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Sample records for chemical oxygen-iodine laser

  1. Scalable chemical oxygen - iodine laser

    SciTech Connect

    Adamenkov, A A; Bakshin, V V; Vyskubenko, B A; Efremov, V I; Il'in, S P; Ilyushin, Yurii N; Kolobyanin, Yu V; Kudryashov, E A; Troshkin, M V

    2011-12-31

    The problem of scaling chemical oxygen - iodine lasers (COILs) is discussed. The results of experimental study of a twisted-aerosol singlet oxygen generator meeting the COIL scalability requirements are presented. The energy characteristics of a supersonic COIL with singlet oxygen and iodine mixing in parallel flows are also experimentally studied. The output power of {approx}7.5 kW, corresponding to a specific power of 230 W cm{sup -2}, is achieved. The maximum chemical efficiency of the COIL is {approx}30%.

  2. An experimental study of the chemical oxygen-iodine laser

    NASA Astrophysics Data System (ADS)

    Vagin, N. P.; Karapetian, D. G.; Konoshenko, A. F.; Kriukov, P. G.; Paziuk, V. S.

    The construction of an oxygen-iodine laser with an output power of up to 400 W based on a chemical singlet oxygen generator is reported. The possibility of achieving high outputs using modular design is demonstrated. The possibility of the operation of chemical oxygen-iodine lasers in the pulsed mode is analyzed, and it is shown that, in this mode, such lasers can operate without a low-temperature trap. In addition, the pulsed mode makes it possible to control the lasing pulse length over a wide range. Possible applications of pulsed chemical oxygen-iodine lasers in thermonuclear fusion are briefly discussed.

  3. Chemical kinetics of discharge-driven oxygen-iodine lasers

    NASA Astrophysics Data System (ADS)

    Azyazov, Valeriy N.; Kabir, Md. Humayun; Antonov, Ivan O.; Heaven, Michael C.

    2007-05-01

    Oxygen-iodine lasers that utilize electrical discharges to produce O II(a1Δ) are currently being developed. The discharge generators differ from those used in chemical oxygen-iodine lasers in that they produce significant amounts of atomic oxygen and traces of ozone. As a consequence of these differences, the chemical kinetics of the discharge laser are markedly different from those of a conventional chemical oxygen-iodine laser (COIL). The reactions of O with iodine include channels that are both beneficial and detrimental to the laser. The beneficial reactions result in the dissociation of I II while the detrimental processes cause direct and indirect removal of I(2P 1/2) (denoted I*, the upper level of the laser). We have examined kinetic processes relevant to the laser through studies of photo-initiated reactions in N IIO/CO II/I II mixtures. The reactions have been monitored using absorption spectroscopy, laser induced fluorescence and time-resolved emission spectroscopy. It has been established that deactivation of I* by O atoms is a critical energy loss process. We have determined a rate constant of (1.2+/-0.1)×10 -11 cm 3 s -1 for this reaction. As part of this effort the branching fraction for the formation of O II(a) from the reaction of O(1D) with N IIO was determined to be 0.38. This result has implications for lasers based on photolysis of O 3/N IIO/I II mixtures and the formation of O II(a) in the upper atmosphere.

  4. New singlet oxygen generator for chemical oxygen-iodine lasers

    NASA Astrophysics Data System (ADS)

    Yoshida, S.; Saito, H.; Fujioka, T.; Yamakoshi, H.; Uchiyama, T.

    1986-11-01

    Experiments have been carried out to investigate a new method for generating O2(1Delta) with long-time operation of an efficient chemical oxygen-iodine laser system in mind. An impinging-jet nozzle was utilized to atomize a H2O2-KOH solution so that the alkaline H2O2/Cl2 reaction might occur in droplet-gas phase with high excitation efficiency. Experimental results indicate that the present generator can yield as high as 80 percent of O2(1Delta) with reasonable O2 flow rate.

  5. Chemical oxygen-iodine laser (COIL) thermal management

    NASA Astrophysics Data System (ADS)

    Truesdell, Keith A.; Helms, Charles A.; Longergan, Thomas; Wisniewski, Charles F.; Scott, Joseph E.; Healey, Keith P.

    1995-03-01

    The chemical oxygen-iodine laser (COIL) has been studied at the Phillips Laboratory since its invention in 1978. One of the most difficult challenges in COIL technology is to produce constant power for more than a few seconds; an essential feature for most applications. The key to developing a laser with these operational characteristics is management of the heat released during the production of singlet delta oxygen. Approximately 10 joules is deposited into the singlet delta oxygen generator (SOG) for every joule extracted as laser power. A recent test series demonstrated run times of 120 seconds at 9 kW by controlling the SOG reaction temperature with a flowing aqueous solution of cold hydroperoxide (BHP). This method of managing the energy released is quite effective but requires a large reservoir of cold BHP.

  6. Repetitively pulsed q-switched chemical oxygen-iodine laser

    SciTech Connect

    Hager, G.D.

    1985-10-07

    This invention overcomes the problems of severe flux-induced density gradients in a continuous-wave subsonic cavity of a chemical oxygen-iodine laser by operating the laser in a repetitively pulsed mode through the incorporation therein of a scaleable intracavity gas-phase Q-switch. This abstract discloses a repetitively cavity containing a lasing medium in the form of a flowing mixture of excited oxygen and iodine atoms and an iodine absorption region within the resonant cavity. The iodine absorption region includes a source of iodine atoms and a magnetic field associated therewith. Selectively altering the magnetic field results in changing the absorption characteristics of the iodine atoms and, therefore, effectively pulses the output of the laser.

  7. 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.

  8. 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 considered for civil commercial applications in the US and overseas.

  9. 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)

  10. Singlet oxygen generator for a supersonic chemical oxygen iodine laser: parametric study and recovery of chemicals

    NASA Astrophysics Data System (ADS)

    Spalek, Otomar; Kodymova, Jarmila

    1997-04-01

    A jet singlet oxygen generator for a supersonic chemical oxygen-iodine laser was studied including singlet delta oxygen, O2(1(Delta) g), and residual chlorine concentration measurements. The investigation was intended mainly for a water vapor measurement in gas effluent of generator in dependence on properties of liquid jets: a chemical composition and temperature of the input liquid (alkaline solution of hydrogen peroxide), a liquid jets diameter and their geometrical arrangement. Effects of these parameters on output power of a small-scale supersonic laser were studied as well. Possible approaches to a chemical fuels management in a chemical oxygen-iodine laser for industrial applications are considered. An 'open loop' cycle with a possible use of sodium hydroxide, and a 'closed loop' cycle with a regeneration of both potassium hydroxide and hydrogen peroxide are discussed.

  11. Intracavity second harmonic generation of chemical oxygen iodine laser with a Brewster cut LBO crystal

    NASA Astrophysics Data System (ADS)

    Shimizu, Tomohiro; Tezuka, Takeo; Chen, Kuntetsu; Hashimoto, Katsuki; Uchiyama, Taro

    1997-04-01

    Second harmonic generation of chemical oxygen iodine laser was investigated with a Brewster cut LBO crystal. By utilizing a Brewster cut LBO crystal the loss in the resonator can be suppressed. Further, by reducing crystal absorption, the crystal can't be heated and go off phase match or even crack due to thermal stress. We could obtain 16.4 W of second harmonic power and keep out the crystal from being destroyed by the damage of thermal stress.

  12. 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)

  13. Mathematical modeling of thick-section cutting with chemical oxygen-iodine laser

    SciTech Connect

    Kar, A.; Rothenflue, J.A.; Latham, W.P.

