear speckle grain size. Circular degree of polarization confirms the presence of a small scatterer and hence Rayleigh diffusion region. For all the treated cut apples, a decrease in the concentration of small particles nearly after the mid-period of storage results in the fast decay of circular degree of polarization. For non-invasive and fast analysis of the chemical constituent of fruits during minimal processing, the laser speckle can be practically used in the food industry.

  10. Measurement Of Atmospheric Peroxy Radicals By Chemical Conversion And Laser-induced Fluorescence Technique

    NASA Astrophysics Data System (ADS)

    Ren, X.; Naik, C.; Mao, J.; Harder, H.; Martinez, M.; Lesher, R.; Brune, W. H.

    2005-12-01

    A new method for measuring atmospheric peroxy radicals is described based on chemical conversion and laser-induced fluorescence (LIF) technique. Peroxy radicals are quantitatively converted into hydroperoxyl radicals (HO2) by the reactions with NO in a low-pressure reactor. The produced HO2 is then detected with an LIF instrument. The characterization and response of this instrument has been evaluated through the laboratory experiments as well as numeric simulations. Relative responses of different organic groups of peroxy radicals to HO2 were measured and the conversion coefficients agree generally well with the model calculations. The dependence of conversion coefficients on different experiment conditions was investigated. For HO2, the LIF signal is calibrated with an HO2 source produced by the photolysis of H2O via a low-pressure mercury lamp. Field measurements of peroxy radicals using this method were conducted at a rural site and preliminary results are presented. The estimated accuracy of the derived HOxROx concentrations is about 40% with a 2σ confidence level. Typical detection limit is about 0.2 pptv for 1-minute averaging times.

  11. Data Analysis of Multi-Laser Standoff Spectral identification of chemical and biological compounds

    SciTech Connect

    Farahi, R H; Zaharov, Viktor; Tetard, Laurene; Thundat, Thomas George; Passian, Ali

    2013-01-01

    With the availability of tunable broadband coherent sources that emit mid-infrared radiation with well-defined beam characteristics, spectroscopies that were traditionally not practical for standoff detection1 or for develop- ment of miniaturized infrared detectors2, 3 have renewed interest. While obtaining compositional information for objects from a distance remains a major challenge in chemical and biological sensing, recently we demonstrated that capitalizing on mid-infrared excitation of target molecules by using quantum cascade lasers and invoking a pump probe scheme can provide spectral fingerprints of substances from a variable standoff distance.3 However, the standoff data is typically associated with random fluctuations that can corrupt the fine spectral features and useful data. To process the data from standoff experiments toward better recognition we consider and apply two types of denoising techniques, namely, spectral analysis and Karhunen-Loeve Transform (KLT). Using these techniques, infrared spectral data have been effectively improved. The result of the analysis illustrates that KLT can be adapted as a powerful data denoising tool for the presented pump-probe infrared standoff spectroscopy.

  12. Laser-Induced Acoustic Desorption/Atmospheric Pressure Chemical Ionization Mass Spectrometry

    PubMed Central

    Gao, Jinshan; Borton, David J.; Owen, Benjamin C.; Jin, Zhicheng; Hurt, Matt; Amundson, Lucas M.; Madden, Jeremy T.; Qian, Kuangnan; Kenttämaa, Hilkka I.

    2010-01-01

    Laser-induced acoustic desorption (LIAD) was successfully coupled to a conventional atmospheric pressure chemical ionization (APCI) source in a linear quadrupole ion trap mass spectrometer (LQIT). Model compounds representing a wide variety of different types, including basic nitrogen and oxygen compounds, aromatic and aliphatic compounds, as well as unsaturated and saturated hydrocarbons, were tested separately and as a mixture. These model compounds were successfully evaporated into the gas phase by using LIAD and then ionized by using APCI with different reagents. Four APCI reagent systems were tested: the traditionally used mixture of methanol and water, neat benzene, neat carbon disulfide, and nitrogen gas (no liquid reagent). The mixture of methanol and water produced primarily protonated molecules, as expected. However, only the most basic compounds yielded ions under these conditions. In sharp contrast, using APCI with either neat benzene or neat carbon disulfide as the reagent resulted in the ionization of all the analytes studied to predominantly yield stable molecular ions. Benzene yielded a larger fraction of protonated molecules than carbon disulfide, which is a disadvantage. A similar amount of fragmentation was observed for these reagents. When the experiment was performed without a liquid reagent(nitrogen gas was the reagent), more fragmentation was observed. Analysis of a known mixture as well as a petroleum cut was also carried out. In summary, the new experiment presented here allows the evaporation of thermally labile compounds, both polar and nonpolar, without dissociation or aggregation, and their ionization to form stable molecular ions. PMID:21472571

  13. Particle Generation by Laser Ablation in Support of Chemical Analysis of High Level Mixed Waste from Plutonium Production Operations

    SciTech Connect

    J. Thomas Dickinson; Michael L. Alexander

    2001-11-30

    Investigate particles produced by laser irradiation and their analysis by Laser Ablation Inductively Coupled Plasma Mass Spectroscopy (LA/ICP-MS), with a view towards optimizing particle production for analysis of high level waste materials and waste glass. LA/ICP-MS has considerable potential to increase the safety and speed of analysis required for the remediation of high level wastes from cold war plutonium production operations. In some sample types, notably the sodium nitrate-based wastes at Hanford and elsewhere, chemical analysis using typical laser conditions depends strongly on the details of sample history composition in a complex fashion, rendering the results of analysis uncertain. Conversely, waste glass materials appear to be better behaved and require different strategies to optimize analysis.

  14. Combined Chemical and Topographic Imaging at Atmospheric Pressure via Microprobe Laser Desorption/Ionization Mass Spectrometry-Atomic Force Microscopy

    SciTech Connect

    Bradshaw, James A; Ovchinnikova, Olga S; Meyer, Kent A; Goeringer, Doug

    2009-01-01

    The operational characteristics and imaging performance are described for a new instrument comprising an atomic force microscope (AFM) coupled with a pulsed laser and a linear ion trap mass spectrometer. The AFM operating mode is used to produce topographic surface images having nanometer-scale spatial and height resolution. Spatially resolved mass spectra of ions, produced from the same surface via microprobe-mode laser desorption/ionization at atmospheric pressure, are then used to create a 100 x 100 m chemical image. The effective spatial resolution of the image (~2 m) was constrained by the limit of detection (estimated to be 109 1010 ions) rather than by the diameter of the focused laser spot or the step size of the AFM sample stage. Thus, it is expected that improvements in imaging performance can be realized by implementation of post-ionization methods.

  15. High sensitivity stand-off detection and quantification of chemical mixtures using an active coherent laser spectrometer (ACLaS)

    NASA Astrophysics Data System (ADS)

    MacLeod, Neil A.; Weidmann, Damien

    2016-05-01

    High sensitivity detection, identification and quantification of chemicals in a stand-off configuration is a highly sought after capability across the security and defense sector. Specific applications include assessing the presence of explosive related materials, poisonous or toxic chemical agents, and narcotics. Real world field deployment of an operational stand-off system is challenging due to stringent requirements: high detection sensitivity, stand-off ranges from centimeters to hundreds of meters, eye-safe invisible light, near real-time response and a wide chemical versatility encompassing both vapor and condensed phase chemicals. Additionally, field deployment requires a compact, rugged, power efficient, and cost-effective design. To address these demanding requirements, we have developed the concept of Active Coherent Laser Spectrometer (ACLaS), which can be also described as a middle infrared hyperspectral coherent lidar. Combined with robust spectral unmixing algorithms, inherited from retrievals of information from high-resolution spectral data generated by satellitebased spectrometers, ACLaS has been demonstrated to fulfil the above-mentioned needs. ACLaS prototypes have been so far developed using quantum cascade lasers (QCL) and interband cascade lasers (ICL) to exploit the fast frequency tuning capability of these solid state sources. Using distributed feedback (DFB) QCL, demonstration and performance analysis were carried out on narrow-band absorbing chemicals (N2O, H2O, H2O2, CH4, C2H2 and C2H6) at stand-off distances up to 50 m using realistic non cooperative targets such as wood, painted metal, and bricks. Using more widely tunable external cavity QCL, ACLaS has also been demonstrated on broadband absorbing chemicals (dichloroethane, HFC134a, ethylene glycol dinitrate and 4-nitroacetanilide solid) and on complex samples mixing narrow-band and broadband absorbers together in a realistic atmospheric background.

  16. Technical progress in industrial COIL

    NASA Astrophysics Data System (ADS)

    Tei, K.; Sugimoto, Daichi; Ito, T.; Watanabe, G.; Vyskubyenko, O.; Takeuchi, N.; Muto, S.; Fujioka, Tomoo

    2005-03-01

    Chemical oxygen-iodine laser (COIL) has a great potential for applications such as decommissioning and dismantlement (D&D) of nuclear reactor, rock destruction and removal and extraction of a natural resource (Methane hydrate) because of the unique characteristics such as power scalability, high optical beam quality and optical fiber beam. Five-kilowatt Chemical oxygen-iodine laser (COIL) test facility has been developed. The chemical efficiency of 27% has been demonstrated with a moderate beam quality for optical fiber coupling. Our research program contains conventional/ejector-COIL scheme, Jet-SOG/Mist-SOG optimization, fiber delivery and long-term operation.

  17. Advanced COIL technologies for field applications

    NASA Astrophysics Data System (ADS)

    Tei, Kazuyoku; Sugimoto, Daichi; Ito, T.; Watanabe, G.; Vyskubenko, O.; Takeuchi, N.; Muto, S.; Kenzo, N.; Fujioka, Tomoo

    2005-01-01

    Chemical oxygen-iodine laser (COIL) has a great potential for applications such as decommissioning and dismantlement (D&D) of nuclear reactor, rock destruction and removal and extraction of a natural resource (Methane hydrate) because of the unique characteristics such as power scalability, high optical beam quality and optical fiber beam. Five-kilowatt Chemical oxygen-iodine laser (COIL) test facility has been developed. The chemical efficiency of 27% has been demonstrated with a moderate beam quality for optical fiber coupling. Our research program contains conventional/ejector-COIL scheme, Jet-SOG/Mist-SOG optimization, fiber delivery and long-term operation.

  18. A miniature laser ablation mass spectrometer for quantitative in situ chemical composition investigation of lunar surface

    NASA Astrophysics Data System (ADS)

    Brigitte Neuland, Maike; Grimaudo, Valentine; Mezger, Klaus; Moreno-García, Pavel; Riedo, Andreas; Tulej, Marek; Wurz, Peter

    2016-04-01

    The chemical composition of planetary bodies, moons, comets and asteroids is a key to understand their origin and evolution [Wurz,2009]. Measurements of the elemental and isotopic composition of rocks yield information about the formation of the planetary body, its evolution and following processes shaping the planetary surface. From the elemental composition, conclusions about modal mineralogy and petrology can be drawn. Isotope ratios are a sensitive indicator for past events on the planetary body and yield information about origin and transformation of the matter, back to events that occurred in the early solar system. Finally, measurements of radiogenic isotopes make it possible to carry out dating analyses. All these topics, particularly in situ dating analyses, quantitative elemental and highly accurate isotopic composition measurements, are top priority scientific questions for future lunar missions. An instrument for precise measurements of chemical composition will be a key element in scientific payloads of future landers or rovers on lunar surface. We present a miniature laser ablation mass spectrometer (LMS) designed for in situ research in planetary and space science and optimised for measurements of the chemical composition of rocks and soils on a planetary surface. By means of measurements of standard reference materials we demonstrate that LMS is a suitable instrument for in situ measurements of elemental and isotopic composition with high precision and accuracy. Measurements of soil standards are used to confirm known sensitivity coefficients of the instrument and to prove the power of LMS for quantitative elemental analyses [Neuland,2016]. For demonstration of the capability of LMS to measure the chemical composition of extraterrestrial material we use a sample of Allende meteorite [Neuland,2014]. Investigations of layered samples confirm the high spatial resolution in vertical direction of LMS [Grimaudo,2015], which allows in situ studying of past

  19. Coupled molecular dynamics-Monte Carlo model to study the role of chemical processes during laser ablation of polymeric materials

    NASA Astrophysics Data System (ADS)

    Prasad, Manish; Conforti, Patrick F.; Garrison, Barbara J.

    2007-08-01

    The coarse grained chemical reaction model is enhanced to build a molecular dynamics (MD) simulation framework with an embedded Monte Carlo (MC) based reaction scheme. The MC scheme utilizes predetermined reaction chemistry, energetics, and rate kinetics of materials to incorporate chemical reactions occurring in a substrate into the MD simulation. The kinetics information is utilized to set the probabilities for the types of reactions to perform based on radical survival times and reaction rates. Implementing a reaction involves changing the reactants species types which alters their interaction potentials and thus produces the required energy change. We discuss the application of this method to study the initiation of ultraviolet laser ablation in poly(methyl methacrylate). The use of this scheme enables the modeling of all possible photoexcitation pathways in the polymer. It also permits a direct study of the role of thermal, mechanical, and chemical processes that can set off ablation. We demonstrate that the role of laser induced heating, thermomechanical stresses, pressure wave formation and relaxation, and thermochemical decomposition of the polymer substrate can be investigated directly by suitably choosing the potential energy and chemical reaction energy landscape. The results highlight the usefulness of such a modeling approach by showing that various processes in polymer ablation are intricately linked leading to the transformation of the substrate and its ejection. The method, in principle, can be utilized to study systems where chemical reactions are expected to play a dominant role or interact strongly with other physical processes.

  20. Chemical-assisted femtosecond laser writing of lab-in-fibers.

    PubMed

    Haque, Moez; Lee, Kenneth K C; Ho, Stephen; Fernandes, Luís A; Herman, Peter R

    2014-10-01

    The lab-on-chip (LOC) platform has presented a powerful opportunity to improve functionalization, parallelization, and miniaturization on planar or multilevel geometries that has not been possible with fiber optic technology. A migration of such LOC devices into the optical fiber platform would therefore open the revolutionary prospect of creating novel lab-in-fiber (LIF) systems on the basis of an efficient optical transport highway for multifunctional sensing. For the LIF, the core optical waveguide inherently offers a facile means to interconnect numerous types of sensing elements along the optical fiber, presenting a radical opportunity for optimizing the packaging and densification of diverse components in convenient geometries beyond that available with conventional LOCs. In this paper, three-dimensional patterning inside the optical fiber by femtosecond laser writing, together with selective chemical etching, is presented as a powerful tool to form refractive index structures such as optical waveguides and gratings as well as to open buried microfluidic channels and optical resonators inside the flexible and robust glass fiber. In this approach, optically smooth surfaces (~12 nm rms) are introduced for the first time inside the fiber cladding that precisely conform to planar nanograting structures when formed by aberration-free focusing with an oil-immersion lens across the cylindrical fiber wall. This process has enabled optofluidic components to be precisely embedded within the fiber to be probed by either the single-mode fiber core waveguide or the laser-formed optical circuits. We establish cladding waveguides, X-couplers, fiber Bragg gratings, microholes, mirrors, optofluidic resonators, and microfluidic reservoirs that define the building blocks for facile interconnection of inline core-waveguide devices with cladding optofluidics. With these components, more advanced, integrated, and multiplexed fiber microsystems are presented demonstrating

  1. Chemical-assisted femtosecond laser writing of lab-in-fibers.

    PubMed

    Haque, Moez; Lee, Kenneth K C; Ho, Stephen; Fernandes, Luís A; Herman, Peter R

    2014-10-01

    The lab-on-chip (LOC) platform has presented a powerful opportunity to improve functionalization, parallelization, and miniaturization on planar or multilevel geometries that has not been possible with fiber optic technology. A migration of such LOC devices into the optical fiber platform would therefore open the revolutionary prospect of creating novel lab-in-fiber (LIF) systems on the basis of an efficient optical transport highway for multifunctional sensing. For the LIF, the core optical waveguide inherently offers a facile means to interconnect numerous types of sensing elements along the optical fiber, presenting a radical opportunity for optimizing the packaging and densification of diverse components in convenient geometries beyond that available with conventional LOCs. In this paper, three-dimensional patterning inside the optical fiber by femtosecond laser writing, together with selective chemical etching, is presented as a powerful tool to form refractive index structures such as optical waveguides and gratings as well as to open buried microfluidic channels and optical resonators inside the flexible and robust glass fiber. In this approach, optically smooth surfaces (~12 nm rms) are introduced for the first time inside the fiber cladding that precisely conform to planar nanograting structures when formed by aberration-free focusing with an oil-immersion lens across the cylindrical fiber wall. This process has enabled optofluidic components to be precisely embedded within the fiber to be probed by either the single-mode fiber core waveguide or the laser-formed optical circuits. We establish cladding waveguides, X-couplers, fiber Bragg gratings, microholes, mirrors, optofluidic resonators, and microfluidic reservoirs that define the building blocks for facile interconnection of inline core-waveguide devices with cladding optofluidics. With these components, more advanced, integrated, and multiplexed fiber microsystems are presented demonstrating

  2. Standoff detection of explosives and chemical agents using broadly tuned external-cavity quantum cascade lasers (EC-QCLs)

    NASA Astrophysics Data System (ADS)

    Takeuchi, Eric B.; Rayner, Timothy; Weida, Miles; Crivello, Salvatore; Day, Timothy

    2007-10-01

    Civilian soft targets such as transportation systems are being targeted by terrorists using IEDs and suicide bombers. Having the capability to remotely detect explosives, precursors and other chemicals would enable these assets to be protected with minimal interruption of the flow of commerce. Mid-IR laser technology offers the potential to detect explosives and other chemicals in real-time and from a safe standoff distance. While many of these agents possess "fingerprint" signatures in the mid-IR (i.e. in the 3-20 micron regime), their effective interrogation by a practical, field-deployable system has been limited by size, complexity, reliability and cost constraints of the base laser technology. Daylight Solutions has addressed these shortcomings by developing compact, portable, broadly tunable mid-IR laser sources based upon external-cavity quantum cascade technology. This technology is now being applied by Daylight in system level architectures for standoff and remote detection of explosives, precursors and chemical agents. Several of these architectures and predicted levels of performance will be presented.

  3. High-resolution chemical depth profiling of solid material using a miniature laser ablation/ionization mass spectrometer.

    PubMed

    Grimaudo, Valentine; Moreno-García, Pavel; Riedo, Andreas; Neuland, Maike B; Tulej, Marek; Broekmann, Peter; Wurz, Peter

    2015-02-17

    High-resolution chemical depth profiling measurements of copper films are presented. The 10 μm thick copper test samples were electrodeposited on a Si-supported Cu seed under galvanostatic conditions in the presence of particular plating additives (SPS, Imep, PEI, and PAG) used in the semiconductor industry for the on-chip metallization of interconnects. To probe the trend of these plating additives toward inclusion into the deposit upon growth, quantitative elemental mass spectrometric measurements at trace level concentration were conducted by using a sensitive miniature laser ablation ionization mass spectrometer (LIMS), originally designed and developed for in situ space exploration. An ultrashort pulsed laser system (τ ∼ 190 fs, λ = 775 nm) was used for ablation and ionization of sample material. We show that with our LIMS system, quantitative chemical mass spectrometric analysis with an ablation rate at the subnanometer level per single laser shot can be conducted. The measurement capabilities of our instrument, including the high vertical depth resolution coupled with high detection sensitivity of ∼10 ppb, high dynamic range ≥10(8), measurement accuracy and precision, is of considerable interest in various fields of application, where investigations with high lateral and vertical resolution of the chemical composition of solid materials are required, these include, e.g., wafers from semiconductor industry or studies on space weathered samples in space research.

  4. Laser assisted modification and chemical metallization of electron-beam deposited ceria thin films

    NASA Astrophysics Data System (ADS)

    Krumov, E.; Starbov, N.; Starbova, K.; Perea, A.; Solis, J.

    2009-11-01

    Excimer laser processing is applied for tailoring the surface morphology and phase composition of CeO 2 ceramic thin films. E-beam evaporation technique is used to deposit samples on stainless steel and silicate glass substrates. The films are then irradiated with ArF* excimer laser pulses under different exposure conditions. Scanning electron microscopy, optical spectrophotometry, X-ray diffractometry and EDS microanalysis are used to characterize the non-irradiated and laser-processed films. Upon UV laser exposure there is large increase of the surface roughness that is accompanied by photo-darkening and ceria reduction. It is shown that the laser induced changes in the CeO 2 films facilitate the deposition of metal nano-aggregates in a commercial copper electroless plating bath. The significance of laser modification as a novel approach for the production of CeO 2 based thin film catalysts is discussed.

  5. Remote Continuous Wave and Pulsed Laser Raman Detection of Chemical Warfare Agents Simulants and Toxic Industrial Compounds

    NASA Astrophysics Data System (ADS)

    Ortiz-Rivera, William; Pacheco-Londoño, Leonardo C.; Hernández-Rivera, Samuel P.

    2010-09-01

    This study describes the design, assembly, testing and comparison of two Remote Raman Spectroscopy (RRS) systems intended for standoff detection of hazardous chemical liquids. Raman spectra of Chemical Warfare Agents Simulants (CWAS) and Toxic Industrial Compounds (TIC) were measured in the laboratory at a 6.6 m source-target distance using continuous wave (CW) laser detection. Standoff distances for pulsed measurements were 35 m for dimethyl methylphosphonate (DMMP) detection and 60, 90 and 140 m for cyclohexane detection. The prototype systems consisted of a Raman spectrometer equipped with a CCD detector (for CW measurements) and an I-CCD camera with time-gated electronics (for pulsed laser measurements), a reflecting telescope, a fiber optic assembly, a single-line CW laser source (514.5, 488.0, 351.1 and 363.8 nm) and a frequency-doubled single frequency Nd:YAG 532 nm laser (5 ns pulses at 10 Hz). The telescope was coupled to the spectrograph using an optical fiber, and filters were used to reject laser radiation and Rayleigh scattering. Two quartz convex lenses were used to collimate the light from the telescope from which the telescope-focusing eyepiece was removed, and direct it to the fiber optic assembly. To test the standoff sensing system, the Raman Telescope was used in the detection of liquid TIC: benzene, chlorobenzene, toluene, carbon tetrachloride, cyclohexane and carbon disulfide. Other compounds studied were CWAS: dimethylmethyl phosphonate, 2-chloroethyl ethyl sulfide and 2-(butylamino)-ethanethiol. Relative Raman scattering cross sections of liquid CWAS were measured using single-line sources at 532.0, 488.0, 363.8 and 351.1 nm. Samples were placed in glass and quartz vials at the standoff distances from the telescope for the Remote Raman measurements. The mass of DMMP present in water solutions was also quantified as part of the system performance tests.

  6. Fabrication of broadband antireflective black metal surfaces with ultra-light-trapping structures by picosecond laser texturing and chemical fluorination

    NASA Astrophysics Data System (ADS)

    Zheng, Buxiang; Wang, Wenjun; Jiang, Gedong; Mei, Xuesong

    2016-06-01

    A hybrid method consisting of ultrafast laser-assisted texturing and chemical fluorination treatment was applied for efficiently enhancing the surface broadband antireflection to fabricate black titanium alloy surface with ultra-light-trapping micro-nanostructure. Based on the theoretical analysis of surface antireflective principle of micro-nanostructures and fluoride film, the ultra-light-trapping micro-nanostructures have been processed using a picosecond pulsed ultrafast laser on titanium alloy surfaces. Then fluorination treatment has been performed by using fluoroalkyl silane solution. According to X-ray diffraction phase analysis of the surface compositions and measurement of the surface reflectance using spectrophotometer, the broadband antireflective properties of titanium alloy surface with micro-nano structural characteristics were investigated before and after fluorination treatment. The results show that the surface morphology of micro-nanostructures processed by picosecond laser has significant effects on the antireflection of light waves to reduce the surface reflectance, which can be further reduced using chemical fluorination treatment. The high antireflection of over 98 % in a broad spectral range from ultraviolet to infrared on the surface of metal material has been achieved for the surface structures, and the broadband antireflective black metal surfaces with an extremely low reflectance of ultra-light-trapping structures have been obtained in the wavelength range from ultraviolet-visible to near-infrared, middle-wave infrared. The average reflectance of microgroove groups structured surface reaches as low as 2.43 % over a broad wavelength range from 200 to 2600 nm. It indicates that the hybrid method comprising of picosecond laser texturing and chemical fluorination can effectively induce the broadband antireflective black metal surface. This method has a potential application for fabricating antireflective surface used to improve the

  7. Electromagnetic launch, then lessening chemical thrust over time as laser beam powered ion thrust grows{emdash}to any orbit

    SciTech Connect

    Morse, T.M.

    1996-03-01

    The ElectroMagnetic (EM) Launch Tube (LT), using High-Temp SuperConduction (HTSC) EM launch coils if developed, will be built in a tall building, or, if not, at a steep angle up the west slope of an extinct volcano. The Reusable Launch Vehicle (RLV) exits the LT at such high velocity that the otherwise violent entry into the atmosphere is made possible by Special-Laser-Launch-Assist (SLLA), which ionizes and expands the atmosphere immediately ahead of the RLV. At first a brief period of chemical thrust is followed by a long period of ion thrust during ascent to orbit. As decades pass and greater ion thrust is developed, the period of chemical thrust shortens until it is no longer needed. The RLV{close_quote}s ion thrusters are powered by laser/maser, beamed first from the launch site, then from two large Solar-Power-Satellites (SPS) 180{degree} apart in Medium Earth Orbit (MEO) orbit. In orbit, the RLV is limited in where it can go only by the amount of propellant it carries or is stored in various orbits. The RLV can land at a launch site on Earth by using both chemical and ion thrust at first, and later by ion thrust alone as developments cause a far lighter RLV to carry no chemical engines/fuel/tanks. {copyright} {ital 1996 American Institute of Physics.}

  8. System and method for laser assisted sample transfer to solution for chemical analysis

    DOEpatents

    Van Berkel, Gary J; Kertesz, Vilmos

    2014-01-28

    A system and method for laser desorption of an analyte from a specimen and capturing of the analyte in a suspended solvent to form a testing solution are described. The method can include providing a specimen supported by a desorption region of a specimen stage and desorbing an analyte from a target site of the specimen with a laser beam centered at a radiation wavelength (.lamda.). The desorption region is transparent to the radiation wavelength (.lamda.) and the sampling probe and a laser source emitting the laser beam are on opposite sides of a primary surface of the specimen stage. The system can also be arranged where the laser source and the sampling probe are on the same side of a primary surface of the specimen stage. The testing solution can then be analyzed using an analytical instrument or undergo further processing.

  9. Remote explosive and chemical agent detection using broadly tunable mid-infrared external cavity quantum cascade lasers

    NASA Astrophysics Data System (ADS)

    Rayner, Timothy; Weida, Miles; Pushkarsky, Michael; Day, Timothy

    2007-04-01

    Terrorists both with IEDs and suicide bombers are targeting civilian infrastructures such as transportation systems. Although explosive detection technologies exist and are used effectively in aviation, these technologies do not lend themselves well to protecting open architecture soft targets, as they are focused on a checkpoint form factor that limits throughput. However, remote detection of explosives and other chemicals would enable these kinds of targets to be protected without interrupting the flow of commerce. Tunable mid-IR laser technology offers the opportunity to detect explosives and other chemicals remotely and quickly. Most chemical compounds, including explosives, have their fundamental vibrational modes in the mid-infrared region (3 to 15μm). There are a variety of techniques that focus on examining interactions that have proven effective in the laboratory but could never work in the field due to complexity, size, reliability and cost. Daylight Solutions has solved these problems by integrating quantum cascade gain media into external tunable cavities. This has resulted in miniaturized, broadly tunable mid-IR laser sources. The laser sources have a capability to tune to +/- 5% of their center wavelength, which means they can sweep through an entire absorption spectrum to ensure very good detection and false alarm performance compared with fixed wavelength devices. These devices are also highly portable, operate at room temperature, and generate 10's to 100's of mW in optical power, in pulsed and continuous wave configurations. Daylight Solutions is in the process of developing a variety of standoff explosive and chemical weapon detection systems using this technology.

  10. Injecting parameters design and performance test of the pre-igniter for continuous wave DF/HF chemical lasers

    NASA Astrophysics Data System (ADS)

    Huang, Bing; Yuan, Shengfu; Yang, Lijia; Fang, Xiaoting

    2014-11-01

    Combustion-driven continuous wave (CW) DF/HF chemical lasers cannot be inflamed successfully sometimes because the spark-plug-igniter is intolerant of ablation especially after long-time operation which deeply affected the reliability of the lasers. In this paper, a pre-igniter is designed as a new igniter system to produce F2 to solve the problem. Based on the engineering practices and the principle that high-intensity spontaneous combustion will happen when mixing F2 and H2. The results of NF3 and H2 reacting with different mole ratios were calculated by CEA software. The operation reliability of the pre-igniter, the mole concentration of F2 in the mixing gas, and the equilibrium temperature were validated by a series of experiments. The experimental results were consistent with the calculated data: with the mole ratio of NF3 to H2 increasing, the equilibrium temperature decreased gradually and finally leveled off; the mole concentration of F2 in the mixing gas first increased and then decreased, achieving the maximum of about 40% when the mole ratio of NF3 to H2 was about 3.2. Experimental results outlined that the pre-igniter performed reliability and could produce high output of F2. The ignition system with a pre-igniter and a spark plug could provide a new alternative for combustion-driven CW DF/HF chemical lasers.

  11. Short- and long-path laser-induced fluorescence in the water column for the detection of dissolved chemicals

    NASA Astrophysics Data System (ADS)

    Sinn, Gert; Mittenzwey, Klaus-Henrik; Harsdorf, Stefan; Reuter, Rainer

    1997-05-01

    Lidar monitoring of surface waters has usually been applied to fluorescent and nonfluorescent soluble chemicals can be investigated. Two signals have to be measured, the total fluorescence lidar intensity L, which is characterized by long path-lengths of the laser radiation in the water column, and the fluorescence F, which originates from the first layers immediately below the water surface. The ratio of both intensities F/L yields the total attenuation coefficient at the laser wavelength considering also nonfluorescent substances besides fluorescent ones. A simple experiment in the laboratory was performed using a nitrogen laser. Water samples containing algae and a defined amount of humic acid were polluted with fluorescent quinine sulphate and nonfluorescent azobencene and p-nitrophenol down to ppb-concentrations. Synchronously, the attenuation coefficients were measured by conventional absorption spectroscopy. Good correlations between the conventional and the lidar-derived attenuation coefficients were achieved, described by squared correlation coefficients of r2 > 0.95. The F/L ratio seems to be a good tool in lidar monitoring of dissolved chemicals in waters.

  12. Stabilization, Injection and Control of Quantum Cascade Lasers, and Their Appli-cation to Chemical Sensing in the Infrared

    SciTech Connect

    Taubman, Matthew S.; Myers, Tanya L.; Cannon, Bret D.; Williams, Richard M.

    2004-12-01

    Quantum cascade lasers (QCLs) are a relatively new type of semiconductor laser operating in the mid- to long-wave infrared. These monopolar multilayered quantum well structures can be fabricated to operate anywhere between 3.5 microns and 20 microns, which includes the molecular fingerprint region of the in-frared. This makes them an ideal choice for infrared chemical sensing, a topic of great interest at present. Frequency stabilization and injection locking increase the utility of QCLs. We present results of locking quantum cascade lasers to optical cavities, achieving relative linewidths down to 5.6 Hz. We report injec-tion locking of one distributed feedback grating QCL with light from a similar QCL, demonstrating capture ranges of up to ±500 MHz, and suppression of amplitude modulation by up to 49 dB. We also present various cavity-enhanced chemical sensors employing the frequency stabilization techniques developed, in-cluding the resonant sideband technique known as Nice-Ohms. Sensitivities of 9.7 x 10-11 cm-1 Hz-1/2 have been achieved in nitrous oxide.

  13. Fabrication of superhydrophilic or superhydrophobic self-cleaning metal surfaces using picosecond laser pulses and chemical fluorination

    NASA Astrophysics Data System (ADS)

    Zheng, Buxiang; Jiang, Gedong; Wang, Wenjun; Mei, Xuesong

    2016-05-01

    Bioinspired superhydrophilic/phobic self-cleaning surfaces have recently drawn a lot of interest in both fundamental and applied research. A hybrid method to produce the self-cleaning property of micro/nanostructured surface using ultra-fast laser pulses followed by chemical fluorination is proposed. The typical micro/nanocomposite structures that form from microporous arrays and microgroove groups have been processed by picosecond laser on titanium alloy surface. The surface hydrophilic/phobic and self-cleaning properties of micro/nanostructures before and after fluorination with fluoroalkyl-silane were investigated using surface contact angle measurements. The results indicate that surface properties change from hydrophilic to hydrophobic after fluorination, and the micro/nanostructured surface with increased roughness contributes to the improvement of surface hydrophobicity. The micro/nanomodification can make the original hydrophilic titanium alloy surface more hydrophilic or superhydrophilic. It also can make an originally hydrophobic fluorinated titanium alloy surface more hydrophobic or superhydrophobic. The produced micro/nanostructured titanium alloy surfaces show excellent self-cleaning properties regardless of the fluorination treatment, although the fluorinated surfaces have slightly better self-cleaning properties. It is found that surface treatment using ultra-fast laser pulses and subsequent chemical fluorination is an effective way to manipulate surface wettability and obtain self-cleaning properties.

  14. Fabrication of silicon nanowire arrays by near-field laser ablation and metal-assisted chemical etching.

    PubMed

    Brodoceanu, D; Alhmoud, H Z; Elnathan, R; Delalat, B; Voelcker, N H; Kraus, T

    2016-02-19

    We present an elegant route for the fabrication of ordered arrays of vertically-aligned silicon nanowires with tunable geometry at controlled locations on a silicon wafer. A monolayer of transparent microspheres convectively assembled onto a gold-coated silicon wafer acts as a microlens array. Irradiation with a single nanosecond laser pulse removes the gold beneath each focusing microsphere, leaving behind a hexagonal pattern of holes in the gold layer. Owing to the near-field effects, the diameter of the holes can be at least five times smaller than the laser wavelength. The patterned gold layer is used as catalyst in a metal-assisted chemical etching to produce an array of vertically-aligned silicon nanowires. This approach combines the advantages of direct laser writing with the benefits of parallel laser processing, yielding nanowire arrays with controlled geometry at predefined locations on the silicon surface. The fabricated VA-SiNW arrays can effectively transfect human cells with a plasmid encoding for green fluorescent protein. PMID:26778665

  15. Influence of pulse duration on the doping quality in laser chemical processing (LCP)—a simulative approach

    NASA Astrophysics Data System (ADS)

    Fell, Andreas; Granek, Filip

    2013-03-01

    The laser chemical processing (LCP) technique for the local doping of crystalline silicon solar cells is investigated. Here, a liquid jet containing a dopant source acts as a waveguide for pulsed laser light, which results in the melting and subsequent doping of the silicon surface. Typical LCP pulse durations are in the 15 ns range, giving satisfactory results for specific parameter settings. While great potential is assumed to exist, optimization of the pulse duration has until now not been deeply investigated, because it is hard to change this parameter in laser systems. Therefore, this paper accesses the influence of the pulse duration by a simulative approach. The model includes optics, thermodynamics, and melt dynamics induced by the liquid jet and dopant diffusion into the silicon melt. It is solved by coupling our existing finite differences Matlab-code LCPSim with the commercial fluid flow solver Ansys Fluent. Simulations of axial symmetric single pulses were performed for pulse durations ranging from 15 ns to 500 ns. Detailed results are given, which show that for longer pulse durations lateral heat conduction significantly homogenizes the inhomogeneous dopant distribution caused by the speckled intensity profile within the liquid jet cross section. The melt expulsion by the liquid jet is low enough that a sufficiently doped layer remains after full resolidification for all pulse durations. Last, temperature gradients are evaluated to give an indication on the amount of laser damage induced by thermal stress.

  16. Optical properties of carbon nanostructures produced by laser irradiation on chemically modified multi-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Santiago, Enrique Vigueras; López, Susana Hernández; Camacho López, Marco A.; Contreras, Delfino Reyes; Farías-Mancilla, Rurik; Flores-Gallardo, Sergio G.; Hernández-Escobar, Claudia A.; Zaragoza-Contreras, E. Armando

    2016-10-01

    This research focused on the nanosecond (Nd: YAG-1064 nm) laser pulse effect on the optical and morphological properties of chemically modified multi-walled carbon nanotubes (MWCNT). Two suspensions of MWCNT in tetrahydrofuran (THF) were prepared, one was submitted to laser pulses for 10 min while the other (blank) was only mechanically homogenized during the same time. Following the laser irradiation, the suspension acquired a yellow-amber color, in contrast to the black translucent appearance of the blank. UV-vis spectroscopy confirmed this observation, showing the blank a higher absorption. Additionally, photoluminescence measurements exhibited a broad blue-green emission band both in the blank and irradiated suspension when excited at 369 nm, showing the blank a lower intensity. However, a modification in the excitation wavelength produced a violet to green tuning in the irradiated suspension, which did not occur in the blank. Lastly, the electron microscopy analysis of the treated nanotubes showed the abundant formation of amorphous carbon, nanocages, and nanotube unzipping, exhibiting the intense surface modification produced by the laser pulse. Nanotube surface modification and the coexistence with the new carbon nanostructures were considered as the conductive conditions for optical properties modification.

  17. Fabrication of silicon nanowire arrays by near-field laser ablation and metal-assisted chemical etching

    NASA Astrophysics Data System (ADS)

    Brodoceanu, D.; Alhmoud, H. Z.; Elnathan, R.; Delalat, B.; Voelcker, N. H.; Kraus, T.

    2016-02-01

    We present an elegant route for the fabrication of ordered arrays of vertically-aligned silicon nanowires with tunable geometry at controlled locations on a silicon wafer. A monolayer of transparent microspheres convectively assembled onto a gold-coated silicon wafer acts as a microlens array. Irradiation with a single nanosecond laser pulse removes the gold beneath each focusing microsphere, leaving behind a hexagonal pattern of holes in the gold layer. Owing to the near-field effects, the diameter of the holes can be at least five times smaller than the laser wavelength. The patterned gold layer is used as catalyst in a metal-assisted chemical etching to produce an array of vertically-aligned silicon nanowires. This approach combines the advantages of direct laser writing with the benefits of parallel laser processing, yielding nanowire arrays with controlled geometry at predefined locations on the silicon surface. The fabricated VA-SiNW arrays can effectively transfect human cells with a plasmid encoding for green fluorescent protein.

  18. Design and chemical synthesis of iodine-containing molecules for application to solar-pumped I* lasers

    NASA Technical Reports Server (NTRS)

    Shiner, C. S.

    1985-01-01

    This work is directed toward the design and chemical synthesis of new media for solar-pumped I* lasers. In view of the desirability of preparing a perfluoroalkyl iodide absorbing strongly at 300 nm, the relationship betwen perfluoroalkyl iodide structure and the corresponding absorption wavelength was reexamined. Analysis of existing data suggests that, in this family of compounds, the absorption maximum shifts to longer wavelength, as desired, as the C-I bond in the lasant is progressively weakened. Weakening of the C-I bond correlates, in turn, with increasing stability of the perfluoroalkyl radical formed upon photodissociation of the iodide. The extremely promising absorption characteristics of perfluoro-tert-butyl iodide can be accounted for on this basis. A new technique of diode laser probing to obtain precise yields of I* atoms in photodissociation was also developed.

  19. Passively mode-locked fiber laser by using monolayer chemical vapor deposition of graphene on D-shaped fiber.

    PubMed

    Chen, Tao; Liao, Changrui; Wang, D N; Wang, Yiping

    2014-05-01

    We demonstrate a monolayer graphene saturable absorber (SA) based on D-shaped fiber for operation of the mode-locked fiber laser. The monolayer graphene is grown by chemical vapor deposition (CVD) on Cu substrate and transferred onto the polymer, and then covered with D-shaped fiber, which allows light-graphene interaction via the evanescent field of the fiber. Due to the side-coupled interaction, the length of graphene is long enough to avoid optical power-induced thermal damage. Using such a graphene-based SA, stable mode-locked solitons with 4.5 nm spectral bandwidth and 713 fs pulsewidth at the 1563 nm wavelength have been obtained under 280 mW pump power. The influence of total cavity dispersion on the optical spectrum and pulse is also investigated by adding different lengths of single-mode fiber in the laser cavity.

  20. Tuning complex transition metal hydroxide nanostructures as active catalysts for water oxidation by a laser-chemical route.