    1996-12-31

    Almost all laser-assisted materials processing involve melting, vaporization and plasma formation. These phenomena affect the utilization of laser energy for materials processing. To account for the effect of these phases, an effective absorptivity is defined, and a simple mathematical model is developed for thick-section stainless cutting with a high power Chemical Oxygen-Iodine Laser (COIL). The model is based on overall energy balance, and it relates the cutting depth with various process parameters that can be used to predict scaled laser materials processing performance to very thick sections. The effects of various process parameters such as laser power, spot size, cutting speed and cutting gas velocity on the cutting depth are discussed. The results of the mathematical model are compared with experimental data. Such comparison provides a means of determining the effective absorptivity during laser materials processing.

  14. 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)

  15. A pressure recovery system for chemical oxygen-iodine laser based on an active diffuser

    NASA Astrophysics Data System (ADS)

    Malkov, V. M.; Kiselev, I. A.; Orlov, A. E.; Shatalov, I. V.

    2011-09-01

    An open-type pressure recovery system (PRS) for chemical oxygen-iodine laser was designed and fabricated. As a first stage, an active diffuser was used in which the ejecting gas supply was organized through nozzles disposed around the channel periphery. The second stage was a supersonic ejector. Numerical simulation data for the viscous turbulent flow with heat release through the diffuser gas-dynamic channel, and also data obtained by testing the active diffuser in operation on a model facility equipped with a vacuum chamber, are reported. The obtained data were used to develop a full-scale setup with exhaust of laser gas into the atmosphere; this has allowed us to optimize the performance characteristics of the setup and substantially improve its mass-dimensional characteristics. Special attention was paid to parameter matching and synchronization of laser start with the operation of PRS components.

  16. High-Pressure Nozzle Bank for a Chemical Oxygen Iodine Laser

    NASA Astrophysics Data System (ADS)

    Takeuchi, Noriyuki; Sugimoto, Daichi; Tei, Kazuyoku; Nanri, Kenzo; Fujioka, Tomoo

    2005-02-01

    A new nozzle bank for an ejector-chemical oxygen-iodine laser consisting of two-dimensional slit nozzles with a trip-jet mixing system was designed, fabricated, and tested with a nitrogen flow operation regime. Computational fluid dynamics (CFD) was used to optimize the trip system design. Horizontal Pitot scan experiments demonstrated that the mixing ability of the trips is excellent. The Mach number of the mixed flow was approximately 3. The average Pitot pressure at the laser cavity was more than 100 Torr. Backpressure tests were conducted, and the results of these tests revealed that the static pressure in the cavity remains constant at approximately 10 Torr until the supersonic diffuser breaks back and the cavity unstarts at a backpressure of approximately 80 Torr.

  17. A computational fluid dynamics simulation of a supersonic chemical oxygen-iodine laser

    NASA Astrophysics Data System (ADS)

    Waichman, K.; Rybalkin, V.; Katz, A.; Dahan, Z.; Barmashenko, B. D.; Rosenwaks, S.

    2007-05-01

    The dissociation of I II molecules at the optical axis of a supersonic chemical oxygen-iodine laser (COIL) was studied via detailed measurements and three dimensional computational fluid dynamics calculations. Comparing the measurements and the calculations enabled critical examination of previously proposed dissociation mechanisms and suggestion of a mechanism consistent with the experimental and theoretical results. The gain, I II dissociation fraction and temperature at the optical axis, calculated using Heidner's model (R.F. Heidner III et al., J. Phys. Chem. 87, 2348 (1983)), are much lower than those measured experimentally. Agreement with the experimental results was reached by using Heidner's model supplemented by Azyazov-Heaven's model (V.N. Azyazov and M.C. Heaven, AIAA J. 44, 1593 (2006)) where I II(A') and vibrationally excited O II(a1Δ) are significant dissociation intermediates.

  18. Chemical oxygen-iodine laser with a cryosorption vacuum pump with different buffer gases

    NASA Astrophysics Data System (ADS)

    Xu, Mingxiu; Fang, Benjie; Sang, Fengting; Geng, Zicai; Li, Yongzhao; JIn, Yuqi

    2015-02-01

    A traditional pressure recovery system is the major obstacle to mobile chemical oxygen-iodine laser (COIL) for its huge volume. A cryosorption vacuum pump was used as the pressure recovery system for different buffer gases. It made COIL become a flexible, quiet and pressure-tight. Experiments were carried out on a verti- COIL, which was designed for N2 and energized by a square-pipe jet singlet oxygen generator (JSOG). The output power with CO2 was 27.3% lower than that with N2, but the zeolite bed showed an adsorption capacity threefold higher for CO2 than for N2 in the continuous operation. The great volume efficiency interested researchers.

  19. Singlet oxygen generators - the heart of chemical oxygen iodine lasers: past, present, and future

    NASA Astrophysics Data System (ADS)

    Hewett, Kevin B.

    2008-10-01

    Since the initial demonstration of chemical oxygen iodine lasers in 1977, researchers have realized that the heart of the COIL system is the singlet oxygen generator. This drives the performance of the system in terms of output power, mass efficiency, engineering complexity, reliability and maintainability. For this reason the singlet oxygen generator has been the focus of intense research and development efforts over the last 30 years. This paper reports on the history of singlet oxygen generators - starting with the simple sparger design used in the initial COIL demonstration and ending with current jet or droplet generators used in laboratories around the world. The relative performance of the different generator types will naturally lead to performance goals for the research efforts of the future.

  20. 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.

  1. ARTICLES: Water vapor content in the active medium of an oxygen-iodine chemical laser

    NASA Astrophysics Data System (ADS)

    Zagidullin, M. V.; Igoshin, Valerii I.; Kupriyanov, N. L.

    1987-03-01

    An analysis is made of a thermophysical model of a chemical singlet-oxygen generator. It is shown that at the exit from a thermally insulated reaction vessel, the water vapor content is approximately three times the oxygen content. Calculations are made of the water vapor content when the solution is cooled and circulated through the reaction vessel. As the total pressure is increased, the efficiency of purification of the oxygen in a water vapor condensation trap deteriorates strongly. This is one of the reasons for the degradation of the active medium of a cw oxygen-iodine laser with increasing oxygen pressure. For a trap comprising a smooth tube and a thermally insulated reaction vessel, the trap radius R and the oxygen pressure at the exit p'O2 should satisfy the condition p'O2 R<12 Torr, so that the laser active zone contains less than 10% of water vapor and no less than 50% of O2(1Δ). The oxygen pressure range can be increased by cooling the solution in the reaction vessel.

  2. 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.

  3. Multiphase reacting flow modeling of singlet oxygen generators for chemical oxygen iodine lasers.

    SciTech Connect

    Salinger, Andrew Gerhard; Pawlowski, Roger Patrick; Hewett, Kevin B.; Madden, Timothy J.; Musson, Lawrence Cale

    2008-08-01

    Singlet oxygen generators are multiphase flow chemical reactors used to generate energetic oxygen to be used as a fuel for chemical oxygen iodine lasers. In this paper, a theoretical model of the generator is presented along with its solutions over ranges of parameter space and oxygen maximizing optimizations. The singlet oxygen generator (SOG) is a low-pressure, multiphase flow chemical reactor that is used to produce molecular oxygen in an electronically excited state, i.e. singlet delta oxygen. The primary product of the reactor, the energetic oxygen, is used in a stage immediately succeeding the SOG to dissociate and energize iodine. The gas mixture including the iodine is accelerated to a supersonic speed and lased. Thus the SOG is the fuel generator for the chemical oxygen iodine laser (COIL). The COIL has important application for both military purposes--it was developed by the US Air Force in the 1970s--and, as the infrared beam is readily absorbed by metals, industrial cutting and drilling. The SOG appears in various configurations, but the one in focus here is a crossflow droplet generator SOG. A gas consisting of molecular chlorine and a diluent, usually helium, is pumped through a roughly rectangular channel. An aqueous solution of hydrogen peroxide and potassium hydroxide is pumped through small holes into the channel and perpendicular to the direction of the gas flow. So doing causes the solution to become aerosolized. Dissociation of the potassium hydroxide draws a proton from the hydrogen peroxide generating an HO{sub 2} radical in the liquid. Chlorine diffuses into the liquid and reacts with the HO{sub 2} ion producing the singlet delta oxygen; some of the oxygen diffuses back into the gas phase. The focus of this work is to generate a predictive multiphase flow model of the SOG in order to optimize its design. The equations solved are the so-called Eulerian-Eulerian form of the multiphase flow Navier-Stokes equations wherein one set of the equations represents the gas phase and another equation set of size m represents the liquid phase. In this case, m is representative of the division of the liquid phase into distinct representations of the various droplet sizes distributed in the reactor. A stabilized Galerkin formulation is used to solve the equation set on a computer. The set of equations is large. There are five equations representing the gas phase: continuity, vector momentum, heat. There are 5m representing the liquid phase: number density, vector momentum, heat. Four mass transfer equations represent the gas phase constituents and there are m advection diffusion equations representing the HO{sub 2} ion concentration in the liquid phase. Thus we are taking advantage of and developing algorithms to harness the power of large parallel computing architectures to solve the steady-state form of these equations numerous times so as to explore the large parameter space of the equations via continuation methods and to maximize the generation of singlet delta oxygen via optimization methods. Presented here will be the set of equations that are solved and the methods we are using to solve them. Solutions of the equations will be presented along with solution paths representing varying aerosol loading-the ratio of liquid to gas mass flow rates-and simple optimizations centered around maximizing the oxygen production and minimizing the amount of entrained liquid in the gas exit stream. Gas-entrained liquid is important to minimize as it can destroy the lenses and mirrors present in the lasing cavity.

  4. Plasma Excited Chemical-Oxygen-Iodine Lasers: Optimizing Injection and Mixing for Positive Gain

    NASA Astrophysics Data System (ADS)

    Babaeva, Natalia Y.; Garcia, Luis A.; Arakoni, Ramesh A.; Kushner, Mark J.

    2007-10-01

    Chemical oxygen-iodine lasers achieve oscillation on the ^2P1/2->^2P3/2 transition of atomic iodine at 1.315 μm by a series of excitation transfers from O2(^1δ). In electrically plasma excited devices (eCOILs), O2(^1δ) is produced in a flowing plasma, typically He/O2, at a few to tens of Torr. The iodine is injected into the flow as a He/I2 mixture immediately upstream (or in) a supersonic nozzle. A small positive gain with I* limited to a narrow boundary layer near the wall indicates slow mixing when the I2 is injected from the wall. This results in low utilization of O2(^1δ). In this paper we discuss results from 1- and 2-dimensional computational investigations of means to optimize gain in eCOILs by using different I2 injection strategies. It was found that due to the plasma generated distribution O2(^1δ), placement of injectors closer to the axis significantly increased gain by facilitating complete O2(^1δ)/I2 mixing. This is partly a function of the inlet flow of NO through the discharge which regulates the density of O atoms produced by electron impact dissociation of O2. By optimizing the nozzle dimensions, their location, and I2 and NO flow rates, the yield of O2(^1δ) required to achieve positive gain can be minimized.

  5. Ejector Chemical Oxygen-Iodine Laser with Supersonic Nozzle Bank Based on a Trip-Jet Mixing System

    NASA Astrophysics Data System (ADS)

    Tei, Kazuyoku; Horioka, Kazuhiko; Nakajima, Mitsuo; Sugimoto, Daichi; Watanabe, Goro; Muto, Shigeki; Fujioka, Tomoo

    2008-05-01

    Nozzle banks for an ejector chemical oxygen-iodine laser consisting of two-dimensional slit nozzles with a trip-jet mixing system were tested in the cold- and hot-flow operation regimes. Horizontal Pitot scan experiments demonstrated that the mixing ability of the trips is excellent. The Mach number of the mixed flow was approximately 3. Gain measurements were conducted, and the results of these measurements revealed that the maximum gain was approximately 0.54 m-1. The gain cut off length exceeded 200 mm. Lasing experiments were also conducted, and the power was approximately 3 kW at a chemical efficiency of approximately 18%.

  6. Chemical Oxygen-Iodine Laser Diluted by CO2/N2 Buffer Gases with a Cryosorption Vacuum Pump

    NASA Astrophysics Data System (ADS)

    Xu, Mingxiu; Sang, Fengting; Jin, Yuqi; Fang, Benjie; Chen, Fang; Geng, Zicai; Li, Yongzhao

    2008-11-01

    Experiments were carried out on a verti-chemical oxygen-iodine laser (COIL), which was designed for N2 and energized by a square-pipe jet singlet oxygen generator (JSOG). A cryosorption vacuum pump was used as the pressure recovery system for CO2 and N2 buffer gases. The output power with CO2 was 27.3% lower than that with N2, but the zeolite bed showed an adsorption capacity threefold higher for CO2 than for N2 in the continuous operation with a Cl2 flow rate of 155 mmol/s and a total flow rate of 430±3 mmol/s.

  7. 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.

  8. Power optimization of small-scale chemical oxygen-iodine laser with jet-type singlet oxygen generator

    SciTech Connect

    Blayvas, I.; Barmashenko, B.D.; Furman, D.; Rosenwaks, S.; Zagidullin, M.V.

    1996-12-01

    Studies of power optimization of a 5-cm gain length chemical oxygen-iodine laser (COIL) energized by a jet-type singlet oxygen generator (JSOG) are presented. For 10 mmol/s of Cl{sub 2} flow rate, output power of 132 W with chemical efficiency of 14.5% was obtained without a water vapor trap. 163 W and 18% were achieved when coholed (173 K) He was introduced downstream of the JSOG; under these conditions, the small-signal gain was estimated to be 0.32% cm{sup {minus}1}. 190 W and 10.5% were obtained for 20 mmol/s of Cl{sub 2} flow rate. Replacing He by N{sub 2} as a buffer gas resulted in a 13% power decrease only. The main key for increasing the chemical efficiency of a COIL without a water vapor trap for a given iodine-oxygen mixing system is found to be high oxygen pressure and low water vapor pressure inside the reaction zone of the JSOG. The last goal was achieved by optimizing the composition and temperature of the basic hydrogen-peroxide solution (BHP). The experimental results are discussed and related to the composition and flow conditions of the gaseous reactants and of the BHP.

  9. Dissociation of I II in chemical oxygen-iodine lasers: experiment, modeling, and pre-dissociation by electrical discharge

    NASA Astrophysics Data System (ADS)

    Katz, A.; Waichman, K.; Dahan, Z.; Rybalkin, V.; Barmashenko, B. D.; Rosenwaks, S.

    2007-06-01

    The dissociation of I II molecules at the optical axis of a supersonic chemical oxygen-iodine laser (COIL) was studied via detailed measurements and three dimensional computational fluid dynamics calculations. Comparing the measurements and the calculations enabled critical examination of previously proposed dissociation mechanisms and suggestion of a mechanism consistent with the experimental and theoretical results obtained in a supersonic COIL for the gain, temperature and I II dissociation fraction at the optical axis. The suggested mechanism combines the recent scheme of Azyazov and Heaven (AIAA J. 44, 1593 (2006)), where I II(A' 3Π 2u), I II(A 3Π 1u) and O II(a1Δ g, v) are significant dissociation intermediates, with the "standard" chain branching mechanism of Heidner et al. (J. Phys. Chem. 87, 2348 (1983)), involving I(2P 1/2) and I II(X1Σ + g, v). In addition, we examined a new method for enhancement of the gain and power in a COIL by applying DC corona/glow discharge in the transonic section of the secondary flow in the supersonic nozzle, dissociating I II prior to its mixing with O II(1Δ). The loss of O II(1Δ) consumed for dissociation was thus reduced and the consequent dissociation rate downstream of the discharge increased, resulting in up to 80% power enhancement. The implication of this method for COILs operating beyond the specific conditions reported here is assessed.