    PubMed

    Niu, Kai-Yang; Lin, Feng; Jung, Suho; Fang, Liang; Nordlund, Dennis; McCrory, Charles C L; Weng, Tsu-Chien; Ercius, Peter; Doeff, Marca M; Zheng, Haimei

    2015-04-01

    Diverse transition metal hydroxide nanostructures were synthesized by laser-induced hydrolysis in a liquid precursor solution for alkaline oxygen evolution reaction (OER). Several active OER catalysts with fine control of composition, structure, and valence state were obtained including (Lix)[Ni0.66Mn0.34(OH)2](NO3)(CO3) · mH2O, Lix[Ni0.67Co0.33(OH)2](NO3)0.25(ORO)0.35 · mH2O, etc. An operate overpotential less than 0.34 V at current density of 10 mA cm(-2) was achieved. Such a controllable laser-chemical route for assessing complex nanostructures in liquids opens many opportunities to design novel functional materials for advanced applications.

  1. Experimental study and chemical application of GaAs semiconductor laser treating trigeminal neuralgia

    NASA Astrophysics Data System (ADS)

    Qiu, Ke-Qum; Cao, Shu-Chen; Wang, Hu-Zhong; Wang, Ke-Ning; Xiao, Ton-Ha; Shen, Ke-Wei

    1993-03-01

    GaAs semiconductor laser was used to treat trigeminal neuralgia with an effective rate of 91.1%, and no side effects were found in 67 cases. Changes in and the recovery of the trigeminal nerve cell were studied with light and electromicroscope. Discussed in this article are the time length and quantity of laser treatment with low power. Experimental study and clinical application of the GaAs semiconductor laser have been carried out in our department since 1987. One-hundred-fifteen patients with various diseases in the maxillofacial region (including 67 cases of trigeminal neuralgia) have been treated with satisfactory effects and without any side-effects. The wavelength of the laser is 904 mu, the largest pulse length is 200 mu, and the average power is 2000 HZ.

  2. SITE - EMERGING TECHNOLOGIES: LASER INDUCED PHOTO- CHEMICAL OXIDATIVE DESTRUCTION OF TOXIC ORGANICS IN LEACHATES AND GROUNDWATERS

    EPA Science Inventory

    The technology described in this report has been developed under the Emerging Technology Program of the Superfund Innovative Technology Evaluation (SITE) Program to photochemically oxidize organic compounds in wastewater by applying ultraviolet radiation using an excimer laser. T...

  3. Microstructure, microhardness, phase analysis and chemical composition of laser remelted FeB-Fe2B surface layers produced on Vanadis-6 steel

    NASA Astrophysics Data System (ADS)

    Bartkowska, Aneta; Swadźba, Radosław; Popławski, Mikołaj; Bartkowski, Dariusz

    2016-12-01

    The paper presents the study results of the diffusion boronized layer and their laser modification. Diffusion boronized processes were carried out on Vanadis-6 steel at 900 °C for 5 h. Boronized layers were characterized by dual-phase microstructure consisting of iron borides having a microhardness in the range from 1800 to 1400 HV. The laser heat treatment was carried out using CO2 laser after diffusion boronizing process. The research goals of this paper was analysis of microstructure, microhardness as well as phase and chemical composition of boronized layers after laser modification. Microstructure of boronized layer after laser modification consisted of remelted zone, heat affected zone and substrate. Remelted zone was characterized by microstructure consisted of boron-martensite eutectic. In this zone, the phases of borides and carbides were detected. Boronized layers after laser modification were characterized by the mild gradient of microhardness from surface to the substrate.

  4. Ion Yields in the Coupled Chemical and Physical Dynamics Model of Matrix-Assisted Laser Desorption/Ionization

    NASA Astrophysics Data System (ADS)

    Knochenmuss, Richard

    2015-08-01

    The Coupled Chemical and Physical Dynamics (CPCD) model of matrix assisted laser desorption ionization has been restricted to relative rather than absolute yield comparisons because the rate constant for one step in the model was not accurately known. Recent measurements are used to constrain this constant, leading to good agreement with experimental yield versus fluence data for 2,5-dihydroxybenzoic acid. Parameters for alpha-cyano-4-hydroxycinnamic acid are also estimated, including contributions from a possible triplet state. The results are compared with the polar fluid model, the CPCD is found to give better agreement with the data.

  5. Identification of vapor-phase chemical warfare agent simulants and rocket fuels using laser-induced breakdown spectroscopy

    SciTech Connect

    Stearns, Jaime A.; McElman, Sarah E.; Dodd, James A.

    2010-05-01

    Application of laser-induced breakdown spectroscopy (LIBS) to the identification of security threats is a growing area of research. This work presents LIBS spectra of vapor-phase chemical warfare agent simulants and typical rocket fuels. A large dataset of spectra was acquired using a variety of gas mixtures and background pressures and processed using partial least squares analysis. The five compounds studied were identified with a 99% success rate by the best method. The temporal behavior of the emission lines as a function of chamber pressure and gas mixture was also investigated, revealing some interesting trends that merit further study.

  6. [Lasers].

    PubMed

    Passeron, T

    2012-11-01

    Lasers are a very effective approach for treating many hyperpigmented lesions. They are the gold standard treatment for actinic lentigos and dermal hypermelanocytosis, such as Ota nevus. Becker nevus, hyperpigmented mosaicisms, and lentigines can also be successfully treated with lasers, but they could be less effective and relapses can be observed. However, lasers cannot be proposed for all types of hyperpigmentation. Thus, freckles and café-au-lait macules should not be treated as the relapses are nearly constant. Due to its complex pathophysiology, melasma has a special place in hyperpigmented dermatoses. Q-switched lasers (using standard parameters or low fluency) should not be used because of consistent relapses and the high risk of post-inflammatory hyperpigmentation. Paradoxically, targeting the vascular component of the melasma lesion with lasers could have a beneficial effect. However, these results have yet to be confirmed. In all cases, a precise diagnosis of the type of hyperpigmentation is mandatory before any laser treatment, and the limits and the potential side effects of the treatment must be clearly explained to patients.

  7. Lasers.

    PubMed

    Passeron, T

    2012-12-01

    Lasers are a very effective approach for treating many hyperpigmented lesions. They are the gold standard treatment for actinic lentigos and dermal hypermelanocytosis, such as Ota nevus. Becker nevus, hyperpigmented mosaicisms, and lentigines can also be successfully treated with lasers, but they could be less effective and relapses can be observed. However, lasers cannot be proposed for all types of hyperpigmentation. Thus, freckles and café-au-lait macules should not be treated as the relapses are nearly constant. Due to its complex pathophysiology, melasma has a special place in hyperpigmented dermatoses. Q-switched lasers (using standard parameters or low fluency) should not be used because of consistent relapses and the high risk of post-inflammatory hyperpigmentation. Paradoxically, targeting the vascular component of the melasma lesion with lasers could have a beneficial effect. However, these results have yet to be confirmed. In all cases, a precise diagnosis of the type of hyperpigmentation is mandatory before any laser treatment, and the limits and the potential side effects of the treatment must be clearly explained to patients.

  8. Chemical-free inactivated whole influenza virus vaccine prepared by ultrashort pulsed laser treatment

    NASA Astrophysics Data System (ADS)

    Tsen, Shaw-Wei David; Donthi, Nisha; La, Victor; Hsieh, Wen-Han; Li, Yen-Der; Knoff, Jayne; Chen, Alexander; Wu, Tzyy-Choou; Hung, Chien-Fu; Achilefu, Samuel; Tsen, Kong-Thon

    2015-05-01

    There is an urgent need for rapid methods to develop vaccines in response to emerging viral pathogens. Whole inactivated virus (WIV) vaccines represent an ideal strategy for this purpose; however, a universal method for producing safe and immunogenic inactivated vaccines is lacking. Conventional pathogen inactivation methods such as formalin, heat, ultraviolet light, and gamma rays cause structural alterations in vaccines that lead to reduced neutralizing antibody specificity, and in some cases, disastrous T helper type 2-mediated immune pathology. We have evaluated the potential of a visible ultrashort pulsed (USP) laser method to generate safe and immunogenic WIV vaccines without adjuvants. Specifically, we demonstrate that vaccination of mice with laser-inactivated H1N1 influenza virus at about a 10-fold lower dose than that required using conventional formalin-inactivated influenza vaccines results in protection against lethal H1N1 challenge in mice. The virus, inactivated by the USP laser irradiation, has been shown to retain its surface protein structure through hemagglutination assay. Unlike conventional inactivation methods, laser treatment did not generate carbonyl groups in protein, thereby reducing the risk of adverse vaccine-elicited T helper type 2 responses. Therefore, USP laser treatment is an attractive potential strategy to generate WIV vaccines with greater potency and safety than vaccines produced by current inactivation techniques.

  9. Laser induced damage characteristics of fused silica optics treated by wet chemical processes

    NASA Astrophysics Data System (ADS)

    Ye, Hui; Li, Yaguo; Yuan, Zhigang; Wang, Jian; Yang, Wei; Xu, Qiao

    2015-12-01

    Laser damage to fused silica continues a main issue of high-power/energy laser systems. HF-based etching technique is known to mitigate laser damage initiation and growth under UV laser illumination. The responses of material surface properties, especially surface damage characteristics to various etching parameters are questioned in the article. Fused silica was submerged into HF-based etchants (HF, NH4F:HF, HF:HNO3 with diverse concentrations) in an attempt to improve its laser-induced damage threshold (LIDT). The results have evidenced that the LIDT relies on, to a greater degree, the etched thickness and the etchant composition. The secondary ion mass spectrometer (SIMS) testing was aimed at relating the LIDT to certain metallic contaminant; however, the LIDT exhibits weak direct correlation with Ce, La, Ca, Fe contaminants. The surfaces with the highest LIDT are, more often than not, such that the surface roughness is <10 nm RMS and few metallic impurities are present. In addition, we tried to link the LIDT to the hardness and Young's modulus of fused silica, but no testing data show that there exists direct dependence of the LIDT on hardness and Young's modulus, which are actually independent of the removed thickness.

  10. Improving UV laser damage threshold of fused silica optics by wet chemical etching technique

    NASA Astrophysics Data System (ADS)

    Ye, Hui; Li, Yaguo; Yuan, Zhigang; Wang, Jian; Xu, Qiao; Yang, Wei

    2015-07-01

    Fused silica is widely used in high-power laser systems because of its good optical performance and mechanical properties. However, laser damage initiation and growth induced by 355 nm laser illumination in optical elements have become a bottleneck in the development of high energy laser system. In order to improve the laser-induced damage threshold (LIDT), the fused silica optics were treated by two types of HF-based etchants: 1.7%wt. HF acid and buffer oxide etchant (BOE: the mixture of 0.4%wt. HF and 12%wt. NH4F), respectively, for varied etching time. Damage testing shows that both the etchants increase the damage threshold at a certain depth of material removal, but further removal of material lowers the LIDT markedly. The etching rates of both etchants keep steady in our processing procedure, ~58 μg/min and ~85 μg/min, respectively. The micro-surface roughness (RMS and PV) increases as etching time extends. The hardness (H) and Young's modulus (E) of the fused silica etched for diverse time, measured by nano-indenter, show no solid evidence that LIDT can be related to hardness or Young's modulus.

  11. Chemical-free inactivated whole influenza virus vaccine prepared by ultrashort pulsed laser treatment.

    PubMed

    Tsen, Shaw-Wei David; Donthi, Nisha; La, Victor; Hsieh, Wen-Han; Li, Yen-Der; Knoff, Jayne; Chen, Alexander; Wu, Tzyy-Choou; Hung, Chien-Fu; Achilefu, Samuel; Tsen, Kong-Thon

    2015-05-01

    There is an urgent need for rapid methods to develop vaccines in response to emerging viral pathogens. Whole inactivated virus (WIV) vaccines represent an ideal strategy for this purpose; however, a universal method for producing safe and immunogenic inactivated vaccines is lacking. Conventional pathogen inactivation methods such as formalin, heat, ultraviolet light, and gamma rays cause structural alterations in vaccines that lead to reduced neutralizing antibody specificity, and in some cases, disastrous T helper type 2-mediated immune pathology. We have evaluated the potential of a visible ultrashort pulsed (USP) laser method to generate safe and immunogenic WIV vaccines without adjuvants. Specifically, we demonstrate that vaccination of mice with laser-inactivated H1N1 influenza virus at about a 10-fold lower dose than that required using conventional formalin-inactivated influenza vaccines results in protection against lethal H1N1 challenge in mice. The virus, inactivated by the USP laser irradiation, has been shown to retain its surface protein structure through hemagglutination assay. Unlike conventional inactivation methods, laser treatment did not generate carbonyl groups in protein, thereby reducing the risk of adverse vaccine-elicited T helper type 2 responses. Therefore, USP laser treatment is an attractive potential strategy to generate WIV vaccines with greater potency and safety than vaccines produced by current inactivation techniques.

  12. Use of external cavity quantum cascade laser compliance voltage in real-time trace gas sensing of multiple chemicals

    NASA Astrophysics Data System (ADS)

    Phillips, Mark C.; Taubman, Matthew S.; Kriesel, Jason

    2015-01-01

    We describe a prototype trace gas sensor designed for real-time detection of multiple chemicals. The sensor uses an external cavity quantum cascade laser (ECQCL) swept over its tuning range of 940-1075 cm-1 (9.30-10.7 μm) at a 10 Hz repetition rate. The sensor was designed for operation in multiple modes, including gas sensing within a multi-pass Heriott cell and intracavity absorption sensing using the ECQCL compliance voltage. In addition, the ECQCL compliance voltage was used to reduce effects of long-term drifts in the ECQCL output power. The sensor was characterized for noise, drift, and detection of chemicals including ammonia, methanol, ethanol, isopropanol, Freon- 134a, Freon-152a, and diisopropyl methylphosphonate (DIMP). We also present use of the sensor for mobile detection of ammonia downwind of cattle facilities, in which concentrations were recorded at 1-s intervals.

  13. Molecular dispersion spectroscopy for chemical sensing using chirped mid-infrared quantum cascade laser.

    PubMed

    Wysocki, Gerard; Weidmann, Damien

    2010-12-01

    A spectroscopic method of molecular detection based on dispersion measurements using a frequency-chirped laser source is presented. An infrared quantum cascade laser emitting around 1912 cm(-1) is used as a tunable spectroscopic source to measure dispersion that occurs in the vicinity of molecular ro-vibrational transitions. The sample under study is a mixture of nitric oxide in dry nitrogen. Two experimental configurations based on a coherent detection scheme are investigated and discussed. The theoretical models, which describe the observed spectral signals, are developed and verified experimentally. The method is particularly relevant to optical sensing based on mid-infrared quantum cascade lasers as the high chirp rates available with those sources can significantly enhance the magnitude of the measured dispersion signals. The method relies on heterodyne beatnote frequency measurements and shows high immunity to variations in the optical power received by the photodetector.

  14. Mechanism for critical behavior of a chemically reactive system under the action of laser radiation

    SciTech Connect

    Vasil'ev, G.K.; Chernyshev, Yu.A.; Makarov, E.F.; Yakushev, V.G.

    1982-07-01

    Several mechanisms, such as thermal vibration instability, have been proposed to describe critical phenomena in the threshold behavior of reactions, but none for laser initiation. A mechanism based on the competition between thermal acceleration of reaction and retardation of reaction due to annihilation is suggested. Laser initiation with excitation of low-atom molecules is examined. A typical two-center chain reaction is schematically represented, and equations are derived in a model analysis. The analysis indicates that pulsed initiation behavior as a function of initial conditions has a critical character. The criticality of laser initiation is not fundamentally different from other forms of pulsed initiation. A threshold dependence on the absorbed energies is not necessary. General analysis carried out in this paper provides a calculation for determining the photothermal explosion mechanism.

  15. (Study of flow properties of wet solids using laser induced photo chemical anemometry)

    SciTech Connect

    Falco, B.

    1992-04-09

    A new diagnostic measurement technique is being developed that will enable the investigation of the dynamics of flowing wet solids. The technique involves the use of Laser Induced Photochemical Anemometry (LIPA), enhanced to enable two photochemical species to be excited. It uses laser induced photochromic and photo luminescent molecules to separately tag the two phases for times long enough for them to distort the tagging. Recording the distortions of the tagging caused by the movement of each phase enables us to obtain local characterization of flow properties of both phases of the wet solids at many positions simultaneously across a pipe.

  16. Systems and methods for laser assisted sample transfer to solution for chemical analysis

    SciTech Connect

    Van Berkel, Gary J.; Kertesz, Vilmos; Ovchinnikova, Olga S.

    2015-09-29

    Systems and methods are described for laser ablation of an analyte from a specimen and capturing of the analyte in a dispensed solvent to form a testing solution. A solvent dispensing and extraction system can form a liquid microjunction with the specimen. The solvent dispensing and extraction system can include a surface sampling probe. The laser beam can be directed through the surface sampling probe. The surface sampling probe can also serve as an atomic force microscopy probe. The surface sampling probe can form a seal with the specimen. The testing solution including the analyte can then be analyzed using an analytical instrument or undergo further processing.

  17. Systems and methods for laser assisted sample transfer to solution for chemical analysis

    DOEpatents

    Van Berkel, Gary J; Kertesz, Vilmos; Ovchinnikova, Olga S

    2013-08-27

    Systems and methods are described for laser ablation of an analyte from a specimen and capturing of the analyte in a dispensed solvent to form a testing solution. A solvent dispensing and extraction system can form a liquid microjunction with the specimen. The solvent dispensing and extraction system can include a surface sampling probe. The laser beam can be directed through the surface sampling probe. The surface sampling probe can also serve as an atomic force microscopy probe. The surface sampling probe can form a seal with the specimen. The testing solution including the analyte can then be analyzed using an analytical instrument or undergo further processing.

  18. Systems and methods for laser assisted sample transfer to solution for chemical analysis

    SciTech Connect

    Van Berkel, Gary J.; Kertesz, Vilmos; Ovchinnikova, Olga S.

    2014-06-03

    Systems and methods are described for laser ablation of an analyte from a specimen and capturing of the analyte in a dispensed solvent to form a testing solution. A solvent dispensing and extraction system can form a liquid microjunction with the specimen. The solvent dispensing and extraction system can include a surface sampling probe. The laser beam can be directed through the surface sampling probe. The surface sampling probe can also serve as an atomic force microscopy probe. The surface sampling probe can form a seal with the specimen. The testing solution including the analyte can then be analyzed using an analytical instrument or undergo further processing.

  19. A laser-based instrument for the study of ultrafast chemical dynamics by soft x-ray-probe photoelectron spectroscopy

    NASA Astrophysics Data System (ADS)

    Nugent-Glandorf, Lora; Scheer, Michael; Samuels, David A.; Bierbaum, Veronica; Leone, Stephen R.

    2002-04-01

    A laser-based instrument is described for the study of femtosecond dissociation dynamics of gas phase molecules via time-resolved vacuum ultraviolet and soft x-ray photoelectron spectroscopy. Visible or UV pump pulses are generated with nonlinear crystal techniques on a Ti:sapphire laser output, while soft x-ray probe pulses are created via high-order harmonic generation of the same laser in rare gases. Here we describe the optical layout of the pump-probe system, the means for separation of the high-order harmonics in the soft x-ray probe beam, including a description of the two grating setup used to compress the high-harmonic pulses and the magnetic bottle photoelectron spectrometer used for data collection. The feasibility of using the generated high-harmonic pulses for an array of gaseous phase photoelectron spectroscopy experiments is established. These include measurements of valence shell and core-level photoelectron transitions in atoms and molecules, the tunability of the soft x-ray harmonic through Rydberg resonances, and the energy bandwidths of the harmonics. Cross correlations between the visible/UV and soft x-ray pulses, by above threshold ionization, are used to establish the pulse timing, pulse duration, and spatial overlap for ultrafast studies. The observed real time photodissociation of Br2 serves as a demonstration of the pump-probe ultrafast technique and the applicability to ultrafast time-resolved chemical dynamics.

  20. Chemically assisted ion beam etching of laser diode facets on nonpolar and semipolar orientations of GaN

    NASA Astrophysics Data System (ADS)

    Kuritzky, L. Y.; Becerra, D. L.; Saud Abbas, A.; Nedy, J.; Nakamura, S.; DenBaars, S. P.; Cohen, D. A.

    2016-07-01

    We demonstrate a vertical (<1° departure) and smooth (2.0 nm root mean square line-edge roughness (LER)) etch by chemically assisted Ar ion beam etching (CAIBE) in Cl2 chemistry that is suitable for forming laser diode (LD) facets on nonpolar and semipolar oriented III-nitride devices. The etch profiles were achieved with photoresist masks and optimized CAIBE chamber conditions including the platen tilt angle and Cl2 flow rate. Co-loaded studies showed similar etch rates of ˜60 nm min-1 for (20\\bar{2}\\bar{1}),(20\\bar{2}1), and m-plane orientations. The etched surfaces of LD facets on these orientations are chemically dissimilar (Ga-rich versus N-rich), but were visually indistinguishable, thus confirming the negligible orientation dependence of the etch. Continuous-wave blue LDs were fabricated on the semipolar (20\\bar{2}\\bar{1}) plane to compare CAIBE and reactive ion etch (RIE) facet processes. The CAIBE process resulted in LDs with lower threshold current densities due to reduced parasitic mirror loss compared with the RIE process. The LER, degree of verticality, and model of the 1D vertical laser mode were used to calculate a maximum uncoated facet reflection of 17% (94% of the nominal) for the CAIBE facet. The results demonstrate the suitability of CAIBE for forming high quality facets for high performance nonpolar and semipolar III-N LDs.

  1. Chemically assisted ion beam etching of laser diode facets on nonpolar and semipolar orientations of GaN

    NASA Astrophysics Data System (ADS)

    Kuritzky, L. Y.; Becerra, D. L.; Saud Abbas, A.; Nedy, J.; Nakamura, S.; DenBaars, S. P.; Cohen, D. A.

    2016-07-01

    We demonstrate a vertical (<1° departure) and smooth (2.0 nm root mean square line-edge roughness (LER)) etch by chemically assisted Ar ion beam etching (CAIBE) in Cl2 chemistry that is suitable for forming laser diode (LD) facets on nonpolar and semipolar oriented III-nitride devices. The etch profiles were achieved with photoresist masks and optimized CAIBE chamber conditions including the platen tilt angle and Cl2 flow rate. Co-loaded studies showed similar etch rates of ∼60 nm min‑1 for (20\\bar{2}\\bar{1}),(20\\bar{2}1), and m-plane orientations. The etched surfaces of LD facets on these orientations are chemically dissimilar (Ga-rich versus N-rich), but were visually indistinguishable, thus confirming the negligible orientation dependence of the etch. Continuous-wave blue LDs were fabricated on the semipolar (20\\bar{2}\\bar{1}) plane to compare CAIBE and reactive ion etch (RIE) facet processes. The CAIBE process resulted in LDs with lower threshold current densities due to reduced parasitic mirror loss compared with the RIE process. The LER, degree of verticality, and model of the 1D vertical laser mode were used to calculate a maximum uncoated facet reflection of 17% (94% of the nominal) for the CAIBE facet. The results demonstrate the suitability of CAIBE for forming high quality facets for high performance nonpolar and semipolar III-N LDs.

  2. Comparison of some effects of modification of a polylactide surface layer by chemical, plasma, and laser methods

    NASA Astrophysics Data System (ADS)

    Moraczewski, Krzysztof; Rytlewski, Piotr; Malinowski, Rafał; Żenkiewicz, Marian

    2015-08-01

    The article presents the results of studies and comparison of selected properties of the modified PLA surface layer. The modification was carried out with three methods. In the chemical method, a 0.25 M solution of sodium hydroxide in water and ethanol was utilized. In the plasma method, a 50 W generator was used, which produced plasma in the air atmosphere under reduced pressure. In the laser method, a pulsed ArF excimer laser with fluency of 60 mJ/cm2 was applied. Polylactide samples were examined by using the following techniques: scanning electron microscopy (SEM), atomic force microscopy (AFM), goniometry and X-ray photoelectron spectroscopy (XPS). Images of surfaces of the modified samples were recorded, contact angles were measured, and surface free energy was calculated. Qualitative and quantitative analyses of chemical composition of the PLA surface layer were performed as well. Based on the survey it was found that the best modification results are obtained using the plasma method.

  3. Stabilization, injection and control of quantum cascade lasers, and their application to chemical sensing in the infrared.

    PubMed

    Taubman, Matthew S; Myers, Tanya L; Cannon, Bret D; Williams, Richard M

    2004-12-01

    Quantum cascade lasers (QCLs) are a relatively new type of semiconductor laser operating in the mid- to long-wave infrared. These monopolar multilayered quantum well structures can be fabricated to operate anywhere between 3.5 and 20 microm, which includes the molecular fingerprint region of the infrared. This makes them an ideal choice for infrared chemical sensing, a topic of great interest at present. Frequency stabilization and injection locking increase the utility of QCLs. We present results of locking QCLs to optical cavities, achieving relative linewidths down to 5.6 Hz. We report injection locking of one distributed feedback grating QCL with light from a similar QCL, demonstrating capture ranges of up to +/-500 MHz, and suppression of amplitude modulation by up to 49 dB. We also present various cavity-enhanced chemical sensors employing the frequency stabilization techniques developed, including the resonant sideband technique known as NICE-OHMS. Sensitivities of 9.7 x 10(-11) cm(-1) Hz(-1/2) have been achieved in pure nitrous oxide.

  4. Chemical Composition of Micrometer-Sized Filaments in an Aragonite Host by a Miniature Laser Ablation/Ionization Mass Spectrometer.

    PubMed

    Tulej, Marek; Neubeck, Anna; Ivarsson, Magnus; Riedo, Andreas; Neuland, Maike B; Meyer, Stefan; Wurz, Peter

    2015-08-01

    Detection of extraterrestrial life is an ongoing goal in space exploration, and there is a need for advanced instruments and methods for the detection of signatures of life based on chemical and isotopic composition. Here, we present the first investigation of chemical composition of putative microfossils in natural samples using a miniature laser ablation/ionization time-of-flight mass spectrometer (LMS). The studies were conducted with high lateral (∼15 μm) and vertical (∼20-200 nm) resolution. The primary aim of the study was to investigate the instrument performance on micrometer-sized samples both in terms of isotope abundance and element composition. The following objectives had to be achieved: (1) Consider the detection and calculation of single stable isotope ratios in natural rock samples with techniques compatible with their employment of space instrumentation for biomarker detection in future planetary missions. (2) Achieve a highly accurate chemical compositional map of rock samples with embedded structures at the micrometer scale in which the rock matrix is easily distinguished from the micrometer structures. Our results indicate that chemical mapping of strongly heterogeneous rock samples can be obtained with a high accuracy, whereas the requirements for isotope ratios need to be improved to reach sufficiently large signal-to-noise ratio (SNR).

  5. Chemical Composition of Micrometer-Sized Filaments in an Aragonite Host by a Miniature Laser Ablation/Ionization Mass Spectrometer.

    PubMed

    Tulej, Marek; Neubeck, Anna; Ivarsson, Magnus; Riedo, Andreas; Neuland, Maike B; Meyer, Stefan; Wurz, Peter

    2015-08-01

    Detection of extraterrestrial life is an ongoing goal in space exploration, and there is a need for advanced instruments and methods for the detection of signatures of life based on chemical and isotopic composition. Here, we present the first investigation of chemical composition of putative microfossils in natural samples using a miniature laser ablation/ionization time-of-flight mass spectrometer (LMS). The studies were conducted with high lateral (∼15 μm) and vertical (∼20-200 nm) resolution. The primary aim of the study was to investigate the instrument performance on micrometer-sized samples both in terms of isotope abundance and element composition. The following objectives had to be achieved: (1) Consider the detection and calculation of single stable isotope ratios in natural rock samples with techniques compatible with their employment of space instrumentation for biomarker detection in future planetary missions. (2) Achieve a highly accurate chemical compositional map of rock samples with embedded structures at the micrometer scale in which the rock matrix is easily distinguished from the micrometer structures. Our results indicate that chemical mapping of strongly heterogeneous rock samples can be obtained with a high accuracy, whereas the requirements for isotope ratios need to be improved to reach sufficiently large signal-to-noise ratio (SNR). PMID:26247475

  6. Continuous-wave (F + H(2)) chemical lasers: a temperature-dependent analytical diffusion model.

    PubMed

    Herbelin, J M

    1976-01-01

    The development of an analytical model for predicting the performance of HF lasers that result from the mixing of atomic fluorine with molecular hydrogen in continuously flowing systems is described. The model combines a temperature-dependent solution for a premixed laser system with laminar or turbulent flame-sheet mixing schemes to generate closed-form expressions for the two conditions of constant pressure (simulating a free jet) and constant density (simulating a partially confined flow). The various approximations, including a fully communicating cavity and characteristic reaction and deactivation lifetimes, are discussed. Scaling laws that relate power to the total pressure and nozzle parameters are developed. Comparison with exact numerical treatments for a wide range of conditions reveals that the model is consistently accurate to ~10%. Finally, the sensitivity of the predictions to the kinetic rate package and the utility of the model for performing parameter studies are indicated.

  7. Quantum cascade laser based active hyperspectral imaging for standoff detection of chemicals on surfaces

    NASA Astrophysics Data System (ADS)

    Hugger, S.; Fuchs, F.; Jarvis, J.; Yang, Q. K.; Rattunde, M.; Ostendorf, R.; Schilling, C.; Driad, R.; Bronner, W.; Aidam, R.; Wagner, J.; Tybussek, T.; Rieblinger, K.

    2016-02-01

    We employ active hyperspectral imaging using tunable mid-infrared (MIR) quantum cascade lasers for contactless identification of solid and liquid contaminations on surfaces. By collecting the backscattered laser radiation with a camera, a hyperspectral data cube, containing the spatially resolved spectral information of the scene is obtained. Data is analyzed using appropriate algorithms to find the target substances even on substrates with a priori unknown spectra. Eye-save standoff detection of residues of explosives and precursors over extended distances is demonstrated and the main purpose of our system. However, it can be applied to any substance with characteristic reflectance / absorbance spectrum. As an example, we present first results of monitoring food quality by distinguishing fresh and mold contaminated peanuts by their MIR backscattering spectrum.

  8. Laser based in-situ and standoff detection of chemical warfare agents and explosives

    NASA Astrophysics Data System (ADS)

    Patel, C. Kumar N.

    2009-09-01

    Laser based detection of gaseous, liquid and solid residues and trace amounts has been developed ever since lasers were invented. However, the lack of availability of reasonably high power tunable lasers in the spectral regions where the relevant targets can be interrogated as well as appropriate techniques for high sensitivity, high selectivity detection has hampered the practical exploitation of techniques for the detection of targets important for homeland security and defense applications. Furthermore, emphasis has been on selectivity without particular attention being paid to the impact of interfering species on the quality of detection. Having high sensitivity is necessary but not a sufficient condition. High sensitivity assures a high probability of detection of the target species. However, it is only recently that the sensor community has come to recognize that any measure of probability of detection must be associated with a probability of false alarm, if it is to have any value as a measure of performance. This is especially true when one attempts to compare performance characteristics of different sensors based on different physical principles. In this paper, I will provide a methodology for characterizing the performance of sensors utilizing optical absorption measurement techniques. However, the underlying principles are equally application to all other sensors. While most of the current progress in high sensitivity, high selectivity detection of CWAs, TICs and explosives involve identifying and quantifying the target species in-situ, there is an urgent need for standoff detection of explosives from safe distances. I will describe our results on CO2 and quantum cascade laser (QCL) based photoacoustic sensors for the detection of CWAs, TICs and explosives as well the very new results on stand-off detection of explosives at distances up to 150 meters. The latter results are critically important for assuring safety of military personnel in battlefield

  9. Laser-Shot-Induced Chemical Reactions inside Nanotubes: a TDDFT investigation

    NASA Astrophysics Data System (ADS)

    Zhang, Hong; Miyamoto, Yoshiyuki; Rubio, Angel

    2011-03-01

    We present the application of the time-dependent density functional theory (TDDFT) on ultrafast laser pulse which induces dynamics in molecules encapsulated by a nanotube. A strong laser pulse polarized perpendicular to the tube axis induces a giant bond-stretch of an HCl molecule inside both C and BN nanotubes. Depending on the initial orientation of the HCl molecule, the subsequent laser-induced dynamics is different. We also observed a radial motion of the nanotube and vacancies appear on the tube wall when the HCl is perpendicular to tube axis. Furthermore, the disintegration of HCl molecules took place when their molecular axis tilted to tube axis. These simulations are important to analyze light-induced nanochemistry and manipulation of nanostructures encapsulated in organic and inorganic nanotubes. The computational scheme used in present work was a combination of the molecular dynamics and real-time propagation of electron wave functions under presence of strong optical field [2,3]. The energy conservation rule was checked to monitor the numerical stability.

  10. Kr/sup +/ laser-induced chemical vapor deposition of W

    SciTech Connect

    Zhang, G.Q.; Szoerenyi, T.; Baeuerle, D.

    1987-07-15

    Kr/sup +/ laser-induced pyrolytic direct writing of W stripes by H/sub 2/ reduction of WF/sub 6/ has been investigated. The reproducibility of the process and the morphology and electrical properties of deposits depend heavily on the partial pressures of both WF/sub 6/ and H/sub 2/; the best results have been obtained with p(WF/sub 6/) = 5 mbar and 100 mbarless than or equal top(H/sub 2/)less than or equal to800 mbar. For a laser focus of 2w/sub 0/ = 7 ..mu..m and laser powers between 30 and 200 mW, the widths of stripes varied between 1.5 and 15 ..mu..m with corresponding thicknesses between 0.1 to 3 ..mu..m. The width of stripes is independent of the scanning speed within the range 20 ..mu..m/sless than or equal toV/sub s/ less than or equal to400 ..mu..m/s. The electrical resistivities of these stripes were about a factor of 1.3--2.3 larger than the bulk value.

  11. Depth-resolved chemical mapping of rock coatings using Laser-Induced Breakdown Spectroscopy: Implications for geochemical investigations on Mars

    NASA Astrophysics Data System (ADS)

    Lefebvre, C.; Catalá-Espí, A.; Sobron, P.; Koujelev, A.; Léveillé, R.

    2016-07-01

    We demonstrate that Laser-Induced Breakdown Spectroscopy (LIBS) is capable of identifying the presence of natural rock coatings, and we define LIBS signatures of complex multi-layered coatings. This is illustrated by detailed LIBS analysis, in Mars-simulated conditions, of a rock collected in the Svalbard Islands, and which is analogous to some altered Martian rocks. The sample is a basaltic rock with sub-mm Ca-Mg-Fe-Si rich mineral coatings. LIBS elemental analysis of several distinct regions on the surface of the rock demonstrates the variability of chemical compositions of the various coatings, which is confirmed by complementary scanning electron microscope (SEM) analysis. Furthermore, the LIBS analysis as a function of the depth at different locations shows chemical variability, indicative of penetration through thin coatings of varying composition. Fine-scale, three-dimensional LIBS analysis is of interest for identifying and characterizing coatings on martian rocks, likely originating from aqueous processes, providing a rapid chemical composition as a function of the layers and further understanding of the formation of the deposits and on planetary evolution.

  12. Laser-induced Fluorescence Spectroscopy for applications in chemical sensing and optical refrigeration

    NASA Astrophysics Data System (ADS)

    Kumi Barimah, Eric

    Laser-induced breakdown spectroscopy (LIBS) is an innovative technique that has been used as a method for fast elemental analysis in real time. Conventional ultraviolet-visible (UV-VIS) LIBS has been applied to detect the elemental composition of different materials, including explosives, pharmaceutical drugs, and biological samples. The extension of conventional LIBS to the infrared region (˜1-12 mum) promises to provide additional information on molecular emission signatures due to rotational-vibrational transitions. In this research, a pulsed Nd: YAG laser operating at 1064 nm was focused onto several sodium compounds (NaCl, NaClO3, Na2CO3 and NaClO4) and potassium compounds (KCl, KClO3, K2CO3 and KClO4) to produce an intense plasma at the target surface. Several distinct infrared (IR) atomic emission signatures were observed from all sodium and potassium containing compounds. The atomic emission lines observed from the investigated samples matched assigned transitions of neutral sodium and potassium atoms published in the National Institute of Standards and Technology (NIST) atomic database. In addition to the intense atomic lines, the rst evidence of molecular LIBS emission structures were observed at ˜10.0 m in KClO3 and NaClO3 for the chlorate anion (ClO3 --1), at ˜6.7 to 8.0 mum in KNO3 and NaNO 3 for the nitrate anion (NO3--1 ), ˜8.0 to 10.0 mum in KClO4 and NaClO4 for perchlorate anion (ClO4--1 ), and ˜6.88 mum and 11.53 mum in Na2CO3 for the carbonate anion (CO3--1 ). The observed molecular emission showed strong correlation with the conventional Fourier Transform Infrared Spectrometry (FTIR) absorption spectra of the investigated samples. IR LIBS was also applied to determine the limit of detection (LOD) for the perchlorate anion in KClO4 using the 8.0 -11.0 mum IR-LIBS emission band. The calibration curve of ClO4 in KClO4 was constructed using peak and integrated emission intensities for known concentrations of mixed KClO4/NH4NO3 samples. The

  13. Chemical and mineralogical analyses of planetary rocks using a laser ablation mass spectrometer for in situ space research

    NASA Astrophysics Data System (ADS)

    Brigitte Neuland, Maike; Mezger, Klaus; Riedo, Andreas; Tulej, Marek; Wurz, Peter

    2015-04-01

    The context chemical analysis is of considerable importance in space research. High resolution in situ studies of planetary materials can yield important information on surface heterogeneity, basic grain mineralogy and chemical composition of surface and subsurface. In turn, these data are the basis for our understanding of the physical and chemical processes which led to the formation and alteration of planetary material [1] [2]. A highly heterogeneous sample of Allende meteorite, representative for extraterrestrial material, is investigated by LMS, a miniature laser ablation mass spectrometer designed for space research [3]. In the current setup a fs-laser ablation ion source is applied, allowing chemical analysis with lateral resolution of about 10-15 μm and sub-micrometre depth resolution [4]. The reflectron TOF mass analyser is used to measure elemental and isotopic composition of the sampled surface. The LMS instrument supports mass resolution 400 and dynamic range of 108 [5]. In the current studies with the fs-ablation ion source significant improvements in the detection efficiency of several metals e.g., Ni, Co, and non-metals e.g., Si, P, S and O, was achieved comparing to our previous setup [6]. Also the values of sensitivity coefficients for these elements are determined to be close to one, which resulted in the substantial improvements of the quantitative element analysis of the sample. Since the ablation crater depth is expected to be about 1 nm/laser shot also the possible changes of the main element or isotope distribution in depth can be analysed to assess their influence on the mineralogical analysis [7]. Several areas on an Allende sample were investigated and the chemical composition across the surface was determined from the mass spectrometric analysis. Also accurate isotope analysis could be conducted for most of main elements with sufficiently high signal to noise ratio. Correlation of elements was conducted and yielded mineralogical maps

  14. Resonant laser ablation ion trap mass spectrometry -- Recent applications for chemical analysis

    SciTech Connect

    Gill, C.G.; Garrett, A.W.; Hemberger, P.H.; Nogar, N.S.

    1995-12-31

    Resonant Laser Ablation (RLA) is a useful ionization process for selectively producing gas phase ions from a solid sample. Recent use of RLA for mass spectrometry by this group and by others has produced a wealth of knowledge and useful analytical techniques. The method relies upon the focusing of modest intensity laser pulses ({le} 10{sup 7} W {center_dot} Cm{sup {minus}2}) upon a sample surface. A small quantity of material is vaporized, and atoms of desired analyte are subsequently ionized by (n + m) photon processes in the gas phase (where n = number of photons to a resonant transition and m = number of photons to exceed the ionization limit). The authors have been using (2 + 1) resonant ionization schemes for this work. Quadrupole ion trap mass spectrometry is realizing a very prominent role in current mass spectrometric research. Ion traps are versatile, powerful and extremely sensitive mass spectrometers, capable of a variety of ionization modes, MS{sup n} type experiments, high mass ranges and high resolution, all for a fraction of the cost of other instrumentation with similar capabilities. Quadrupole ion traps are ideally suited to pulsed ionization sources such as laser ionization methods, since their normal operational method (Mass Selective Instability) relies upon the storage of ions from a finite ionization period followed by ejection and detection of these ions based upon their mass to charge ratios. The paper describes selective ionization for trace atomic analysis, selective reagent ion source for ion chemistry investigations, and the analysis of ``difficult`` environmental contaminants, i.e., TBP.

  15. Line-shape flattening resulting from hypersonic nozzle wedge flow in low-pressure chemical lasers.

    PubMed

    Livingston, P M; Bullock, D L

    1980-07-01

    The new hypersonic wedge nozzle (HYWN) supersonic wedge nozzle design produces a significant component of directed gas flow along the optical axis of a laser cavity comparable to thermal speeds. The gain-line-shape function is broadened and the refractive-index line shape is also spread as a function of wedge-flow half-angle. An analytical treatment as well as a numerical study is presented that evaluates the Doppler-directed-flow impact on the number of longitudinal modes and their frequencies as well as on gain and refractive-index saturation of those that lase in a Fabry-Perot cavity.

  16. Flavin mononucleotide biomolecular laser: longitudinal mode structure, polarization, and temporal characteristics as probes of local chemical environment.

    PubMed

    Rivera, José A; Eden, J Gary

    2016-05-16

    A detailed characterization of the flavin mononucleotide (FMN) biomolecular laser, optically pumped in a stable resonator, is reported here. Photoexcitation of the molecule at 355 nm results in lasing over the ~566.5-573.5 nm spectral region, and the threshold pump energy density is measured to be 110 ± 10 µJ/mm2 for a 10 mM FMN/water solution. Over twenty longitudinal modes are observed when the cavity length L and the energy pump fluence Ep are 375 µm and 300 µJ/mm2, respectively. Partial substitution of glycerol for water as the solvent results in a factor of four reduction in the threshold pump energy fluence (to < 30 µJ/mm2) and a quadrupling of the slope efficiency. This effect is attributed to the O2 - mediated photoconversion of FMN molecules in the triplet state to the singlet species. For pump intensities a factor of 2.5 above threshold, the laser pulse width is ~2 ns FWHM, and the output intensity decays exponentially with a photon lifetime of 1.7 ns. The addition of glycerol to a FMN/water solution also suppresses s-polarized emission (yielding P = 0.78 ± 0.08), presumably as a result of the inhibition of FMN rotational diffusion. The sensitivity of the spectral and optical properties of this and other biomolecular lasers to the chemical environment underscores the value of coherent emission as a biochemical or biomedical diagnostic tool, particularly insofar as molecule-molecule interactions are concerned. PMID:27409906

  17. Comparison of the structural and chemical composition of two unique micro/nanostructures produced by femtosecond laser interactions on nickel

    SciTech Connect

    Zuhlke, Craig A.; Anderson, Troy P.; Alexander, Dennis R.

    2013-09-16

    The structural and chemical composition of two unique microstructures formed on nickel, with nanoscale features, produced using femtosecond laser surface processing (FLSP) techniques is reported in this paper. These two surface morphologies, termed mounds and nanoparticle-covered pyramids, are part of a larger class of self-organized micro/nanostructured surfaces formed using FLSP. Cross-sections of the structures produced using focused ion beam milling techniques were analyzed with a transmission electron microscope. Both morphologies have a solid core with a layer of nanoparticles on the surface. Energy dispersive X-ray spectroscopy by scanning transmission electron microscopy studies reveal that the nanoparticles are a nickel oxide, while the core material is pure nickel.

  18. Increasing the output power of single 808-nm laser diodes using diamond submounts produced by microwave plasma chemical vapour deposition

    SciTech Connect

    Ashkinazi, E E; Bezotosnyi, V V; Bondarev, Vadim Yu; Kovalenko, V I; Konov, Vitalii I; Krokhin, Oleg N; Oleshchenko, V A; Pevtsov, Valerii F; Popov, Yurii M; Popovich, A F; Ral'chenko, Viktor G; Cheshev, E A

    2012-11-30

    We have designed and fabricated submounts from synthetic diamond grown by microwave plasma chemical vapour deposition and developed an economical process for metallising such submounts. Laser diode chips having an 808-nm emission wavelength, 3-mm-long cavity and 130-mm-wide stripe contact were mounted on copper heat sinks with the use of diamond submounts differing in quality. The devices were tested for more than 150 h in continuous mode at an output power of 8 W on diamond with a thermal conductivity of 700 W m{sup -1} K{sup -1}, and no changes in their output power were detected. On diamond with a thermal conductivity of 1600 W m{sup -1} K{sup -1}, stable cw operation for 24 h at an output power of 12 W was demonstrated. (letters)

  19. Mid-IR quantum cascade lasers as an enabling technology for a new generation of chemical analyzers for liquids

    NASA Astrophysics Data System (ADS)

    Lendl, B.; Reidl-Leuthner, C.; Ritter, W.

    2011-01-01

    This presentation introduces a chemical analyzer (The ERACHECK) which is based on quantum cascade laser technology for measuring oil-in-water. Using these mid-IR lasers, it was possible to develop a portable, robust and highly precise analyzer for the measurement of oil-in-water, a parameter which is vital in the petrochemical industry for process control and environmental analysis. The overall method employs a liquid-liquid extraction step of the aqueous sample using a cyclic, aliphatic hydrocarbon such as cyclohexane. Quantification is based on measurement of the C-H deformation vibrations of the extracted hydrocarbons in the cyclic extraction solvent. The developed method is linear from 0.5 - 2000 ppm of oil in water, with precisions well below 15% in terms of r.s.d for repeated measurements. The portability of the ERACHECK and its robustness has been key for its successful use on oil rigs as well as petrochemical production sites on land. The values provided by the ERACHECK correlate well with those obtained by the former CFC (Freon 113) based method for oil in water, which is no longer in use in industrialized countries due to the ozone depleting effect of the CFCs employed.

  20. Laser fluorescence studies of the chemical interactions of sodium species with sulfur bearing fuels

    NASA Technical Reports Server (NTRS)

    Steinberg, M.; Schofield, K.

    1983-01-01

    By using a large matrix of fuel rich and fuel lean H2/O2/N2 and fuel rich C2H2/O2/N2 flames, the behavior of sodium and its interactions with sulfur at high temperatures was extensively characterized. OH concentrations were measured for each flame using the previously validated laser induced fluorescence technique. Sodium atomic concentrations were obtained by the saturated laser fluorescence method. Measurements were made in the absence and presence of up to 2% sulfur. In oxygen rich systems sodium is depleted by NaO2 and NaOH formation. The relative amounts of each are controlled by the degree of nonequilibration of the flame radicals and by the temperature. The bond strength of NaO2 was established. For the first time, a complete understanding of the complex behavior of sodium in fuel lean H2/O2 flames has emerged and computer modeling has permitted various rate constants of Na, NaO2 and NaOH reactions to be approximately fixed.

  1. Similarity between the mechanisms of soft-laser radiation and chemical adaptogen action

    NASA Astrophysics Data System (ADS)

    Reznikov, Leonid L.; Pavlova, Rimma N.; Murzin, Alexander G.; Boiko, Vladimir A.; Pupkova, Ludmila S.; Soms, Leonid N.

    1993-07-01

    The comparative studies of SLR effects vs chemical adaptogens effects on animals poisoned by industrial poisons and SLR as compared to traditional radio-protectors effects on gamma- irradiated animals were carried out. Obtained results show the stressed adaptogenous effect of SLR.

  2. Effects of texturization due to chemical etching and laser on the optical properties of multicrystalline silicon for applications in solar cells

    NASA Astrophysics Data System (ADS)

    Vera, D.; Mass, J.; Manotas, M.; Cabanzo, R.; Mejia, E.

    2016-02-01

    In this work we carried out the texturization of surfaces of multicrystalline silicon type-p in order to decrease the reflection of light on the surface, using the chemical etching method and then a treatment with laser. In the first method, it was immersed in solutions of HF:HNO3:H2O, HF:HNO3:CH3COOH, HF:HNO3:H3PO4, in the proportion 14:01:05, during 30 seconds, 1, 2 and 3 minutes. Subsequently with a laser (ND:YAG) grids were generated beginning with parallel lines separated 50μm. The samples were analyzed by means of diffuse spectroscopy (UV-VIS) and scanning electron micrograph (SEM) before and after the laser treatment. The lowest result of reflectance obtained by HF:HNO3:H2O during 30 seconds, was of 15.5%. However, after applying the treatment with laser the reflectance increased to 17.27%. On the other hand, the samples treated (30 seconds) with acetic acid and phosphoric acid as diluents gives as a result a decrease in the reflectance values after applying the laser treatment from 21.97% to 17.79% and from 27.73% to 20.03% respectively. The above indicates that in some cases it is possible to decrease the reflectance using jointly the method of chemical etching and then a laser treatment.

  3. Combining Transmission Geometry Laser Ablation and a Non Contact Continuous Flow Surface Sampling Probe/Electrospray Emitter for Mass Spectrometry-Based Chemical Imaging

    SciTech Connect

    Ovchinnikova, Olga S; Kertesz, Vilmos; Van Berkel, Gary J

    2011-01-01

    This paper describes the coupling of ambient pressure transmission geometry laser ablation with a liquid phase sample collection into a continuous flow surface sampling probe/electrospray emitter for mass spectrometry based chemical imaging. The flow probe/emitter device was placed in close proximity to the surface to collect the sample plume produced by laser ablation. The sample collected was immediately aspirated into the probe and on to the electrospray emitter, ionized and detected with the mass spectrometer. Freehand drawn ink lines and letters and an inked fingerprint on microscope slides were analyzed. The circular laser ablation area was about 210 m in diameter and under the conditions used in these experiments the spatial resolution, as determined by the size of the surface features distinguished in the chemical images, was about 100 m.

  4. Forced convection and transport effects during hyperbaric laser chemical vapor deposition

    SciTech Connect

    Maxwell, James L; Chavez, Craig A; Espinoza, Miguel; Black, Marcie; Maskaly, Karlene; Boman, Mats

    2009-01-01

    This work explores mass transport processes during HP-LCYD, including the transverse forced-flow of precursor gases through a nozzle to enhance fiber growth rates. The use of laser trapping and suspension of nano-scale particles in the precursor flow is also described, providing insights into the nature of the gas flow, including jetting from the fiber tip and thermodiffusion processes near the reaction zone. The effects of differing molecular-weight buffer gases is also explored in conjunction with the Soret effect, and it is found that nucleation at the deposit surface (and homogeneous nucleation in the gas phase) can be enhanced/ retarded, depending on the buffer gas molecular weight. To demonstrate that extensive microstructures can be grown simultaneously, three-dimensional fiber arrays are also grown in-parallel using diffractive optics--without delatory effects from neighboring reaction sites.

  5. Experimental Investigation of Supersonic Mixing Mechanisms of HYLTE Nozzle for DF Chemical Laser

    NASA Astrophysics Data System (ADS)

    Yan, Shao; Jin, Zhou; Sunping, Zhang; Lin, Lai

    2011-02-01

    Utilizing experimental techniques of Nano-particle based Planar Laser Scattering (NPLS) and schlieren photography, the flow patterns and mixing characteristics of a designed HYLTE (HYpersonic Low TEmperature) nozzle were investigated in this paper. In order to visualize the non-reacting flowfield of supersonic angled jets into a supersonic crossflow in the HYLTE nozzle, a testing section with windows was designed and manufactured. The effects of different total pressure ratio of the twin jets to the freestream and different injectants on supersonic mixing are examined. Instantaneous side- and end-view NPLS images provide transverse penetration and lateral spread information for the secondary twin jets. As an assistant method, schlieren photos display the shock patterns that exist in the HYLTE nozzle.

  6. Solution-Based Synthesis of Crystalline Silicon from Liquid Silane through Laser and Chemical Annealing

    DOE PAGES

    Iyer, Ganjigunte R. S.; Hobbie, Erik K.; Guruvenket, Srinivasan; Hoey, Justin M.; Anderson, Kenneth J.; Lovaasen, John; Gette, Cody; Schulz, Douglas L.; Swenson, Orven F.; Elangovan, Arumugasamy; et al

    2012-05-23

    We report a solution process for the synthesis of crystalline silicon from the liquid silane precursor cyclohexasilane (Si6H12). Polysilane films were crystallized through thermal and laser annealing, with plasma hydrogenation at atmospheric pressure generating further structural changes in the films. The evolution from amorphous to microcrystalline is characterized using scanning electron microscopy (SEM), atomic force microscopy (AFM), Raman spectroscopy and impedance spectroscopy. A four-decade enhancement in the electrical conductivity is attributed to a disorder-order transition in a bonded Si network. Lastly, our results demonstrate a potentially attractive approach that employs a solution process coupled with ambient post-processing to produce crystallinemore » silicon thin films.« less

  7. Solution-Based Synthesis of Crystalline Silicon from Liquid Silane through Laser and Chemical Annealing

    SciTech Connect

    Iyer, Ganjigunte R. S.; Hobbie, Erik K.; Guruvenket, Srinivasan; Hoey, Justin M.; Anderson, Kenneth J.; Lovaasen, John; Gette, Cody; Schulz, Douglas L.; Swenson, Orven F.; Elangovan, Arumugasamy; Boudjouk, P.

    2012-05-23

    We report a solution process for the synthesis of crystalline silicon from the liquid silane precursor cyclohexasilane (Si6H12). Polysilane films were crystallized through thermal and laser annealing, with plasma hydrogenation at atmospheric pressure generating further structural changes in the films. The evolution from amorphous to microcrystalline is characterized using scanning electron microscopy (SEM), atomic force microscopy (AFM), Raman spectroscopy and impedance spectroscopy. A four-decade enhancement in the electrical conductivity is attributed to a disorder-order transition in a bonded Si network. Lastly, our results demonstrate a potentially attractive approach that employs a solution process coupled with ambient post-processing to produce crystalline silicon thin films.

  8. Particle generation by laser ablation in support of chemical analysis of high level mixed waste from plutonium production operations. 1998 annual progress report

    SciTech Connect

    Dickinson, J.T.; Alexander, M.L.

    1998-06-01

    'The authors goal is to provide fundamental mechanistic studies of laser produced particulate formation in support of the use of Laser Assisted-Inductively Coupled Plasma-Mass Spectroscopy (LA-ICP-MS) to be used for analysis of radioactive/toxic materials. The work reported here represents the first nine months of this 3-year project. The major focus of these studies is determining the detailed mechanisms and character of the particulates generated by laser ablation of solid targets relevant to sampling materials for chemical analysis using inductively coupled mass spectroscopy, ICP-MS. In this application, particles generated by laser ablation must be transported to the plasma torch of the ICP-MS, often through a hollow tube with an interior diameter of a few mm. Proper digestion and ionization of particles in the plasma limits particle sizes to under a micron. Thus the production of submicron particles which truly represent the stoichiometry of the specimen is of critical importance.'

  9. Possibilities of improving the performance of an autonomous cw chemical DF laser by replacing the slot nozzles by the ramp ones in the nozzle array

    SciTech Connect

    Bashkin, A S; Gurov, L V; Kurdyukov, M V

    2011-08-31

    The results of a comparative numerical study of the performance of an autonomous cw chemical DF laser are obtained by simulating the processes in the nozzles and laser cavity where several configurations of slot and ramp nozzle arrays are employed. Three-dimensional Navier-Stokes equations solved with the Ansys CFX software are used to describe the reacting multicomponent flow in the nozzles and laser cavity. To investigate lasing characteristics, a supplementary code is developed and is used to calculate the radiation intensity in the Fabry-Perot resonator, taking into account its nonuniform distribution along the aperture width and height. It is shown that the use of the nozzle array consisting of ramp nozzles, which, in contrast to the slot nozzles, provide enhanced mixing of the reactants makes it possible to improve the laser performance in the case of a high-pressure (more than 15 Torr) active medium. (control of radiation parameters)

  10. Design and performance of a sensor system for detection of multiple chemicals using an external cavity quantum cascade laser

    NASA Astrophysics Data System (ADS)

    Phillips, Mark C.; Taubman, Matthew S.; Bernacki, Bruce E.; Cannon, Bret D.; Schiffern, John T.; Myers, Tanya L.

    2010-01-01

    We describe the performance of a sensor system designed for simultaneous detection of multiple chemicals with both broad and narrow absorption features. The sensor system consists of a broadly tunable external cavity quantum cascade laser (ECQCL), multi-pass Herriott cell, and custom low-noise electronics. The ECQCL features a fast wavelength tuning rate of 2265 cm-1/s (15660 nm/s) over the range of 1150-1270 cm-1 (7.87-8.70 μm), which permits detection of molecules with broad absorption features and dynamic concentrations, while the 0.2 cm-1 spectral resolution of the ECQCL system allows measurement of small molecules with atmospherically broadened absorption lines. High-speed amplitude modulation and low-noise electronics are used to improve the ECQCL performance for direct absorption measurements. We demonstrate simultaneous detection of Freon-134a (1,1,1,2-tetrafluoroethane), ammonia (NH3), and nitrous oxide (N2O) at low-ppb concentrations in field measurements of atmospheric chemical releases from a point source.

  11. Design and Performance of a Sensor System for Detection of Multiple Chemicals Using an External Cavity Quantum Cascade Laser

    SciTech Connect

    Phillips, Mark C.; Taubman, Matthew S.; Bernacki, Bruce E.; Cannon, Bret D.; Schiffern, John T.; Myers, Tanya L.

    2010-01-23

    We describe the performance of a sensor system designed for simultaneous detection of multiple chemicals with both broad and narrow absorption features. The sensor system consists of a broadly tunable external cavity quantum cascade laser (ECQCL), multi-pass Herriott cell, and custom low-noise electronics. The ECQCL features a rapid wavelength tuning rate of 2265 cm 1/s (15660 nm/s) over its tuning range of 1150-1270 cm 1 (7.87-8.70 μm), which permits detection of molecules with broad absorption features and dynamic concentrations, while the 0.2 cm-1 spectral resolution of the ECQCL system allows measurement of small molecules with atmospherically broadened absorption lines. High-speed amplitude modulation and low-noise electronics are used to improve the ECQCL performance for direct absorption measurements. We demonstrate simultaneous detection of Freon-134a (1,1,1,2-tetrafluoroethane), ammonia (NH3), and nitrous oxide (N2O) at low-ppb concentrations in field measurements of atmospheric chemical releases from a point source.

  12. Mesoscale elucidation of laser-assisted chemical deposition of Sn nanostructured electrodes

    SciTech Connect

    Liu, Zhixiao; Mukherjee, Partha P.; Deng, Biwei; Cheng, Gary J.; Deng, Huiqiu

    2015-06-07

    Nanostructured tin (Sn) is a promising high-capacity electrode for improved performance in lithium-ion batteries for electric vehicles. In this work, Sn nanoisland growth for nanostructured electrodes assisted by the pulse laser irradiation has been investigated based on a mesoscale modeling formalism. The influence of pertinent processing conditions, such as pulse duration, heating/cooling rates, and atom flux, on the Sn nanostructure formation is specifically considered. The interaction between the adsorbed atom and the substrate, represented by the adatom diffusion barrier, is carefully studied. It is found that the diffusion barrier predominantly affects the distribution of Sn atoms. For both α-Sn and β-Sn, the averaged coordination number is larger than 3 when the diffusion barrier equals to 0.15 eV. The averaged coordination number decreases as the diffusion barrier increases. The substrate temperature, which is determined by heating/cooling rates and pulse duration, can also affect the formation of Sn nanoislands. For α-Sn, when applied low heating/cooling rates, nanoislands cannot form if the diffusion barrier is larger than 0.35 eV.

  13. Chemical kinetic studies of atmospheric reactions using tunable diode laser spectroscopy

    NASA Technical Reports Server (NTRS)

    Worsnop, Douglas R.; Nelson, David D.; Zahniser, Mark S.

    1993-01-01

    IR absorption using tunable diode laser spectroscopy provides a sensitive and quantitative detection method for laboratory kinetic studies of atmospheric trace gases. Improvements in multipass cell design, real time signal processing, and computer controlled data acquisition and analysis have extended the applicability of the technique. We have developed several optical systems using off-axis resonator mirror designs which maximize path length while minimizing both the sample volume and the interference fringes inherent in conventional 'White' cells. Computerized signal processing using rapid scan (300 kHz), sweep integration with 100 percent duty cycle allows substantial noise reduction while retaining the advantages of using direct absorption for absolute absorbance measurements and simultaneous detection of multiple species. Peak heights and areas are determined by curve fitting using nonlinear least square methods. We have applied these techniques to measurements of: (1) heterogeneous uptake chemistry of atmospheric trace gases (HCl, H2O2, and N2O5) on aqueous and sulfuric acid droplets; (2) vapor pressure measurements of nitric acid and water over prototypical stratospheric aerosol (nitric acid trihydrate) surfaces; and (3) discharge flow tube kinetic studies of the HO2 radical using isotopic labeling for product channel and mechanistic analysis. Results from each of these areas demonstrate the versatility of TDL absorption spectroscopy for atmospheric chemistry applications.

  14. Mesoscale elucidation of laser-assisted chemical deposition of Sn nanostructured electrodes

    NASA Astrophysics Data System (ADS)

    Liu, Zhixiao; Deng, Biwei; Cheng, Gary J.; Deng, Huiqiu; Mukherjee, Partha P.

    2015-06-01

    Nanostructured tin (Sn) is a promising high-capacity electrode for improved performance in lithium-ion batteries for electric vehicles. In this work, Sn nanoisland growth for nanostructured electrodes assisted by the pulse laser irradiation has been investigated based on a mesoscale modeling formalism. The influence of pertinent processing conditions, such as pulse duration, heating/cooling rates, and atom flux, on the Sn nanostructure formation is specifically considered. The interaction between the adsorbed atom and the substrate, represented by the adatom diffusion barrier, is carefully studied. It is found that the diffusion barrier predominantly affects the distribution of Sn atoms. For both α-Sn and β-Sn, the averaged coordination number is larger than 3 when the diffusion barrier equals to 0.15 eV. The averaged coordination number decreases as the diffusion barrier increases. The substrate temperature, which is determined by heating/cooling rates and pulse duration, can also affect the formation of Sn nanoislands. For α-Sn, when applied low heating/cooling rates, nanoislands cannot form if the diffusion barrier is larger than 0.35 eV.

  15. Chemical Production by Pulse-Laser Irradiation on Ices: Simulation of Impact Shock-Induced Chemistry on Icy Satellites

    NASA Astrophysics Data System (ADS)

    Nna-Mvondo, Delphine; Khare, B. N.; Ishihara, T.; McKay, C. P.; Cruikshank, D. P.; Borucki, W. J.

    2007-12-01

    Several icy satellites of the outer planets show a variety of impact cratering features. The effect of impact by extraterrestrial objects into the surface is commonly related to physical changes. Most of the research applied to impacts on ices has been developed to study and understand the cratering formation process and their physical, geophysical characteristics. Chemical changes and synthesis occurring on icy planetary surfaces are generally explained by the influence of UV photons and high-energy charged particles on ices. Nonetheless, impact process onto ices could be a source of local or global endogenic process and could be especially advantageous as an efficient energy source for driving interesting chemistry. Upon impact on icy surface, the kinetic energy of the impacting body is transferred to the ground liberating a great deal of stress energy which could initiate in situ aqueous melts of the ice, hydrolysis and other chemical reactions in the fracture zone beneath the crater. Here we present a novel experimental method to study the chemistry in planetary ices induced by impact shocks. Impact shocks were simulated in laboratory using a powerful pulsed laser (Q-switched Nd-YAG laser, 1064 nm). We have irradiated at 77K icy mixtures of H2O / CO2, H2O / Na2CO3, H2O / CH3OH and finally H2O / CH3OH / (NH4)2SO4. GC-MS and FTIR analyses show that hydrogen peroxide, carbon monoxide and methanol are formed in irradiated H2O / CO2 ices. Ice containing sodium carbonate generates under simulated impact CO and CO2 which are also produced in impacted H2O / CH3OH and H2O / CH3OH / (NH4)2SO4 ices. But, in both latter icy mixtures, methane and more complex molecules are also formed. We have detected acetone, methyl formate and dimethyl formal. Adding ammonium sulfate to ice containing methanol induces the production of N2O, HCN and CH3CN.

  16. Design and chemical synthesis of iodine-containing molecules for application to solar-pumped I* lasers

    NASA Technical Reports Server (NTRS)

    Shiner, C. S.

    1986-01-01

    The design and chemical synthesis of new media for solar pumped iodine molecule lasers are explored. In an effort to prepare an iodo fluorocarbon compound absorbing strongly at 300 nm or above, the synthesis of perfluoro allylic iodides was investigated. These compounds furnish especially stable allylic radicals upon photodissociation. The desired red shift is anticipated in the absorption maximum could correlate with increasing radical stability. This expectation was based upon the analysis, previously reported, of the structures and absorption maxima of compounds studied earlier. A previously unknown substance was prepared, a prototypical target molecule, perfluoro-3-iodocyclopent-1-ene. It was obtained by reaction of perfluorocyclopentene with sulfur trioxide under the influence of antimony pentafluoride catalyst, followed by treatment of the resulting allylic fluorosulfonate with sodium iodide in sulfoland solvent. Preliminary data indicate that the absorption maximum for the iodo fluorocarbon is not shifted significantly to longer wavelength. It is not certain whether this result reflects an unexpected influence of the cyclic structure upon the position of the absorption maximum.

  17. A hyphenated optical trap capillary electrophoresis laser induced native fluorescence system for single-cell chemical analysis

    PubMed Central

    Cecala, Christine; Rubakhin, Stanislav S.; Mitchell, Jennifer W.; Gillette, Martha U.; Sweedler, Jonathan V.

    2013-01-01

    Single-cell measurements allow a unique glimpse into cell-to-cell heterogeneity; even small changes in selected cells can have a profound impact on an organism’s physiology. Here an integrated approach to single-cell chemical sampling and assay are described. Capillary electrophoresis (CE) with laser-induced native fluorescence (LINF) has the sensitivity to characterize natively-fluorescent indoles and catechols within individual cells. While the separation and detection approaches are well established, the sampling and injection of individually selected cells requires new approaches. We describe an optimized system that interfaces a single-beam optical trap with CE and multichannel LINF detection. A cell is localized within the trap and then the capillary inlet is positioned near the cell using a computer-controlled micromanipulator. Hydrodynamic injection allows cell lysis to occur within the capillary inlet, followed by the CE separation and LINF detection. The use of multiple emission wavelengths allows improved analyte identification based on differences in analyte fluorescence emission profiles and migration time. The system enables injections of individual rat pinealocytes and quantification of their endogenous indoles, including serotonin, N-acetyl-serotonin, 5-hydroxyindole-3-acetic acid, tryptophol and others. The amounts detected in individual cells incubated in 5-hydroxytryptophan ranged from 10−14 mol to 10−16 mol, an order of magnitude higher than observed in untreated pinealocytes. PMID:22543409

  18. Periodic nanostructuring of Er/Yb-codoped IOG1 phosphate glass by using ultraviolet laser-assisted selective chemical etching

    SciTech Connect

    Pappas, C.; Pissadakis, S.

    2006-12-01

    The patterning of submicron period ({approx_equal}500 nm) Bragg reflectors in the Er/Yb-codoped IOG1 Schott, phosphate glass is demonstrated. A high yield patterning technique is presented, wherein high volume damage is induced into the glass matrix by exposure to intense ultraviolet 213 nm, 150 ps Nd:YAG laser radiation and, subsequently, a chemical development in potassium hydroxide (KOH)/ethylenediamine tetra-acetic acid (EDTA) aqueous solution selectively etches the exposed areas. The electronic changes induced by the 213 nm ultraviolet irradiation are examined by employing spectrophotometric measurements, while an estimation of the refractive index changes recorded is provided by applying Kramers-Kronig transformation to the absorption change data. In addition, real time diffraction efficiency measurements were obtained during the formation of the volume damage grating. After the exposure, the growth of the relief grating pattern in time was measured at fixed time intervals and the dependence of the grating depth on the etching time and exposure conditions is presented. The gratings fabricated are examined by atomic and scanning electron microscopies to reveal the relief topology of the structures. Gratings with average depth of 120 nm and excellent surface quality were fabricated by exposing the IOG1 phosphate glass to 36 000 pulses of 208 mJ/cm{sup 2} energy density, followed by developing in the KOH/EDTA agent for 6 min.

  19. High Temperature Nanocomposites For Nuclear Thermal Propulsion and In-Space Fabrication by Hyperbaric Pressure Laser Chemical Vapor Deposition

    NASA Astrophysics Data System (ADS)

    Maxwell, J. L.; Webb, N. D.; Espinoza, M.; Cook, S.; Houts, M.; Kim, T.

    Nuclear Thermal Propulsion (NTP) is an indispensable technology for the manned exploration of the solar system. By using Hyperbaric Pressure Laser Chemical Vapor Deposition (HP-LCVD), the authors propose to design and build a promising next-generation fuel element composed of uranium carbide UC embedded in a latticed matrix of highly refractory Ta4HfC5 for an NTP rocket capable of sustaining temperatures up to 4000 K, enabling an Isp of up to 1250 s. Furthermore, HP-LCVD technology can also be harnessed to enable 3D rapid prototyping of a variety of materials including metals, ceramics and composites, opening up the possibility of in-space fabrication of components, replacement parts, difficult-to-launch solar sails and panels and a variety of other space structures. Additionally, rapid prototyping with HP-LCVD makes a feasible "live off the land" strategy of interplanetary and interstellar exploration ­ the precursors commonly used in the technology are found, often in abundance, on other solar system bodies either as readily harvestable gas (e.g. methane) or as a raw material that could be converted into a suitable precursor (e.g. iron oxide into ferrocene on Mars).

  20. First-Principles Simulations of Chemical Reactions in an HCl Molecule Embedded inside a C or BN Nanotube Induced by Ultrafast Laser Pulses

    NASA Astrophysics Data System (ADS)

    Miyamoto, Yoshiyuki; Zhang, Hong; Rubio, Angel

    2010-12-01

    We show by first-principles simulations that ultrafast laser pulses induce different chemical reactions in a molecule trapped inside a nanotube. A strong laser pulse polarized perpendicular to the tube axis induces a giant bond stretch of an encapsulated HCl molecule in semiconducting carbon nanotube or in a BN nanotube. Depending on the initial orientation of the HCl molecule, the subsequent laser-induced dynamics is different: either complete disintegration or rebonding of the HCl molecule. Radial motion of the nanotube is always observed and a vacancy appears on the tube wall when the HCl is perpendicular to the tube axis. Those results are important to analyze confined nanochemistry and to manipulate molecules and nanostructures encapsulated in organic and inorganic nanotubes.

  1. First-principles simulations of chemical reactions in an HCl molecule embedded inside a C or BN nanotube induced by ultrafast laser pulses.

    PubMed

    Miyamoto, Yoshiyuki; Zhang, Hong; Rubio, Angel

    2010-12-10

    We show by first-principles simulations that ultrafast laser pulses induce different chemical reactions in a molecule trapped inside a nanotube. A strong laser pulse polarized perpendicular to the tube axis induces a giant bond stretch of an encapsulated HCl molecule in semiconducting carbon nanotube or in a BN nanotube. Depending on the initial orientation of the HCl molecule, the subsequent laser-induced dynamics is different: either complete disintegration or rebonding of the HCl molecule. Radial motion of the nanotube is always observed and a vacancy appears on the tube wall when the HCl is perpendicular to the tube axis. Those results are important to analyze confined nanochemistry and to manipulate molecules and nanostructures encapsulated in organic and inorganic nanotubes.

  2. First-Principles Simulations of Chemical Reactions in an HCl Molecule Embedded inside a C or BN Nanotube Induced by Ultrafast Laser Pulses

    SciTech Connect

    Miyamoto, Yoshiyuki; Zhang Hong; Rubio, Angel

    2010-12-10

    We show by first-principles simulations that ultrafast laser pulses induce different chemical reactions in a molecule trapped inside a nanotube. A strong laser pulse polarized perpendicular to the tube axis induces a giant bond stretch of an encapsulated HCl molecule in semiconducting carbon nanotube or in a BN nanotube. Depending on the initial orientation of the HCl molecule, the subsequent laser-induced dynamics is different: either complete disintegration or rebonding of the HCl molecule. Radial motion of the nanotube is always observed and a vacancy appears on the tube wall when the HCl is perpendicular to the tube axis. Those results are important to analyze confined nanochemistry and to manipulate molecules and nanostructures encapsulated in organic and inorganic nanotubes.

  3. Airborne intercomparison of HOx measurements using laser-induced fluorescence and chemical ionization mass spectrometry during ARCTAS

    NASA Astrophysics Data System (ADS)

    Ren, X.; Mao, J.; Brune, W. H.; Cantrell, C. A.; Mauldin, R. L., III; Hornbrook, R. S.; Kosciuch, E.; Olson, J. R.; Crawford, J. H.; Chen, G.; Singh, H. B.

    2012-03-01

    The hydroxyl (OH) and hydroperoxyl (HO2) radicals, collectively called HOx, play central roles in tropospheric chemistry. Accurate measurements of OH and HO2 are critical to examine our understanding of atmospheric chemistry. Intercomparisons of different techniques for detecting OH and HO2 are vital to evaluate their measurement capabilities. Three instruments that measured OH and/or HO2 radicals were deployed on the NASA DC-8 aircraft throughout Arctic Research of the Composition of the Troposphere from Aircraft and Satellites (ARCTAS), in the spring and summer of 2008. One instrument was the Penn State Airborne Tropospheric Hydrogen Oxides Sensor (ATHOS) for OH and HO2 measurements based on Laser-Induced Fluorescence (LIF) spectroscopy. A second instrument was the NCAR Selected-Ion Chemical Ionization Mass Spectrometer (SI-CIMS) for OH measurement. A third instrument was the NCAR Peroxy Radical Chemical Ionization Mass Spectrometer (PeRCIMS) for HO2 measurement. Formal intercomparison of LIF and CIMS was conducted for the first time on a same aircraft platform. The three instruments were calibrated by quantitative photolysis of water vapor by UV light at 184.9 nm with three different calibration systems. The absolute accuracies were ±32% (2σ) for the LIF instrument, ±65% (2σ) for the SI-CIMS instrument, and ±50% (2σ) for the PeRCIMS instrument. In general, good agreement was obtained between the CIMS and LIF measurements of both OH and HO2 measurements. Linear regression of the entire data set yields [OH]CIMS = 0.89 × [OH]LIF + 2.8 × 105 cm-3 with a correlation coefficient, r2 = 0.72 for OH and [HO2]CIMS = 0.86 × [HO2]LIF + 3.9 parts per trillion by volume (pptv, equivalent to pmol mol-1) with a correlation coefficient, r2 = 0.72 for HO2. In general, the difference between CIMS and LIF instruments for OH and HO2 measurements can be explained by their combined measurement uncertainties. Comparison with box model results shows some similarities for both

  4. Airborne intercomparison of HOx measurements using laser-induced fluorescence and chemical ionization mass spectrometry during ARCTAS

    NASA Astrophysics Data System (ADS)

    Ren, X.; Mao, J.; Brune, W. H.; Cantrell, C. A.; Mauldin, R. L., III; Hornbrook, R. S.; Kosciuch, E.; Olson, J. R.; Crawford, J. H.; Chen, G.; Singh, H. B.

    2012-08-01

    The hydroxyl (OH) and hydroperoxyl (HO2) radicals, collectively called HOx, play central roles in tropospheric chemistry. Accurate measurements of OH and HO2 are critical to examine our understanding of atmospheric chemistry. Intercomparisons of different techniques for detecting OH and HO2 are vital to evaluate their measurement capabilities. Three instruments that measured OH and/or HO2 radicals were deployed on the NASA DC-8 aircraft throughout Arctic Research of the Composition of the Troposphere from Aircraft and Satellites (ARCTAS) in the spring and summer of 2008. One instrument was the Penn State Airborne Tropospheric Hydrogen Oxides Sensor (ATHOS) for OH and HO2 measurements based on Laser-Induced Fluorescence (LIF) spectroscopy. A second instrument was the NCAR Selected-Ion Chemical Ionization Mass Spectrometer (SI-CIMS) for OH measurement. A third instrument was the NCAR Peroxy Radical Chemical Ionization Mass Spectrometer (PeRCIMS) for HO2 measurement. Formal intercomparison of LIF and CIMS was conducted for the first time on a same aircraft platform. The three instruments were calibrated by quantitative photolysis of water vapor by ultraviolet (UV) light at 184.9 nm with three different calibration systems. The absolute accuracies were ±32% (2σ) for the LIF instrument, ±65% (2σ) for the SI-CIMS instrument, and ±50% (2σ) for the PeRCIMS instrument. In general, good agreement was obtained between the CIMS and LIF measurements of both OH and HO2 measurements. Linear regression of the entire data set yields [OH]CIMS = 0.89 × [OH]LIF + 2.8 × 104 cm-3 with a correlation coefficient r2 = 0.72 for OH, and [HO2]CIMS = 0.86 × [HO2]LIF + 3.9 parts per trillion by volume (pptv, equivalent to pmol mol-1) with a correlation coefficient r2 = 0.72 for HO2. In general, the difference between CIMS and LIF instruments for OH and HO2 measurements can be explained by their combined measurement uncertainties. Comparison with box model results shows some

  5. Total microcystins analysis in water using laser diode thermal desorption-atmospheric pressure chemical ionization-tandem mass spectrometry.

    PubMed

    Roy-Lachapelle, Audrey; Fayad, Paul B; Sinotte, Marc; Deblois, Christian; Sauvé, Sébastien

    2014-04-11

    A new approach for the analysis of the cyanobacterial microcystins (MCs) in environmental water matrices has been developed. It offers a cost efficient alternative method for the fast quantification of total MCs using mass spectrometry. This approach permits the quantification of total MCs concentrations without requiring any derivatization or the use of a suite of MCs standards. The oxidation product 2-methyl-3-methoxy-4-phenylbutyric acid (MMPB) was formed through a Lemieux oxidation and represented the total concentration of free and bound MCs in water samples. MMPB was analyzed using laser diode thermal desorption-atmospheric pressure chemical ionization coupled to tandem mass spectrometry (LDTD-APCI-MS/MS). LDTD is a robust and reliable sample introduction method with ultra-fast analysis time (<15 s sample(-1)). Several oxidation and LDTD parameters were optimized to improve recoveries and signal intensity. MCs oxidation recovery yield was 103%, showing a complete reaction. Internal calibration with standard addition was achieved with the use of 4-phenylbutyric acid (4-PB) as internal standard and showed good linearity (R(2)>0.999). Limits of detection and quantification were 0.2 and 0.9 μg L(-1), respectively. These values are comparable with the WHO (World Health Organization) guideline of 1 μg L(-1) for total microcystin-LR congener in drinking water. Accuracy and interday/intraday variation coefficients were below 15%. Matrix effect was determined with a recovery of 91%, showing no significant signal suppression. This work demonstrates the use of the LDTD-APCI-MS/MS interface for the screening, detection and quantification of total MCs in complex environmental matrices.

  6. Laser Systems

    NASA Technical Reports Server (NTRS)

    1985-01-01

    Tunable diode lasers are employed as radiation sources in high resolution infrared spectroscopy to determine spectral characteristics of gaseous compounds. With other laser systems, they are produced by Spectra-Physics, and used to monitor chemical processes, monitor production of quantity halogen lamps, etc. The Laser Analytics Division of Spectra-Physics credits the system's reliability to a program funded by Langley in the 1970s. Company no longer U.S.-owned. 5/22/97

  7. Laser thermal effect on silicon nitride ceramic based on thermo-chemical reaction with temperature-dependent thermo-physical parameters

    NASA Astrophysics Data System (ADS)

    Pan, A. F.; Wang, W. J.; Mei, X. S.; Wang, K. D.; Zhao, W. Q.; Li, T. Q.

    2016-07-01

    In this study, a two-dimensional thermo-chemical reaction model with temperature-dependent thermo-physical parameters on Si3N4 with 10 ns laser was developed to investigate the ablated size, volume and surface morphology after single pulse. For model parameters, thermal conductivity and heat capacity of β-Si3N4 were obtained from first-principles calculations. Thermal-chemical reaction rate was fitted by collision theory, and then, reaction element length was deduced using the relationship between reaction rate and temperature distribution. Furthermore, plasma absorption related to energy loss was approximated as a function of electron concentration in Si3N4. It turned out that theoretical ablated volume and radius increased and then remained constant with increasing laser energy, and the maximum ablated depth was not in the center of the ablated zone. Moreover, the surface maximum temperature of Si3N4 was verified to be above 3000 K within pulse duration, and it was much higher than its thermal decomposition temperature of 1800 K, which indicated that Si3N4 was not ablated directly above the thermal decomposition temperature. Meanwhile, the single pulse ablation of Si3N4 was performed at different powers using a TEM00 10 ns pulse Nd:YAG laser to validate the model. The model showed a satisfactory consistence between the experimental data and numerical predictions, presenting a new modeling technology that may significantly increase the accuracy of the predicated results for laser ablation of materials undergoing thermo-chemical reactions.

  8. Investigation by laser induced breakdown spectroscopy, X-ray fluorescence and X-ray powder diffraction of the chemical composition of white clay ceramic tiles from Veliki Preslav

    NASA Astrophysics Data System (ADS)

    Blagoev, K.; Grozeva, M.; Malcheva, G.; Neykova, S.

    2013-01-01

    The paper presents the results of the application of laser induced breakdown spectroscopy, X-ray fluorescence spectrometry, and X-ray powder diffraction in assessing the chemical and phase composition of white clay decorative ceramic tiles from the medieval archaeological site of Veliki Preslav, a Bulgarian capital in the period 893-972 AC, well-known for its original ceramic production. Numerous white clay ceramic tiles with highly varied decoration, produced for wall decoration of city's churches and palaces, were found during the archaeological excavations in the old capital. The examination of fourteen ceramic tiles discovered in one of the city's monasteries is aimed at characterization of the chemical profile of the white-clay decorative ceramics produced in Veliki Preslav. Combining different methods and comparing the obtained results provides complementary information regarding the white-clay ceramic production in Veliki Preslav and complete chemical characterization of the examined artefacts.