  10. Toward understanding the dissociation of I2 in chemical oxygen-iodine lasers: Combined experimental and theoretical studies

    NASA Astrophysics Data System (ADS)

    Waichman, K.; Rybalkin, V.; Katz, A.; Dahan, Z.; Barmashenko, B. D.; Rosenwaks, S.

    2007-07-01

    The dissociation of I2 molecules at the optical axis of a supersonic chemical oxygen-iodine laser (COIL) was studied via detailed measurements and three-dimensional computational fluid dynamics calculations. The measurements, briefly reported in a recent paper [Rybalkin et al., Appl. Phys. Lett. 89, 021115 (2006)] and reanalyzed in detail here, revealed that the number N of consumed O2(aΔg1) molecules per dissociated I2 molecule depends on the experimental conditions: it is 4.5±0.4 for typical conditions and I2 densities applied for optimal operation of the COIL but increases at lower I2 densities. Comparing the measurements and the calculations enabled critical examination of previously proposed dissociation mechanisms and suggestion of a mechanism consistent with the experimental and theoretical results obtained in a supersonic COIL for the gain, temperature, I2 dissociation fraction, and N at the optical axis. The suggested mechanism combines the recent scheme of Azyazov and Heaven [AIAA J. 44, 1593 (2006)], where I2(A'Π2u3), I2(AΠ1u3), and O2(aΔg1,v) are significant dissociation intermediates, with the "standard" chain branching mechanism of Heidner III et al. [J. Phys. Chem. 87, 2348 (1983)], involving I(P1/22) and I2(XΣg +1,v).

  11. 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.

  12. Optically (solar) pumped oxygen-iodine lasers

    NASA Astrophysics Data System (ADS)

    Danilov, O. B.; Zhevlakov, A. P.; Yur'ev, M. S.

    2014-07-01

    We present the results of theoretical and experimental studies demonstrating the possibility of developing an oxygen-iodine laser (OIL) with direct optical pumping of molecular oxygen involving inter-molecular interaction with charge transfer from donor molecule (buffer gas) to acceptor molecule (oxygen). This interaction lifts degeneracy of the lower energy states of molecular oxygen and increases its absorption cross section in the visible spectral region and the UV Herzberg band, where high quantum yield of singlet oxygen is achieved (QY ˜ 1 and QY ˜ 2, respectively) at the same time. A pulse-periodic optical pump sources with pulse energy of ˜50 kJ, pulse duration of ˜25 μs, and repetition rate of ˜10 Hz, which are synchronized with the mechanism of singlet oxygen generation, are developed. This allows implementation of a pulse-periodic oxygen-iodine laser with an efficiency of ˜25%, optical efficiency of ˜40%, and parameter L/ T ˜ 1/1.5, where T is the thermal energy released in the laser active medium upon generation of energy L. It is demonstrated that, under direct solar pumping of molecular oxygen, the efficiency parameter of the OIL can reach L/ T ˜ 1/0.8 in a wide range of scaling factors.

  13. 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.

  14. Deactivation rate of I{sub 2} molecules (X, v {>=} 30) in the medium of a chemical oxygen-iodine laser

    SciTech Connect

    Pichugin, S Yu

    2008-08-31

    The effective deactivation rate constants are calculated for I{sub 2}(X) molecules at vibrational levels with v {>=} 30 colliding with N{sub 2} and O{sub 2} molecules in the medium of a chemical oxygen-iodine laser. The calculated constants (4x10{sup -12} cm{sup 3} s{sup -1} and 3x10{sup -12} cm{sup 3} s{sup -1}) are less by half plus than the corresponding constants found earlier in the paper of Lawrence et al., where the dissociation of I{sub 2} was neglected in calculations. (lasers, active media)

  15. Oxygen-iodine laser research at RFNC-VNIIEF

    NASA Astrophysics Data System (ADS)

    Adamenkov, Anatoliy A.; Deryugin, Yuri N.; Vyskubenko, Boris A.; Ilyin, Sergei P.; Kalinovsky, V. V.; Kolobyanin, Yuriy V.; Konovalov, V. V.; Krukovsky, Ivan M.; Kudryashov, Evgeniy A.; Nikolaev, V. D.

    1998-12-01

    The paper presents the most important efforts in the Chemical Oxygen-Iodine Laser (COIL) research carried on at Russian Federal Nuclear Center VNIIEF and some of their results. In particular, they include experimental data on the laser generation output of subsonic COIL on the water vapor concentration in singlet oxygen, calculated generation values of a supersonic COIL having high singlet oxygen pressure at the nozzle inlet, and experiments with the twisted-aerosol- flow singlet oxygen generator (TASOG) for up to 100 Torr pressures. Requirements are discussed for the supersonic high- pressure COIL components, such as singlet oxygen generator and the system for singlet oxygen mixing with iodine.

  16. Frequency-doubled pulsed chemical oxygen-iodine laser as an efficient pump source for high-power solid state lasers

    NASA Astrophysics Data System (ADS)

    Kryukov, P. G.

    1995-12-01

    Output laser parameters are enhanced significantly by using laser pumping. An excellent example is usage of laser diodes for solid-state laser pumping. Although there are permanent advances towards development of this technique, its application for laser systems of more than 100 J output requires time, significant effort and expense. I propose another pumping source based on a rather simple and inexpensive technique and admitted scaling up to energy values which are beyond the reach now with the diodes. This is a pulsed chemical oxygen-iodine laser (COIL) with intracavity frequency doubling. The COIL operates on a laser transition of atomic iodine (1.315 micrometer). The upper laser level populates via energy transfer from metastable oxygen molecules (O2(1(Delta) )-singlet oxygen) which formed in a rather simple chemical reaction between an alkaline solution of hydrogen peroxide and gaseous chlorine. The COIL is a gas laser of low pressure (not more than several torrs), having high output parameters and efficiency. A peculiar mechanism of inversion formation makes it difficult to realize a pulsed mode operation by conventional techniques. In particular, there is a limitation of energy stored in large volume. This problem has been solved in our laboratory by forming of atomic iodine with external exposure on some iodides. As a result a pulsed COIL system with an external initiation arose. High optical quality of an active medium and rather high intensity permit us to get 100% intracavity frequency doubling. The wavelength (657.5 nm) is suitable for pumping of some efficient laser materials such as Cr:LiSAF, and garnets codoped with Cr3+ and TR3+ ions. The proposed laser system has the following advantages: (1) scaling by merely increasing the size of the laser, (2) regulated pulse duration from 20 microseconds, (3) well-collimated beam, and (4) repetition rate of about tens Hz. There is a possibility to use the proposed laser system to pump large-size laser elements of laser-drivers for ICF. It is especially interesting to use the proposed pumping source for chirped pulse amplification. Energy of 100 - 200 J can be obtained with currently available pulsed COILs. Thereby a real ability opens for generation of ultrashort pulses of petawatt level output power.

  17. 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.

  18. 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)

  19. 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)

  20. Overview of iodine generation for oxygen-iodine lasers

    NASA Astrophysics Data System (ADS)

    Jirásek, Vít.