  9. Microstructure, chemical composition and properties of the surface layer of M2 steel after laser melting under different conditions

    NASA Astrophysics Data System (ADS)

    Kusiński, Jan

    1995-02-01

    Metallographical (optical, SEM, TEM), microprobe, wear resistance and microhardness investigations of M2 high-speed tool steel surface melted by continuous CO 2 (with different power) and Nd:YAG pulsed lasers are described. It became apparent that there was a considerable influence of the laser type, scanning velocity, gas jet atmosphere and the antireflective graphite coating on the melted zone dimensions and its as-resolidified structure. The notable differences between the microstructures of the melted zones were related to the laser type and laser power. In comparison to the uncoated specimens, laser melting of the specimens coated with a colloidal graphite layer resulted in significantly increased dimensions of the laser-affected layer and a coarser as-resolidified structure. Depletion of the Cr, V, Mn and C in the resolidified zone after treatment under oxygen atmosphere was related with the high reaction efficiency of these elements to oxygen. Hardness of the melted zone in the uncoated samples was higher than that of both the graphite-coated samples and the conventionally hardened matrix. The lathe tools treated by the Nd:YAG pulsed-laser radiation showed the longest cutting life-time.

  10. The role of physical and chemical properties of Pd nanostructured materials immobilized on inorganic carriers on ion formation in atmospheric pressure laser desorption/ionization mass spectrometry.

    PubMed

    Silina, Yuliya E; Koch, Marcus; Volmer, Dietrich A

    2014-06-01

    Fundamental parameters influencing the ion-producing efficiency of palladium nanostructures (nanoparticles [Pd-NP], nanoflowers, nanofilms) during laser irradiation were studied in this paper. The nanostructures were immobilized on the surface of different solid inorganic carrier materials (porous and mono-crystalline silicon, anodic porous aluminum oxide, glass and polished steel) by using classical galvanic deposition, electroless local deposition and sputtering. It was the goal of this study to investigate the influence of both the nanoparticular layer as well as the carrier material on ion production for selected analyte molecules. Our experiments demonstrated that the dimensions of the synthesized nanostructures, the thickness of the active layers, surface disorders, thermal conductivity and physically or chemically adsorbed water influenced signal intensities of analyte ions during surface-assisted laser desorption/ionization (SALDI) while no effects such as plasmon resonance, photoelectric effect or catalytic activity were expected to occur. Excellent LDI abilities were seen for Pd-NPs immobilized on steel, while Pd nanoflowers on porous silicon exhibited several disadvantages; viz, strong memory effects, dependency of the analytical signal on amount of physically and chemically adsorbed water inside porous carrier, reduced SALDI activity from unstable connections between Pd and semiconductor material, decrease of the melting point of pure silicon after Pd immobilization and resulting strong laser ablation of metal/semiconductor complex, as well as significantly changed surface morphology after laser irradiation. The analytical performance of Pd-NP/steel was further improved by applying a hydrophobic coating to the steel surface before galvanic deposition. This procedure increased the distance between Pd-NPs, thus reducing thermal stress upon LDI; it simultaneously decreased spot sizes of deposited sample solutions.

  11. Design of Laser Based Monitoring Systems for Compliance Management of Odorous and Hazardous Air Pollutants in Selected Chemical Industrial Estates at Hyderabad, India

    NASA Astrophysics Data System (ADS)

    Sudhakar, P.; Kalavathi, P.; Ramakrishna Rao, D.; Satyanarayna, M.

    2014-12-01

    Industrialization can no longer sustain without internalization of the concerns of the receiving environment and land-use. Increased awareness and public pressure, coupled with regulatory instruments and bodies exert constant pressure on industries to control their emissions to a level acceptable to the receiving environment. However, when a group of industries come-up together as an industrial estate, the cumulative impacts of all the industries together often challenges the expected/desired quality of receiving environment, requiring stringent pollution control and monitoring measures. Laser remote sensing techniques provide powerful tools for environmental monitoring. These methods provide range resolved measurements of concentrations of various gaseous pollutants and suspended particulate matter (SPM) not only in the path of the beam but over the entire area. A three dimensional mapping of the pollutants and their dispersal can be estimated using the laser remote sensing methods on a continuous basis. Laser Radar (Lidar) systems are the measurements technology used in the laser remote sensing methods. Differential absorption lidar (DIAL) and Raman Lidar technologies have proved to be very useful for remote sensing of air pollutants. DIAL and Raman lidar systems can be applied for range resolved measurements of molecules like SO2, NO2, O3 Hg, CO, C2H4, H2O, CH4, hydrocarbons etc. in real time on a continuous basis. This paper describes the design details of the DAIL and Raman lidar techniques for measurement of various hazardous air pollutants which are being released into the atmosphere by the chemical industries operating in the Bachupally industrial Estate area at Hyderabad, India. The relative merits of the two techniques have been studied and the minimum concentration of pollutants that can be measured using these systems are presented. A dispersion model of the air pollutants in the selected chemical industrial estates at Hyderabad has been developed.

  12. The role of physical and chemical properties of Pd nanostructured materials immobilized on inorganic carriers on ion formation in atmospheric pressure laser desorption/ionization mass spectrometry.

    PubMed

    Silina, Yuliya E; Koch, Marcus; Volmer, Dietrich A

    2014-06-01

    Fundamental parameters influencing the ion-producing efficiency of palladium nanostructures (nanoparticles [Pd-NP], nanoflowers, nanofilms) during laser irradiation were studied in this paper. The nanostructures were immobilized on the surface of different solid inorganic carrier materials (porous and mono-crystalline silicon, anodic porous aluminum oxide, glass and polished steel) by using classical galvanic deposition, electroless local deposition and sputtering. It was the goal of this study to investigate the influence of both the nanoparticular layer as well as the carrier material on ion production for selected analyte molecules. Our experiments demonstrated that the dimensions of the synthesized nanostructures, the thickness of the active layers, surface disorders, thermal conductivity and physically or chemically adsorbed water influenced signal intensities of analyte ions during surface-assisted laser desorption/ionization (SALDI) while no effects such as plasmon resonance, photoelectric effect or catalytic activity were expected to occur. Excellent LDI abilities were seen for Pd-NPs immobilized on steel, while Pd nanoflowers on porous silicon exhibited several disadvantages; viz, strong memory effects, dependency of the analytical signal on amount of physically and chemically adsorbed water inside porous carrier, reduced SALDI activity from unstable connections between Pd and semiconductor material, decrease of the melting point of pure silicon after Pd immobilization and resulting strong laser ablation of metal/semiconductor complex, as well as significantly changed surface morphology after laser irradiation. The analytical performance of Pd-NP/steel was further improved by applying a hydrophobic coating to the steel surface before galvanic deposition. This procedure increased the distance between Pd-NPs, thus reducing thermal stress upon LDI; it simultaneously decreased spot sizes of deposited sample solutions. PMID:24913399

  13. Quantitative measurement of the chemical composition of geological standards with a miniature laser ablation/ionization mass spectrometer designed for in situ application in space research

    NASA Astrophysics Data System (ADS)

    Neuland, M. B.; Grimaudo, V.; Mezger, K.; Moreno-García, P.; Riedo, A.; Tulej, M.; Wurz, P.

    2016-03-01

    A key interest of planetary space missions is the quantitative determination of the chemical composition of the planetary surface material. The chemical composition of surface material (minerals, rocks, soils) yields fundamental information that can be used to answer key scientific questions about the formation and evolution of the planetary body in particular and the Solar System in general. We present a miniature time-of-flight type laser ablation/ionization mass spectrometer (LMS) and demonstrate its capability in measuring the elemental and mineralogical composition of planetary surface samples quantitatively by using a femtosecond laser for ablation/ionization. The small size and weight of the LMS make it a remarkable tool for in situ chemical composition measurements in space research, convenient for operation on a lander or rover exploring a planetary surface. In the laboratory, we measured the chemical composition of four geological standard reference samples USGS AGV-2 Andesite, USGS SCo-l Cody Shale, NIST 97b Flint Clay and USGS QLO-1 Quartz Latite with LMS. These standard samples are used to determine the sensitivity factors of the instrument. One important result is that all sensitivity factors are close to 1. Additionally, it is observed that the sensitivity factor of an element depends on its electron configuration, hence on the electron work function and the elemental group in agreement with existing theory. Furthermore, the conformity of the sensitivity factors is supported by mineralogical analyses of the USGS SCo-l and the NIST 97b samples. With the four different reference samples, the consistency of the calibration factors can be demonstrated, which constitutes the fundamental basis for a standard-less measurement-technique for in situ quantitative chemical composition measurements on planetary surface.

  14. Herbert P. Broida Prize Talk: Experimental realization of coherent control of molecular dynamics and chemical reactions with feedback-optimized laser pulses--Quantum Control of Femtochemistry

    NASA Astrophysics Data System (ADS)

    Gerber, Gustav

    2009-05-01

    By using coherent control techniques we control the behavior of quantum systems on their natural fs-time scale by applying ultrashort coherent light fields in the wavelength range from the IR to the UV. These laser pulses can be variably shaped in space and time using a laser pulse shaper consisting of a liquid-crystal display. [1] Laser-optimized femtochemistry in the gas phase and liquid phase is one field in which this new technique is successfully employed. Automated optimization of branching ratios and total product yields of gas phase photodissociation reactions as well as chemically selective molecular excitation in the liquid phase is performed [2][3]. Structural changes of a molecule in the liquid phase have been controlled by laser-optimized photoisomerization of a cyanine dye molecule [4] and of retinal in bacteriorhodopsin [5]. So far, optimal control techniques have been restricted to gas phase and condensed phase optimization experiments. Recently we have demonstrated femtosecond laser-assisted catalytic reactions on a Pd(100) single crystal surface. By applying a closed-loop optimal control scheme, we manipulate these reactions and selectively optimize the ratio of different bond-forming reaction channels, in contrast to previous quantum control experiments aiming at bond-cleavage. The results represent a first step towards selective photocatalysis of molecules. [4pt] [1] T. Baumert et al, Appl. Phys. B 65, 779 (1997)[0pt] [2] A. Assion et al, Science 282, 919(1998); T. Brixner et al, J. Mod. Opt. 50, 539 (2003)[0pt] [3] T. Brixner et al, Nature, Vol. 414, 57 (2001) and J. Chem. Phys. 118, 3692 (2003)[0pt] [4] G. Krampert et al, Phys. Rev. Lett. 94, 068305 (2005)[0pt] [5] G. Vogt et al, Chem. Phys. Lett. 433, 211 (2006) P. Nuernberger et al, Phys. Chem. Chem. Phys. 9, 2470 (2007)

  15. Efficient oscillation regimes of an HF laser pumped by a nonchain chemical reaction initiated by a self-sustained discharge

    SciTech Connect

    Panchenko, Aleksei N; Orlovskii, Viktor M; Tarasenko, Viktor F; Baksht, E Kh

    2003-05-31

    The amplitude - time and spectral characteristics of laser radiation and discharge characteristics in mixtures of SF{sub 6} with hydrogen and hydrocarbons at a high lasing efficiency are investigated. Lasing efficiencies of {approx}10 % with respect to the deposited energy are obtained under the pumping from capacitive and inductive energy storage units. It is shown that, during a pump pulse, the maximum efficiencies are achieved at high values of the parameter E/p in the laser gap. When profiled electrodes and UV preionisation are used, a specific output energy of a nonchain HF laser of {approx}140 J L{sup -1} atm{sup -1} and a lasing efficiency of {approx}4.5 % with respect to the stored energy were obtained. It is shown that the emission spectrum of a nonchain HF laser operating at high lasing efficiencies becomes significantly wider and cascade lasing is realised on the {nu}(3-2) {yields} {nu}(2-1) {yields} {nu}(1-0) vibrational transitions at several rotational lines. (lasers)

  16. Optimization of chemical and instrumental parameters in hydride generation laser-induced breakdown spectrometry for the determination of arsenic, antimony, lead and germanium in aqueous samples.

    PubMed

    Yeşiller, Semira Unal; Yalçın, Serife

    2013-04-01

    A laser induced breakdown spectrometry hyphenated with on-line continuous flow hydride generation sample introduction system, HG-LIBS, has been used for the determination of arsenic, antimony, lead and germanium in aqueous environments. Optimum chemical and instrumental parameters governing chemical hydride generation, laser plasma formation and detection were investigated for each element under argon and nitrogen atmosphere. Arsenic, antimony and germanium have presented strong enhancement in signal strength under argon atmosphere while lead has shown no sensitivity to ambient gas type. Detection limits of 1.1 mg L(-1), 1.0 mg L(-1), 1.3 mg L(-1) and 0.2 mg L(-1) were obtained for As, Sb, Pb and Ge, respectively. Up to 77 times enhancement in detection limit of Pb were obtained, compared to the result obtained from the direct analysis of liquids by LIBS. Applicability of the technique to real water samples was tested through spiking experiments and recoveries higher than 80% were obtained. Results demonstrate that, HG-LIBS approach is suitable for quantitative analysis of toxic elements and sufficiently fast for real time continuous monitoring in aqueous environments.

  17. Chemical and Isotopic Analysis of Trace Organic Matter on Meteorites and Interstellar Dust Using a Laser Microprobe Instrument

    NASA Technical Reports Server (NTRS)

    Zare, Richard N.; Boyce, Joseph M. (Technical Monitor)

    2001-01-01

    Polycyclic Aromatic Hydrocarbons (PAHs) are of considerable interest today because they are ubiquitous on Earth and in the interstellar medium (ISM). In fact, about 20% of cosmic carbon in the galaxy is estimated to be in the form of PAHs. Investigation of these species has obvious uses for determining the cosmochemistry of the solar system. Work in this laboratory has focused on four main areas: 1) Mapping the spatial distribution of PAHs in a variety of meteoritic samples and comparing this distribution with mineralogical features of the meteorite to determine whether a correlation exists between the two. 2) Developing a method for detection of fullerenes in extraterrestrial samples using microprobe Laser Desorption Ionization Mass Spectroscopy and utilizing this technique to investigate fullerene presence, while exploring the possibility of spatially mapping the fullerene distribution in these samples through in situ detection. 3) Investigating a possible formation pathway for meteoritic and ancient terrestrial kerogen involving the photochemical reactions of PAHs with alkanes under prebiotic and astrophysically relevant conditions. 4) Studying reaction pathways and identifying the photoproducts generated during the photochemical evolution of PAH-containing interstellar ice analogs as part of an ongoing collaboration with researchers at the Astrochemistry Lab at NASA Ames. All areas involve elucidation of the solar system formation and chemistry using microprobe Laser Desorption Laser Ionization Mass Spectrometry. A brief description of microprobe Laser Desorption Ionization Mass Spectroscopy, which allows selective investigation of subattomole levels of organic species on the surface of a sample at 10-40 micrometer spatial resolution, is given.

  18. Design and chemical synthesis of iodine-containing molecules for application to solar-pumped I* lasers

    NASA Technical Reports Server (NTRS)

    Shiner, Christopher S.

    1986-01-01

    Research is directed toward the design and synthesis of new media for solar-pumped I* lasers. Since the most effective existing lasants are perfluoroalkyl iodides, a strategy was proposed for the development of improved materials of this type with absorption maxima at 300 nm. Absorption spectra were synthesized and measured for prototypical species containing iodine bound to boron, iron, and cobalt.

  19. Treatment of Acne Vulgaris With Salicylic Acid Chemical Peel and Pulsed Dye Laser: A Split Face, Rater-Blinded, Randomized Controlled Trial

    PubMed Central

    Lekakh, Olga; Mahoney, Anne Marie; Novice, Karlee; Kamalpour, Julia; Sadeghian, Azeen; Mondo, Dana; Kalnicky, Cathy; Guo, Rong; Peterson, Anthony; Tung, Rebecca

    2015-01-01

    Introduction: Pulsed dye laser (PDL) has been used to treat acne lesions and scar erythema by interrupting superficial vasculature. Salicylic acid chemical peels are employed chiefly due to their lipophilic, comedolytic, and anti-inflammatory properties. Although studies have looked at peels and laser therapy independently in acne management, we examined these treatments in combination. Our primary objective was to evaluate the safety and efficacy of concurrent use of salicylic acid peels with PDL versus salicylic acid peels alone in the treatment of moderate to severe acne vulgaris. Methods: Adult patients with moderate to severe acne were included. Subjects received a total of 3 treatments at 3-week intervals. Per randomized split-face treatment, at week 0, one half of the subject’s face was treated with PDL (595 nm) followed by whole face application of a 30% salicylic acid peel. At weeks 3 and 6, the treatments were repeated. At 0 and 9 weeks, patients were assessed with the Global Evaluation Acne (GEA) scale and Dermatology Life Quality Index (DLQI) questionnaire. Results: Nineteen subjects were enrolled, and 18 completed the study. Significant improvement in acne was seen in both the combined (laser and peel) and chemical peel alone treatment arms (P < .0005 and P = .001). Using the GEA scale score, compared to week 0, the mean difference in acne improvement at week 9 was -1.61 in the combination therapy group versus -1.11 in the peel only group. Based on the GEA scale scoring, a statistically significant greater difference in acne improvement was seen, from week 0 to week 9, in the combination treatment group compared with the peel only group (P = .003). Conclusion: While acne subjects had significant benefit from the salicylic acid peel alone, they experienced greater significant benefit from PDL treatment used in conjunction with salicylic acid peels. The adjunctive utilization of PDL to salicylic acid peel therapy can lead to better outcomes in acne

  20. Development of routines for simultaneous in situ chemical composition and stable Si isotope ratio analysis by femtosecond laser ablation inductively coupled plasma mass spectrometry.

    PubMed

    Frick, Daniel A; Schuessler, Jan A; von Blanckenburg, Friedhelm

    2016-09-28

    Stable metal (e.g. Li, Mg, Ca, Fe, Cu, Zn, and Mo) and metalloid (B, Si, Ge) isotope ratio systems have emerged as geochemical tracers to fingerprint distinct physicochemical reactions. These systems are relevant to many Earth Science questions. The benefit of in situ microscale analysis using laser ablation (LA) over bulk sample analysis is to use the spatial context of different phases in the solid sample to disclose the processes that govern their chemical and isotopic compositions. However, there is a lack of in situ analytical routines to obtain a samples' stable isotope ratio together with its chemical composition. Here, we evaluate two novel analytical routines for the simultaneous determination of the chemical and Si stable isotope composition (δ(30)Si) on the micrometre scale in geological samples. In both routines, multicollector inductively coupled plasma mass spectrometry (MC-ICP-MS) is combined with femtosecond-LA, where stable isotope ratios are corrected for mass bias using standard-sample-bracketing with matrix-independent calibration. The first method is based on laser ablation split stream (LASS), where the laser aerosol is split and introduced simultaneously into both the MC-ICP-MS and a quadrupole ICP-MS. The second method is based on optical emission spectroscopy using direct observation of the MC-ICP-MS plasma (LA-MC-ICP-MS|OES). Both methods are evaluated using international geological reference materials. Accurate and precise Si isotope ratios were obtained with an uncertainty typically better than 0.23‰, 2SD, δ(30)Si. With both methods major element concentrations (e.g., Na, Al, Si, Mg, Ca) can be simultaneously determined. However, LASS-ICP-MS is superior over LA-MC-ICP-MS|OES, which is limited by its lower sensitivity. Moreover, LASS-ICP-MS offers trace element analysis down to the μg g(-1)-range for more than 28 elements due to lower limits of detection, and with typical uncertainties better than 15%. For in situ simultaneous

  1. Development of routines for simultaneous in situ chemical composition and stable Si isotope ratio analysis by femtosecond laser ablation inductively coupled plasma mass spectrometry.

    PubMed

    Frick, Daniel A; Schuessler, Jan A; von Blanckenburg, Friedhelm

    2016-09-28

    Stable metal (e.g. Li, Mg, Ca, Fe, Cu, Zn, and Mo) and metalloid (B, Si, Ge) isotope ratio systems have emerged as geochemical tracers to fingerprint distinct physicochemical reactions. These systems are relevant to many Earth Science questions. The benefit of in situ microscale analysis using laser ablation (LA) over bulk sample analysis is to use the spatial context of different phases in the solid sample to disclose the processes that govern their chemical and isotopic compositions. However, there is a lack of in situ analytical routines to obtain a samples' stable isotope ratio together with its chemical composition. Here, we evaluate two novel analytical routines for the simultaneous determination of the chemical and Si stable isotope composition (δ(30)Si) on the micrometre scale in geological samples. In both routines, multicollector inductively coupled plasma mass spectrometry (MC-ICP-MS) is combined with femtosecond-LA, where stable isotope ratios are corrected for mass bias using standard-sample-bracketing with matrix-independent calibration. The first method is based on laser ablation split stream (LASS), where the laser aerosol is split and introduced simultaneously into both the MC-ICP-MS and a quadrupole ICP-MS. The second method is based on optical emission spectroscopy using direct observation of the MC-ICP-MS plasma (LA-MC-ICP-MS|OES). Both methods are evaluated using international geological reference materials. Accurate and precise Si isotope ratios were obtained with an uncertainty typically better than 0.23‰, 2SD, δ(30)Si. With both methods major element concentrations (e.g., Na, Al, Si, Mg, Ca) can be simultaneously determined. However, LASS-ICP-MS is superior over LA-MC-ICP-MS|OES, which is limited by its lower sensitivity. Moreover, LASS-ICP-MS offers trace element analysis down to the μg g(-1)-range for more than 28 elements due to lower limits of detection, and with typical uncertainties better than 15%. For in situ simultaneous

  2. Photoexcitation of lasers and chemical reactions for NASA missions: A theoretical study. [optical pumping in high pressure gas

    NASA Technical Reports Server (NTRS)

    Javan, A.; Guerra, M.

    1981-01-01

    The possibility of obtaining CW laser oscillation by optical pumping in the infrared at an elevated gas pressure is reviewed. A specific example utilizing a mixture of CO and NO gases is included. The gas pressures considered are in excess of several atmospheres. Laser frequency tuning over a broad region becomes possible at such elevated gas pressures due to collisional broadening of the amplifying transitions. The prior-rate and surprisal analysis are applied to obtain detailed VV and VT rates for CO and NO molecules and the transfer rates in a CO-NO gas mixture. The analysis is capable of giving temperature dependence of the rate constants. Computer estimates of the rates are presented for vibrational levels up to v = 50. The results show that in the high-lying vibrational states the VV transfer rates with Delta nu = 2 become appreciable.

  3. Facile and Chemically Pure Preparation of YVO4:Eu3+ Colloid with Novel Nanostructure via Laser Ablation in Water

    PubMed Central

    Wang, Haohao; Odawara, Osamu; Wada, Hiroyuki

    2016-01-01

    A YVO4:Eu3+ colloid with an interesting nanostructure was formed by pulsed laser ablation in deionized water without any additives or surfactants. Analyses of particle morphology, composition and optical properties were accomplished by SEM, TEM, EDS PL and UV-vis. Ovoid-like particles formed by the agglomeration of numerous nanocrystals were observed by SEM and TEM, while EDS with area-mode analysis revealed that the content of dopant ion was well retained within the nanoparticles. In addition, the formation mechanism is deduced and discussed for the first time in this research. The findings of this study could provide new insights into the understanding of laser-induced oxide materials and offer an opportunity for other research groups to pursue red emitting nanophosphors with outstandingly purity. PMID:26842419

  4. Development of a deep-sea laser-induced breakdown spectrometer for in situ multi-element chemical analysis

    NASA Astrophysics Data System (ADS)

    Thornton, Blair; Takahashi, Tomoko; Sato, Takumi; Sakka, Tetsuo; Tamura, Ayaka; Matsumoto, Ayumu; Nozaki, Tatsuo; Ohki, Toshihiko; Ohki, Koichi

    2015-01-01

    Spectroscopy is emerging as a technique that can expand the envelope of modern oceanographic sensors. The selectivity of spectroscopic techniques enables a single instrument to measure multiple components of the marine environment and can form the basis for versatile tools to perform in situ geochemical analysis. We have developed a deep-sea laser-induced breakdown spectrometer (ChemiCam) and successfully deployed the instrument from a remotely operated vehicle (ROV) to perform in situ multi-element analysis of both seawater and mineral deposits at depths of over 1000 m. The instrument consists of a long-nanosecond duration pulse-laser, a spectrometer and a high-speed camera. Power supply, instrument control and signal telemetry are provided through a ROV tether. The instrument has two modes of operation. In the first mode, the laser is focused directly into seawater and spectroscopic measurements of seawater composition are performed. In the second mode, a fiber-optic cable assembly is used to make spectroscopic measurements of mineral deposits. In this mode the laser is fired through a 4 m long fiber-optic cable and is focused onto the target's surface using an optical head and a linear stage that can be held by a ROV manipulator. In this paper, we describe the instrument and the methods developed to process its measurements. Exemplary measurements of both seawater and mineral deposits made during deployments of the device at an active hydrothermal vent field in the Okinawa trough are presented. Through integration with platforms such as underwater vehicles, drilling systems and subsea observatories, it is hoped that this technology can contribute to more efficient scientific surveys of the deep-sea environment.

  5. Chemical characterization of single micro- and nano-particles by optical catapulting-optical trapping-laser-induced breakdown spectroscopy

    NASA Astrophysics Data System (ADS)

    Fortes, Francisco J.; Fernández-Bravo, Angel; Javier Laserna, J.

    2014-10-01

    Spectral identification of individual micro- and nano-sized particles by the sequential intervention of optical catapulting, optical trapping and laser-induced breakdown spectroscopy is presented. The three techniques are used for different purposes. Optical catapulting (OC) serves to put the particulate material under inspection in aerosol form. Optical trapping (OT) permits the isolation and manipulation of individual particles from the aerosol, which are subsequently analyzed by laser-induced breakdown spectroscopy (LIBS). Once catapulted, the dynamics of particle trapping depends both on the laser beam characteristics (power and intensity gradient) and on the particle properties (size, mass and shape). Particles are stably trapped in air at atmospheric pressure and can be conveniently manipulated for a precise positioning for LIBS analysis. The spectra acquired from the individually trapped particles permit a straightforward identification of the material inspected. Variability of LIBS signal for the inspection of Ni microspheres was 30% relative standard deviation. OC-OT-LIBS permits the separation of particles in a heterogeneous mixture and the subsequent analysis of the isolated particle of interest. In order to evaluate the sensitivity of the approach, the number of absolute photons emitted by a single trapped particle was calculated. The limit of detection (LOD) for Al2O3 particles was calculated to be 200 attograms aluminium.

  6. The chemical digestion of Ti6Al7Nb scaffolds produced by Selective Laser Melting reduces significantly ability of Pseudomonas aeruginosa to form biofilm.

    PubMed

    Junka, Adam F; Szymczyk, Patrycja; Secewicz, Anna; Pawlak, Andrzej; Smutnicka, Danuta; Ziółkowski, Grzegorz; Bartoszewicz, Marzenna; Chlebus, Edward

    2016-01-01

    In our previous work we reported the impact of hydrofluoric and nitric acid used for chemical polishing of Ti-6Al-7Nb scaffolds on decrease of the number of Staphylococcus aureus biofilm forming cells. Herein, we tested impact of the aforementioned substances on biofilm of Gram-negative microorganism, Pseudomonas aeruginosa, dangerous pathogen responsible for plethora of implant-related infections. The Ti-6Al-7Nb scaffolds were manufactured using Selective Laser Melting method. Scaffolds were subjected to chemical polishing using a mixture of nitric acid and fluoride or left intact (control group). Pseudomonal biofilm was allowed to form on scaffolds for 24 hours and was removed by mechanical vortex shaking. The number of pseudomonal cells was estimated by means of quantitative culture and Scanning Electron Microscopy. The presence of nitric acid and fluoride on scaffold surfaces was assessed by means of IR and rentgen spetorscopy. Quantitative data were analysed using the Mann-Whitney test (P ≤ 0.05). Our results indicate that application of chemical polishing correlates with significant drop of biofilm-forming pseudomonal cells on the manufactured Ti-6Al-7Nb scaffolds ( p = 0.0133, Mann-Whitney test) compared to the number of biofilm-forming cells on non-polished scaffolds. As X-ray photoelectron spectroscopy revealed the presence of fluoride and nitrogen on the surface of scaffold, we speculate that drop of biofilm forming cells may be caused by biofilm-supressing activity of these two elements.

  7. Application of in vivo laser scanning confocal microscopy for evaluation of ocular surface diseases: lessons learned from pterygium, meibomian gland disease, and chemical burns.

    PubMed

    Wang, Yan; Le, Qihua; Zhao, Feng; Hong, Jiaxu; Xu, Jianjiang; Zheng, Tianyu; Sun, Xinghuai

    2011-10-01

    In vivo laser scanning confocal microscopy (LSCM) has been widely used to evaluate the alterations caused by ocular surface diseases at a cellular level in the living eye. In this review, we focus on its use in the diagnosis of pterygium, meibomian gland (MG) disease, and chemical burns. Histopathologic changes occurring in pterygium can be examined in situ using in vivo LSCM. Alterations at the junction of the pterygium and the cornea, which cannot be observed in excised tissue samples, can be observed. MGs play an important role in maintaining the health of the ocular surface. Meibomian gland dysfunction (MGD) is one of the most common ocular surface diseases. The use of in vivo LSCM helps in the diagnosis of MGD and provides a way to examine the microstructure of MG acinar units and measure their size. In vivo LSCM also provides a new perspective in understanding the contribution of the MG to the health of the ocular surface. Chemical burns are one of the most common ocular injuries, and in vivo LSCM can provide images of the goblet cells on the corneal surface. This is a hallmark of limbal stem cell deficiency. The application of in vivo LSCM to assessing chemical burns requires extension, allowing for evaluation of the limbus structure and ocular surface changes after reconstructive ocular surgery.

  8. The chemical digestion of Ti6Al7Nb scaffolds produced by Selective Laser Melting reduces significantly ability of Pseudomonas aeruginosa to form biofilm.

    PubMed

    Junka, Adam F; Szymczyk, Patrycja; Secewicz, Anna; Pawlak, Andrzej; Smutnicka, Danuta; Ziółkowski, Grzegorz; Bartoszewicz, Marzenna; Chlebus, Edward

    2016-01-01

    In our previous work we reported the impact of hydrofluoric and nitric acid used for chemical polishing of Ti-6Al-7Nb scaffolds on decrease of the number of Staphylococcus aureus biofilm forming cells. Herein, we tested impact of the aforementioned substances on biofilm of Gram-negative microorganism, Pseudomonas aeruginosa, dangerous pathogen responsible for plethora of implant-related infections. The Ti-6Al-7Nb scaffolds were manufactured using Selective Laser Melting method. Scaffolds were subjected to chemical polishing using a mixture of nitric acid and fluoride or left intact (control group). Pseudomonal biofilm was allowed to form on scaffolds for 24 hours and was removed by mechanical vortex shaking. The number of pseudomonal cells was estimated by means of quantitative culture and Scanning Electron Microscopy. The presence of nitric acid and fluoride on scaffold surfaces was assessed by means of IR and rentgen spetorscopy. Quantitative data were analysed using the Mann-Whitney test (P ≤ 0.05). Our results indicate that application of chemical polishing correlates with significant drop of biofilm-forming pseudomonal cells on the manufactured Ti-6Al-7Nb scaffolds ( p = 0.0133, Mann-Whitney test) compared to the number of biofilm-forming cells on non-polished scaffolds. As X-ray photoelectron spectroscopy revealed the presence of fluoride and nitrogen on the surface of scaffold, we speculate that drop of biofilm forming cells may be caused by biofilm-supressing activity of these two elements. PMID:27150429

  9. Rapid High Spatial Resolution Chemical Characterization of Soil Structure to Illuminate Nutrient Distribution Mechanisms Related to Carbon Cycling Using Laser Ablation Aerosol Mass Spectrometry

    NASA Astrophysics Data System (ADS)

    Hicks, R. K.; Alexander, M. L. L.; Newburn, M. K.

    2015-12-01

    Soils contain approximately half of Earth's terrestrial carbon. As such, it is important to understand the factors that control the cycling of this soil organic carbon between the land and the atmosphere. Models that attribute the persistence of soil organic carbon to the intrinsic properties of the molecules themselves are inconsistent with recent observations— for example, materials that are more thermodynamically stable have been found to have a shorter lifetime in soils than ones that are less stable, and vice versa. A new explanation has therefore been posited that invokes ecosystem properties as a whole, and not just intrinsic molecular properties, as the kinetic factor controlling soil carbon dynamics. Because soil dynamics occur on a small scale, techniques with high spatial resolution are required for their study. Existing techniques such as TOF-SIMS require preparation of the sample and introduction into a high vacuum system, and do not address the need to examine large numbers of sample systems without perturbation of chemical and physical properties. To address this analytical challenge, we have coupled a laser ablation (LA) module to an Aerodyne aerosol mass spectrometer (AMS), thereby enabling sample introduction and subsequent measurement of small amounts of soil organic matter by the laser ablation aerosol mass spectrometer (LA-AMS). Due to the adjustable laser beam width, the LA-AMS can probe spot sizes ranging from 1-150 μm in diameter, liberating from 10-100 ng/pulse. With a detection limit of 1 pM, the AMS allows for chemical characterization of the ablated material in terms of elemental ratios, compound classes, and TOC/TOM ratios. Furthermore, the LA-AMS is capable of rapid, in-situ sampling under ambient conditions, thereby eliminating the need for sample processing or transport before analysis. Here, we will present the first results from systematic studies aimed at validating the LA-AMS method as well as results from initial measurements

  10. Time-Resolved O3 Chemical Chain Reaction Kinetics Via High-Resolution IR Laser Absorption Methods

    NASA Technical Reports Server (NTRS)

    Kulcke, Axel; Blackmon, Brad; Chapman, William B.; Kim, In Koo; Nesbitt, David J.

    1998-01-01

    Excimer laser photolysis in combination with time-resolved IR laser absorption detection of OH radicals has been used to study O3/OH(v = 0)/HO2 chain reaction kinetics at 298 K, (i.e.,(k(sub 1) is OH + 03 yields H02 + 02 and (k(sub 2) is H02 + 03 yields OH + 202). From time-resolved detection of OH radicals with high-resolution near IR laser absorption methods, the chain induction kinetics have been measured at up to an order of magnitude higher ozone concentrations ([03] less than or equal to 10(exp 17) molecules/cu cm) than accessible in previous studies. This greater dynamic range permits the full evolution of the chain induction, propagation, and termination process to be temporally isolated and measured in real time. An exact solution for time-dependent OH evolution under pseudo- first-order chain reaction conditions is presented, which correctly predicts new kinetic signatures not included in previous OH + 03 kinetic analyses. Specifically, the solutions predict an initial exponential loss (chain "induction") of the OH radical to a steady-state level ([OH](sub ss)), with this fast initial decay determined by the sum of both chain rate constants, k(sub ind) = k(sub 1) + k(sub 2). By monitoring the chain induction feature, this sum of the rate constants is determined to be k(sub ind) = 8.4(8) x 10(exp -14) cu cm/molecule/s for room temperature reagents. This is significantly higher than the values currently recommended for use in atmospheric models, but in excellent agreement with previous results from Ravishankara et al.

  11. Laser satellite power systems

    SciTech Connect

    Walbridge, E.W.

    1980-01-01

    A laser satellite power system (SPS) converts solar power captured by earth-orbiting satellites into electrical power on the earth's surface, the satellite-to-ground transmission of power being effected by laser beam. The laser SPS may be an alternative to the microwave SPS. Microwaves easily penetrate clouds while laser radiation does not. Although there is this major disadvantage to a laser SPS, that system has four important advantages over the microwave alternative: (1) land requirements are much less, (2) radiation levels are low outside the laser ground stations, (3) laser beam sidelobes are not expected to interfere with electromagnetic systems, and (4) the laser system lends itself to small-scale demonstration. After describing lasers and how they work, the report discusses the five lasers that are candidates for application in a laser SPS: electric discharge lasers, direct and indirect solar pumped lasers, free electron lasers, and closed-cycle chemical lasers. The Lockheed laser SPS is examined in some detail. To determine whether a laser SPS will be worthy of future deployment, its capabilities need to be better understood and its attractiveness relative to other electric power options better assessed. First priority should be given to potential program stoppers, e.g., beam attenuation by clouds. If investigation shows these potential program stoppers to be resolvable, further research should investigate lasers that are particularly promising for SPS application.

  12. Divergence and polarisation of radiation of a wide-aperture chemical DF laser with an unstable resonator

    NASA Astrophysics Data System (ADS)

    Agroskin, V. Ya; Bravyi, B. G.; Vasil'ev, G. K.; Gur'ev, V. I.; Karel'skii, V. G.; Kashtanov, S. A.; Makarov, E. F.; Sotnichenko, S. A.; Chernyshev, Yu A.

    2016-08-01

    Influence of a plane-parallel plate, placed inside an unstable resonator and entirely overlapping the beam cross section, on the polarisation and divergence of wide-aperture DF-laser radiation is studied at various angles of plate inclination to the resonator axis. It is shown that the plate inside a resonator has no effect on the radiation divergence and only requires a corresponding shift of a convex mirror in order to keep the resonator confocal. A noticeable change in the radiation polarisation has been observed only at angles of plate inclination greater than 20° at angles of above 45° the radiation becomes actually linearly polarised.

  13. Comparison of the Er,Cr:YSGG laser with a chemical vapour deposition bur and conventional techniques for cavity preparation: a microleakage study.

    PubMed

    Yazici, A Rüya; Yıldırım, Zeren; Antonson, Sibel A; Kilinc, Evren; Koch, Daniele; Antonson, Donald E; Dayangaç, Berrin; Ozgünaltay, Gül

    2012-01-01

    The aim of this study was to compare the effects of the Er,Cr:YSGG laser using chemical vapour deposition (CVD) bur cavity preparation with conventional preparation methods including a diamond bur and a carbide bur on the microleakage with two different adhesive systems. A total of 40 extracted human premolars were randomly assigned to four experimental groups according to the cavity preparation technique: group I diamond bur (Diatech); group II carbide bur (Diatech); group III Er,Cr:YSGG laser (Biolase Millennium II); and group IV CVD bur (CVDentUS). Using the different preparation techniques, Class V standardized preparations were performed on the buccal and lingual surfaces with gingival margins on the dentin and occlusal margins on the enamel. Each preparation group was randomly assigned to two subgroups (five teeth, ten preparations) according to the type of adhesive: an etch-and-rinse adhesive (Adper Single Bond), and a single-step self-etch adhesive (AdheSE One). All preparations were restored with a nanohybrid composite resin in a single increment. Following thermocycling (×500; 5-55°C), the teeth were immersed in basic fuchsin and sectioned in the orovestibular direction. Dye penetration was evaluated under a light microscope by two blinded examiners. Data were statistically analysed with the Kruskal-Wallis and Wilcoxon tests (p<0.05). There were no statistically significant differences between the preparation techniques with either of the two adhesive systems (p>0.05). Comparing the enamel and dentin leakage scores within each group, no statistically significant differences were found (p>0.05). The Er,Cr:YSGG laser cavity preparation did not differ from preparation with CVD, diamond or carbide bur in terms of microleakage with the different adhesive systems.

  14. Resonant and nonresonant vibrational excitation of ammonia molecules in the growth of gallium nitride using laser-assisted metal organic chemical vapour deposition

    NASA Astrophysics Data System (ADS)

    Golgir, Hossein Rabiee; Zhou, Yun Shen; Li, Dawei; Keramatnejad, Kamran; Xiong, Wei; Wang, Mengmeng; Jiang, Li Jia; Huang, Xi; Jiang, Lan; Silvain, Jean Francois; Lu, Yong Feng

    2016-09-01

    The influence of exciting ammonia (NH3) molecular vibration in the growth of gallium nitride (GaN) was investigated by using an infrared laser-assisted metal organic chemical vapor deposition method. A wavelength tunable CO2 laser was used to selectively excite the individual vibrational modes. Resonantly exciting the NH-wagging mode (v2) of NH3 molecules at 9.219 μm led to a GaN growth rate of 84 μm/h, which is much higher than the reported results. The difference between the resonantly excited and conventional thermally populated vibrational states was studied via resonant and nonresonant vibrational excitations of NH3 molecules. Resonant excitation of various vibrational modes was achieved at 9.219, 10.35, and 10.719 μm, respectively. Nonresonant excitation was conducted at 9.201 and 10.591 μm, similar to conventional thermal heating. Compared to nonresonant excitation, resonant excitation noticeably promotes the GaN growth rate and crystalline quality. The full width at half maximum value of the XRD rocking curves of the GaN (0002) and GaN (10-12) diffraction peaks decreased at resonant depositions and reached its minimum value of 45 and 53 arcmin, respectively, at the laser wavelength of 9.219 μm. According to the optical emission spectroscopic studies, resonantly exciting the NH3 v2 mode leads to NH3 decomposition at room temperature, reduces the formation of the TMGa:NH3 adduct, promotes the supply of active species in GaN formation, and, therefore, results in the increased GaN growth rate.