    2012-01-01

    A review of the methods for generation of iodine for oxygen-iodine lasers (OIL) is presented. The chemical and physical methods for production of both atomic (AI) and molecular (MI) iodine have been searched in order to improve the efficiency and/or technology of OILs. These trials were motivated by the estimations that a substantial part of singlet oxygen (SO) could be saved with these methods and the onset of the laser active medium will be accelerated. Vapour of MI can be generated by the evaporation of solid or pressurized liquid I2, or synthesized in situ by the reaction of Cl2 with either HI or CuI2. The chemical methods of generation of AI are based on the substitution of I atom in a molecule of HI or ICl by another halogen atom produced usually chemically. The discharge methods include the dissociation of various iodine compounds (organic iodides, I2, HI) in the RF, MW, DC-pulsed or DC-vortex stabilized discharge. Combined methods use discharge dissociation of molecules (H2, F2) to gain atoms which subsequently react to replace AI from the iodine compound. The chemical methods were quite successful in producing AI (up to the 100% yield), but the enhancement of the laser performance was not reported. The discharge methods had been subsequently improving and are today able to produce up to 0.4 mmol/s of AI at the RF power of 500 W. A substantial enhancement of the discharge- OIL performance (up to 40%) was reported. In the case of Chemical-OIL, the enhancement was reported only under the conditions of a low I2/O2 ratio, where the "standard" I2 dissociation by SO is slow. The small-signal gain up to 0.3 %/cm was achieved on the supersonic COIL using the HI dissociated in the RF discharge. Due to the complicated kinetics of the RI-I-I2-SO system and a strong coupling with the gas flow and mixing, the theoretical description of the problem is difficult. It, however, seems that we can expect the major improvement of the OIL performance for those systems, where the SO yield is rather low (DOIL) or for the high-pressure COIL, where the quenching processes are important and the shortage of the distance needed for the preparation of active media is essential.

  1. Analytic study of the chain dark decomposition reaction of iodides - atomic iodine donors - in the active medium of a pulsed chemical oxygen-iodine laser: 2. Limiting parameters of the branching chain dark decomposition reaction of iodides

    SciTech Connect

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

    2009-08-31

    The final stages in the development of a branching chain decomposition reaction of iodide in the active medium of a pulsed chemical oxygen-iodine laser (COIL) are analysed. Approximate expressions are derived to calculate the limiting parameters of the chain reaction: the final degree of iodide decomposition, the maximum concentration of excited iodine atoms, the time of its achievement, and concentrations of singlet oxygen and iodide at that moment. The limiting parameters, calculated by using these expressions for a typical composition of the active medium of a pulsed COIL, well coincide with the results of numerical calculations. (active media)

  2. Oxygen-iodine ejector laser with a centrifugal bubbling singlet-oxygen generator

    SciTech Connect

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

    2005-10-31

    It is shown that if a supersonic oxygen-iodine ejector laser is fed by singlet oxygen from a centrifugal bubbling generator operating at a centrifugal acceleration of {approx}400g, the laser output power achieves a value 1264 W at a chemical efficiency of 24.6% for an alkaline hydrogen peroxide flow rate of 208 cm{sup 3}s{sup -1} and a specific chlorine load of 1.34 mmol s{sup -1} per square centimetre of the bubble layer. (lasers)

  3. 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)

  4. The research of Iodine pool pressure of chemical oxygen-iodine laser in non-equilibrium condition and its automatic control system design

    NASA Astrophysics Data System (ADS)

    Zhou, Songqing; Qu, Pubo; Ren, Weiyan

    2013-05-01

    In the working process of chemical oxy-iodigenne laser(COIL), the change of iodine pool pressure is complicated. As a result, it causes some mis-judgements, such as the damage of heater and the leakage of iodine steam. Further more, when the heater electric circuit is in a single working status, and after the heater switch is on or off, there exists a buffer time for the stabilization of iodine pool pressure, which is a relatively long time, and the minimum buffer pressure exceeds to 19 torr . Of course, it increases the preparing time for steady operation of laser, and reduces the quality of laser beam. In this paper, we study the iodine pool pressure of COIL in non-equilibrium condition, and analyze the mutation and the serious buffer phenomenon of iodine steam pressure. At the same time, we design an automatic control system for iodine pool pressure, which consists of five modules, such as data collection, automatic control, manual control, heater electric circuit, and the setting and display of pressure. This system uses two kinds of heater electric circuits, in this way, the serious buffer phenomenon of iodine pool pressure is effectively avoided. As a result, the maximal buffer pressure reduces to 4 torr, this makes sure that the iodine steam pressure is suitable for the operation of COIL, which produces a good condition for the steady operation of laser system and an excellent laser output.

  5. Dissociation of molecular iodine in RF discharge for oxygen-iodine lasers

    NASA Astrophysics Data System (ADS)

    Jirásek, V.; Schmiedberger, J.; Čenský, M.; Kodymová, J.

    2012-04-01

    The dissociation of molecular iodine in 40 MHz-RF discharge was studied experimentally. This generation of atomic iodine is aimed at use in oxygen-iodine lasers. The discharge was ignited in a mixture of I2 + buffer gas fast-flowing through the cylindrical chamber and the discharge products were injected into a supersonic flow of nitrogen. The atomic iodine number density was measured in a low-pressure cavity after mixing with nitrogen and the dissociation fraction was calculated related to the input I2 flow rate. The dissociation fraction of 46.2% was achieved at 0.22 mmol/s of I2 and 7 mmol/s of Ar and RF power of 500 W. Argon and helium were used as a buffer gas; discharge stability and dissociation efficiency were better with argon. At the I2 flow rate corresponding to the operation of a 1 kW chemical oxygen-iodine laser, the dissociation fraction was about 20%. The dissociation efficiency (the fraction of absorbed energy used for the dissociation) significantly decreased with increasing in the specific energy. At a reasonable I2 flow rate (0.32 mmol/s), the maximum achieved efficiency was 8.5% and the corresponding energy cost was 8.9 eV per dissociating of one I2 molecule. The input energy of more than 3 kJ per 1 mmol of I2 is needed for dissociating at least 50% of I2. The obtained dependencies on the gas flow rates infer a good chance for scaling-up of the tested RF discharge generator for the intended application.

  6. Plasma chemistry of iodine atoms production for CW oxygen-iodine laser

    NASA Astrophysics Data System (ADS)

    Mikheyev, P. A.; Ufimtsev, N. I.; Demyanov, A. V.; Kochetov, I. V.; Napartovich, A. P.

    2012-01-01

    Usage of iodine atoms instead of molecules in oxygen-iodine laser permits to expand its range of operation parameters and improve the weight per power ratio. Results of experiments and modeling of plasma chemistry processes resulting in CH3I dissociation in a planar 40 MHz discharge are presented, showing that addition of oxygen or water into Ar:He:CH3I mixtures can lead to a noticeable increase in CH3I dissociation rate and inhibit iodine recombination during transport.

  7. 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.

  8. 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)

  9. 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

  10. 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)

  11. 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.

  12. Gas-Flow Slab RF Discharge as a Source of Singlet Delta Oxygen for Oxygen Iodine Laser

    NASA Astrophysics Data System (ADS)

    Ionin, Andrey A.; Klimachev, Yurii M.; Kochetov, Igor V.; Napartovich, Anatoly P.; Rulev, Oleg A.; Seleznev, Leonid V.; Sinitsyn, Dmitry V.