  15. Investigation of the chemical stability of the laser-induced fluorescence tracers acetone, diethylketone, and toluene under IC engine conditions using Raman spectroscopy.

    PubMed

    Trost, Johannes; Zigan, Lars; Eichmann, Simone C; Seeger, Thomas; Leipertz, Alfred

    2013-09-01

    This paper reports on an investigation of the chemical stability of the common laser-induced fluorescence (LIF) tracers acetone, diethylketone, and toluene. Stability is analyzed using linear Raman spectroscopy inside a heated pressure cell with optical access, which is used for the LIF calibration of these tracers. The measurements examine the influence of temperature, pressure, and residence time on tracer oxidation, which occurs without a rise in temperature or pressure inside the cell, highlighting the need for optical detection. A comparison between the three different tracers shows large differences, with diethylketone having the lowest and toluene by far the highest stability. An analysis of the sensitivity of the measurement shows that the detection limit of the oxidized tracer is well below 3% molar fraction, which is typical for LIF applications in combustion devices such as internal combustion (IC) engines. Furthermore, the effect on the LIF signal intensity is examined in an isothermal turbulent mixing study. PMID:24085091

  16. Performance of chemical vapor deposition fabricated graphene absorber mirror in Yb3+ : Sc2SiO5 mode-locked laser

    NASA Astrophysics Data System (ADS)

    Cai, Wei; Li, Yaqi; Zhu, Hongtong; Jiang, Shouzhen; Xu, Shicai; Liu, Jie; Zheng, Lihe; Su, Liangbi; Xu, Jun

    2014-12-01

    A reflective graphene saturable absorber mirror (SAM) was successfully fabricated by chemical vapor deposition technology. A stable diode-pumped passively mode-locked Yb3+:Sc2SiO5 laser using a graphene SAM as a saturable absorber was accomplished for the first time. The measured average output power amounts to 351 mW under the absorbed pump power of 12.5 W. Without prisms compensating for dispersion, the minimum pulse duration of 7 ps with a repetition rate of 97 MHz has been obtained at the central wavelength of 1063 nm. The corresponding peak power and the maximum pulse energy were 516 W and 3.6 nJ, respectively.

  17. Investigation of the chemical stability of the laser-induced fluorescence tracers acetone, diethylketone, and toluene under IC engine conditions using Raman spectroscopy.

    PubMed

    Trost, Johannes; Zigan, Lars; Eichmann, Simone C; Seeger, Thomas; Leipertz, Alfred

    2013-09-01

    This paper reports on an investigation of the chemical stability of the common laser-induced fluorescence (LIF) tracers acetone, diethylketone, and toluene. Stability is analyzed using linear Raman spectroscopy inside a heated pressure cell with optical access, which is used for the LIF calibration of these tracers. The measurements examine the influence of temperature, pressure, and residence time on tracer oxidation, which occurs without a rise in temperature or pressure inside the cell, highlighting the need for optical detection. A comparison between the three different tracers shows large differences, with diethylketone having the lowest and toluene by far the highest stability. An analysis of the sensitivity of the measurement shows that the detection limit of the oxidized tracer is well below 3% molar fraction, which is typical for LIF applications in combustion devices such as internal combustion (IC) engines. Furthermore, the effect on the LIF signal intensity is examined in an isothermal turbulent mixing study.

  18. The effect of deposition atmosphere on the chemical composition of TiN and ZrN thin films grown by pulsed laser deposition

    NASA Astrophysics Data System (ADS)

    Craciun, D.; Socol, G.; Stefan, N.; Dorcioman, G.; Hanna, M.; Taylor, C. R.; Lambers, E.; Craciun, V.

    2014-05-01

    Very thin TiN and ZrN films (<500 nm) were grown on (1 0 0) Si substrates at temperatures up to 500 °C by the pulsed laser deposition (PLD) technique using a KrF excimer laser under residual vacuum or various mixtures of CH4 or N2. Auger electron spectroscopy investigations found that films contained a relatively low oxygen concentration, usually below 3.0 at%. Films deposited under residual vacuum or very low N2 pressures (<3 × 10-3 Pa) contained 3-6 at% C atoms in the bulk. This fraction grew to 8-10 at% when the deposition was performed under an atmosphere of 2 × 10-3 Pa CH4. To avoid C atoms incorporation into the bulk a deposition pressure of 10 Pa N2 was required. X-ray photoelectron spectroscopy investigations found that oxygen was mostly bonded in an oxynitride type of compound, while carbon was bonded into a metallic carbide. The presence of C atoms in the chemical composition of the TiN or ZrN improved the measured hardness of the films.

  19. Ground state lasing at 1.30 microm from InAs/GaAs quantum dot lasers grown by metal-organic chemical vapor deposition.

    PubMed

    Guimard, Denis; Ishida, Mitsuru; Bordel, Damien; Li, Lin; Nishioka, Masao; Tanaka, Yu; Ekawa, Mitsuru; Sudo, Hisao; Yamamoto, Tsuyoshi; Kondo, Hayato; Sugawara, Mitsuru; Arakawa, Yasuhiko

    2010-03-12

    We investigated the effects of post-growth annealing on the photoluminescence (PL) characteristics of InAs/GaAs quantum dots (QDs) grown by metal-organic chemical vapor deposition (MOCVD). The onset temperature at which both the peak linewidth and the PL intensity degraded and the blueshift of the ground state emission wavelength occurred was found to depend on both the QD density and the In composition of the capping layer. This behavior is particularly important in view of QD integration in photonic devices. From the knowledge of the dependences of the PL characteristics after annealing on the QD and capping growth conditions, ground state lasing at 1.30 microm could be demonstrated from InAs/GaAs QDs grown by MOCVD. Finally, we compared the laser characteristics of InAs/GaAs QDs with those of InAs/Sb:GaAs QDs, grown according to the antimony-mediated growth technique, and showed that InAs/Sb:GaAs QDs are more appropriate for laser fabrication at 1.3 microm by MOCVD.

  20. Determining the order of deposition of natural latent fingerprints and laser printed ink using chemical mapping with secondary ion mass spectrometry.

    PubMed

    Attard Montalto, Nicola; Ojeda, Jesús J; Jones, Benjamin J

    2013-03-01

    Time-of-flight secondary ion mass spectrometry (ToF-SIMS) chemical mapping was used to investigate the order of deposition of natural latent fingerprints and laser printed ink on paper. This feasibility study shows that sodium, potassium and C(3)H(5) positive ions were particularly abundant endogenous components of the natural fingerprints and also present in the paper examined, but were mostly absent in the laser printed ink. Mapping of these ions enables the observation of friction ridges from latent prints on the ink surface, only when a fingerprint was deposited above the layer of ink. As a demonstration of proof of concept, blind testing of 21 samples from three donors resulted in a 100% success rate. The sensitivity of this technique was investigated within this trial through the examination of up to fifth depletion fingerprints and ageing of up to 28 days. Migration of fingerprint and paper components to the ink surface, although observed with increased ageing time, was not found to compromise determination of the deposition sequence.

  1. The influence of multivariate analysis methods and target grain size on the accuracy of remote quantitative chemical analysis of rocks using laser induced breakdown spectroscopy

    NASA Astrophysics Data System (ADS)

    Anderson, Ryan B.; Morris, Richard V.; Clegg, Samuel M.; Bell, James F.; Wiens, Roger C.; Humphries, Seth D.; Mertzman, Stanley A.; Graff, Trevor G.; McInroy, Rhonda

    2011-10-01

    Laser-induced breakdown spectroscopy (LIBS) was used to quantitatively analyze 195 rock slab samples with known bulk chemical compositions, 90 pressed-powder samples derived from a subset of those rocks, and 31 pressed-powder geostandards under conditions that simulate the ChemCam instrument on the Mars Science Laboratory Rover (MSL), Curiosity. The low-volatile (<2 wt.%) silicate samples (90 rock slabs, corresponding powders, and 22 geostandards) were split into training, validation, and test sets. The LIBS spectra and chemical compositions of the training set were used with three multivariate methods to predict the chemical compositions of the test set. The methods were partial least squares (PLS), multilayer perceptron artificial neural networks (MLP ANNs) and cascade correlation (CC) ANNs. Both the full LIBS spectrum and the intensity at five pre-selected spectral channels per major element (feature selection) were used as input data for the multivariate calculations. The training spectra were supplied to the algorithms without averaging ( i.e. five spectra per target) and with averaging ( i.e. all spectra from the same target averaged and treated as one spectrum). In most cases neural networks did not perform better than PLS for our samples. PLS2 without spectral averaging outperformed all other procedures on the basis of lowest quadrature root mean squared error (RMSE) for both the full test set and the igneous rocks test set. The RMSE for PLS2 using the igneous rock slab test set is: 3.07 wt.% SiO 2, 0.87 wt.% TiO 2, 2.36 wt.% Al 2O 3, 2.20 wt.% Fe 2O 3, 0.08 wt.% MnO, 1.74 wt.% MgO, 1.14 wt.% CaO, 0.85 wt.% Na 2O, 0.81 wt.% K 2O. PLS1 with feature selection and averaging had a higher quadrature RMSE than PLS2, but merits further investigation as a method of reducing data volume and computation time and potentially improving prediction accuracy, particularly for samples that differ significantly from the training set. Precision and accuracy were influenced

  2. Chemical analysis of pharmaceuticals and explosives in fingermarks using matrix-assisted laser desorption ionization/time-of-flight mass spectrometry.

    PubMed

    Kaplan-Sandquist, Kimberly; LeBeau, Marc A; Miller, Mark L

    2014-02-01

    Chemical analysis of latent fingermarks, "touch chemistry," has the potential of providing intelligence or forensically relevant information. Matrix-assisted laser desorption ionization/time-of-flight mass spectrometry (MALDI/TOF MS) was used as an analytical platform for obtaining mass spectra and chemical images of target drugs and explosives in fingermark residues following conventional fingerprint development methods and MALDI matrix processing. There were two main purposes of this research: (1) develop effective laboratory methods for detecting drugs and explosives in fingermark residues and (2) determine the feasibility of detecting drugs and explosives after casual contact with pills, powders, and residues. Further, synthetic latent print reference pads were evaluated as mimics of natural fingermark residue to determine if the pads could be used for method development and quality control. The results suggest that artificial amino acid and sebaceous oil residue pads are not suitable to adequately simulate natural fingermark chemistry for MALDI/TOF MS analysis. However, the pads were useful for designing experiments and setting instrumental parameters. Based on the natural fingermark residue experiments, handling whole or broken pills did not transfer sufficient quantities of drugs to allow for definitive detection. Transferring drugs or explosives in the form of powders and residues was successful for preparing analytes for detection after contact with fingers and deposition of fingermark residue. One downfall to handling powders was that the analyte particles were easily spread beyond the original fingermark during development. Analyte particles were confined in the original fingermark when using transfer residues. The MALDI/TOF MS was able to detect procaine, pseudoephedrine, TNT, and RDX from contact residue under laboratory conditions with the integration of conventional fingerprint development methods and MALDI matrix. MALDI/TOF MS is a nondestructive

  3. Chemical analysis of pharmaceuticals and explosives in fingermarks using matrix-assisted laser desorption ionization/time-of-flight mass spectrometry.

    PubMed

    Kaplan-Sandquist, Kimberly; LeBeau, Marc A; Miller, Mark L

    2014-02-01

    Chemical analysis of latent fingermarks, "touch chemistry," has the potential of providing intelligence or forensically relevant information. Matrix-assisted laser desorption ionization/time-of-flight mass spectrometry (MALDI/TOF MS) was used as an analytical platform for obtaining mass spectra and chemical images of target drugs and explosives in fingermark residues following conventional fingerprint development methods and MALDI matrix processing. There were two main purposes of this research: (1) develop effective laboratory methods for detecting drugs and explosives in fingermark residues and (2) determine the feasibility of detecting drugs and explosives after casual contact with pills, powders, and residues. Further, synthetic latent print reference pads were evaluated as mimics of natural fingermark residue to determine if the pads could be used for method development and quality control. The results suggest that artificial amino acid and sebaceous oil residue pads are not suitable to adequately simulate natural fingermark chemistry for MALDI/TOF MS analysis. However, the pads were useful for designing experiments and setting instrumental parameters. Based on the natural fingermark residue experiments, handling whole or broken pills did not transfer sufficient quantities of drugs to allow for definitive detection. Transferring drugs or explosives in the form of powders and residues was successful for preparing analytes for detection after contact with fingers and deposition of fingermark residue. One downfall to handling powders was that the analyte particles were easily spread beyond the original fingermark during development. Analyte particles were confined in the original fingermark when using transfer residues. The MALDI/TOF MS was able to detect procaine, pseudoephedrine, TNT, and RDX from contact residue under laboratory conditions with the integration of conventional fingerprint development methods and MALDI matrix. MALDI/TOF MS is a nondestructive

  4. Characterization of Pad-Wafer Contact and Surface Topography in Chemical Mechanical Planarization Using Laser Confocal Microscopy

    NASA Astrophysics Data System (ADS)

    Sun, Ting; Zhuang, Yun; Borucki, Leonard; Philipossian, Ara

    2010-06-01

    In this study, an optical method using laser confocal microscopy was developed to measure the surface contact area and topography of pads under a dry and static condition. A custom-made pad sample holder with a sapphire window and a miniature load cell was used to collect pad surface contact images at controlled loads. By extracting the black spots in the collected images, pad contact area and contact summit density were obtained. The analysis of a post polishing pad sample (8,289×921 µm2) showed that the contact area increased from 0.026 to 0.045% when the pressure increased from 2 to 4 psi and increased further to 0.059% when the pressure increased to 6 psi. The contact summit density also exhibited a linear increase with the applied pressure. The above results were consistent with the Greenwood and Williamson theory, which predicted a linear relationship between pad contact area and contact summit density. Laser confocal microscopy was also used to measure pad surface topography by establishing probability density functions (PDFs) of pad surface height.

  5. Characterization of Pad-Wafer Contact and Surface Topography in Chemical Mechanical Planarization Using Laser Confocal Microscopy

    NASA Astrophysics Data System (ADS)

    Ting Sun,; Yun Zhuang,; Leonard Borucki,; Ara Philipossian,

    2010-06-01

    In this study, an optical method using laser confocal microscopy was developed to measure the surface contact area and topography of pads under a dry and static condition. A custom-made pad sample holder with a sapphire window and a miniature load cell was used to collect pad surface contact images at controlled loads. By extracting the black spots in the collected images, pad contact area and contact summit density were obtained. The analysis of a post polishing pad sample (8{,}289× 921 μm2) showed that the contact area increased from 0.026 to 0.045% when the pressure increased from 2 to 4 psi and increased further to 0.059% when the pressure increased to 6 psi. The contact summit density also exhibited a linear increase with the applied pressure. The above results were consistent with the Greenwood and Williamson theory, which predicted a linear relationship between pad contact area and contact summit density. Laser confocal microscopy was also used to measure pad surface topography by establishing probability density functions (PDFs) of pad surface height.

  6. Evaluation of the laser-induced breakdown spectroscopy technique for determination of the chemical composition of copper concentrates

    NASA Astrophysics Data System (ADS)

    Łazarek, Łukasz; Antończak, Arkadiusz J.; Wójcik, Michał R.; Drzymała, Jan; Abramski, Krzysztof M.

    2014-07-01

    Laser-induced breakdown spectroscopy (LIBS), like many other spectroscopic techniques, is a comparative method. Typically, in qualitative analysis, synthetic certified standard with a well-known elemental composition is used to calibrate the system. Nevertheless, in all laser-induced techniques, such calibration can affect the accuracy through differences in the overall composition of the chosen standard. There are also some intermediate factors, which can cause imprecision in measurements, such as optical absorption, surface structure and thermal conductivity. In this work the calibration performed for the LIBS technique utilizes pellets made directly from the tested materials (old well-characterized samples). This choice produces a considerable improvement in the accuracy of the method. This technique was adopted for the determination of trace elements in industrial copper concentrates, standardized by conventional atomic absorption spectroscopy with a flame atomizer. A series of copper flotation concentrate samples was analyzed for three elements: silver, cobalt and vanadium. We also proposed a method of post-processing the measurement data to minimize matrix effects and permit reliable analysis. It has been shown that the described technique can be used in qualitative and quantitative analyses of complex inorganic materials, such as copper flotation concentrates. It was noted that the final validation of such methodology is limited mainly by the accuracy of the characterization of the standards.

  7. Tunable lasers- an overview

    SciTech Connect

    Guenther, B.D.; Buser, R.G.

    1982-08-01

    This overview of tunable lasers describes their applicability to spectroscopy in the ultraviolet and middle infrared ranges; to rapid on-line diagnostics by ultrashort cavity lasers; to exploration, by the free electron laser, for its wide tuning in the far infrared to submillimeter region; to remote detection, in areas such as portable pollution monitors, on-line chemical analyzers, auto exhaust analyzers, and production line controls; to photochemistry; and to other potential areas in diagnostics, communications, and medical and biological sciences. The following lasers are characterized by their tunability: solid state lasers, primarily alexandrite, with a tuning range of ca 1000 Angstroms; color center lasers; semiconductor lasers; dye lasers; gas lasers, where high-pressure CO/sub 2/ discharges are the best known example for a wide tunability range, and research is continuing in systems such as the alkali dimers; and, at wavelengths beyond 10 micrometers, the possibilities beyond Cerenkov and free electron lasers.

  8. Widely tunable mode-hop free external cavity quantum cascade lasers for high resolution spectroscopy and chemical sensing

    NASA Astrophysics Data System (ADS)

    Wysocki, G.; Lewicki, R.; Curl, R. F.; Tittel, F. K.; Diehl, L.; Capasso, F.; Troccoli, M.; Hofler, G.; Bour, D.; Corzine, S.; Maulini, R.; Giovannini, M.; Faist, J.

    2008-09-01

    Recent progress in the development of room temperature, continuous wave, widely tunable, mode-hop-free mid-infrared external cavity quantum cascade laser (EC-QCL) spectroscopic sources is reported. A single mode tuning range of 155 cm-1 (˜ 8% of the center wavelength) with a maximum power of 11.1 mW and 182 cm-1 (˜ 15% of the center wavelength) with a maximum power of 50 mW was obtained for 5.3 and 8.4 μm EC-QCLs respectively. This technology is particularly suitable for high resolution spectroscopic applications, multi species trace-gas detection and spectroscopic measurements of broadband absorbers. Several examples of spectroscopic measurements performed using EC-QCL based spectrometers are demonstrated.

  9. Modification of the chemical composition, morphology, and antireflection properties of WSe x films formed by pulsed laser deposition

    NASA Astrophysics Data System (ADS)

    Grigoriev, S. N.; Nevolin, V. N.; Fominski, V. Yu.; Romanov, R. I.; Volosova, M. A.

    2014-09-01

    We have studied the possibility of controlling important structural characteristics of WSe x films, which belong to the class of layered materials and have good prospects for application in modern nano- and optoelectronic devices. It is established that, by using thermal treatment and ion irradiation during pulsed laser deposition (PLD) in the shadow of an antidroplet shield, it is possible to vary the Se/W atomic ratio from 5 to 1.5, change the character of atomic packing, and obtain films with either smooth or rough surfaces. An increase in the height of parabolic protrusions on the surface up to 200-500 nm leads to a decrease in the optical reflection coefficient in a broad wavelength range from 30% (typical of smooth films) to 6%, which can favor a significant increase in the efficiency of solar cells based on semiconductor films of this type.

  10. Infrared Scattering Scanning Near-Field Optical Microscopy Using An External Cavity Quantum Cascade Laser For Nanoscale Chemical Imaging And Spectroscopy of Explosive Residues

    SciTech Connect

    Craig, Ian M.; Phillips, Mark C.; Taubman, Matthew S.; Josberger, Erik E.; Raschke, Markus Bernd

    2013-02-04

    Infrared scattering scanning near-field optical microscopy (s-SNOM) is an apertureless superfocusing technique that uses the antenna properties of a conducting atomic force microscope (AFM) tip to achieve infrared spatial resolution below the diffraction limit. The instrument can be used either in imaging mode, where a fixed wavelength light source is tuned to a molecular resonance and the AFM raster scans an image, or in spectroscopy mode where the AFM is held stationary over a feature of interest and the light frequency is varied to obtain a spectrum. In either case, a strong, stable, coherent infrared source is required. Here we demonstrate the integration of a broadly tunable external cavity quantum cascade laser (ECQCL) into an s-SNOM and use it to obtain infrared spectra of microcrystals of chemicals adsorbed onto gold substrates. Residues of the explosive compound tetryl was deposited onto gold substrates. s-SNOM experiments were performed in the 1260-1400 cm-1 tuning range of the ECQCL, corresponding to the NO2 symmetric stretch vibrational fingerprint region. Vibrational infrared spectra were collected on individual chemical domains with a collection area of *500nm2 and compared to ensemble averaged far-field reflection-absorption infrared spectroscopy (RAIRS) results.

  11. Multivariate approach to the chemical mapping of uranium in sandstone-hosted uranium ores analyzed using double pulse Laser-Induced Breakdown Spectroscopy

    NASA Astrophysics Data System (ADS)

    Klus, Jakub; Mikysek, Petr; Prochazka, David; Pořízka, Pavel; Prochazková, Petra; Novotný, Jan; Trojek, Tomáš; Novotný, Karel; Slobodník, Marek; Kaiser, Jozef

    2016-09-01

    The goal of this work is to provide high resolution mapping of uranium in sandstone-hosted uranium ores using Laser-Induced Breakdown Spectroscopy (LIBS) technique. In order to obtain chemical image with highest possible spatial resolution, LIBS system in orthogonal double pulse (DP LIBS) arrangement was employed. Owing to this experimental arrangement the spot size of 50 μm in diameter resulting in lateral resolution of 100 μm was reached. Despite the increase in signal intensity in DP LIBS modification, the detection of uranium is challenging. The main cause is the high density of uranium spectral lines, which together with broadening of LIBS spectral lines overreaches the resolution of commonly used spectrometers. It results in increased overall background radiation with only few distinguishable uranium lines. Three different approaches in the LIBS data treatment for the uranium detection were utilized: i) spectral line intensity, ii) region of apparent background and iii) multivariate data analysis. By utilizing multivariate statistical methods, a specific specimen features (in our case uranium content) were revealed by processing complete spectral information obtained from broadband echelle spectrograph. Our results are in a good agreement with conventional approaches such as line fitting and show new possibilities of processing spectral data in mapping. As a reference technique to LIBS was employed X-ray Fluorescence (XRF). The XRF chemical images used in this paper have lower resolution (approximately 1-2 mm per image point), nevertheless the elemental distribution is apparent and corresponds to presented LIBS experiments.

  12. Laser Safety Device

    NASA Technical Reports Server (NTRS)

    1992-01-01

    A major focus of work done at Air Products and Chemicals' Laser Application Laboratory is on use of ultraviolet radiation using high energy excimer lasers. Because light within the wavelength of excimer lasers is invisible, it can cause serious damage to eyes and tissue. To contain the laser beam, Air Products Incorporated a Jet Propulsion Laboratory invention described in a technical support package into its beam stops. The technology interrupts the laser pathway and allows workers to remain in the target area without shutting off the laser.

  13. Laser-induced breakdown spectroscopy (LIBS) technique for the determination of the chemical composition of complex inorganic materials

    NASA Astrophysics Data System (ADS)

    Łazarek, Łukasz; Antończak, Arkadiusz J.; Wójcik, Michał R.; Kozioł, Paweł E.; Stepak, Bogusz; Abramski, Krzysztof M.

    2014-08-01

    Laser-induced breakdown spectroscopy (LIBS) is a fast, fully optical method, that needs little or no sample preparation. In this technique qualitative and quantitative analysis is based on comparison. The determination of composition is generally based on the construction of a calibration curve namely the LIBS signal versus the concentration of the analyte. Typically, to calibrate the system, certified reference materials with known elemental composition are used. Nevertheless, such samples due to differences in the overall composition with respect to the used complex inorganic materials can influence significantly on the accuracy. There are also some intermediate factors which can cause imprecision in measurements, such as optical absorption, surface structure, thermal conductivity etc. This paper presents the calibration procedure performed with especially prepared pellets from the tested materials, which composition was previously defined. We also proposed methods of post-processing which allowed for mitigation of the matrix effects and for a reliable and accurate analysis. This technique was implemented for determination of trace elements in industrial copper concentrates standardized by conventional atomic absorption spectroscopy with a flame atomizer. A series of copper flotation concentrate samples was analyzed for contents of three elements, that is silver, cobalt and vanadium. It has been shown that the described technique can be used to qualitative and quantitative analyses of complex inorganic materials, such as copper flotation concentrates.

  14. Confocal laser scanning microscopy elucidation of the micromorphology of the leaf cuticle and analysis of its chemical composition.

    PubMed

    Nadiminti, Pavani P; Rookes, James E; Boyd, Ben J; Cahill, David M

    2015-11-01

    Electron microscopy techniques such as transmission electron microscopy (TEM) and scanning electron microscopy (SEM) have been invaluable tools for the study of the micromorphology of plant cuticles. However, for electron microscopy, the preparation techniques required may invariably introduce artefacts in cuticle preservation. Further, there are a limited number of methods available for quantifying the image data obtained through electron microscopy. Therefore, in this study, optical microscopy techniques were coupled with staining procedures and, along with SEM were used to qualitatively and quantitatively assess the ultrastructure of plant leaf cuticles. Leaf cryosections of Triticum aestivum (wheat), Zea mays (maize), and Lupinus angustifolius (lupin) were stained with either fat-soluble azo stain Sudan IV or fluorescent, diarylmethane Auramine O and were observed under confocal laser scanning microscope (CLSM). For all the plant species tested, the cuticle on the leaf surfaces could be clearly resolved in many cases into cuticular proper (CP), external cuticular layer (ECL), and internal cuticular layer (ICL). Novel image data analysis procedures for quantifying the epicuticular wax micromorphology were developed, and epicuticular waxes of L. angustifolius were described here for the first time. Together, application of a multifaceted approach involving the use of a range of techniques to study the plant cuticle has led to a better understanding of cuticular structure and provides new insights into leaf surface architecture.

  15. Novel two-step laser ablation and ionization mass spectrometry (2S-LAIMS) of actor-spectator ice layers: probing chemical composition of D2O ice beneath a H2O ice layer.

    PubMed

    Yang, Rui; Gudipati, Murthy S

    2014-03-14

    In this work, we report for the first time successful analysis of organic aromatic analytes imbedded in D2O ices by novel infrared (IR) laser ablation of a layered non-absorbing D2O ice (spectator) containing the analytes and an ablation-active IR-absorbing H2O ice layer (actor) without the analyte. With these studies we have opened up a new method for the in situ analysis of solids containing analytes when covered with an IR laser-absorbing layer that can be resonantly ablated. This soft ejection method takes advantage of the tenability of two-step infrared laser ablation and ultraviolet laser ionization mass spectrometry, previously demonstrated in this lab to study chemical reactions of polycyclic aromatic hydrocarbons (PAHs) in cryogenic ices. The IR laser pulse tuned to resonantly excite only the upper H2O ice layer (actor) generates a shockwave upon impact. This shockwave penetrates the lower analyte-containing D2O ice layer (spectator, a non-absorbing ice that cannot be ablated directly with the wavelength of the IR laser employed) and is reflected back, ejecting the contents of the D2O layer into the vacuum where they are intersected by a UV laser for ionization and detection by a time-of-flight mass spectrometer. Thus, energy is transmitted from the laser-absorbing actor layer into the non-absorbing spectator layer resulting its ablation. We found that isotope cross-contamination between layers was negligible. We also did not see any evidence for thermal or collisional chemistry of PAH molecules with H2O molecules in the shockwave. We call this "shockwave mediated surface resonance enhanced subsurface ablation" technique as "two-step laser ablation and ionization mass spectrometry of actor-spectator ice layers." This method has its roots in the well-established MALDI (matrix assisted laser desorption and ionization) method. Our method offers more flexibility to optimize both the processes--ablation and ionization. This new technique can thus be potentially

  16. Novel two-step laser ablation and ionization mass spectrometry (2S-LAIMS) of actor-spectator ice layers: Probing chemical composition of D{sub 2}O ice beneath a H{sub 2}O ice layer

    SciTech Connect

    Yang, Rui Gudipati, Murthy S.

    2014-03-14

    In this work, we report for the first time successful analysis of organic aromatic analytes imbedded in D{sub 2}O ices by novel infrared (IR) laser ablation of a layered non-absorbing D{sub 2}O ice (spectator) containing the analytes and an ablation-active IR-absorbing H{sub 2}O ice layer (actor) without the analyte. With these studies we have opened up a new method for the in situ analysis of solids containing analytes when covered with an IR laser-absorbing layer that can be resonantly ablated. This soft ejection method takes advantage of the tenability of two-step infrared laser ablation and ultraviolet laser ionization mass spectrometry, previously demonstrated in this lab to study chemical reactions of polycyclic aromatic hydrocarbons (PAHs) in cryogenic ices. The IR laser pulse tuned to resonantly excite only the upper H{sub 2}O ice layer (actor) generates a shockwave upon impact. This shockwave penetrates the lower analyte-containing D{sub 2}O ice layer (spectator, a non-absorbing ice that cannot be ablated directly with the wavelength of the IR laser employed) and is reflected back, ejecting the contents of the D{sub 2}O layer into the vacuum where they are intersected by a UV laser for ionization and detection by a time-of-flight mass spectrometer. Thus, energy is transmitted from the laser-absorbing actor layer into the non-absorbing spectator layer resulting its ablation. We found that isotope cross-contamination between layers was negligible. We also did not see any evidence for thermal or collisional chemistry of PAH molecules with H{sub 2}O molecules in the shockwave. We call this “shockwave mediated surface resonance enhanced subsurface ablation” technique as “two-step laser ablation and ionization mass spectrometry of actor-spectator ice layers.” This method has its roots in the well-established MALDI (matrix assisted laser desorption and ionization) method. Our method offers more flexibility to optimize both the processes—ablation and

  17. Novel two-step laser ablation and ionization mass spectrometry (2S-LAIMS) of actor-spectator ice layers: probing chemical composition of D2O ice beneath a H2O ice layer.

    PubMed

    Yang, Rui; Gudipati, Murthy S

    2014-03-14

    In this work, we report for the first time successful analysis of organic aromatic analytes imbedded in D2O ices by novel infrared (IR) laser ablation of a layered non-absorbing D2O ice (spectator) containing the analytes and an ablation-active IR-absorbing H2O ice layer (actor) without the analyte. With these studies we have opened up a new method for the in situ analysis of solids containing analytes when covered with an IR laser-absorbing layer that can be resonantly ablated. This soft ejection method takes advantage of the tenability of two-step infrared laser ablation and ultraviolet laser ionization mass spectrometry, previously demonstrated in this lab to study chemical reactions of polycyclic aromatic hydrocarbons (PAHs) in cryogenic ices. The IR laser pulse tuned to resonantly excite only the upper H2O ice layer (actor) generates a shockwave upon impact. This shockwave penetrates the lower analyte-containing D2O ice layer (spectator, a non-absorbing ice that cannot be ablated directly with the wavelength of the IR laser employed) and is reflected back, ejecting the contents of the D2O layer into the vacuum where they are intersected by a UV laser for ionization and detection by a time-of-flight mass spectrometer. Thus, energy is transmitted from the laser-absorbing actor layer into the non-absorbing spectator layer resulting its ablation. We found that isotope cross-contamination between layers was negligible. We also did not see any evidence for thermal or collisional chemistry of PAH molecules with H2O molecules in the shockwave. We call this "shockwave mediated surface resonance enhanced subsurface ablation" technique as "two-step laser ablation and ionization mass spectrometry of actor-spectator ice layers." This method has its roots in the well-established MALDI (matrix assisted laser desorption and ionization) method. Our method offers more flexibility to optimize both the processes--ablation and ionization. This new technique can thus be potentially

  18. Laser-assisted one-pot fabrication of calcium phosphate-based submicrospheres with internally crystallized magnetite nanoparticles through chemical precipitation.

    PubMed

    Nakamura, Maki; Oyane, Ayako; Sakamaki, Ikuko; Ishikawa, Yoshie; Shimizu, Yoshiki; Kawaguchi, Kenji

    2015-04-14

    In this paper, we have further developed our simple (one-pot) and rapid (short irradiation time) laser fabrication process of submicrometer spheres composed of amorphous calcium iron phosphate. In our previous process, laser irradiation was applied to a calcium phosphate (CaP) reaction mixture supplemented with ferric ions (Fe(3+)) as a light-absorbing agent. Because the intention of the present study was to fabricate magnetite-encapsulated CaP-based submicrometer spheres, ferrous ions (Fe(2+)) were used as a light-absorbing agent rather than ferric ions. The ferrous ions served as a light-absorbing agent and facilitated the fabrication of submicrometer and micrometer spheres of amorphous calcium iron phosphate. The sphere formation and growth were better promoted by the use of ferrous ions as compared with the use of ferric ions. The chemical composition of the spheres was controllable through adjustment of the experimental conditions. By the addition of sodium hydroxide to the CaP reaction mixture supplemented with ferrous ions, fabrication of CaP-based magnetic submicrometer spheres was successfully achieved. Numerous magnetite and wüstite nanoparticles were coprecipitated or segregated into the CaP-based spherical amorphous matrix via light-material interaction during the CaP precipitation process. The magnetic properties of the magnetite and wüstite formed in the CaP-based spheres were investigated by magnetization measurements. The present process and the resulting CaP-based spheres are expected to have great potential for biomedical applications.

  19. A spectrometer on chemical vapour deposition-diamond basis for the measurement of the charge-state distribution of heavy ions in a laser-generated plasma

    SciTech Connect

    Cayzac, Witold; Frank, Alexander; Schumacher, Dennis; Roth, Markus; Blazevic, Abel; Wamers, Felix; Traeger, Michael; Berdermann, Eleni; Voss, Bernd; Hessling, Thomas

    2013-04-15

    This article reports on the development and the first applications of a new spectrometer which enables the precise and time-resolved measurement of both the energy loss and the charge-state distribution of ion beams with 10 < Z < 30 at energies of 4-8 MeV/u after their interaction with a laser-generated plasma. The spectrometer is based on five 20 Multiplication-Sign 7 mm{sup 2} large and 20 {mu}m thick polycrystalline diamond samples produced via the Chemical Vapour Deposition (CVD) process and was designed with the help of ion-optical simulations. First experiments with the spectrometer were successfully carried out at GSI using {sup 48}Ca ions at an energy of 4.8 MeV/u interacting with a carbon plasma generated by the laser irradiation of a thin foil target. Owing to the high rate capability and the short response time of the spectrometer, pulsed ion beams with 10{sup 3}-10{sup 4} ions per bunch at a bunch frequency of 108 MHz could be detected. The temporal evolution of the five main charge states of the calcium ion beams as well as the corresponding energy loss values could be measured simultaneously. Due to the outstanding properties of diamond as a particle detector, a beam energy resolution ({Delta}E/E) Almost-Equal-To 0.1% could be reached using the presented experimental method, while a precision of 10% in the energy loss and charge-state distribution data was obtained.

  20. Ultra-fast analysis of anatoxin-A using laser diode thermal desorption-atmospheric pressure chemical ionization-tandem mass spectrometry: validation and resolution from phenylalanine.

    PubMed

    Lemoine, Pascal; Roy-Lachapelle, Audrey; Prévost, Michèle; Tremblay, Patrice; Solliec, Morgan; Sauvé, Sébastien

    2013-01-01

    A novel approach for the analysis of the cyanobacterial toxin, anatoxin-a (ANA-a), in an environmentally relevant matrix, using laser diode thermal desorption-atmospheric pressure chemical ionization-tandem mass spectrometry (LDTD-APCI-MS/MS) is presented. The ultra-fast analysis time (15 s/sample) provided by the LDTD-APCI interface is strengthened by its ability to remove interference from phenylalanine (PHE), an isobaric interference in ANA-a analysis by MS/MS. Thus the LDTD-APCI interface avoids the time consuming steps of derivatization, chromatographic separation or solid-phase extraction prior to analysis. Method development and instrumental parameter optimizations were focused toward signal enhancement of ANA-a, and signal removal of a PHE interference as high as 500 μg/L. External calibration in a complex matrix gave detection and quantification limit values of 1 and 3 μg/L respectively, as well as good linearity (R(2) > 0.999) over nearly two orders of magnitude. Internal calibration with clomiphene (CLO) is possible and method performance was similar to that obtained by external calibration. This work demonstrated the utility of the LDTD-APCI source for ultra-fast detection and quantification of ANA-a in environmental aqueous matrices, and confirmed its ability to suppress the interference of PHE without sample preparation or chromatographic separation.

  1. Determination of Os by isotope dilution-inductively coupled plasma-mass spectrometry with the combination of laser ablation to introduce chemically separated geological samples

    NASA Astrophysics Data System (ADS)

    Sun, Yali; Ren, Minghao; Xia, Xiaoping; Li, Congying; Sun, Weidong

    2015-11-01

    A method was developed for the determination of trace Os in geological samples by laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) with the combination of chemical separation and preconcentration. Samples are digested using aqua regia in Carius tubes, and the Os analyte is converted into volatile OsO4, which is distilled and absorbed with HBr. The HBr solution is concentrated for further Os purification using the microdistillation technique. The purified Os is dissolved in 10 μl of 0.02% sucrose-0.005% H3PO4 solution and then evaporated on pieces of perfluoroalkoxy (PFA) film, resulting in the formation of a tiny object (< 3 × 104 μm2 superficial area). Using LA-ICP-MS measurements, the object can give Os signals at least 100 times higher than those provided by routine solution-ICP-MS while successfully avoiding the memory effect. The procedural blank and detection limit in the developed technique are 3.0 pg and 1.8 pg for Os, respectively when 1 g of samples is taken. Reference materials (RM) are analyzed, and their Os concentrations obtained by isotope dilution are comparable to reference or literature values. Based on the individual RM results, the precision is estimated within the range of 0.6 to 9.4% relative standard deviation (RSD), revealing that this method is applicable to the determination of trace Os in geological samples.

  2. The influence of laser-induced nanosecond rise-time stress waves on the microstructure and surface chemical activity of single crystal Cu nanopillars

    PubMed Central

    Youssef, G.; Crum, R.; Prikhodko, S. V.; Seif, D.; Po, G.; Ghoniem, N.; Kodambaka, S.; Gupta, V.

    2013-01-01

    An apparatus and test procedure for fabrication and loading of single crystal metal nanopillars under extremely high pressures (>1 GPa) and strain rates (>107 s−1), using laser-generated stress waves, are presented. Single-crystalline Cu pillars (∼1.20 μm in tall and ∼0.45 μm in diameter) prepared via focused ion beam milling of Cu(001) substrates are shock-loaded using this approach with the dilatational stress waves propagating along the [001] axis of the pillars. Transmission electron microscopy observations of shock-loaded pillars show that dislocation density decreases and that their orientation changes with increasing stress wave amplitude, indicative of dislocation motion. The shock-loaded pillars exhibit enhanced chemical reactivity when submerged in oil and isopropyl alcohol solutions, due likely to the exposure of clean surfaces via surface spallation and formation of surface steps and nanoscale facets through dislocation motion to the surface of the pillars, resulting in growth of thin oxide films on the surfaces of the pillars. PMID:23526837

  3. Reactions of laser-ablated U atoms with HF: infrared spectra and quantum chemical calculations of HUF, UH, and UF in noble gas solids.

    PubMed

    Vent-Schmidt, Thomas; Andrews, Lester; Riedel, Sebastian

    2015-03-19

    Reactions of laser-ablated U atoms with HF produce HUF as the major product and UH and UF as minor products, which are identified from their argon and neon matrix infrared spectra. Our assignment of HUF is confirmed by the observation of DUF and close agreement with observed and calculated vibrational frequencies and deuterium shifts in the vibrational frequencies. Our previous observation of the UH diatomic molecule from argon matrix experiments with H2, HD, and D2 as reagents is confirmed through its present observation with HF and DF, and with recent higher level quantum chemical calculations. The HF reaction provides a lower concentration of F in the system and thus simplifies the fluorine chemistry relative to similar U atom reactions with F2, and the new matrix identification of UF here is consistent with recent high level calculations on UF. In addition, we find evidence for the higher oxidation state secondary reaction products UHF2, UHF3, and UH2F2. PMID:25080179

  4. The influence of laser-induced nanosecond rise-time stress waves on the microstructure and surface chemical activity of single crystal Cu nanopillars

    SciTech Connect

    Youssef, G.; Crum, R.; Seif, D.; Po, G.; Prikhodko, S. V.; Kodambaka, S.; Ghoniem, N.; Gupta, V.