    2010-10-01

    Results of experimental and theoretical study of singlet delta oxygen (SDO) production in transverse gas flow RF slab discharge for an electric discharge oxygen-iodine laser are presented. The electric discharge facility operating in both pulse-periodic and CW mode was manufactured: gas flow duct including multi-path cryogenic heat exchanger, dielectric slab channel, and slab electrode system incorporated in the channel for RF discharge ignition. Experiments on SDO production in transverse gas flow RF discharge were carried out. SDO production depending on gas mixture content and pressure, gas flow velocity, low-frequency modulation of RF power and RF discharge power was experimentally studied. It was shown that SDO yield increased with gas pressure decrease, gas flow deceleration and helium dilution of oxygen at the same input power. CW RF discharge was demonstrated to be the most efficient for SDO production at the same averaged input power of RF discharge. SDO yield was demonstrated to be not less than 10%.

  13. Catalytic enhancement of singlet oxygen production and optical gain in electric discharge oxygen-iodine laser systems

    NASA Astrophysics Data System (ADS)

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

    2011-03-01

    We are investigating catalytically enhanced production of singlet oxygen, O2(a1▵g), observed by reaction of O2/He discharge effluents over an iodine oxide film surface in a microwave discharge-flow reactor at 320 K. We have previously reported a two-fold increase in the O2(a) yields by this process, and corresponding enhancement of I(2P1/2) excitation and small-signal gain upon injection of I2 and NO2. In this paper we review observed I* excitation behavior and correlations of the catalytically generated O2(a) with atomic oxygen over a large range of discharge-flow conditions to develop a conceptual reaction mechanism for the phenomena. We describe a first-generation catalytic module for the PSI supersonic MIDJet/EOIL reactor, and tests with this module for catalyst coating deposition and enhancement of the small-signal gain observed in the supersonic flow. The results present compelling evidence for catalytic production of vibrationally excited O2(X,v) and its participation in the I* excitation process. The observed catalytic effects could significantly benefit the development of high-power electrically driven oxygen-iodine laser systems.

  14. 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)

  15. 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.

  16. Singlet-oxygen generator on base of solid-state fullerene-containing structures for fullerene-oxygen-iodine laser design: physical principles

    NASA Astrophysics Data System (ADS)

    Belousova, Inna M.; Belousov, V. P.; Danilov, Oleg B.; Ermakov, A. V.; Kiselev, V. M.; Krys'ko, A. V.; Murav'eva, T. D.; Ponomarev, A. N.; Sosnov, Eugene N.

    2005-03-01

    The singlet oxygen generator development is the basic problem of fullerene oxygen iodine laser design. Physival principles of singlet oxygen generator on the base of solid-state fullerene-containing structures were investigated. The solid-state singlet oxygen generator is a surface of membranous structures with embedded fullerenes (fullerites) of fullerene-like nanostructures - astralenes. Singlet oxygen is generated by interaction of molecular oxygen, sorbed by the surface and fullerene-like nanostructures, photoexcited by optical pump. The singlet oxygen entrance in gas phase occurs as a desorption wave, caused by surface heating by optical pump. The effectiveness of molecular oxygen sorption by fullerene C60 and astralen depending on temperature, the extent of nanostructures heating, oxygen pressure and morphology of coating was studies.

  17. 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%.

  18. 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.

  19. Oxygen-iodine active medium with external production of iodine in a DC glow discharge

    NASA Astrophysics Data System (ADS)

    Mikheyev, Pavel A.; Azyazov, Valeriy N.; Mezhenin, Adrew V.; Ufimtsev, Nikolay I.; Shepelenko, Alexander A.; Voronov, Anatoly I.; Kupryaev, Nikolay V.; Pichugin, Sergey Yu.; Vorobyov, Mikhail V.

    2007-05-01

    Experiments with a flow cell apparatus imitating conditions of oxygen-iodine laser, equipped with a chemical jet singlet oxygen generator and an electric discharge iodine generator have been performed. I II and CH 3I in the flow of Ar were used as atomic iodine precursors. The distributions of the electronically excited species along the flow were examined detecting their optical emissions. A straightforward comparison of two methods of oxygen-iodine medium production - conventional, by means of I II dissociation in the singlet oxygen flow and with iodine atoms produced externally in the electric discharge - was performed. It was found that stored electron energy lifetime had been about 30% longer, when iodine was produced from CH 3I in the discharge, compared to the conventional I II dissociation in the singlet oxygen flow. It was observed that maximums of the I(2P 1/2) and I II(B) concentrations had shifted to the nozzle plane, when I II in Ar carrier was subjected to the glow discharge, pointing to a nearly twofold increase in the I II dissociation rate. Contrary to the known results for low iodine and singlet oxygen concentrations, squared dependence of the amplitude of the I II(B) luminescence maximum with I(2P 1/2) concentration was observed in the dissociation region for both methods of iodine production.

  20. Chemical lasers

    NASA Astrophysics Data System (ADS)

    Khariton, Y.

    1984-08-01

    The application and the advances of quantum electronics, specifically, of optical quantum generators lasers is reviewed. Materials are cut, their surfaces are machined, chemical transformations of substances are carried out, surgical operations are performed, data are transmitted, three dimensional images are produced and the content of microimpurities, in the atmosphere, are analyzed by use of a beam. Laser technology is used in conducting investigations in the most diverse fields of the natural and technical sciences from controlled thermonuclear fusion to genetics. Many demands are placed on lasers as sources of light energy. The importance of low weight, compactness of the optical generator and the efficiency of energy conversion processes is emphasized.

  1. Chemical lasers

    NASA Astrophysics Data System (ADS)

    Ablekov, V. K.; Denisov, Iu. N.; Proshkin, V. V.

    1983-08-01

    Recent developments in the theory and application of chemical lasers (CLs) are surveyed in a translation of a book published in Russian in 1980. The laws governing the gas-phase chemical reactions typical of CLs are introduced, the principles of quantum-mechanical description of molecular systems are reviewed, and the kinetics of CL processes are examined. The four general classes of CL are then presented in detail: static-gas, subsonic, supersonic, and detonation CLs. Graphs, diagrams, and drawings of experimental setups are provided.

  2. 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.

  3. Singlet oxygen generator for a solar powered chemically pumped iodine laser

    NASA Technical Reports Server (NTRS)

    Busch, G. E.

    1984-01-01

    The potential of solid phase endoperoxides as a means to produce single-delta oxygen in the gas phase in concentrations useful to chemical oxygen-iodine lasers was investigated. The 1,4 - endoperoxide of ethyl 3- (4-methyl - 1-naphthyl) propanoate was deposited over an indium-oxide layer on a glass plate. Single-delta oxygen was released from the endoperoxide upon heating the organic film by means of an electrical discharge through the conductive indium oxide coating. The evolution of singlet-delta oxygen was determined by measuring the dimol emission signal at 634 nm. Comparison of the measured signal with an analytic model leads to two main conclusions: virtually all the oxygen being evolved is in the singlet-delta state and in the gas phase, and there is no significant quenching other than energy pooling on the time scale of the experiment (approximately 10 msec). The use of solid phase endoperoxide as a singlet-delta oxygen generator for an oxygen-iodine laser appears promising.

  4. Singlet oxygen generator for a solar powered chemically pumped iodine laser. Final Report

    SciTech Connect

    Busch, G.E.

    1984-04-01

    The potential of solid phase endoperoxides as a means to produce single-delta oxygen in the gas phase in concentrations useful to chemical oxygen-iodine lasers was investigated. The 1,4 - endoperoxide of ethyl 3- (4-methyl - 1-naphthyl) propanoate was deposited over an indium-oxide layer on a glass plate. Single-delta oxygen was released from the endoperoxide upon heating the organic film by means of an electrical discharge through the conductive indium oxide coating. The evolution of singlet-delta oxygen was determined by measuring the dimol emission signal at 634 nm. Comparison of the measured signal with an analytic model leads to two main conclusions: virtually all the oxygen being evolved is in the singlet-delta state and in the gas phase, and there is no significant quenching other than energy pooling on the time scale of the experiment (approximately 10 msec). The use of solid phase endoperoxide as a singlet-delta oxygen generator for an oxygen-iodine laser appears promising.

  5. 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.

  6. Visible chemical lasers

    NASA Astrophysics Data System (ADS)

    Perram, Glen P.

    Applications for visible chemical lasers, which show great potential as highly efficient, wavelength agile, deployable, high brightness laser systems are discussed. These systems provide important and unique opportunities for both directed energy weapons and diagnostic applications. Issues discussed in this paper include concepts, requirements and approaches to visible chemical lasers. A survey of candidate energy transfer system is also given, with emphasis on excited NF and nitrogen driven lasers. The long term, low level investment in this techonology area during the past decade firmly establishes the opportunity for a lasing demonstration in the near term.

  7. Partial feedback unstable resonator on small scale supersonic large aperture chemical laser

    NASA Astrophysics Data System (ADS)

    Wang, Hongyan; Wang, Rui; Li, Lei

    2015-05-01

    There is always a challenge on large aperture medium power laser's resonator design, stable resonator would supports significant higher order transverse modes, folded and telescope stable resonator are too complex and not preferred by engineers, unstable resonator need rather large round trip gain to compensate its high geometric out-coupling, which is difficult for this kind of laser since its gain length is limited due to the power level and large aperture. Partial feedback unstable resonator had been proposed to tackle this difficulty since the early days of laser development, however, the debates of its effect never stopped even with those distinguished optical resonator scientists such as Siegman, Anan'ev, and Weber. Recently integrated partial feedback unstable resonator design had been successfully demonstrated on a medium size chemical oxygen iodine laser. In this paper, we carry this resonator configuration on a small scale discharge driven supersonic nozzle array Hydrogen Fluoride chemical laser, a typical large aperture short gain length device. With magnification equals 4/3, we successfully get ten Watts level ring beam output.

  8. 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…

  9. Development of safe infrared gas lasers

    NASA Astrophysics Data System (ADS)

    Mainuddin; Singhal, Gaurav; Tyagi, R. K.; Maini, A. K.

    2013-04-01

    Infrared gas lasers find application in numerous civil and military areas. Such lasers are therefore being developed at different institutions around the world. However, the development of chemical infrared gas lasers such as chemical oxygen iodine lasers (COIL) involves the use of several hazardous chemicals. In order to exploit full potential of these lasers, one must take diligent care of the safety issues associated with the handling of these chemicals and the involved processes. The present paper discusses the safety aspects to be taken into account in the development of these infrared gas lasers including various detection sensors working in conjunction with a customized data acquisition system loaded with safety interlocks for safe operation. The developed safety schemes may also be implemented for CO2 gas dynamic laser (GDL) and hydrogen fluoride-deuterium fluoride (HF-DF) Laser.

  10. 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.

  11. 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.

  12. Laser spectroscopy for studying chemical processes

    NASA Astrophysics Data System (ADS)

    Wolfrum, J.

    1988-07-01

    In recent years, various methods have been developed to observe and to influence the course of chemical reactions using laser radiation. By selectively increasing the translational, rotational, and vibrational energies and by controlling the relative orientation of the reaction partners with tunable infrared and UV lasers, direct insight can be gained into the molecular course of the breaking and re-forming of chemical bonds. As exmaples for the application of lasers in chemical synthesis the production of monomers and catalysts is discussed. The application of linear and nonlinear laser spectroscopic methods, such as laser-induced fluorescence (LIF), Coherent anti-Stokes Raman Scattering (CARS), infrared-absorption measurements with tunable diode and molecular lasers is described for non-intrusive observation of the interaction of transport processes with chemical reactions used in industrial processes with high temporal, spectral and spatial resolution. Finally the application of a UV laser microbeam apparatus in genetic engineering for laser-induced cell fusion, genetic transformation of plant cells as well as diagnosis of human diseases by laser-microdissection of chromosomes is described.

  13. Chemical stabilization of laser dyes

    NASA Astrophysics Data System (ADS)

    Koch, Tad H.

    1987-05-01

    Coumarin laser dyes upon excitation degrade to produce products which absorb at the lasing wavelength. This results in attenuation of dye laser output through interference of stimulated emission. The roles of singlet oxygen and excitation intensity on dye degradation were explored. Singlet oxygen is formed but its reactions with the dye do not appear to be a major cause of dye laser output deterioration. High light intensity results in dye sensitized, solvent oligomerization to yield materials which interfere with dye stimulated emission. 1, 4-Diazabicyclo2,2,2octane (DABCO)inhibits this oligomerization.

  14. XeCl laser chemical problems

    NASA Astrophysics Data System (ADS)

    Tennant, R.

    Problems concerning the development of a long-life, high-energy, and high-pulse-rate XeCl laser are partly related to the occurrence of chemical processes which produce harmful effects on laser components. These effects are related to optical damage, corrosion of laser materials, and gas contamination. A description is presented of a number of approaches designed to minimize or control the deleterious chemical processes. Attention is also given to recommended materials of construction, XeCl gas reprocessing, and an XeCl clean-up system. On the basis of the obtained improvements, it is believed that it will be possible to manufacture reliable systems capable of delivering higher average powers at higher pulse rates for at least 1,000 million pulses.

  15. 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.

  16. Optical Bench For Chemical Laser Testing

    NASA Astrophysics Data System (ADS)

    Durie, D. S. L.

    1981-08-01

    An optical bench for developmental testing of chemical laser hard-ware is described. It is specially designed to withstand the vibration and thermal disturbances inherent in this type of laser, and has universal features which enable it to accept a variety of nozzle and mirror sizes. The paper deals with the adaptation of traditional designs to meet new requirements in the areas of bench deflection, adjustable mirror mounts, and remote mirror actuation for closed cavity power measurements. In particular, a noncantilever mount with offset pivot for heavy mirrors is described.

  17. 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 vertical and horizontal plane. Mechanical tests and finite element analysis were undertaken to verify that the gimbal drives and mounting hardware had sufficient capacity to handle the inertia of the large 22-inch diameter mirror while maintaining adequate mirror flatness. This paper will provide an overview of the remote chemical detection system and will describe innovative optical mechanical solutions developed to overcome several alignment and stability issues.

  18. Chemically assisted laser ablation ICP mass spectrometry.

    PubMed

    Hirata, Takafumi

    2003-01-15

    A new laser ablation technique combined with a chemical evaporation reaction has been developed for elemental ratio analysis of solid samples using an inductively coupled plasma mass spectrometer (ICPMS). Using a chemically assisted laser ablation (CIA) technique developed in this study, analytical repeatability of the elemental ratio measurement was successively improved. To evaluate the reliability of the CLA-ICPMS technique, Pb/U isotopic ratios were determined for zircon samples that have previously been analyzed by other techniques. Conventional laser ablation for Pb/U shows a serious elemental fractionation during ablation mainly due to the large difference in elemental volatility between Pb and U. In the case of Pb/U ratio measurement, a Freon R-134a gas (1,1,1,2-tetrafluoroethane) was introduced into the laser cell as a fluorination reactant. The Freon gas introduced into the laser cell reacts with the ablated sample U, and refractory U compounds are converted to a volatile U fluoride compound (UF6) under the high-temperature condition at the ablation site. This avoids the redeposition of U around the ablation pits. Although not all the U is reacted with Freon, formation of volatile UF compounds improves the transmission efficiency of U. Typical precision of the 206Pb/238U ratio measurement is 3-5% (2sigma) for NIST SRM 610 and Nancy 91500 zircon standard, and the U-Pb age data obtained here show good agreement within analytical uncertainties with the previously reported values. Since the observed Pb/U ratio for solid samples is relatively insensitive to laser power and ablation time, optimization of ablation conditions or acquisition parameters no longer needs to be performed on a sample-to-sample basis. PMID:12553756

  19. 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.