    2013-02-28

    An apparatus and test procedure for fabrication and loading of single crystal metal nanopillars under extremely high pressures (>1 GPa) and strain rates (>10{sup 7} s{sup -1}), using laser-generated stress waves, are presented. Single-crystalline Cu pillars ({approx}1.20 {mu}m in tall and {approx}0.45 {mu}m in diameter) prepared via focused ion beam milling of Cu(001) substrates are shock-loaded using this approach with the dilatational stress waves propagating along the [001] axis of the pillars. Transmission electron microscopy observations of shock-loaded pillars show that dislocation density decreases and that their orientation changes with increasing stress wave amplitude, indicative of dislocation motion. The shock-loaded pillars exhibit enhanced chemical reactivity when submerged in oil and isopropyl alcohol solutions, due likely to the exposure of clean surfaces via surface spallation and formation of surface steps and nanoscale facets through dislocation motion to the surface of the pillars, resulting in growth of thin oxide films on the surfaces of the pillars.

  5. Relation between crystallinity and chemical nature of surface on wettability: A study on pulsed laser deposited TiO{sub 2} thin films

    SciTech Connect

    Shirolkar, Mandar M.; Phase, Deodatta; Sathe, Vasant; Choudhary, Ram Janay; Rodriguez-Carvajal, J.

    2011-06-15

    Pure titania (TiO{sub 2}) polycrystalline thin films in rutile, anatase and mixed phase have been grown on amorphous glass substrates by pulsed laser deposition method at various oxygen gas pressure. Wettability investigations have been carried out on these films. Consistent with our previous report [J. Phys. D: Appl. Phys. 41, 155308 (2008)] it has been observed that for nearly same surface roughness large contact angle or superhydrophobicity is present when sample has a pure single phase and lower contact angle or hydrophobicity when mixed phases were present. Structural characterizations suggest that in addition to roughness, pure phase film surface associated with hydrophobic sites and mixed phase film surface show association of both hydrophobic and hydrophilic sites, which might be inducing specific wetting character. UV treatment induces superhydrophilicity in the films. It was observed that UV irradiation causes nonequilibrium state on the TiO{sub 2} surface, leading to changes in the electron density, which in turn produces decrement in the crystallinity and lattice expansion. Reversible changes in the wetting state on the pure phase surfaces were observed to be faster than those on the mixed phase surfaces. We tried to establish the possible relation between crystalline phases, chemical nature of surface on reversible wettability besides the main governing parameter viz. surface roughness.

  6. Effects of surfactants and electrolytes on chemical oscillation at a water/nitrobenzene interface investigated by quasi-elastic laser scattering method.

    PubMed

    Toyota, Taro; Uchiyama, Koyo; Kimura, Takahiro; Nomoto, Tomonori; Fujinami, Masanori

    2013-01-01

    We used a time-resolved interfacial tension measurement method with quasi-elastic laser scattering to investigate the effects of electrolytes and various surfactants on the nonlinear dynamics of the chemical oscillation that occurred at a water/nitrobenzene interface when a surfactant was added to the interface through a capillary. For both cationic and anionic surfactants, an electrolyte in the water phase was required for slow desorption of the surfactant from the interface. In the absence of an electrolyte, repulsion between the polar head groups of the ionic surfactants hindered adsorption of the surfactant molecules at the interface, resulting in their rapid desorption. In contrast, the presence of an electrolyte induced adsorption of the surfactant ions by screening their charged polar heads. Zwitterionic and nonionic surfactants were also examined and we deduced that the salting out effect of the surfactant produced by the presence of an electrolyte results in strongly attractive interactions between the surfactant molecules and the water/nitrobenzene interface.

  7. Influence of plasma density on the chemical composition and structural properties of pulsed laser deposited TiAlN thin films

    SciTech Connect

    Quiñones-Galván, J. G.; Camps, Enrique; Muhl, S.; Flores, M.; Campos-González, E.

    2014-05-15

    Incorporation of substitutional Al into the TiN lattice of the ternary alloy TiAlN results in a material with improved properties compared to TiN. In this work, TiAlN thin films were grown by the simultaneous ablation of Ti and Al targets in a nitrogen containing reactive atmosphere. The deposit was formed on silicon substrates at low deposition temperature (200 °C). The dependence of the Al content of the films was studied as a function of the ion density of the plasma produced by the laser ablation of the Al target. The plasma parameters were measured by means of a planar Langmuir probe and optical emission spectroscopy. The chemical composition of the films was measured by energy dispersive X-ray spectroscopy. The results showed a strong dependence of the amount of aluminum incorporated in the films with the plasma density. The structural characterization of the deposits was carried out by Raman spectroscopy, X-ray diffraction, and transmission electron microscopy, where the substitutional incorporation of the Al into the TiN was demonstrated.

  8. Fast epitaxial growth of a-axis- and c-axis-oriented YBa 2Cu 3O 7- δ films on (1 0 0) LaAlO 3 substrate by laser chemical vapor deposition

    NASA Astrophysics Data System (ADS)

    Zhao, Pei; Ito, Akihiko; Tu, Rong; Goto, Takashi

    2011-02-01

    a-axis- and c-axis-oriented YBa2Cu3O7-δ (YBCO) films were epitaxially grown on (1 0 0) LaAlO3 substrates by laser chemical vapor deposition. The preferred orientation in the YBCO film changed from the a-axis to the c-axis with increasing laser powers from 77 to 158 W (the deposition temperatures from 951 to 1087 K). The a-axis-oriented YBCO film showed in-plane epitaxial growth of YBCO [0 0 1]//LAO [0 0 1], and the c-axis-oriented YBCO film showed that of YBCO [0 1 0]//LAO [0 0 1]. A c-axis-oriented YBCO film with a high critical temperature of 90 K was prepared at a deposition rate of 90 μm h-1, about 2-1000 times higher than that of metalorganic chemical vapor deposition.

  9. Metastable alloy nanoparticles, metal-oxide nanocrescents and nanoshells generated by laser ablation in liquid solution: influence of the chemical environment on structure and composition.

    PubMed

    Scaramuzza, Stefano; Agnoli, Stefano; Amendola, Vincenzo

    2015-11-14

    Alloy nanoparticles are characterized by the combination of multiple interesting properties, which are attractive for technological and scientific purposes. A frontier topic of this field is nanoalloys with compositions not thermodynamically allowed at ordinary temperature and pressure (i.e. metastable), because they require out-of-equilibrium synthetic approaches. Recently, laser ablation synthesis in solution (LASiS) was successfully applied for the realization of metastable nanoalloys because of the fast kinetics of nanoparticle formation. However, the role played by the chemical environment on the final composition and structure of laser generated nanoalloys still has to be fully elucidated. Here, we investigated the influence of different synthetic conditions on the LASiS of metastable nanoalloys composed of Au and Fe, such as the use of water instead of ethanol, the bubbling of inert gases and the addition of a few vol% of H2O2 and H2O. The two elements showed different reactivity when LASiS was performed in water instead of ethanol, while minor effects were observed from bubbling pure gases such as N2, Ar and CO2 in the liquid solution. Moreover, the plasmonic response and the structure of the nanoalloys were sensibly modified by adding H2O2 to water. We also found that nanoparticle production is dramatically influenced just by adding 0.2% of H2O in ethanol. These results suggest that the formation of a cavitation bubble with long lifetime and large size during LASiS is useful for the preservation of the metastable alloy composition, whereas an oxidative environment hampers the formation of metastable alloy nanoparticles. Overall, by acting on the type of solvent and solutes, we were able to switch from a traditional synthetic approach for the composition of Au-Fe nanoalloys to one using a reactive environment, which gives unconventional structures such as metal@iron-oxide nanoshells and nanocrescents of oxide supported on metal nanospheres. These results

  10. Controllable high-throughput high-quality femtosecond laser-enhanced chemical etching by temporal pulse shaping based on electron density control.

    PubMed

    Zhao, Mengjiao; Hu, Jie; Jiang, Lan; Zhang, Kaihu; Liu, Pengjun; Lu, Yongfeng

    2015-01-01

    We developed an efficient fabrication method of high-quality concave microarrays on fused silica substrates based on temporal shaping of femtosecond (fs) laser pulses. This method involves exposures of fs laser pulse trains followed by a wet etching process. Compared with conventional single pulses with the same processing parameters, the temporally shaped fs pulses can enhance the etch rate by a factor of 37 times with better controllability and higher quality. Moreover, we demonstrated the flexibility of the proposed method in tuning the profile of the concave microarray structures by changing the laser pulse delay, laser fluence, and pulse energy distribution ratio. Micro-Raman spectroscopy was conducted to elucidate the stronger modification induced by the fs laser pulse trains in comparison with the single pulses. Our calculations show that the controllability is due to the effective control of localized transient free electron densities by temporally shaping the fs pulses. PMID:26307148

  11. Effect of various buffer-layer structures on the material quality and dislocation density of high composition Al/sub x/Ga/sub 1/. sqrt. /sub x/As laser material grown by metalorganic chemical vapor deposition

    SciTech Connect

    Givens, M.E.; Coleman, J.J.; Zmudzinski, C.A.; Bryan, R.P.; Emanuel, M.A.; Miller, L.M.

    1988-05-15

    The effect of various types of buffer layers on the generation and propagation of dislocations in epitaxial layers of high composition (x = 0.85) Al/sub x/Ga/sub 1/..sqrt../sub x/As grown by metalorganic chemical vapor deposition (MOCVD) on horizontal Bridgman (HB) and liquid-encapsulated Czochralski (LEC) substrates is examined. Bulk epilayers of high composition (x = 0.85) Al/sub x/Ga/sub 1/..sqrt../sub x/As and graded-barrier quantum-well laser structures with confining layers of the same composition were grown simultaneously on high-qualitylow etch-pit density (EPD) HB substrates and comparatively lower qualityhigh EPD LEC substrates with one of four types of compositionally graded andor superlattice buffer-layer structures. The bulk material was characterized by delineation and measurement of surface EPD and the observation of overall surface morphology. Data are also presented on the device characteristics of graded-barrier quantum-well laser diodes grown with these same buffer layers in order to determine the correlation between dislocation density and laser threshold current. The various buffer-layer structures were seen to be effective in reducing the defect density and improving the surface morphology of high composition epilayers grown on both HB and LEC substrates. The threshold-current density of the laser diodes, however, was independent of both the type of prelayer andor substrate utilized

  12. Calculus fragmentation in laser lithotripsy.

    PubMed

    Welch, A J; Kang, H W; Lee, H; Teichman, J M H

    2004-03-01

    The intracorporeal treatment of urinary calculi with lasers is presented, which describes laser-calculus interactions associated with lithotripsy. Reliable fragmentation of calculi with diverse compositions and minimal collateral tissue damage are primarily contingent upon laser parameters (wavelength, pulse duration, and pulse energy) and physical properties of calculi (optical, mechanical, and chemical). The pulse duration governs the dominant mechanism in calculi fragmentation, which is either photothermal or photoacoustical/photomechanical. Lasers with long pulse durations (i.e. > tens of micros) induce a temperature rise in the laser-affected zone with minimal acoustic waves; material is removed by means of vaporization, melting, mechanical stress, and/or chemical decomposition. Short-pulsed laser ablation (i.e. < 10 micros), on the other hand, produces shock waves, and the resultant mechanical energy fragments calculi. Work continues throughout the world to evaluate the feasibility of advanced lasers in lithotripsy and to optimize laser parameters and light delivery systems pertinent to efficient fragmentation of calculi.

  13. Direct chemical-analysis of uv laser-ablation products of organic polymers by using selective ion monitoring mode in gas-chromatography mass-spectrometry

    USGS Publications Warehouse

    Cho, Yirang; Lee, H.W.; Fountain, S.T.; Lubman, D.M.

    1994-01-01

    Trace quantities of laser ablated organic polymers were analyzed by using commercial capillary column gas chromatography/mass spectrometry; the instrument was modified so that the laser ablation products could be introduced into the capillary column directly and the constituents of each peak in the chromatogram were identified by using a mass spectrometer. The present study takes advantage of the selective ion monitoring mode for significantly improving the sensitivity of the mass spectrometer as a detector, which is critical in analyzing the trace quantities and confirming the presence or absence of the species of interest in laser ablated polymers. The initial composition of the laser ablated polymers was obtained by using an electron impact reflectron time-of-flight mass spectrometer and the possible structure of the fragments observed in the spectra was proposed based on the structure of the polymers.

  14. Bond Strength of Two Resin Cements to Dentin After Disinfection Pretreatment: Effects of Er,Cr:YSGG Laser Compared with Chemical Antibacterial Agent

    PubMed Central

    Shafiei, Fereshteh; Fekrazad, Reza; Shafiei, Ehsan

    2013-01-01

    Abstract Objective: This study compared the effects of two disinfection procedures (2% chlorhexidine [CHX] solution versus Er,Cr:YSGG laser irradiation) on the shear bond strength of ED primer II/Panavia F2.0 (ED/P) and Excite DSC/Variolink N (Ex/V). Background data: Different methods are used for cavity disinfection prior to adhesive cementation, which may influence the bonding ability of resin cements. Methods: Flat dentin surfaces were prepared on 100 extracted premolars and randomly divided into 10 groups. In the eight experimental groups, indirect composite samples were cemented with either ED/P or Ex/V under three disinfecting conditions on the dentin surface as follows: (1) CHX application before ED primer II/ after etching, (2) wet laser irradiation (Er,Cr:YSGG laser, 20 Hz, 0.75 W, 15% water +15% air), (3) dry laser irradiation with no water and air cooling. The control groups had no disinfectant application. After 24 h water storage, bond strength test was performed. The data (MPa) were analyzed using two way ANOVA and Tukey tests. Results: The lowest and highest bond strengths were obtained by dry laser and wet laser (10.18±2.67 and 17.36±2.94 for ED/P, 9.64±2.66 and 20.07±3.36 for Ex/V, respectively). For each cement, two-by-two comparisons of four groups revealed significant differences only for dry laser with others (p<0.001). Conclusions: The use of CHX and Er,Cr:YSGG laser at the low fluences with water/air cooling as the antibacterial agents does not adversely influence the bonding ability of the etch-and-rinse and the self-etch cements. PMID:23600378

  15. Lasers in materials processing

    SciTech Connect

    Davis, J.I.; Rockower, E.B.

    1981-01-01

    A status report on the uranium Laser Isotope Separation (LIS) Program at the Lawrence Livermore National Laboratory is presented. Prior to this status report, process economic analysis is presented so as to understand how the unique properties of laser photons can be best utilized in the production of materials and components despite the high cost of laser energy. The characteristics of potential applications that are necessary for success are identified, and those factors that have up to now frustrated attempts to find commercially viable laser induced chemical and physical process for the production of new or existing materials are pointed out.

  16. Instabilities and structure formation in laser processing

    SciTech Connect

    Baeuerle, D.; Arenholz, E.; Arnold, N.; Heitz, J.; Kargl, P.B.

    1996-12-31

    This paper gives an overview on different types of instabilities and structure formation in various fields of laser processing. Among the examples discussed in detail are non-coherent structures observed in laser-induced chemical vapor deposition (LCVD), in laser-induced surface modifications, and in laser ablation of polymers.

  17. Lasers '85; Proceedings of the Eighth International Conference, Las Vegas, NV, Dec. 2-6, 1985

    SciTech Connect

    Wang, C.P.

    1986-01-01

    The present conference on laser technology development encompasses issues in such areas as VUV and X-ray lasers; optical phase conjugation and nonlinear optics; laser applications in medicine; methods for optical processing; laser and nonlinear spectroscopy; ultrashort-pulse lasers and their applications; frequency selection in pulsed lasers; and interactions between laser beams, material surfaces, and material volumes. Also treated are laser applications in the Strategic Defense Initiative program, chemical laser design and performance, the lasing of biophysical materials, laser diagnostics in fluids and plasma, semiconductor laser diodes and arrays, solid state lasers, radiation- and solar-pumped lasers, laser cavities and propagation, remote sensing with lasers and fiber-optics, coupled resonators and diode lasers, industrial applications of lasers, excimer lasers, optoelectronics, CO/sub 2/ lasers, fiber-optic sensors, alexandrite lasers, free electron lasers, and IR and visible wavelength lasers.

  18. Laser Technology.

    ERIC Educational Resources Information Center

    Gauger, Robert

    1993-01-01

    Describes lasers and indicates that learning about laser technology and creating laser technology activities are among the teacher enhancement processes needed to strengthen technology education. (JOW)

  19. Lasers '86; Proceedings of the Ninth International Conference on Lasers and Applications, Orlando, FL, Nov. 3-7, 1986

    SciTech Connect

    Mcmillan, R.W.

    1987-01-01

    Laser physics, technology, and applications are examined in reviews and reports. Topics addressed include VUV and X-ray lasers, vibrational energy transfer and kinetics, medical applications, ultrashort lasers and spectroscopy, surface and material interactions, lasers in atmospheric physics, and fiber-optic systems. Consideration is given to alexandrite lasers, four-wave mixing and nonlinear optics, chemical lasers, semiconductor lasers, photothermal and photoacoustic spectroscopy, dye lasers, optical phase conjugation and SBS, excimer lasers, SDI laser applications, remote-sensing with lasers, FELs, and applications in chemistry. Diagrams, drawings, graphs, and photographs are provided.

  20. Laser rocket system analysis

    NASA Technical Reports Server (NTRS)

    Jones, W. S.; Forsyth, J. B.; Skratt, J. P.

    1979-01-01

    The laser rocket systems investigated in this study were for orbital transportation using space-based, ground-based and airborne laser transmitters. The propulsion unit of these systems utilizes a continuous wave (CW) laser beam focused into a thrust chamber which initiates a plasma in the hydrogen propellant, thus heating the propellant and providing thrust through a suitably designed nozzle and expansion skirt. The specific impulse is limited only by the ability to adequately cool the thruster and the amount of laser energy entering the engine. The results of the study showed that, with advanced technology, laser rocket systems with either a space- or ground-based laser transmitter could reduce the national budget allocated to space transportation by 10 to 345 billion dollars over a 10-year life cycle when compared to advanced chemical propulsion systems (LO2-LH2) of equal capability. The variation in savings depends upon the projected mission model.

  1. [Study of flow properties of wet solids using laser induced photo chemical anemometry]. Quarterly technical progress report, July--September 1991

    SciTech Connect

    Falco, B.

    1992-04-09

    A new diagnostic measurement technique is being developed that will enable the investigation of the dynamics of flowing wet solids. The technique involves the use of Laser Induced Photochemical Anemometry (LIPA), enhanced to enable two photochemical species to be excited. It uses laser induced photochromic and photo luminescent molecules to separately tag the two phases for times long enough for them to distort the tagging. Recording the distortions of the tagging caused by the movement of each phase enables us to obtain local characterization of flow properties of both phases of the wet solids at many positions simultaneously across a pipe.

  2. Large-energy, wavelength-tunable, all-fiber passively Q-switched Er:Yb-codoped double-clad fiber laser with mono-layer chemical vapor deposition graphene.

    PubMed

    Wu, Duanduan; Xiong, Fengfu; Zhang, Cankun; Chen, Shanshan; Xu, Huiying; Cai, Zhiping; Cai, Weiwei; Che, Kaijun; Luo, Zhengqian

    2014-07-01

    We demonstrate a large-energy, wavelength-tunable, all-fiber passively Q-switched Er:Yb-codoped laser using a mono-layer chemical vapor deposition (CVD) graphene saturable absorber (SA). By exploiting the large laser gain of Er:Yb double-clad fiber and optimizing the coupling ratio of the output coupler, not only can the mono-layer CVD graphene SA be protected from oversaturation and thermal damage, but also a large pulse energy up to 1.05 μJ (corresponding to the average output power of 25.6 mW) is thus achieved. Using a tunable fiber Fabry-Perot filter, stable Q-switched pulses can operate with a tunable range from 1530.97 to 1546.92 nm, covering a wavelength range of ∼16  nm. The Q-switching states at the different lasing wavelengths have been observed and recorded. The Q-switched repetition rate and the pulse duration (with the minimum one of 2.6 μs) have been characterized as well. This is, to the best of our knowledge, the largest pulse energy from an all-fiber graphene Q-switched laser. PMID:25089965

  3. Understanding lasers

    SciTech Connect

    Gibilisco, S.

    1989-01-01

    Covering all different types of laser applications-Gibilisco offers an overview of this fascinating phenomenon of light. Here he describes what lasers are and how they work and examines in detail the different kinds of lasers in use today. Topics of particular interest include: the way lasers work; the different kinds of lasers; infrared, ultraviolet and x-ray lasers; use of lasers in industry and manufacturing; use of lasers for long-distance communications; fiberoptic communications; the way laser shows work; the reality of Star Wars; lasers in surgical and medical applications; and holography and the future of laser technology.

  4. Mixed-layered bismuth-oxygen-iodine materials for capture and waste disposal of radioactive iodine

    SciTech Connect

    Krumhansl, James L; Nenoff, Tina M

    2013-02-26

    Materials and methods of synthesizing mixed-layered bismuth oxy-iodine materials, which can be synthesized in the presence of aqueous radioactive iodine species found in caustic solutions (e.g. NaOH or KOH). This technology provides a one-step process for both iodine sequestration and storage from nuclear fuel cycles. It results in materials that will be durable for repository conditions much like those found in Waste Isolation Pilot Plant (WIPP) and estimated for Yucca Mountain (YMP). By controlled reactant concentrations, optimized compositions of these mixed-layered bismuth oxy-iodine inorganic materials are produced that have both a high iodine weight percentage and a low solubility in groundwater environments.

  5. Mixed-layered bismuth--oxygen--iodine materials for capture and waste disposal of radioactive iodine

    DOEpatents

    Krumhansl, James L; Nenoff, Tina M

    2015-01-06

    Materials and methods of synthesizing mixed-layered bismuth oxy-iodine materials, which can be synthesized in the presence of aqueous radioactive iodine species found in caustic solutions (e.g. NaOH or KOH). This technology provides a one-step process for both iodine sequestration and storage from nuclear fuel cycles. It results in materials that will be durable for repository conditions much like those found in Waste Isolation Pilot Plant (WIPP) and estimated for Yucca Mountain (YMP). By controlled reactant concentrations, optimized compositions of these mixed-layered bismuth oxy-iodine inorganic materials are produced that have both a high iodine weight percentage and a low solubility in groundwater environments.

  6. Two-dimensional simulation of an unstable resonator with a stable core.

    PubMed

    Endo, M; Kawakami, M; Nanri, K; Takeda, S; Fujioka, T

    1999-05-20

    An optical resonator simulation code based on the idea of a partially coherent optical field has been developed and used to optimize the design parameters of an unstable resonator with a stable core. The resonator was intended for use with low-gain, large-bore lasers, such as the chemical oxygen-iodine laser (COIL). First the design parameters of the resonator were optimized by the simulation code; then a set of mirrors was fabricated for a small-scale COIL. A 14-W output with M(2) = 29 was obtained. The experimentally obtained results were in good agreement with calculations. PMID:18319925

  7. A high-repetition rate scheme for synchrotron-based picosecond laser pump/x-ray probe experiments on chemical and biological systems in solution

    SciTech Connect

    Lima, Frederico A.; Milne, Christopher J.; Amarasinghe, Dimali C. V.; Rittmann-Frank, Mercedes Hannelore; Veen, Renske M. van der; Reinhard, Marco; Pham, Van-Thai; Karlsson, Susanne; Mourik, Frank van; Chergui, Majed; Johnson, Steven L.; Grolimund, Daniel; Borca, Camelia; Huthwelker, Thomas; Janousch, Markus; Abela, Rafael

    2011-06-15

    We present the extension of time-resolved optical pump/x-ray absorption spectroscopy (XAS) probe experiments towards data collection at MHz repetition rates. The use of a high-power picosecond laser operating at an integer fraction of the repetition rate of the storage ring allows exploitation of up to two orders of magnitude more x-ray photons than in previous schemes based on the use of kHz lasers. Consequently, we demonstrate an order of magnitude increase in the signal-to-noise of time-resolved XAS of molecular systems in solution. This makes it possible to investigate highly dilute samples at concentrations approaching physiological conditions for biological systems. The simplicity and compactness of the scheme allows for straightforward implementation at any synchrotron beamline and for a wide range of x-ray probe techniques, such as time-resolved diffraction or x-ray emission studies.

  8. Rapid on-site detection of explosives on surfaces by ambient pressure laser desorption and direct inlet single photon ionization or chemical ionization mass spectrometry.

    PubMed

    Ehlert, S; Hölzer, J; Rittgen, J; Pütz, M; Schulte-Ladbeck, R; Zimmermann, R

    2013-09-01

    Considering current security issues, powerful tools for detection of security-relevant substances such as traces of explosives and drugs/drug precursors related to clandestine laboratories are required. Especially in the field of detection of explosives and improvised explosive devices, several relevant compounds exhibit a very low vapor pressure. Ambient pressure laser desorption is proposed to make these substances available in the gas phase for the detection by adapted mass spectrometers or in the future with ion-mobility spectrometry as well. In contrast to the state-of-the-art thermal desorption approach, by which the sample surface is probed for explosive traces by a wipe pad being transferred to a thermal desorber unit, by the ambient pressure laser desorption approach presented here, the sample is directly shockwave ablated from the surface. The laser-dispersed molecules are sampled by a heated sniffing capillary located in the vicinity of the ablation spot into the mass analyzer. This approach has the advantage that the target molecules are dispersed more gently than in a thermal desorber unit where the analyte molecules may be decomposed by the thermal intake. In the technical realization, the sampling capillary as well as the laser desorption optics are integrated in the tip of an endoscopic probe or a handheld sampling module. Laboratory as well as field test scenarios were performed, partially in cooperation with the Federal Criminal Police Office (Bundeskriminalamt, BKA, Wiesbaden, Germany), in order to demonstrate the applicability for various explosives, drugs, and drug precursors. In this work, we concentrate on the detection of explosives. A wide range of samples and matrices have been investigated successfully.

  9. USE OF MULTI-PHOTON LASER-SCANNING MICROSCOPY TO DESCRIBE THE DISTRIBUTION OF XENOBIOTIC CHEMICALS IN FISH EARLY LIFE STAGES

    EPA Science Inventory

    To better understand the mechanisms by which persistent bioaccumulative toxicants (PBTs) produce toxicity during fish early life stages (ELS), dose response relationships need to be determined in relation to the dynamic distribution of chemicals in sensitive tissues. In this stud...

  10. IR laser chemistry

    NASA Astrophysics Data System (ADS)

    Quack, Martin

    1995-01-01

    Recent progress in IR laser chemistry is reviewed with stress on the conceptual background and experimental advances from our research group. In particular we discuss various experimental schemes in laser chemistry as related to thermal reactions and ordinary photochemistry, and new results in time and frequency resolved kinetic IR spectroscopy at the limit defined by the uncertainty relation. The recent detection of hyperfine effects in IR laser chemistry is reviewed as well as nonlinear intensity dependence over many orders of magnitude including observations of nonlinear intensity fall-off and IR laser ionization of molecules. An outlook is presented on different time scales for intramolecular processes and the resulting future possibilities of IR laser chemical reaction control.

  11. Chemical contamination remote sensing

    NASA Technical Reports Server (NTRS)

    Carrico, J. P.; Phelps, K. R.; Webb, E. N.; Mackay, R. A.; Murray, E. R.

    1986-01-01

    A ground mobile laser test bed system was assembled to assess the feasibility of detection of various types of chemical contamination using Differential Scattering (DISC) and Differential Absorption (DIAL) Lidar techniques. Field experiments with the test bed system using chemical simulants were performed. Topographic reflection and range resolved DIAL detection of vapors as well as DISC detection of aerosols and surface contamination were achieved. Review of detection principles, design of the test bed system, and results of the experiments are discussed.

  12. Qualitative and quantitative spectro-chemical analysis of dates using UV-pulsed laser induced breakdown spectroscopy and inductively coupled plasma mass spectrometry.

    PubMed

    Mehder, A O; Habibullah, Y B; Gondal, M A; Baig, Umair

    2016-08-01

    Laser Induced Breakdown Spectroscopy (LIBS) is demonstrated for the spectral analysis of nutritional and toxic elements present in several varieties of date fruit samples available in the Saudi Arabia market. The method analyzes the optical emission of a test sample when subjected to pulsed laser ablation. In this demonstration, our primary focus is on calcium (Ca) and magnesium (Mg), as nutritional elements, and on chromium (Cr), as a toxic element. The local thermodynamic equilibrium (LTE) condition was confirmed prior to the elemental characterization of date samples to ensure accuracy of the LIBS analysis. This was achieved by measuring parameters associated with the plasma, such as the electron temperature and the electron number density. These plasma parameters aid interpretation of processes such as ionization, dissociation, and excitation occurring in the plasma plume formed by ablating the date palm sample. The minimum detection limit was established from calibration curves that involved plotting the LIBS signal intensity as a function of standard date samples with known concentrations. The concentration of Ca and Mg detected in different varieties of date samples was between 187 and 515 and 35-196mgL(-1) respectively, while Cr concentration measured between 1.72 and 7.76mgL(-1). In order to optimize our LIBS system, we have studied how the LIBS signal intensity depends on the incident laser energy and the delay time. In order to validate our LIBS analysis results, standard techniques such as inductively coupled plasma mass spectrometry (ICP-MS) were also applied on an identical (duplicate) date samples as those used for the LIBS analysis. The LIBS results exhibit remarkable agreement with those obtained from the ICP-MS analysis. In addition, the finger print wavelengths of other elements present in date samples were also identified and are reported here, which has not been previously reported, to the best of our knowledge.

  13. Qualitative and quantitative spectro-chemical analysis of dates using UV-pulsed laser induced breakdown spectroscopy and inductively coupled plasma mass spectrometry.

    PubMed

    Mehder, A O; Habibullah, Y B; Gondal, M A; Baig, Umair

    2016-08-01

    Laser Induced Breakdown Spectroscopy (LIBS) is demonstrated for the spectral analysis of nutritional and toxic elements present in several varieties of date fruit samples available in the Saudi Arabia market. The method analyzes the optical emission of a test sample when subjected to pulsed laser ablation. In this demonstration, our primary focus is on calcium (Ca) and magnesium (Mg), as nutritional elements, and on chromium (Cr), as a toxic element. The local thermodynamic equilibrium (LTE) condition was confirmed prior to the elemental characterization of date samples to ensure accuracy of the LIBS analysis. This was achieved by measuring parameters associated with the plasma, such as the electron temperature and the electron number density. These plasma parameters aid interpretation of processes such as ionization, dissociation, and excitation occurring in the plasma plume formed by ablating the date palm sample. The minimum detection limit was established from calibration curves that involved plotting the LIBS signal intensity as a function of standard date samples with known concentrations. The concentration of Ca and Mg detected in different varieties of date samples was between 187 and 515 and 35-196mgL(-1) respectively, while Cr concentration measured between 1.72 and 7.76mgL(-1). In order to optimize our LIBS system, we have studied how the LIBS signal intensity depends on the incident laser energy and the delay time. In order to validate our LIBS analysis results, standard techniques such as inductively coupled plasma mass spectrometry (ICP-MS) were also applied on an identical (duplicate) date samples as those used for the LIBS analysis. The LIBS results exhibit remarkable agreement with those obtained from the ICP-MS analysis. In addition, the finger print wavelengths of other elements present in date samples were also identified and are reported here, which has not been previously reported, to the best of our knowledge. PMID:27216665

  14. Engineering Light: Quantum Cascade Lasers

    SciTech Connect

    Claire Gmachl

    2010-03-17

    Quantum cascade lasers are ideal for environmental sensing and medical diagnostic applications. Gmachl discusses how these lasers work, and their applications, including their use as chemical trace gas sensors. As examples of these applications, she briefly presents results from her field campaign at the Beijing Olympics, and ongoing campaigns in Texas, Maryland, and Ghana.

  15. Engineering Light: Quantum Cascade Lasers

    ScienceCinema

    Claire Gmachl

    2016-07-12

    Quantum cascade lasers are ideal for environmental sensing and medical diagnostic applications. Gmachl discusses how these lasers work, and their applications, including their use as chemical trace gas sensors. As examples of these applications, she briefly presents results from her field campaign at the Beijing Olympics, and ongoing campaigns in Texas, Maryland, and Ghana.

  16. USE OF WHOLE BODY CHEMICAL RESIDUE ANALYSIS AND LASER SCREENING CONFOCAL MICROSCOPY TO DESCRIBE DISTRIBUTION OF PBTS IN FISH EARLY LIFE STAGES

    EPA Science Inventory

    Fish early life stages (ELS) are more sensitive than juveniles or adults to many persistent bioaccumulative toxicants (PBTs). To better understand the mechanisms by which these chemicals produce toxicity during fish ELS, dose-response relationships need to be determined in relat...

  17. Development of a flow injection analysis (FIA) system for the measurement of heavy metals using a fiber optic chemical sensor based on laser-induced fluorescence

    NASA Astrophysics Data System (ADS)

    Zhang, Jingdong; Prestel, Harald; Gahr, Achim; Niessner, Reinhard

    2000-05-01

    The development of a fiber optic sensor system is described, for the on-line detection of heavy metal ions in water. This is based on laser-induced fluorescence spectroscopy of suitable metal-ligand complexes. The sensor system is designed to measure heavy metal ions in the field. Flow injection analysis (FIA) is coupled with the sensor system, to overcome problems of a slow diffusion rate of heavy metals through the membrane of an in situ sensor head. Preliminary experiments show the new FIA system has good reproducibility, a high sample analysis rate and it can measure heavy metal ions (Cu(II), Ni(II), Cd(II) and Zn(II)) at the ppb level, when using the appropriate ligands.

  18. [Characteristics of laser light].

    PubMed

    Takac, S; Stojanović, S

    1999-01-01

    Laser is one of the greatest technical discoveries of the 20th century. It is important in basic sciences, but particularly in diagnosis and therapy of various pathologic conditions of human organism. It is electromagnetic radiation, not X-irradiation and, as such, it is not expected to produce new generation of iatrogenic malignancies. Laser falls between infrared and ultraviolet on the spectrum mainly in the visible light spectrum. Properties of laser light are: monochromacity (the same color), coherence (all of the light waves are in phase both spatially and temporally), collimation (all rays are parallel to each other and do not diverge significantly even over long distances). Lasers were first conceived by Einstein in 1917 when he wrote his "Zur Quantum Theorie der Strahlung" (the quantum theory of radiation) which enumerated concepts of stimulated and spontaneous emission and absorption. Drs. Arthur Schawlow and Charles Townes, in 1956, extended lasers into the optical frequency range and Maiman, in 1960, operated the first laser using ruby as the active medium (ruby laser). Laser is an acronym for Light Amplification by Stimulated Emission of Radiation. To understand the acronym, it is necessary to understand the basic physics of the atom. However, if the atom that is in the excited state is struck by another photon of energy before it returns to the ground state, two photons of equal frequency and energy, travelling in the same direction and in perfect spatial and temporal harmony, are produced. This phenomenon is termed stimulated emission of radiation. An external power source hyperexcites the atoms in the laser medium so that the number of atoms possessing upper energy levels exceeds the number of atoms in a power energy level, a condition termed a population inversion. This "pumping system" which imparts additional energy to the atoms may be optical, mechanical, or chemical. These atoms in a hyperexcited state spontaneously emit photons of light. The

  19. Method for laser induced isotope enrichment

    SciTech Connect

    Pronko, Peter P.; Vanrompay, Paul A.; Zhang, Zhiyu

    2004-09-07

    Methods for separating isotopes or chemical species of an element and causing enrichment of a desired isotope or chemical species of an element utilizing laser ablation plasmas to modify or fabricate a material containing such isotopes or chemical species are provided. This invention may be used for a wide variety of materials which contain elements having different isotopes or chemical species.

  20. Laser-heated thruster

    NASA Technical Reports Server (NTRS)

    Kemp, N. H.; Lewis, P. F.

    1980-01-01

    The development of a computer program for the design of the thrust chamber for a CW laser heated thruster was examined. Hydrodgen was employed as the propellant gas and high temperature absorber. The laser absorption coefficient of the mixture/laser radiation combination is given in temperature and species densities. Radiative and absorptive properties are given to determine radiation from such gas mixtures. A computer code for calculating the axisymmetric channel flow of a gas mixture in chemical equilibrium, and laser energy absorption and convective and radiative heating is described. It is concluded that: (1) small amounts of cesium seed substantially increase the absorption coefficient of hydrogen; (2) cesium is a strong radiator and contributes greatly to radiation of cesium seeded hydrogen; (3) water vapor is a poor absorber; and (4) for 5.3mcm radiation, both H2O/CO and NO/CO seeded hydrogen mixtures are good absorbers.

  1. Laser removal of sludge from steam generators

    DOEpatents

    Nachbar, Henry D.

    1990-01-01

    A method of removing unwanted chemical deposits known as sludge from the metal surfaces of steam generators with laser energy is provided. Laser energy of a certain power density, of a critical wavelength and frequency, is intermittently focused on the sludge deposits to vaporize them so that the surfaces are cleaned without affecting the metal surface (sludge substrate). Fiberoptic tubes are utilized for laser beam transmission and beam direction. Fiberoptics are also utilized to monitor laser operation and sludge removal.

  2. A borane laser

    NASA Astrophysics Data System (ADS)

    Cerdán, Luis; Braborec, Jakub; Garcia-Moreno, Inmaculada; Costela, Angel; Londesborough, Michael G. S.

    2015-01-01

    Emission from electronically excited species forms the basis for an important class of light sources—lasers. So far, commercially available solution-processed blue-emitting laser materials are based on organic compounds or semiconductor nanocrystals that have significant limitations: either low solubility, low chemical- and/or photo-stability and/or uncompetitive prices. Here we report a novel and competitive alternative to these existing laser materials that is based on boron hydrides, inorganic cluster compounds with a rich and diverse chemistry. We demonstrate that solutions of the borane anti-B18H22 show, under pulsed excitation, blue laser emission at 406 nm with an efficiency (ratio of output/input energies) of 9.5%, and a photostability superior to many of the commercially available state-of-the-art blue laser dyes. This demonstration opens the doors for the development of a whole new class of laser materials based on a previously untapped resource for laser technology—the boranes.

  3. Laser therapy of muscle injuries.

    PubMed

    Dawood, Munqith S; Al-Salihi, Anam Rasheed; Qasim, Amenah Wala'a

    2013-05-01

    Low-level lasers are used in general therapy and healing process due to their good photo-bio-stimulation effects. In this paper, the effects of diode laser and Nd:YAG laser on the healing process of practically managed skeletal muscle trauma has been successfully studied. Standard impact trauma was induced by using a specially designed mechanical device. The impacted muscle was left for 3 days for complete development of blunt trauma. After that it was irradiated by five laser sessions for 5 days. Two types of lasers were used; 785-nm diode laser and 1.064-nm Nd:YAG laser, both in continuous and pulsed modes. A special electronic circuit was designed and implemented to modulate the diode laser for this purpose. Tissue samples of crushed skeletal muscle have been dissected from the injured irradiated muscle then bio-chemically analyzed for the regeneration of contractile and collagenous proteins using Lowry assay for protein determination and Reddy and Enwemeka assay for hydroxyproline determination. The results showed that both lasers stimulate the regeneration capability of traumatized skeletal muscle. The diode laser in CW and pulsed modes showed better results than the Nd:YAG in accelerating the preservation of the normal tissue content of collagenous and contractile proteins beside controlling the regeneration of non-functional fibrous tissue. This study proved that the healing achieved by the laser treatment was faster than the control group by 15-20 days.

  4. A tomographic technique for the simultaneous imaging of temperature, chemical species, and pressure in reactive flows using absorption spectroscopy with frequency-agile lasers

    SciTech Connect

    Cai, Weiwei; Kaminski, Clemens F.

    2014-01-20

    This paper proposes a technique that can simultaneously retrieve distributions of temperature, concentration of chemical species, and pressure based on broad bandwidth, frequency-agile tomographic absorption spectroscopy. The technique holds particular promise for the study of dynamic combusting flows. A proof-of-concept numerical demonstration is presented, using representative phantoms to model conditions typically prevailing in near-atmospheric or high pressure flames. The simulations reveal both the feasibility of the proposed technique and its robustness. Our calculations indicate precisions of ∼70 K at flame temperatures and ∼0.05 bars at high pressure from reconstructions featuring as much as 5% Gaussian noise in the projections.

  5. Controlling Chemical Reactions by Short, Intense Mid-Infrared Laser Pulses: Comparison of Linear and Circularly Polarized Light in Simulations of ClCHO(+) Fragmentation.

    PubMed

    Shi, Xuetao; Thapa, Bishnu; Li, Wen; Schlegel, H Bernhard

    2016-02-25

    Enhanced mode selective fragmentation of oriented ClCHO(+) → Cl + HCO(+), H + ClCO(+), HCl(+) + CO with linear polarized intense mid-IR pulses was demonstrated in our previous computational study ( J. Phys. Chem. Lett. 2012 , 3 , 2541 ). Simulations of angle-dependent strong field ionization of ClCHO indicate the ionization rate in the molecular plane is nearly twice as large as perpendicular to the plane, suggesting a degree of planar alignment can be obtained experimentally for ClCHO(+), starting from neutral molecules. Classical trajectory calculations with a 4 cycle 7 μm laser pulse (peak intensity of 1.26 × 10(14) W/cm(2)) show that circularly polarized light with the electric field in the plane of the molecule deposits more energy and yields larger branching ratios for higher energy fragmentation channels than linearly polarized light with the same maximum field strength. These results suggest circularly polarized mid-IR pulses can not only achieve control on reactions but also provide an experimentally accessible implementation.

  6. Chemical recognition software

    SciTech Connect

    Wagner, J.S.; Trahan, M.W.; Nelson, W.E.; Hargis, P.H. Jr.; Tisone, G.C.

    1994-06-01

    We have developed a capability to make real time concentration measurements of individual chemicals in a complex mixture using a multispectral laser remote sensing system. Our chemical recognition and analysis software consists of three parts: (1) a rigorous multivariate analysis package for quantitative concentration and uncertainty estimates, (2) a genetic optimizer which customizes and tailors the multivariate algorithm for a particular application, and (3) an intelligent neural net chemical filter which pre-selects from the chemical database to find the appropriate candidate chemicals for quantitative analyses by the multivariate algorithms, as well as providing a quick-look concentration estimate and consistency check. Detailed simulations using both laboratory fluorescence data and computer synthesized spectra indicate that our software can make accurate concentration estimates from complex multicomponent mixtures, even when the mixture is noisy and contaminated with unknowns.

  7. Chemical recognition software

    SciTech Connect

    Wagner, J.S.; Trahan, M.W.; Nelson, W.E.; Hargis, P.J. Jr.; Tisone, G.C.

    1994-12-01

    We have developed a capability to make real time concentration measurements of individual chemicals in a complex mixture using a multispectral laser remote sensing system. Our chemical recognition and analysis software consists of three parts: (1) a rigorous multivariate analysis package for quantitative concentration and uncertainty estimates, (2) a genetic optimizer which customizes and tailors the multivariate algorithm for a particular application, and (3) an intelligent neural net chemical filter which pre-selects from the chemical database to find the appropriate candidate chemicals for quantitative analyses by the multivariate algorithms, as well as providing a quick-look concentration estimate and consistency check. Detailed simulations using both laboratory fluorescence data and computer synthesized spectra indicate that our software can make accurate concentration estimates from complex multicomponent mixtures. even when the mixture is noisy and contaminated with unknowns.

  8. Remote sensing of chemical warfare agent by CO2 -lidar

    NASA Astrophysics Data System (ADS)

    Geiko, Pavel P.; Smirnov, Sergey S.

    2014-11-01

    The possibilities of remote sensing of chemical warfare agent by differential absorption method were analyzed. The CO2 - laser emission lines suitable for sounding of chemical warfare agent with provision for disturbing absorptions by water vapor were choose. The detection range of chemical warfare agents was estimated for a lidar based on CO2 - laser The other factors influencing upon echolocation range were analyzed.

  9. Laser Analyzer

    NASA Technical Reports Server (NTRS)

    1993-01-01

    Dopant level analysis is important to the laser system designer because it allows him to model the laser's performance. It also allows the end user to determine what went wrong when a laser fails to perform as expected. Under a Small Business Innovation Research (SBIR) contract, Scientific Materials Corporation has developed a process for producing uniform laser rods in which the amount of water trapped in the crystal during growth is reduced. This research led to the formation of a subsidiary company, Montana Analytical Services, which conducts analysis of laser rods for dopant ion concentrations. This is a significant advance in laser technology.

  10. Pulsed excimer laser processing for cost-effective solar cells

    NASA Technical Reports Server (NTRS)

    Wong, David C.

    1985-01-01

    The application of excimer laser in the fabrication of photovoltaic devices was investigated extensively. Processes included junction formation, laser assisted chemical vapor deposition metallization, and laser assisted chemical vapor deposition surface passivation. Results demonstrated that implementation of junction formation by laser annealing in production is feasible because of excellent control in junction depth and quality. Both metallization and surface passivation, however, were found impractical to be considered for manufacturing at this stage.

  11. Lasers of All Sizes

    NASA Astrophysics Data System (ADS)

    Balcou, Philippe; Forget, Sébastien Robert-Philip, Isabelle

    2015-10-01

    * Introduction * The Laser in All Its Forms * Gas lasers * Dye lasers * Solid-state lasers * Lasers for Every Taste * The rise of lasers * Lasers of all sizes * The colors of the rainbow... and beyond * Shorter and shorter lasers * Increasingly powerful lasers * Lasers: A Universal Tool? * Cutting, welding, and cleaning * Communicating * Treating illnesses * Measuring * Supplying energy? * Entertaining * Understanding * Conclusion

  12. Investigation of passive and active silica-tin oxide nanostructured optical fibers fabricated by "inverse dip-coating" and "powder in tube" method based on the chemical sol-gel process and laser emission

    NASA Astrophysics Data System (ADS)

    Granger, G.; Restoin, C.; Roy, P.; Jamier, R.; Rougier, S.; Duclere, J.-R.; Lecomte, A.; Dauliat, R.; Blondy, J.-M.

    2015-05-01

    This paper presents a study of original nanostructured optical fibers based on the SiO2-SnO2-(Yb3+) system. Two different processes have been developed and compared: the sol-gel chemical method associated to the "inverse dip-coating" (IDC) and the "powder in tube" (PIT). The microstructural and optical properties of the fibers are studied according to the concentration of SnO2. X-Ray Diffraction as well as Transmission Electron Microscopy studies show that the SnO2 crystallizes into the cassiterite phase as nanoparticles with a diameter ranging from 4 to 50 nm as a function of tin oxide concentration. A comparative study highlights a better conservation of SnO2 into the fiber core with the PIT approach according to the refractive index profile and energy dispersive X-Ray spectrometry measurement. The attenuation evaluated by the classic cut-back method gives respectively values higher than 3 dB/m and 0.2 dB/m in the visible (VIS) and infrared (IR) ranges for the PIT fibers whereas background losses reach 0.5 dB/m in the VIS range for IDC fibers. The introduction of ytterbium ions into the core of PIT fibers, directly in the first chemical step, leads to a laser emission (between 1050 and 1100 nm) according to the fiber length under 850 nm wavelength pumping. Luminescence studies have demonstrated the influence of the tin oxide on the rare earth optical properties especially by the modification of the absorption (850 to 1000 nm) and emission (950 to 1100 nm) by discretization of the bands, as well as on the IR emission lifetime evaluated to 10 μs.

  13. Laser microphone

    DOEpatents

    Veligdan, James T.

    2000-11-14

    A microphone for detecting sound pressure waves includes a laser resonator having a laser gain material aligned coaxially between a pair of first and second mirrors for producing a laser beam. A reference cell is disposed between the laser material and one of the mirrors for transmitting a reference portion of the laser beam between the mirrors. A sensing cell is disposed between the laser material and one of the mirrors, and is laterally displaced from the reference cell for transmitting a signal portion of the laser beam, with the sensing cell being open for receiving the sound waves. A photodetector is disposed in optical communication with the first mirror for receiving the laser beam, and produces an acoustic signal therefrom for the sound waves.

  14. High-sensitivity matrix-assisted laser desorption/ionization Fourier transform mass spectrometry analyses of small carbohydrates and amino acids using oxidized carbon nanotubes prepared by chemical vapor deposition as matrix.

    PubMed

    Wang, Cui-hong; Li, Jian; Yao, Sheng-jun; Guo, Yin-long; Xia, Xing-hua

    2007-12-01

    In matrix-assisted laser desorption/ionization (MALDI) Fourier transform mass spectrometry (FTMS) analyses of small oligosaccharides and amino acids, high sensitivities for oligosaccharides (10 fmol) were obtained by introducing oxidized carbon nanotubes (CNTs) with short and open-end structure as valuable matrix. The CNTs were deposited in porous anodic alumina (PAA) templates by chemical vapor deposition. Transmission electron microscopy (TEM) images show that those CNTs include low levels of amorphous carbon. Thus, the background interference signals generally caused by amorphous carbon powder in CNTs can be reduced effectively. Experiments also confirmed that the FTMS signal intensity of CNTs prepared in PAA template is much lower than that of commercial multi-wall carbon nanotubes (MCNTs). Moreover, the purified process for CNTs with mixed acid (H2SO4 and HNO3) also contributed to the minimization of background. Intense signals corresponding to alkali cation adduct of neutral carbohydrates and amino acids have been acquired. In addition, reliable quantitative analyses for urine and corn root were also achieved successfully. The present work will open a new way to the application of oxidized CNTs as an effective matrix in MALDI MS research.

  15. Development of selective laser treatment techniques using mid-infrared tunable nanosecond pulsed laser.

    PubMed

    Ishii, Katsunori; Saiki, Masayuki; Hazama, Hisanao; Awazu, Kunio

    2010-01-01

    Mid-infrared (MIR) laser with a specific wavelength can excite the corresponding biomolecular site to regulate chemical, thermal and mechanical interactions to biological molecules and tissues. In laser surgery and medicine, tunable MIR laser irradiation can realize the selective and less-invasive treatments and the special diagnosis by vibrational spectroscopic information. This paper showed a novel selective therapeutic technique for a laser angioplasty of atherosclerotic plaques and a laser dental surgery of a carious dentin using a MIR tunable nanosecond pulsed laser.

  16. Laser ignition

    DOEpatents

    Early, James W.; Lester, Charles S.

    2004-01-13

    Sequenced pulses of light from an excitation laser with at least two resonator cavities with separate output couplers are directed through a light modulator and a first polarzing analyzer. A portion of the light not rejected by the first polarizing analyzer is transported through a first optical fiber into a first ignitor laser rod in an ignitor laser. Another portion of the light is rejected by the first polarizing analyzer and directed through a halfwave plate into a second polarization analyzer. A first portion of the output of the second polarization analyzer passes through the second polarization analyzer to a second, oscillator, laser rod in the ignitor laser. A second portion of the output of the second polarization analyzer is redirected by the second polarization analyzer to a second optical fiber which delays the beam before the beam is combined with output of the first ignitor laser rod. Output of the second laser rod in the ignitor laser is directed into the first ignitor laser rod which was energized by light passing through the first polarizing analyzer. Combined output of the first ignitor laser rod and output of the second optical fiber is focused into a combustible fuel where the first short duration, high peak power pulse from the ignitor laser ignites the fuel and the second long duration, low peak power pulse directly from the excitation laser sustains the combustion.

  17. Laser space propulsion overview

    NASA Astrophysics Data System (ADS)

    Phipps, Claude; Luke, James; Helgeson, Wesley

    2007-03-01

    In this paper, we review the history of laser space propulsion from its earliest theoretical conceptions to modern practical applicatons. Applications begin with the "Lightcraft" flights of Myrabo and include practical thrusters for satellites now completing development as well as proposals for space debris removal and direct launch of payloads into orbit. We consider laser space propulsion in the most general sense, in which laser radiation is used to propel a vehicle in space. In this sense, the topic includes early proposals for pure photon propulsion, laser ablation propulsion, as well as propulsion using lasers to detonate a gas, expel a liquid, heat and expel a gas, or even to propagate power to a remote conventional electric thruster. We also discuss the most recent advances in LSP. For the first time, it is possible to consider space propulsion engines which exhibit thrust of one to several newtons while simultaneously delivering 3,000 seconds, or greater, specific impulse. No other engine concept can do both in a compact format. These willl use onboard, rather than remote, lasers. We will review the concept of chemically augmented electric propulsion, which can provide overall thrust efficiency greater than unity while maintaining very low mass to power ratio, high mean time to failure and broad operating range. The main advantage of LSP is exhaust velocity which can be instantaneously varied from 2km/s to 30km/s, simply by varying laser pulsewidth and focal spot size on target. The laser element will probably be a diode-pumped, fiber master-oscillator-power-amplifier (MOPA) system. Liquid fuels are necessary for volumetric efficiency and reliable performance at the multi-kW optical power levels required for multi-N thrust.

  18. Development of mid-IR lasers for Laser Remote Sensing

    NASA Technical Reports Server (NTRS)

    Soibel, Alexander; Mansour, Kamjou; Spiers, Gary; Forouhar, Siamak

    2005-01-01

    There is an existing need in JPL and in NASA for development of mid-IR lasers, such as Quantum Cascade (QC) lasers, for in-situ and remote laser spectrometers. Mid-IR, compact, low power consumption laser spectrometers have a great potential for detection and measurements of planetary gases and biological important biomarker molecules such as H20, H202, CH4, and many additional chemical species on Mars and other Solar system planets. Another potential application of QC lasers for future NASA mission is in high power remote Laser Reflectance Spectrometers (LRS). In LSR instrument, mid-infrared lasers will act as the illumination source for conducting active mid-IR reflectance spectroscopy of solid-surfaced objects in the outer Solar System. These spectrometers have the potential to provide an incredible amount of information about the compositions of surfaces in the outer Solar System. In this work, we will discuss our current effort at JPL to advance QC lasers to a level that the laser performance, operational requirements and reliability be compatible with the instruments demands for space exploration applications.

  19. CW laser pumped emerald laser

    SciTech Connect

    Shand, M.L.; Lai, S.T.

    1984-02-01

    A CW laser-pumped emerald laser is reported. A 34 percent output power slope efficiency is observed with longitudinal pumping by a krypton laser in a nearly concentric cavity. The laser has been tuned from 728.8 to 809.0 nm. Losses in emerald are larger than those of alexandrite determined in a similar cavity. The present data also indicate that the excited state absorption minimum is shifted from that of alexandrite. 13 references.

  20. Laser surface modification of PEEK

    NASA Astrophysics Data System (ADS)

    Riveiro, A.; Soto, R.; Comesaña, R.; Boutinguiza, M.; del Val, J.; Quintero, F.; Lusquiños, F.; Pou, J.

    2012-09-01

    Polyether-ether-ketone (PEEK) is a synthetic thermoplastic polymer with excellent mechanical and chemical properties, which make it attractive for the field of reconstructive surgery. Nevertheless, this material has a poor interfacial biocompatibility due to its large chemical stability which induces poor adhesive bonding properties. The possibilities of enhancing the PEEK adhesive properties by laser treatments have been explored in the past. This paper presents a systematic approach to discern the role of laser irradiation wavelength on the surface modification of PEEK under three laser wavelengths (λ = 1064, 532, and 355 nm) with the aim to determine the most adequate processing conditions to increase the roughness and wettability, the main parameters affecting cell adhesion characteristics of implants. Overall results show that the ultraviolet (λ = 355 nm) laser radiation is the most suitable one to enhance surface wettability of PEEK.

  1. Cutaneous lasers.

    PubMed

    Fedok, Fred G; Garritano, Frank; Portela, Antonio

    2013-02-01

    There has been a remarkable development and evolution of laser technology, leading to adaptation of lasers for medical use and the treatment of skin problems and disorders. Many treatments that required incisional surgery and other invasive methods are now preferentially treated with a laser. Although laser advances have resulted in the availability of some amazing tools, they require the clinical skill and judgment of the clinician for their optimal use. This article provides a clinically oriented overview of many of the lasers valuable in facial plastic surgery. Basic science, clinical adaptations, and patient management topics are covered.

  2. Fs-laser processing of polydimethylsiloxane

    SciTech Connect

    Atanasov, Petar A. Nedyalkov, Nikolay N.; Valova, Eugenia I.; Georgieva, Zhenya S.; Armyanov, Stefan A.; Kolev, Konstantin N.; Amoruso, Salvatore; Wang, Xuan; Bruzzese, Ricardo; Sawczak, Miroslaw; Śliwiński, Gerard

    2014-07-14

    We present an experimental analysis on surface structuring of polydimethylsiloxane films with UV (263 nm) femtosecond laser pulses, in air. Laser processed areas are analyzed by optical microscopy, SEM, and μ-Raman spectroscopy. The laser-treated sample shows the formation of a randomly nanostructured surface morphology. μ-Raman spectra, carried out at both 514 and 785 nm excitation wavelengths, prior and after laser treatment allow evidencing the changes in the sample structure. The influence of the laser fluence on the surface morphology is studied. Finally, successful electro-less metallization of the laser-processed sample is achieved, even after several months from the laser-treatment contrary to previous observation with nanosecond pulses. Our findings address the effectiveness of fs-laser treatment and chemical metallization of polydimethylsiloxane films with perspective technological interest in micro-fabrication devices for MEMS and nano-electromechanical systems.

  3. Laser polishing of niobium for SRF applications

    SciTech Connect

    Zhao, Liang; Klopf, J. Michael; Reece, Charles E.; Kelley, Michael

    2013-09-01

    Smooth interior surfaces are desired for niobium SRF cavities, now obtained by buffered chemical polish (BCP) and/or electropolish (EP). Laser polishing is a potential alternative, having advantages of speed, freedom from chemistry and in-process inspection. Here we show that laser polishing can produce smooth topography with Power Spectral Density (PSD) measurements similar to that obtained by EP. We studied the influence of the laser power density and laser beam raster rate on the surface topography. These two factors need to be combined carefully to smooth the surface without damaging it. Computational modeling was used to simulate the surface temperature and explain the mechanism of laser polishing.

  4. Laser device

    DOEpatents

    Scott, Jill R.; Tremblay, Paul L.

    2004-11-23

    A laser device includes a target position, an optical component separated a distance J from the target position, and a laser energy source separated a distance H from the optical component, distance H being greater than distance J. A laser source manipulation mechanism exhibits a mechanical resolution of positioning the laser source. The mechanical resolution is less than a spatial resolution of laser energy at the target position as directed through the optical component. A vertical and a lateral index that intersect at an origin can be defined for the optical component. The manipulation mechanism can auto align laser aim through the origin during laser source motion. The laser source manipulation mechanism can include a mechanical index. The mechanical index can include a pivot point for laser source lateral motion and a reference point for laser source vertical motion. The target position can be located within an adverse environment including at least one of a high magnetic field, a vacuum system, a high pressure system, and a hazardous zone. The laser source and an electro-mechanical part of the manipulation mechanism can be located outside the adverse environment. The manipulation mechanism can include a Peaucellier linkage.

  5. Laser device

    DOEpatents

    Scott, Jill R.; Tremblay, Paul L.

    2007-07-10

    A laser device includes a target position, an optical component separated a distance J from the target position, and a laser energy source separated a distance H from the optical component, distance H being greater than distance J. A laser source manipulation mechanism exhibits a mechanical resolution of positioning the laser source. The mechanical resolution is less than a spatial resolution of laser energy at the target position as directed through the optical component. A vertical and a lateral index that intersect at an origin can be defined for the optical component. The manipulation mechanism can auto align laser aim through the origin during laser source motion. The laser source manipulation mechanism can include a mechanical index. The mechanical index can include a pivot point for laser source lateral motion and a reference point for laser source vertical motion. The target position can be located within an adverse environment including at least one of a high magnetic field, a vacuum system, a high pressure system, and a hazardous zone. The laser source and an electro-mechanical part of the manipulation mechanism can be located outside the adverse environment. The manipulation mechanism can include a Peaucellier linkage.

  6. Laser ignition

    DOEpatents

    Early, James W.; Lester, Charles S.

    2003-01-01

    In the apparatus of the invention, a first excitation laser or other excitation light source is used in tandem with an ignitor laser to provide a compact, durable, engine deployable fuel ignition laser system. Reliable fuel ignition is provided over a wide range of fuel conditions by using a single remote excitation light source for one or more small lasers located proximate to one or more fuel combustion zones. In a third embodiment, alternating short and long pulses of light from the excitation light source are directed into the ignitor laser. Each of the embodiments of the invention can be multiplexed so as to provide laser light energy sequentially to more than one ignitor laser.

  7. Compact Quantum Cascade Laser Transmitter

    SciTech Connect

    Anheier, Norman C.; Hatchell, Brian K.; Gervais, Kevin L.; Wojcik, Michael D.; Krishnaswami, Kannan; Bernacki, Bruce E.

    2009-04-01

    ): In this paper we present design considerations, thermal and optical modeling results, and device performance for a ruggedized, compact laser transmitter that utilizes a room temperature quantum cascade (QC) laser source. The QC laser transmitter is intended for portable mid-infrared (3-12 µm) spectroscopy applications, where the atmospheric transmission window is relatively free of water vapor interference and where the molecular rotational vibration absorption features can be used to detect and uniquely identify chemical compounds of interest. Initial QC laser-based sensor development efforts were constrained by the complications of cryogenic operation. However, improvements in both QC laser designs and fabrication processes have provided room-temperature devices that now enable significant miniaturization and integration potential for national security, environmental monitoring, atmospheric science, and industrial safety applications.

  8. Methods for determining optical power, for power-normalizing laser measurements, and for stabilizing power of lasers via compliance voltage sensing

    DOEpatents

    Taubman, Matthew S; Phillips, Mark C

    2015-04-07

    A method is disclosed for power normalization of spectroscopic signatures obtained from laser based chemical sensors that employs the compliance voltage across a quantum cascade laser device within an external cavity laser. The method obviates the need for a dedicated optical detector used specifically for power normalization purposes. A method is also disclosed that employs the compliance voltage developed across the laser device within an external cavity semiconductor laser to power-stabilize the laser mode of the semiconductor laser by adjusting drive current to the laser such that the output optical power from the external cavity semiconductor laser remains constant.

  9. Metal atom oxidation laser

    DOEpatents

    Jensen, R.J.; Rice, W.W.; Beattie, W.H.

    1975-10-28

    A chemical laser which operates by formation of metal or carbon atoms and reaction of such atoms with a gaseous oxidizer in an optical resonant cavity is described. The lasing species are diatomic or polyatomic in nature and are readily produced by exchange or other abstraction reactions between the metal or carbon atoms and the oxidizer. The lasing molecules may be metal or carbon monohalides or monoxides. (auth)

  10. Metal atom oxidation laser

    DOEpatents

    Jensen, R.J.; Rice, W.W.; Beattie, W.H.

    1975-10-28

    A chemical laser which operates by formation of metal or carbon atoms and reaction of such atoms with a gaseous oxidizer in an optical resonant cavity is described. The lasing species are diatomic or polyatomic in nature and are readily produced by exchange or other abstraction reactions between the metal or carbon atoms and the oxidizer. The lasing molecules may be metal or carbon monohalides or monoxides.

  11. Continuous wave laser irradiation of explosives

    SciTech Connect

    McGrane, Shawn D.; Moore, David S.

    2010-12-01

    Quantitative measurements of the levels of continuous wave (CW) laser light that can be safely applied to bare explosives during contact operations were obtained at 532 nm, 785 nm, and 1550 nm wavelengths. A thermal camera was used to record the temperature of explosive pressed pellets and single crystals while they were irradiated using a measured laser power and laser spot size. A visible light image of the sample surface was obtained before and after the laser irradiation. Laser irradiation thresholds were obtained for the onset of any visible change to the explosive sample and for the onset of any visible chemical reaction. Deflagration to detonation transitions were not observed using any of these CW laser wavelengths on single crystals or pressed pellets in the unconfined geometry tested. Except for the photochemistry of DAAF, TATB and PBX 9502, all reactions appeared to be thermal using a 532 nm wavelength laser. For a 1550 nm wavelength laser, no photochemistry was evident, but the laser power thresholds for thermal damage in some of the materials were significantly lower than for the 532 nm laser wavelength. No reactions were observed in any of the studied explosives using the available 300 mW laser at 785 nm wavelength. Tables of laser irradiance damage and reaction thresholds are presented for pressed pellets of PBX9501, PBX9502, Composition B, HMX, TATB, RDX, DAAF, PETN, and TNT and single crystals of RDX, HMX, and PETN for each of the laser wavelengths.

  12. Diclofenac in municipal wastewater treatment plant: quantification using laser diode thermal desorption--atmospheric pressure chemical ionization--tandem mass spectrometry approach in comparison with an established liquid chromatography-electrospray ionization-tandem mass spectrometry method.

    PubMed

    Lonappan, Linson; Pulicharla, Rama; Rouissi, Tarek; Brar, Satinder K; Verma, Mausam; Surampalli, Rao Y; Valero, José R

    2016-02-12

    Diclofenac (DCF), a prevalent non-steroidal anti-inflammatory drug (NSAID) is often detected in wastewater and surface water. Analysis of the pharmaceuticals in complex matrices is often laden with challenges. In this study a reliable, rapid and sensitive method based on laser diode thermal desorption/atmospheric pressure chemical ionization (LDTD/APCI) coupled with tandem mass spectrometry (MS/MS) has been developed for the quantification of DCF in wastewater and wastewater sludge. An established conventional LC-ESI-MS/MS (liquid chromatography-electrospray ionization-tandem mass spectrometry) method was compared with LDTD-APCI-MS/MS approach. The newly developed LDTD-APCI-MS/MS method reduced the analysis time to 12s in lieu of 12 min for LC-ESI-MS/MS method. The method detection limits for LDTD-APCI-MS/MS method were found to be 270 ng L(-1) (LOD) and 1000 ng L(-1) (LOQ). Furthermore, two extraction procedures, ultrasonic assisted extraction (USE) and accelerated solvent extraction (ASE) for the extraction of DCF from wastewater sludge were compared and ASE with 95.6 ± 7% recovery was effective over USE with 86 ± 4% recovery. The fate and partitioning of DCF in wastewater (WW) and wastewater sludge (WWS) in wastewater treatment plant was also monitored at various stages of treatment in Quebec Urban community wastewater treatment plant. DCF exhibited affinity towards WW than WWS with a presence about 60% of DCF in WW in contrary with theoretical prediction (LogKow=4.51).

  13. Optical monitoring of laser-generated plasma during laser welding

    NASA Astrophysics Data System (ADS)

    Connolly, John O.; Beirne, Gareth J.; O'Connor, Gerard M.; Glynn, Thomas J.; Conneely, Alan J.

    2000-03-01

    Process monitoring is a vital part of industrial laser applications that enables intelligent control of processes by observing acoustic, optical, thermal and other emissions. By monitoring these emission during laser processing, it is possible to ascertain characteristics that help diagnose features of the laser processed material and hence to optimize the technique. An experimental set up of observing plasmas during laser spot welding is described here. A pulsed Nd:YAG laser was used to spot-weld a variety of materials of different thickness, the plasmas generated during welding were monitored by a number of techniques, and the data obtained was used to characterize the welds. In the study photodiodes were set at different angles and observed the intensity and generation of the plasmas during the laser spot-welding process thereby giving a weld 'signature.' A portable spectrometer was used off-axis to obtain spectra of the emissions from the plasmas. Post process analysis was performed on the materials by mechanical polishing and chemical etching and observations of weld penetration depth and weld quality were correlated with the data collected on the plasmas. Different cover gases were also used during laser welding and the results of the effects of the various gases on the plasma are shown. The results indicate the relationship between laser weld generated plasma characteristics and weld features such as penetration depth. A direct correlation between the intensities of the photodiode and portable spectrometer signals was observed with weld penetration depth.

  14. Laser-supported detonation waves and pulsed laser propulsion

    SciTech Connect

    Kare, J.T.

    1989-01-01

    A laser thermal rocket uses the energy of a large remote laser, possibly ground-based, to heat an inert propellant and generate thrust. Use of a pulsed laser allows the design of extremely simple thrusters with very high performance compared to chemical rockets. The temperatures, pressures, and fluxes involved in such thrusters (10{sup 4} K, 10{sup 2} atmospheres, 10{sup 7} w/cm{sup 2}) typically result in the creation of laser-supported detonation (LSD) waves. The thrust cycle thus involves a complex set of transient shock phenomena, including laser-surface interactions in the ignition if the LSD wave, laser-plasma interactions in the LSD wave itself, and high-temperature nonequilibrium chemistry behind the LSD wave. The SDIO Laser Propulsion Program is investigating these phenomena as part of an overall effort to develop the technology for a low-cost Earth-to-orbit laser launch system. We will summarize the program's approach to developing a high performance thruster, the double-pulse planar thruster, and present an overview of some results obtained to date, along with a discussion of the many research questions still outstanding in this area. 16 refs., 7 figs.

  15. Laser-supported detonation waves and pulsed laser propulsion

    SciTech Connect

    Kare, J. )

    1990-07-30

    A laser thermal rocket uses the energy of a large remote laser, possibly ground-based, to heat an inert propellant and generate thrust. Use of a pulsed laser allows the design of extremely simple thrusters with very high performance compared to chemical rockets. The temperatures, pressures, and fluxes involved in such thrusters (10{sup 4} K, 10{sup 2} atmospheres, 10{sup 7} w/cm{sup 2}) typically result in the creation of laser-supported detonation (LSD) waves. The thrust cycle thus involves a complex set of transient shock phenomena, including laser-surface interactions in the ignition of the LSD wave, laser-plasma interactions in the LSD wave itself, and high-temperature nonequilibrium chemistry behind the LSD wave. The SDIO Laser Propulsion Program is investigating these phenomena as part of an overall effort to develop the technology for a low-cost Earth-to-orbit laser launch system. We will summarize the Program's approach to developing a high performance thruster, the double-pulse planar thruster, and present an overview of some results obtained to date, along with a discussion of the many research question still outstanding in this area.

  16. Newer Trends in Laser Tattoo Removal

    PubMed Central

    Shah, Swapnil D; Aurangabadkar, Sanjeev J

    2015-01-01

    Q switched lasers are the current gold standard for laser tattoo removal. Though these systems are generally quite effective in clearing tattoos & have an established safety record, certain limitations exist while following the standard protocol. To overcome these limitation newer techniques such as multipass method, combination treatments with chemical agent and other laser have been introduced. These methods help in faster, less painful and complication free tattoo removal. PMID:25949019

  17. Status of laser enrichment technology updated

    NASA Astrophysics Data System (ADS)

    Sakabe, Y.

    1986-08-01

    The principles of uranium enrichment by a laser method, the technology's current status and future prospects, centered on research and development activity at the Japan Atomic Energy Research Institute and the Institute of Physical and Chemical Research are described.

  18. Quantum Cascade Lasers in Biomedical Infrared Imaging.

    PubMed

    Bird, Benjamin; Baker, Matthew J

    2015-10-01

    Technological advances, namely the integration of quantum cascade lasers (QCLs) within an infrared (IR) microscope, are enabling the development of valuable label-free biomedical-imaging tools capable of targeting and detecting salient chemical species within practical clinical timeframes.

  19. Biocavity Lasers

    SciTech Connect

    Gourley, P.L.; Gourley, M.F.

    2000-10-05

    Laser technology has advanced dramatically and is an integral part of today's healthcare delivery system. Lasers are used in the laboratory analysis of human blood samples and serve as surgical tools that kill, burn or cut tissue. Recent semiconductor microtechnology has reduced the size o f a laser to the size of a biological cell or even a virus particle. By integrating these ultra small lasers with biological systems, it is possible to create micro-electrical mechanical systems that may revolutionize health care delivery.

  20. Laser ignition

    DOEpatents

    Early, James W.; Lester, Charles S.

    2002-01-01

    In the apparatus of the invention, a first excitation laser or other excitation light source capable of producing alternating beams of light having different wavelengths is used in tandem with one or more ignitor lasers to provide a compact, durable, engine deployable fuel ignition laser system. Reliable fuel ignition is provided over a wide range of fuel conditions by using the single remote excitation light source for pumping one or more small lasers located proximate to one or more fuel combustion zones with alternating wavelengths of light.

  1. Laser apparatus

    DOEpatents

    Lewis, Owen; Stogran, Edmund M.

    1980-01-01

    Laser apparatus is described wherein an active laser element, such as the disc of a face-pumped laser, is mounted in a housing such that the weight of the element is supported by glass spheres which fill a chamber defined in the housing between the walls of the housing and the edges of the laser element. The uniform support provided by the spheres enable the chamber and the pump side of the laser element to be sealed without affecting the alignment or other optical properties of the laser element. Cooling fluid may be circulated through the sealed region by way of the interstices between the spheres. The spheres, and if desired also the cooling fluid may contain material which absorbs radiation at the wavelength of parasitic emissions from the laser element. These parasitic emissions enter the spheres through the interface along the edge surface of the laser element and it is desirable that the index of refraction of the spheres and cooling fluid be near the index of refraction of the laser element. Thus support, cooling, and parasitic suppression functions are all accomplished through the use of the arrangement.

  2. Experimental results on the dissociation of molecular iodine in the presence of singlet oxygen molecules

    NASA Astrophysics Data System (ADS)

    Zagidullin, M. V.; Khvatov, N. A.; Malyshev, M. S.; Svistun, M. I.

    2016-08-01

    The experimental results on the dissociation of iodine molecules in the presence of single oxygen molecules under a widerange variation of the oxygen-iodine composition are presented. The rate constants are determined as 4.3 × 10-17 cm3 s-1 for the reaction O2(1Δ) + O2(1Δ) → O2(1Σ) + O2(3Σ) (reaction 1), 2.8 × 10-13 cm3 s-1 for the reaction O2(1Δ) + I(2P1/2) → O2(1Σ) + I(2P3/2) (4) and 8.3 × 10-11 cm3 s-1 for the reaction O2(1Σ) + I2 → O2(3Σ) + 2I (2). The analysis of the experimental results shows that for different compositions of the active medium of the oxygen-iodine laser the iodine dissociation occurs via the chain of reactions 1, 2, O2(1Δ) + I(2P3/2) → O2(3Σ) + I(2P1/2), 4 and in the cascade process I2 + I(2P1/2) → I2(u) + I(2P3/2), I2(u) + O2(1Δ) → 2I + O2(3Σ). For typical active medium compositions of the supersonic chemical oxygen-iodine laser, the contributions of each of the mechanisms to the dissociation are comparable. The experiments carried out did not reveal any contribution from the vibrationally excited oxygen molecules to the iodine dissociation. Thus, the performed experiments and the conclusions drawn from them completely confirm the mechanism of iodine dissociation, proposed earlier.

  3. Atmospheric pressure femtosecond laser imaging mass spectrometry

    NASA Astrophysics Data System (ADS)

    Coello, Yves; Gunaratne, Tissa C.; Dantus, Marcos

    2009-02-01

    We present a novel imaging mass spectrometry technique that uses femtosecond laser pulses to directly ionize the sample. The method offers significant advantages over current techniques by eliminating the need of a laser-absorbing sample matrix, being suitable for atmospheric pressure sampling, and by providing 10μm resolution, as demonstrated here with a chemical image of vegetable cell walls.

  4. Atomic-vapor-laser isotope separation

    SciTech Connect

    Davis, J.I.

    1982-10-01

    This paper gives a brief history of the scientific considerations leading to the development of laser isotope separation (LIS) processes. The close relationship of LIS to the broader field of laser-induced chemical processes is evaluated in terms of physical criteria to achieve an efficient production process. Atomic-vapor LIS processes under development at Livermore are reviwed. 8 figures.

  5. Laser peening for reducing hydrogen embrittlement

    DOEpatents

    Hackel, Lloyd A.; Zaleski, Tania M.; Chen, Hao-Lin; Hill, Michael R.; Liu, Kevin K.

    2010-05-25

    A laser peening process for the densification of metal surfaces and sub-layers and for changing surface chemical activities provides retardation of the up-take and penetration of atoms and molecules, particularly Hydrogen, which improves the lifetime of such laser peened metals. Penetration of hydrogen into metals initiates an embrittlement that leaves the material susceptible to cracking.

  6. Ultrashort-pulse laser generated nanoparticles of energetic materials

    DOEpatents

    Welle, Eric J.; Tappan, Alexander S.; Palmer, Jeremy A.

    2010-08-03

    A process for generating nanoscale particles of energetic materials, such as explosive materials, using ultrashort-pulse laser irradiation. The use of ultrashort laser pulses in embodiments of this invention enables one to generate particles by laser ablation that retain the chemical identity of the starting material while avoiding ignition, deflagration, and detonation of the explosive material.

  7. Lasers in Cancer Treatment

    MedlinePlus

    ... Cancer Treatment On This Page What is laser light? What is laser therapy, and how is it ... future hold for laser therapy? What is laser light? The term “ laser ” stands for light amplification by ...

  8. Heterodyne laser spectroscopy system

    DOEpatents

    Wyeth, Richard W.; Paisner, Jeffrey A.; Story, Thomas

    1989-01-01

    A heterodyne laser spectroscopy system utilizes laser heterodyne techniques for purposes of laser isotope separation spectroscopy, vapor diagnostics, processing of precise laser frequency offsets from a reference frequency and the like, and provides spectral analysis of a laser beam.

  9. Heterodyne laser spectroscopy system

    DOEpatents

    Wyeth, Richard W.; Paisner, Jeffrey A.; Story, Thomas

    1990-01-01

    A heterodyne laser spectroscopy system utilizes laser heterodyne techniques for purposes of laser isotope separation spectroscopy, vapor diagnostics, processing of precise laser frequency offsets from a reference frequency, and provides spectral analysis of a laser beam.

  10. Laser Therapy

    MedlinePlus

    ... Non-ablative Laser Rejuvenation Non-invasive Body Contouring Treatments Skin Cancer Skin Cancer Information Free Skin Cancer Screenings Skin ... Non-ablative Laser Rejuvenation Non-invasive Body Contouring Treatments Skin Cancer Skin Cancer Information Free Skin Cancer Screenings Skin ...

  11. Laser Crystal

    NASA Technical Reports Server (NTRS)

    1998-01-01

    Lightning Optical Corporation, under an SBIR (Small Business Innovative Research) agreement with Langley Research Center, manufactures oxide and fluoride laser gain crystals, as well as various nonlinear materials. The ultimate result of this research program is the commercial availability in the marketplace of a reliable source of high-quality, damage resistant laser material, primarily for diode-pumping applications.

  12. Nanochemical effects in femtosecond laser ablation of metals

    SciTech Connect

    Vorobyev, A. Y.; Guo, Chunlei

    2013-02-18

    We study chemical energy released from the oxidation of aluminum in multipulse femtosecond laser ablation in air and oxygen. Our study shows that the released chemical energy amounts to about 13% of the incident laser energy, and about 50% of the ablated material is oxidized. The ablated material mass per laser pulse is measured to be on the nanogram scale. Our study indicates that femtosecond laser ablation is capable of inducing nanochemical reactions since the femtosecond laser pulse can controllably produce nanoparticles, clusters, and atoms from a solid target.

  13. Laser device

    DOEpatents

    Scott, Jill R.; Tremblay, Paul L.

    2008-08-19

    A laser device includes a virtual source configured to aim laser energy that originates from a true source. The virtual source has a vertical rotational axis during vertical motion of the virtual source and the vertical axis passes through an exit point from which the laser energy emanates independent of virtual source position. The emanating laser energy is collinear with an orientation line. The laser device includes a virtual source manipulation mechanism that positions the virtual source. The manipulation mechanism has a center of lateral pivot approximately coincident with a lateral index and a center of vertical pivot approximately coincident with a vertical index. The vertical index and lateral index intersect at an index origin. The virtual source and manipulation mechanism auto align the orientation line through the index origin during virtual source motion.

  14. Laser ablation of concrete.

    SciTech Connect

    Savina, M.

    1998-10-05

    Laser ablation is effective both as an analytical tool and as a means of removing surface coatings. The elemental composition of surfaces can be determined by either mass spectrometry or atomic emission spectroscopy of the atomized effluent. Paint can be removed from aircraft without damage to the underlying aluminum substrate, and environmentally damaged buildings and sculptures can be restored by ablating away deposited grime. A recent application of laser ablation is the removal of radioactive contaminants from the surface and near-surface regions of concrete. We present the results of ablation tests on concrete samples using a high power pulsed Nd:YAG laser with fiber optic beam delivery. The laser-surface interaction was studied on various model systems consisting of Type I Portland cement with varying amounts of either fine silica or sand in an effort to understand the effect of substrate composition on ablation rates and mechanisms. A sample of non-contaminated concrete from a nuclear power plant was also studied. In addition, cement and concrete samples were doped with non-radioactive isotopes of elements representative of cooling waterspills, such as cesium and strontium, and analyzed by laser-resorption mass spectrometry to determine the contamination pathways. These samples were also ablated at high power to determine the efficiency with which surface contaminants are removed and captured. The results show that the neat cement matrix melts and vaporizes when little or no sand or aggregate is present. Surface flows of liquid material are readily apparent on the ablated surface and the captured aerosol takes the form of glassy beads up to a few tens of microns in diameter. The presence of sand and aggregate particles causes the material to disaggregate on ablation, with intact particles on the millimeter size scale leaving the surface. Laser resorption mass spectrometric analysis showed that cesium and potassium have similar chemical environments in the

  15. Chemical Reactors.

    ERIC Educational Resources Information Center

    Kenney, C. N.

    1980-01-01

    Describes a course, including content, reading list, and presentation on chemical reactors at Cambridge University, England. A brief comparison of chemical engineering education between the United States and England is also given. (JN)

  16. Quantum cascade laser investigations of CH{sub 4} and C{sub 2}H{sub 2} interconversion in hydrocarbon/H{sub 2} gas mixtures during microwave plasma enhanced chemical vapor deposition of diamond

    SciTech Connect

    Ma Jie; Cheesman, Andrew; Ashfold, Michael N. R.; Hay, Kenneth G.; Wright, Stephen; Langford, Nigel; Duxbury, Geoffrey; Mankelevich, Yuri A.

    2009-08-01

    CH{sub 4} and C{sub 2}H{sub 2} molecules (and their interconversion) in hydrocarbon/rare gas/H{sub 2} gas mixtures in a microwave reactor used for plasma enhanced diamond chemical vapor deposition (CVD) have been investigated by line-of-sight infrared absorption spectroscopy in the wavenumber range of 1276.5-1273.1 cm{sup -1} using a quantum cascade laser spectrometer. Parameters explored include process conditions [pressure, input power, source hydrocarbon, rare gas (Ar or Ne), input gas mixing ratio], height (z) above the substrate, and time (t) after addition of hydrocarbon to a pre-existing Ar/H{sub 2} plasma. The line integrated absorptions so obtained have been converted to species number densities by reference to the companion two-dimensional (r,z) modeling of the CVD reactor described in Mankelevich et al. [J. Appl. Phys. 104, 113304 (2008)]. The gas temperature distribution within the reactor ensures that the measured absorptions are dominated by CH{sub 4} and C{sub 2}H{sub 2} molecules in the cool periphery of the reactor. Nonetheless, the measurements prove to be of enormous value in testing, tensioning, and confirming the model predictions. Under standard process conditions, the study confirms that all hydrocarbon source gases investigated (methane, acetylene, ethane, propyne, propane, and butane) are converted into a mixture dominated by CH{sub 4} and C{sub 2}H{sub 2}. The interconversion between these two species is highly dependent on the local gas temperature and the H atom number density, and thus on position within the reactor. CH{sub 4}->C{sub 2}H{sub 2} conversion occurs most efficiently in an annular shell around the central plasma (characterized by 1400CH{sub 4} is favored in the more distant regions where T{sub gas}<1400 K. Analysis of the multistep interconversion mechanism reveals substantial net consumption of H atoms accompanying the CH{sub 4}->C{sub 2}H{sub 2

  17. Chemical sensor

    NASA Technical Reports Server (NTRS)

    Rauh, R. David (Inventor)

    1990-01-01

    A sensor for detecting a chemical substance includes an insertion element having a structure which enables insertion of the chemical substance with a resulting change in the bulk electrical characteristics of the insertion element under conditions sufficient to permit effective insertion; the change in the bulk electrical characteristics of the insertion element is detected as an indication of the presence of the chemical substance.

  18. Autokeratomileusis Laser

    NASA Astrophysics Data System (ADS)

    Kern, Seymour P.

    1987-03-01

    Refractive defects such as myopia, hyperopia, and astigmatism may be corrected by laser milling of the cornea. An apparatus combining automatic refraction/keratometry and an excimer type laser for precision reshaping of corneal surfaces has been developed for testing. When electronically linked to a refractometer or keratometer or holographic imaging device, the laser is capable of rapidly milling or ablating corneal surfaces to preselected dioptric power shapes without the surgical errors characteristic of radial keratotomy, cryokeratomileusis or epikeratophakia. The excimer laser simultaneously generates a synthetic Bowman's like layer or corneal condensate which appears to support re-epithelialization of the corneal surface. An electronic feedback arrangement between the measuring instrument and the laser enables real time control of the ablative milling process for precise refractive changes in the low to very high dioptric ranges. One of numerous options is the use of a rotating aperture wheel with reflective portions providing rapid alternate ablation/measurement interfaced to both laser and measurement instrumentation. The need for the eye to be fixated is eliminated or minimized. In addition to reshaping corneal surfaces, the laser milling apparatus may also be used in the process of milling both synthetic and natural corneal inlays for lamellar transplants.

  19. Alkali metal vapors - Laser spectroscopy and applications

    NASA Technical Reports Server (NTRS)

    Stwalley, W. C.; Koch, M. E.

    1980-01-01

    The paper examines the rapidly expanding use of lasers for spectroscopic studies of alkali metal vapors. Since the alkali metals (lithium, sodium, potassium, rubidium and cesium) are theoretically simple ('visible hydrogen'), readily ionized, and strongly interacting with laser light, they represent ideal systems for quantitative understanding of microscopic interconversion mechanisms between photon (e.g., solar or laser), chemical, electrical and thermal energy. The possible implications of such understanding for a wide variety of practical applications (sodium lamps, thermionic converters, magnetohydrodynamic devices, new lasers, 'lithium waterfall' inertial confinement fusion reactors, etc.) are also discussed.

  20. Bioactive ceramic glasses in situ synthesized by laser melting

    NASA Astrophysics Data System (ADS)

    Taca, Mihaela; Vasile, Eugeniu; Boroica, Lucica; Udrea, Mircea; Medianu, Rares; Munteanu, Maria Cristina

    2008-10-01

    The synthesis of bioactive glass from raw materials even during the laser deposition process, could provide formation of a biocompatible layer on the metallic prosthesis. During the laser irradiation melting and ultrarapid solidification of ceramic materials occur and glasses controlled by the process parameters (especially laser power and solidification rate) will be obtained. The aim of the present paper is to study the influence of the processing parameters on the laser synthesized glasses chemical composition, structure and bioactive behaviour.

  1. Laser-evoked coloration in polymers

    NASA Astrophysics Data System (ADS)

    Zheng, H. Y.; Rosseinsky, David; Lim, G. C.

    2005-05-01

    Laser-evoked coloration in polymers has long been a major aim of polymer technology for potential applications in product surface decoration, marking personalised images and logos. However, the coloration results reported so far were mostly attributed to laser-induced thermal-chemical reactions. The laser-irradiated areas are characterized with grooves due to material removal. Furthermore, only single color was laser-induced in any given polymer matrix. To induce multiple colors in a given polymer matrix with no apparent surface material removal is most desirable and challenging and may be achieved through laser-induced photo-chemical reactions. However, little public information is available at present. We report that two colors of red and green have been produced on an initially transparent CPV/PVA samples through UV laser-induced photo-chemical reactions. This is believed the first observation of laser-induced multiple-colors in the given polymer matrix. It is believed that the colorants underwent photo-effected electron transfer with suitable electron donors from the polymers to change from colorless bipyridilium Bipm 2+ to the colored Bipm + species. The discovery may lead to new approaches to the development of laser-evoked multiple coloration in polymers.

  2. Laser goniometer

    DOEpatents

    Fairer, George M.; Boernge, James M.; Harris, David W.; Campbell, DeWayne A.; Tuttle, Gene E.; McKeown, Mark H.; Beason, Steven C.

    1993-01-01

    The laser goniometer is an apparatus which permits an operator to sight along a geologic feature and orient a collimated lamer beam to match the attitude of the feature directly. The horizontal orientation (strike) and the angle from horizontal (dip), are detected by rotary incremental encoders attached to the laser goniometer which provide a digital readout of the azimuth and tilt of the collimated laser beam. A microprocessor then translates the square wave signal encoder outputs into an ASCII signal for use by data recording equipment.

  3. Explosive laser

    DOEpatents

    Robinson, C.P.; Jensen, R.J.; Davis, W.C.; Sullivan, J.A.

    1975-09-01

    This patent relates to a laser system wherein reaction products from the detonation of a condensed explosive expand to form a gaseous medium with low translational temperature but high vibration population. Thermal pumping of the upper laser level and de-excitation of the lower laser level occur during the expansion, resulting in a population inversion. The expansion may be free or through a nozzle as in a gas-dynamic configuration. In one preferred embodiment, the explosive is such that its reaction products are CO$sub 2$ and other species that are beneficial or at least benign to CO$sub 2$ lasing. (auth)

  4. Laser ablation in analytical chemistry - A review

    SciTech Connect

    Russo, Richard E.; Mao, Xianglei; Liu, Haichen; Gonzalez, Jhanis; Mao, Samuel S.

    2001-10-10

    Laser ablation is becoming a dominant technology for direct solid sampling in analytical chemistry. Laser ablation refers to the process in which an intense burst of energy delivered by a short laser pulse is used to sample (remove a portion of) a material. The advantages of laser ablation chemical analysis include direct characterization of solids, no chemical procedures for dissolution, reduced risk of contamination or sample loss, analysis of very small samples not separable for solution analysis, and determination of spatial distributions of elemental composition. This review describes recent research to understand and utilize laser ablation for direct solid sampling, with emphasis on sample introduction to an inductively coupled plasma (ICP). Current research related to contemporary experimental systems, calibration and optimization, and fractionation is discussed, with a summary of applications in several areas.

  5. Growth of ferroelectric Ba{sub 0.8}Sr{sub 0.2}TiO{sub 3} epitaxial films by ultraviolet pulsed laser irradiation of chemical solution derived precursor layers

    SciTech Connect

    Queraltó, A.; Pérez del Pino, A. Mata, M. de la; Tristany, M.; Gómez, A.; Obradors, X.; Puig, T.; Arbiol, J.

    2015-06-29

    Highly crystalline epitaxial Ba{sub 0.8}Sr{sub 0.2}TiO{sub 3} (BST) thin-films are grown on (001)-oriented LaNiO{sub 3}-buffered LaAlO{sub 3} substrates by pulsed laser irradiation of solution derived barium-zirconium-titanium precursor layers using a UV Nd:YAG laser source at atmospheric conditions. The structural analyses of the obtained films, studied by X-ray diffractometry and transmission electron microscopy, demonstrate that laser processing allows the growth of tens of nm-thick BST epitaxial films with crystalline structure similar to that of films obtained through conventional thermal annealing methods. However, the fast pulsed nature of the laser employed leads to crystallization kinetic evolution orders of magnitude faster than in thermal treatments. The combination of specific photothermal and photochemical mechanisms is the main responsible for the ultrafast epitaxial laser-induced crystallization. Piezoresponse microscopy measurements demonstrate equivalent ferroelectric behavior in laser and thermally annealed films, being the piezoelectric constant ∼25 pm V{sup −1}.

  6. Laser research and development in the Northeast; Proceedings of the Meeting, Cambridge, MA, Sept. 16, 17, 1986

    SciTech Connect

    Trainor, D.W.; Chicklis, E.P.

    1987-01-01

    The development and scaling of excimer lasers with emphasis on both electron-beam and discharge pumpings; a chemical means of generating laser action in the visible region; the use of stimulated Raman techniques to improve the beam quality output of systems employing excimer lasers; the research and development of CO/sub 2/ lasers; a CO/sub 2/ laser amplifier for radar applications; medical laser usage; and laser monitors for trace species in environmental and industrial processes are examined. Consideration is given to high power laser research and development for laser energetics; linear and nonlinear frequency converters; 450 nm laser operation in Tm(3+):YLF; alexandrite lasers and their applications; and the performance limitations of vibronic lasers. Topics discussed include the laser ignition of oil spills; the application of laser rangers to submunitions; the design and application of laser intensity stabilizers; and a 535 nm active atomic line filter that uses the Tl metastable state as an absorbing medium.

  7. Laser barometer

    SciTech Connect

    Abercrombie, K.R.; Shiels, D.; Rash, T.

    1998-04-01

    This paper describes an invention of a pressure measuring instrument which uses laser radiation to sense the pressure in an enclosed environment by means of measuring the change in refractive index of a gas - which is pressure dependent.

  8. Laser fusion

    SciTech Connect

    Smit, W.A.; Boskma, P.

    1980-12-01

    Unrestricted laser fusion offers nations an opportunity to circumvent arms control agreements and develop thermonuclear weapons. Early laser weapons research sought a clean radiation-free bomb to replace the fission bomb, but this was deceptive because a fission bomb was needed to trigger the fusion reaction and additional radioactivity was induced by generating fast neutrons. As laser-implosion experiments focused on weapons physics, simulating weapons effects, and applications for new weapons, the military interest shifted from developing a laser-ignited hydrogen bomb to more sophisticated weapons and civilian applications for power generation. Civilian and military research now overlap, making it possible for several countries to continue weapons activities and permitting proliferation of nuclear weapons. These countries are reluctant to include inertial confinement fusion research in the Non-Proliferation Treaty. 16 references. (DCK)

  9. Laser bronchoscopy.

    PubMed

    Duhamel, D R; Harrell, J H

    2001-11-01

    Because the lung cancer epidemic shows no signs of abating, little doubt exists that the need for interventional bronchoscopists will persist for many years to come. The Nd:YAG laser and the rigid bronchoscope remain crucial weapons in the fight against lung cancer. With more than 4000 published interventions pertaining to it, this combination is ideal for treating central airways obstruction. The safety and efficacy of laser bronchoscopy has been well established, and the reported incidence of complications is impressively low. If complications were to arise, a skilled bronchoscopist can manage them easily by using the beneficial attributes of the rigid bronchoscope. Many complications can be avoided by implementing the established safety procedures and techniques. A solid understanding of laser physics and tissue interactions is a necessity to anyone performing laser surgery. The team approach, relying on communication among the bronchoscopist, anesthesiologist, laser technician, and nurses, leads to a safer and more successful procedure. It is important to remember, however, that this is typically a palliative procedure, and therefore the focus should be on alleviating symptoms and improving quality of life. Unfortunately, because not every patient is a candidate for laser bronchoscopy, there are specific characteristics of endobronchial lesions that make them more or less amenable to resection. Each year a promising new technology is being developed, such as argon plasma coagulation, cryotherapy, and endobronchial electrosurgery. Although it is unclear what role these technologies will have, prospective controlled studies must be done to help clarify this question. The future may lay in combining these various technologies along with Nd:YAG laser bronchoscopy to maximize the therapeutic, palliative, and possibly even curative effect. As the experience of the medical community with Nd:YAG laser bronchoscopy continues to grow and as more health-care professionals

  10. Laser Technology

    NASA Technical Reports Server (NTRS)

    1989-01-01

    Amoco Laser Company, a subsidiary of Amoco Corporation, has developed microlasers for the commercial market based on a JPL concept for optical communications over interplanetary distances. Lasers emit narrow, intense beams of light or other radiation. The beams transmit communication signals, drill, cut or melt materials or remove diseased body tissue. The microlasers cover a broad portion of the spectrum, and performance is improved significantly. Current applications include medical instrumentation, color separation equipment, telecommunications, etc.

  11. Laser optomechanics

    PubMed Central

    Yang, Weijian; Adair Gerke, Stephen; Wei Ng, Kar; Rao, Yi; Chase, Christopher; Chang-Hasnain, Connie J.

    2015-01-01

    Cavity optomechanics explores the interaction between optical field and mechanical motion. So far, this interaction has relied on the detuning between a passive optical resonator and an external pump laser. Here, we report a new scheme with mutual coupling between a mechanical oscillator supporting the mirror of a laser and the optical field generated by the laser itself. The optically active cavity greatly enhances the light-matter energy transfer. In this work, we use an electrically-pumped vertical-cavity surface-emitting laser (VCSEL) with an ultra-light-weight (130 pg) high-contrast-grating (HCG) mirror, whose reflectivity spectrum is designed to facilitate strong optomechanical coupling, to demonstrate optomechanically-induced regenerative oscillation of the laser optomechanical cavity. We observe >550 nm self-oscillation amplitude of the micromechanical oscillator, two to three orders of magnitude larger than typical, and correspondingly a 23 nm laser wavelength sweep. In addition to its immediate applications as a high-speed wavelength-swept source, this scheme also offers a new approach for integrated on-chip sensors. PMID:26333804

  12. Laser Angioplasty

    NASA Technical Reports Server (NTRS)

    1990-01-01

    The principal method of dealing with coronary artery blockage is bypass surgery. A non-surgical alternative available to some patients is balloon angioplasty. For several years, medical researchers have been exploring another alternative that would help a wider circle of patients than the balloon treatment and entail less risk than bypass surgery. A research group is on the verge of an exciting development: laser angioplasty with a 'cool' type of laser, called an excimer laser, that does not damage blood vessel walls and offers non-surgical cleansing of clogged arteries with extraordinary precision. The system is the Dymer 200+ Excimer Laser Angioplasty System, developed by Advanced Intraventional Systems. Used in human clinical tests since 1987, the system is the first fully integrated 'cool' laser capable of generating the requisite laser energy and delivering the energy to target arteries. Thirteen research hospitals in the U.S. have purchased Dymer 200+ systems and used them in clinical trials in 121 peripheral and 555 coronary artery cases. The success rate in opening blocked coronary arteries is 85 percent, with fewer complications than in balloon angioplasty. Food and Drug Administration approval for the system is hoped for in the latter part of 1990. * Advanced Intraventional Systems became Spectranetics in 1994 and discontinued the product.

  13. Laser neutralization

    SciTech Connect

    Peterson, O.G.

    1986-06-17

    Laser photodetachment of the excess electron to neutralize relativistic ions offers many advantages over the more conventional collisional methods using gases or thin foils as the neutralization agents. Probably the two most important advantages of laser photodetachment are the generation of a compact and low divergence beam, and the production of intense neutral beams at very high efficiency (approximately 90%). The high intensities or high current densities of the neutral beam result from the fixed maximum divergence that can be added to the beam by photodetachment of the charge using laser intensity of fixed wavelength and incident angle. The high neutralization efficiency is possible because there is no theoretical maximum to the neutralization efficiency, although higher efficiencies require higher laser powers and, therefore, costs. Additional advantages include focusability of the laser light onto the ion beam to maximize its efficacy. There certainly is no residual gas left in the particle beam path as is typical with gas neutralizers. The photodetachment process leaves the neutral atoms in the ground state so there is no excited state fluorescence to interfere with the subsequent beam sensing. Finally, since the beams to be neutralized are very high powered, for a large range of neutralization efficiencies the neutral beam can be increased more by increasing the power to the laser neutralizer than by adding an equal amount of power to the primary accelerator. 26 figs.

  14. Laser optomechanics

    NASA Astrophysics Data System (ADS)

    Yang, Weijian; Adair Gerke, Stephen; Wei Ng, Kar; Rao, Yi; Chase, Christopher; Chang-Hasnain, Connie J.

    2015-09-01

    Cavity optomechanics explores the interaction between optical field and mechanical motion. So far, this interaction has relied on the detuning between a passive optical resonator and an external pump laser. Here, we report a new scheme with mutual coupling between a mechanical oscillator supporting the mirror of a laser and the optical field generated by the laser itself. The optically active cavity greatly enhances the light-matter energy transfer. In this work, we use an electrically-pumped vertical-cavity surface-emitting laser (VCSEL) with an ultra-light-weight (130 pg) high-contrast-grating (HCG) mirror, whose reflectivity spectrum is designed to facilitate strong optomechanical coupling, to demonstrate optomechanically-induced regenerative oscillation of the laser optomechanical cavity. We observe >550 nm self-oscillation amplitude of the micromechanical oscillator, two to three orders of magnitude larger than typical, and correspondingly a 23 nm laser wavelength sweep. In addition to its immediate applications as a high-speed wavelength-swept source, this scheme also offers a new approach for integrated on-chip sensors.

  15. Laser optomechanics.

    PubMed

    Yang, Weijian; Gerke, Stephen Adair; Ng, Kar Wei; Rao, Yi; Chase, Christopher; Chang-Hasnain, Connie J

    2015-01-01

    Cavity optomechanics explores the interaction between optical field and mechanical motion. So far, this interaction has relied on the detuning between a passive optical resonator and an external pump laser. Here, we report a new scheme with mutual coupling between a mechanical oscillator supporting the mirror of a laser and the optical field generated by the laser itself. The optically active cavity greatly enhances the light-matter energy transfer. In this work, we use an electrically-pumped vertical-cavity surface-emitting laser (VCSEL) with an ultra-light-weight (130 pg) high-contrast-grating (HCG) mirror, whose reflectivity spectrum is designed to facilitate strong optomechanical coupling, to demonstrate optomechanically-induced regenerative oscillation of the laser optomechanical cavity. We observe >550 nm self-oscillation amplitude of the micromechanical oscillator, two to three orders of magnitude larger than typical, and correspondingly a 23 nm laser wavelength sweep. In addition to its immediate applications as a high-speed wavelength-swept source, this scheme also offers a new approach for integrated on-chip sensors.

  16. [Chemical weapons and chemical terrorism].

    PubMed

    Nakamura, Katsumi

    2005-10-01

    Chemical Weapons are kind of Weapons of Mass Destruction (WMD). They were used large quantities in WWI. Historically, large quantities usage like WWI was not recorded, but small usage has appeared now and then. Chemical weapons are so called "Nuclear weapon for poor countrys" because it's very easy to produce/possession being possible. They are categorized (1) Nerve Agents, (2) Blister Agents, (3) Cyanide (blood) Agents, (4) Pulmonary Agents, (5) Incapacitating Agents (6) Tear Agents from the viewpoint of human body interaction. In 1997 the Chemical Weapons Convention has taken effect. It prohibits chemical weapons development/production, and Organization for the Prohibition of Chemical Weapons (OPCW) verification regime contributes to the chemical weapons disposal. But possibility of possession/use of weapons of mass destruction by terrorist group represented in one by Matsumoto and Tokyo Subway Sarin Attack, So new chemical terrorism countermeasures are necessary.

  17. Chemical microsensors

    DOEpatents

    Li, DeQuan; Swanson, Basil I.

    1995-01-01

    An article of manufacture is provided including a substrate having an oxide surface layer and a selective thin film of a cyclodextrin derivative chemically bound upon said substrate, said film is adapted for the inclusion of a selected organic compound therewith. Such an article can be either a chemical sensor capable of detecting a resultant mass change from inclusion of the selected organic compound or a chemical separator capable of reversibly selectively separating a selected organic compound.

  18. Gas and metal vapor lasers and applications; Proceedings of the Meeting, Los Angeles, CA, Jan. 22, 23, 1991

    NASA Astrophysics Data System (ADS)

    Kim, Jin J.; Tittel, Frank K.

    Various papers on gas and metal vapor lasers and applications are presented. Individual topics addressed include: high-power copper vapor laser development, modified off-axis unstable resonator for copper vapor laser, industrial applications of metal vapor lasers, newly developed excitation circuit for kHz pulsed lasers, copper vapor laser precision processing, development of solid state pulse power supply for copper vapor laser, multiple spectral structure of the 578.2-nm line for copper vapor laser, adsorption of bromine in CuBr laser, processing of polytetrafluoroethylene with high-power VUV laser radiation, characterization of a subpicosecond XeF(C - A) excimer laser, X-ray preionization for high-repetition-rate discharge excimer lasers. Also discussed are: investigation of microwave-pumped excimer and rare-gas laser transitions, influence of gas composition of XeCl laser performance, output power stabilization of a XeCl excimer laser by HCl gas injection, excimer laser machining of optical fiber taps, diagnostics of a compact UV-preionized XeCl laser with BCl3 halogen donor, blackbody-pumped CO32 lasers using Gaussian and waveguide cavities, chemical problems of high-power sealed-off CO lasers, laser action of Xe and Ne pumped by electron beam, process monitoring during CO2 laser cutting, double-pulsed TEA CO2 laser, superhigh-gain gas laser, high-power ns-pulse iodine laser provided with SBS mirror. (No individual items are abstracted in this volume)

  19. Laser beam monitoring system

    DOEpatents

    Weil, Bradley S.; Wetherington, Jr., Grady R.

    1985-01-01

    Laser beam monitoring systems include laser-transparent plates set at an angle to the laser beam passing therethrough and light sensor for detecting light reflected from an object on which the laser beam impinges.

  20. Laser physics and laser-tissue interaction.

    PubMed

    Welch, A J; Torres, J H; Cheong, W F

    1989-01-01

    Within the last few years, lasers have gained increasing use in the management of cardiovascular disease, and laser angioplasty has become a widely performed procedure. For this reason, a basic knowledge of lasers and their applications is essential to vascular surgeons, cardiologists, and interventional radiologists. To elucidate some fundamental concepts regarding laser physics, we describe how laser light is generated and review the properties that make lasers useful in medicine. We also discuss beam profile and spotsize, as well as dosimetric specifications for laser angioplasty. After considering laser-tissue interaction and light propagation in tissue, we explain how the aforementioned concepts apply to direct laser angioplasty and laser-balloon angioplasty. An understanding of these issues should prove useful not only in performing laser angioplasty but in comparing the reported results of various laser applications.

  1. Early history of high-power lasers

    NASA Astrophysics Data System (ADS)

    Sutton, George W.

    2002-02-01

    This paper gives the history of the invention and development of early high power lasers, to which the author contributed and had personal knowledge. The earliest hint that a high power laser could be built came from the electric CO2-N2-He laser of Javan. It happened that the director of the Avco-Everett Research Laboratory had written his Ph.D. dissertation on the deactivation of the vibrational excitation of N2 in an expanding flow under Edward Teller, then at Columbia Univ. The director then started an in-house project to determine if gain could be achieved in a mixture similar to Javan's by means of a shock tunnel where a shock heated mixture of N2, CO2, and He gas was expanded through a supersonic nozzle into a cavity. This concept was named by the author as the gasdynamic laser (GDL). The paper traces the history of the initial gain measurements, the Mark II laser, the RASTA laser, the Tri-Service laser, its troubles and solutions, the United Technology's XLD gasdynamic laser, and their ALL laser. The history of the coastal Crusader will also be mentioned. Also discussed are the early experiments on a combustion-driven chemical laser, and its subsequent rejection by the director.

  2. Contamination and UV lasers: lessons learned

    NASA Astrophysics Data System (ADS)

    Daly, John G.

    2015-09-01

    Laser induced damage to optical elements has been a subject of significant research, development, and improvement, since the first lasers were built over the last 50 years. Better materials, with less absorption, impurities, and defects are available, as well as surface coatings with higher laser damage resistance. However, the presence of contamination (particles, surface deposition films, or airborne) can reduce the threshold for damage by several orders of magnitude. A brief review of the anticipated laser energy levels for damage free operation is presented as a lead into the problems associated with contamination for ultraviolet (UV) laser systems. As UV lasers become more common in applications especially in areas such as lithography, these problems have limited reliability and added to costs. This has been characterized as Airborne Molecular Contamination (AMC) in many published reports. Normal engineering guidelines such as screening materials within the optical compartment for low outgassing levels is the first step. The use of the NASA outgassing database (or similar test methods) with low Total Mass Loss (TML) and Condensed Collected Volatiles Collected Mass (CVCM) is a good baseline. Energetic UV photons are capable of chemical bond scission and interaction with surface contaminant or airborne materials results in deposition of obscuring film laser footprints that continue to degrade laser system performance. Laser systems with average powers less than 5 mW have been shown to exhibit aggressive degradation. Lessons learned over the past 15 years with UV laser contamination and steps to reduce risk will be presented.

  3. Chemical Calcium Indicators

    PubMed Central

    Paredes, R. Madelaine; Etzler, Julie C.; Watts, Lora Talley; Lechleiter, James D.

    2008-01-01

    Our understanding of the underlying mechanisms of Ca2+ signaling as well as our appreciation for its ubiquitous role in cellular processes and has been rapidly advanced, in large part, due to the development of fluorescent Ca2+ indicators. In this chapter, we discuss some of the most common chemical Ca2+ indicators that are widely used for the investigation of intracellular Ca2+ signaling. Advantages, limitations and relevant procedures will be presented for each dye including their spectral qualities, dissociation constants, chemical forms, loading methods and equipment for optimal imaging. Chemical indicators that are now available allow for intracellular Ca2+ detection over a very large range (<50 nM to >50 μM). Higher affinity indicators can be used to quantify Ca2+ levels in the cytosol while lower affinity indicators can be optimized for measuring Ca2+ in subcellular compartments with higher concentrations. Indicators can be classified into either single wavelength or ratiometric dyes. Both classes require specific lasers, filters, and/or detection methods that are dependent upon their spectral properties and both classes have advantages and limitations. Single wavelength indicators are generally very bright and optimal for Ca2+ detection when more than one fluorophore is being imaging. Ratiometric indicators can be calibrated very precisely and they minimize the most common problems associated with chemical Ca2+ indicators including uneven dye loading, leakage, photobleaching and changes in cell volume. Recent technical advances that permit in vivo Ca2+ measurements will also be discussed. PMID:18929663

  4. Tunable solid state lasers

    SciTech Connect

    Hammerling, R.; Budgor, A.B.; Pinto, A.

    1985-01-01

    This book presents the papers given at a conference on solid state lasers. Topics considered at the conference included transition-metal-doped lasers, line-narrowed alexandrite lasers, NASA specification, meteorological lidars, laser materials spectroscopy, laser pumped single pass gain, vibronic laser materials growth, crystal growth methods, vibronic laser theory, cross-fertilization through interdisciplinary fields, and laser action of color centers in diamonds.

  5. Header For Laser Diode

    NASA Technical Reports Server (NTRS)

    Rall, Jonathan A. R.; Spadin, Paul L.

    1990-01-01

    Header designed to contain laser diode. Output combined incoherently with outputs of other laser diodes in grating laser-beam combiner in optical communication system. Provides electrical connections to laser diode, cooling to thermally stabilize laser operation, and optomechanical adjustments that steer and focus laser beam. Range of adjustments provides for correction of worst-case decentering and defocusing of laser beam encountered with laser diodes. Mechanical configuration made simple to promote stability and keep cost low.

  6. Laser textured surface gradients

    NASA Astrophysics Data System (ADS)

    Ta, Van Duong; Dunn, Andrew; Wasley, Thomas J.; Li, Ji; Kay, Robert W.; Stringer, Jonathan; Smith, Patrick J.; Esenturk, Emre; Connaughton, Colm; Shephard, Jonathan D.

    2016-05-01

    This work demonstrates a novel technique for fabricating surfaces with roughness and wettability gradients and their subsequent applications for chemical sensors. Surface roughness gradients on brass sheets are obtained directly by nanosecond laser texturing. When these structured surfaces are exposed to air, their wettability decreases with time (up to 20 days) achieving both spatial and temporal wettability gradients. The surfaces are responsive to organic solvents. Contact angles of a series of dilute isopropanol solutions decay exponentially with concentration. In particular, a fall of 132° in contact angle is observed on a surface gradient, one order of magnitude higher than the 14° observed for the unprocessed surface, when the isopropanol concentration increased from 0 to 15.6 wt%. As the wettability changes gradually over the surface, contact angle also changes correspondingly. This effect offers multi-sensitivity at different zones on the surface and is useful for accurate measurement of chemical concentration.

  7. Chemical sensors

    DOEpatents

    Lowell, J.R. Jr.; Edlund, D.J.; Friesen, D.T.; Rayfield, G.W.

    1991-07-02

    Sensors responsive to small changes in the concentration of chemical species are disclosed. The sensors comprise a mechanochemically responsive polymeric film capable of expansion or contraction in response to a change in its chemical environment. They are operatively coupled to a transducer capable of directly converting the expansion or contraction to a measurable electrical response. 9 figures.

  8. Chemical Peels

    MedlinePlus

    ... the complications or potential side effects of a chemical peel? Temporary or permanent change in skin color, particularly for women on birth control pills, who subsequently become pregnant or have a history of brownish facial ... after having a chemical peel? All peels require some follow-up care: ...

  9. Chemical preconcentrator

    DOEpatents

    Manginell, Ronald P.; Frye-Mason, Gregory C.

    2001-01-01

    A chemical preconcentrator is disclosed with applications to chemical sensing and analysis. The preconcentrator can be formed by depositing a resistive heating element (e.g. platinum) over a membrane (e.g. silicon nitride) suspended above a substrate. A coating of a sorptive material (e.g. a microporous hydrophobic sol-gel coating or a polymer coating) is formed on the suspended membrane proximate to the heating element to selective sorb one or more chemical species of interest over a time period, thereby concentrating the chemical species in the sorptive material. Upon heating the sorptive material with the resistive heating element, the sorbed chemical species are released for detection and analysis in a relatively high concentration and over a relatively short time period. The sorptive material can be made to selectively sorb particular chemical species of interest while not substantially sorbing other chemical species not of interest. The present invention has applications for use in forming high-sensitivity, rapid-response miniaturized chemical analysis systems (e.g. a "chem lab on a chip").

  10. Chemical sensors

    DOEpatents

    Lowell, Jr., James R.; Edlund, David J.; Friesen, Dwayne T.; Rayfield, George W.

    1991-01-01

    Sensors responsive to small changes in the concentration of chemical species are disclosed, comprising (a) a mechanochemically responsive polymeric film capable of expansion or contraction in response to a change in its chemical environment, operatively coupled to (b) a transducer capable of directly converting said expansion or contraction to a measurable electrical response.

  11. Chemical Emergencies

    MedlinePlus

    ... agents such as sarin and VX. Many hazardous chemicals are used in industry - for example, chlorine, ammonia, and benzene. Some can be made from everyday items such as household cleaners. Although there are no guarantees of safety during a chemical emergency, you can take actions to protect yourself. ...

  12. Chemical threats.

    PubMed

    Fry, Donald E

    2006-06-01

    The use of chemical agents as military weapons has been recognized for many centuries but reached the most feared and publicized level during World War I. Considerable political effort has been exercised in the twentieth century to restrict military strategies with chemicals. However, considerable concern currently exists that chemical weapons may be used as agents in civilian terrorism. The distribution of acetaminophen tablets contaminated with potassium cyanide and the release of sarin in the Tokyo sub-way system show that larger-scale deployment of chemical agents can be a reality. This reality makes it necessary for civilian disaster-planning strategies to incorporate an understanding of chemical agents, their effects, and the necessary treatment.

  13. Laser barometer

    DOEpatents

    Abercrombie, Kevin R.; Shiels, David; Rash, Tim

    2001-02-06

    A pressure measuring instrument that utilizes the change of the refractive index of a gas as a function of pressure and the coherent nature of a laser light to determine the barometric pressure within an environment. As the gas pressure in a closed environment varies, the index of refraction of the gas changes. The amount of change is a function of the gas pressure. By illuminating the gas with a laser light source, causing the wavelength of the light to change, pressure can be quantified by measuring the shift in fringes (alternating light and dark bands produced when coherent light is mixed) in an interferometer.

  14. Excimer lasers

    NASA Technical Reports Server (NTRS)

    Palmer, A. J.; Hess, L. D.; Stephens, R. R.

    1976-01-01

    A theoretical and experimental investigation into the possibility of achieving CW discharge pumped excimer laser oscillation is reported. Detailed theoretical modeling of capillary discharge pumping of the XeF and KXe and K2 excimer systems was carried out which predicted the required discharge parameters for reaching laser threshold on these systems. Capillary discharge pumping of the XeF excimer system was investigated experimentally. The experiments revealed a lower excimer level population density than predicted theoretically by about an order of magnitude. The experiments also revealed a fluorine consumption problem in the discharge in agreement with theory.

  15. Laser Resonator

    NASA Technical Reports Server (NTRS)

    Harper, L. L. (Inventor)

    1983-01-01

    An optical resonator cavity configuration has a unitary mirror with oppositely directed convex and concave reflective surfaces disposed into one fold and concertedly reversing both ends of a beam propagating from a laser rod disposed between two total internal reflection prisms. The optical components are rigidly positioned with perpendicularly crossed virtual rooflines by a compact optical bed. The rooflines of the internal reflection prisms, are arranged perpendicularly to the axis of the laser beam and to the optical axes of the optical resonator components.

  16. Investigation on femtosecond laser-assisted microfabrication in silica glasses

    NASA Astrophysics Data System (ADS)

    Liu, Hewei; Chen, Feng; Yang, Qing; Si, Jinhai; Hou, Xun

    2010-11-01

    Fabrication of microstructures embedded in silica glasses using a femtosecond (fs)-laser-assisted chemical etching technique is systematically studied in this work. By scanning the laser pulses inside samples followed by the treatment of 5%-diluted hydrofluoric (HF) acid, groups of straight channels are fabricated and the relationship between the etching rate and processing parameters, including laser power, scanning speed, scanning time and laser polarization, is demonstrated. Based on the optimization of these parameters, complicated microstructures such as channels, cavities and their combinations are manufactured. The work has great potential applications in microelectromechanical systems, biomedical detection and chemical analysis.

  17. Spectroscopic chemical analysis methods and apparatus

    NASA Technical Reports Server (NTRS)

    Hug, William F. (Inventor); Reid, Ray D. (Inventor)

    2010-01-01

    Spectroscopic chemical analysis methods and apparatus are disclosed which employ deep ultraviolet (e.g. in the 200 nm to 300 nm spectral range) electron beam pumped wide bandgap semiconductor lasers, incoherent wide bandgap semiconductor light emitting devices, and hollow cathode metal ion lasers to perform non-contact, non-invasive detection of unknown chemical analytes. These deep ultraviolet sources enable dramatic size, weight and power consumption reductions of chemical analysis instruments. Chemical analysis instruments employed in some embodiments include capillary and gel plane electrophoresis, capillary electrochromatography, high performance liquid chromatography, flow cytometry, flow cells for liquids and aerosols, and surface detection instruments. In some embodiments, Raman spectroscopic detection methods and apparatus use ultra-narrow-band angle tuning filters, acousto-optic tuning filters, and temperature tuned filters to enable ultra-miniature analyzers for chemical identification. In some embodiments Raman analysis is conducted simultaneously with native fluorescence spectroscopy to provide high levels of sensitivity and specificity in the same instrument.

  18. Spectroscopic chemical analysis methods and apparatus

    NASA Technical Reports Server (NTRS)

    Hug, William F. (Inventor); Reid, Ray D. (Inventor)

    2009-01-01

    Spectroscopic chemical analysis methods and apparatus are disclosed which employ deep ultraviolet (e.g. in the 200 nm to 300 nm spectral range) electron beam pumped wide bandgap semiconductor lasers, incoherent wide bandgap semiconductor light emitting devices, and hollow cathode metal ion lasers to perform non-contact, non-invasive detection of unknown chemical analytes. These deep ultraviolet sources enable dramatic size, weight and power consumption reductions of chemical analysis instruments. Chemical analysis instruments employed in some embodiments include capillary and gel plane electrophoresis, capillary electrochromatography, high performance liquid chromatography, flow cytometry, flow cells for liquids and aerosols, and surface detection instruments. In some embodiments, Raman spectroscopic detection methods and apparatus use ultra-narrow-band angle tuning filters, acousto-optic tuning filters, and temperature tuned filters to enable ultra-miniature analyzers for chemical identification. In some embodiments Raman analysis is conducted simultaneously with native fluorescence spectroscopy to provide high levels of sensitivity and specificity in the same instrument.

  19. Laser dusting of delicate objects

    NASA Astrophysics Data System (ADS)

    Asmus, John F.; Abraham, Meg

    2005-06-01

    Since the inception of the laser-divestment process, emphasis has focused on the treatment of reasonably durable materials. Marble, limestone, sandstone, and bronze are foremost among these. In most situations the objective of laser divestment is the removal of superficial corrosion or chemical-decomposition products. To a lesser extent laser ablation is also used to treat diverse surface problems for a spectrum of other historic and artistic substrates such as paper, vellum, ivory, paint, and plaster. Although materials of this sort are not particularly strong, their optical, thermodynamical, and mechanical properties are sufficiently propitious to enable successful laser treatment (with the exercise of precise control). There is another, quite different, cleaning problem encountered in the maintenance of museum collections. This is often referred to as "dusting" (in contrast to "divestment" or "conservation"). Vacuuming, wiping, blowing, and feather dusting are used most often to improve the cosmetic appearance of museum objects after dust and aerosols have accumulated on exposed surfaces. However, many collections include extremely friable pieces composed of feathers, fir, hair, plant fibers, or mummified skin. Conventional dusting may be impossible in such instances. From experimental observations and theoretical analyses we speculate that at very low fluxes laser-induced acoustic and electrostatic forces are responsible for the ejection of debris. Laboratory experiments demonstrated that laser dusting was effective on feathers and textiles, The practical viability of laser dusting was demonstrated by laser-cleaning two very large sand sculptures by San Diego artist C.R. Faust. In contrast, all conventional cleaning techniques damaged the surface by dislodging sand grains.

  20. Cleaning laser spark spectroscopy for online cleaning quality control method development

    NASA Astrophysics Data System (ADS)

    Mutin, T. Y.; Smirnov, V. N.; Veiko, V. P.; Volkov, S. A.

    2010-07-01

    This work is dedicated to spectroscopic investigations of laser spark during the laser cleaning process. The goal is to proof its analytical possibilities for chemical composition determination for online cleaning quality control. Photographic recordings of laser spark were performed to estimate its parameters. Fiber spectrometer was used to analyze the emission of cleaning process established with fiber laser. Conclusions have been made about fiber laser radiation usability for spectroscopic purpose.