  20. 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.

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

    NASA Astrophysics Data System (ADS)

    Wade, Richard C.; Ulrich, Peter B.

    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.

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. Remote chemical sensing with quantum cascade lasers

    NASA Astrophysics Data System (ADS)

    Harper, Warren W.; Strasburg, Jana D.

    2004-09-01

    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 retroreflector. 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 ~1x10-4 could be achieved with 5 seconds of data averaging, even under high turbulence conditions.

  8. 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.

  9. 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. PMID:12777015

  10. Hydrogen fluoride chemical laser cascade dynamics under cavity loss modulation

    NASA Astrophysics Data System (ADS)

    Li, Lei; Wang, Hongyan

    2015-02-01

    Under cavity loss modulation, enormous dynamic behaviors will come up in B type cascade laser. In this paper, we built a two-wavelength cascade transition balanced equation model for CW HF chemical laser, 2P(5) and 1P(6) line were taken as cascade pair. We carried out cavity loss modulation experiment on a small scale supersonic discharge driven hydrogen fluoride chemical laser. From the view of phase space, we explained the characteristics by nonlinear time series analysis tools.

  11. Properties of O2(1?)-I(2P1/2) laser medium with a dc glow discharge iodine atom generator

    NASA Astrophysics Data System (ADS)

    Mikheyev, Pavel A.; Azyazov, Valeriy N.

    2008-12-01

    Experiments were carried out in a flow cell apparatus under conditions corresponding to those of a typical oxygen-iodine laser. The cell was equipped with a chemical jet type singlet oxygen generator and an electric discharge for the production of iodine atoms. The properties of the discharge generator and the active medium were studied using laser-induced fluorescence and emission spectroscopy. I2 or CH3I entrained in a carrier flow of Ar were used as atomic iodine precursors. About 50% of the iodine contained in CH3I molecules was extracted in the generator. 2.6% of the electric power loaded into the discharge was used in CH3I dissociation. Right after the discharge 80%-90% of the iodine flow consisted of atoms. However, due to recombination during transport, only 20%-50% of atoms remained at the point of injection into the oxygen flow. A straightforward comparison of two methods of oxygen-iodine medium productionconventional, by means of I2 dissociation in the singlet oxygen flow and with iodine atoms produced externally in the electric dischargewas performed. It was found that the lifetime for the energy stored in singlet oxygen was about 30% longer, when atomic iodine was produced from CH3I in the discharge, as compared to the conventional chemical dissociation of I2 in the singlet oxygen flow.

  12. Remote Chemical Sensing Using Quantum Cascade Lasers

    SciTech Connect

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

    2004-01-20

    Research done by the IR sensors team at PNNL is focused on developing advanced spectroscopic methods for detecting signatures of nuclear, chemical, biological and explosives weapons or weapons production. The sensors we develop fall into two categories: remote sensors that can be operated at distances ranging from 150 m to 10 km, and point sensors that are used for in-situ inspection and detection. FY03 has seen an explosion in FM DIAL progress with the net result being solid confirmation that FM DIAL is a technique capable of remote chemical monitoring in a wide variety of venues. For example, FM DIAL was used to detect a small plume of hydrogen sulfide, a candidate CW agent, released in the desert environment of the Hanford 200 Area site. These experiments were conducted over a range of physical conditions including outside temperatures ranging from 70 F to 105 F and turbulence conditions ranging from quiescent to chaotic. We are now rapidly developing the information needed to design prototype FM DIAL systems that are optimized for specific applications that include scenarios such as fixed position stand-off detection and mobile UAV mounted remote monitoring. Just as an example, in FY04 we will use FM DIAL to detect both in-facility and outdoor release of enriched UF6. The rapid progress in FM DIAL research made in FY03 is attributed to several advances. First, final construction of a custom-designed trailer allowed the instrument to be housed in a mobile temperature-controlled environment. This allowed the experiment to be transported to several locations so that data could be collected under a range of physical conditions. This has led to a better understanding of a variety of experimental noise sources. With this knowledge, we have been able to implement several changes in the way the FM DIAL data is collected and processed, with the net result being a drastic improvement in our confidence of analyte concentration measurement and an improvement i n the 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.

  13. Laser-induced gas breakdown - Spectroscopic and chemical studies.

    NASA Technical Reports Server (NTRS)

    De Montgolfier, PH.; Dumont, P.; Mille, Y.; Villermaux, J.

    1972-01-01

    Discussion of the results of several experimental investigations on laser-induced gas breakdown. The experiments included time-resolved spectroscopy, direct detection of H atoms with a TiO2 probe, and chemical reactions; each of them provided insight into the behavior of the medium at different times. Chemical reactions and explosions have been initiated by the laser beam when a plasma was created. No primary multiphotonic absorption and no macroscopic chemical reactions were observed below the breakdown threshold.

  14. Laser-based instrumentation for the detection of chemical agents

    SciTech Connect

    Hartford, A. Jr.; Sander, R.K.; Quigley, G.P.; Radziemski, L.J.; Cremers, D.A.

    1982-01-01

    Several laser-based techniques are being evaluated for the remote, point, and surface detection of chemical agents. Among the methods under investigation are optoacoustic spectroscopy, laser-induced breakdown spectroscopy (LIBS), and synchronous detection of laser-induced fluorescence (SDLIF). Optoacoustic detection has already been shown to be capable of extremely sensitive point detection. Its application to remote sensing of chemical agents is currently being evaluated. Atomic emission from the region of a laser-generated plasma has been used to identify the characteristic elements contained in nerve (P and F) and blister (S and Cl) agents. Employing this LIBS approach, detection of chemical agent simulants dispersed in air and adsorbed on a variety of surfaces has been achieved. Synchronous detection of laser-induced fluorescence provides an attractive alternative to conventional LIF, in that an artificial narrowing of the fluorescence emission is obtained. The application of this technique to chemical agent simulants has been successfully demonstrated. 19 figures.

  15. Chemical-free cleaning using excimer lasers

    NASA Astrophysics Data System (ADS)

    Lizotte, Todd E.; O'Keeffe, Terence R.

    1996-04-01

    A critical requirement in many industrial processes is the cleaning of oils and grease, oxides, solvent residues, particles, thin films and other contaminants from surfaces. There is a particularly acute need in the electronics industry for cleaning semiconductor wafers and computer chips and in the metals industry for removing oxides and other contaminants. Cleaning traditionally is done by various wet chemical processes, almost all consuming large amounts of water and producing large amounts of hazardous wastes. To further complicate this, some of these cleaning agents and vast water consumption are undergoing stringent restrictions. The Radiance ProcessSM is a novel, patented Excimer Laser approach to dry surface cleaning. The process has removed particles from 80 microns to submicron sizes, paints, inks, oxides, fingerprints, hazes, parts of molecules and metallic ions in fingerprints. The process does not ablate, melt or damage the underlying surface. Micro-roughening on some Silicon and Gallium Arsenide is on the order of 1A or less. This paper will discuss the various applications with this process and the latest results from a beta wafer cleaning prototype test bed system that is being built under an EPA grant and joint partnership between Radiance Services Company, Neuman Micro Technologies, Inc. and the Microelectronics Research Laboratory.

  16. 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.

  17. 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.

  18. 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.

  19. 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

  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 stabilization of the coumarin 1 dye laser

    SciTech Connect

    von Trebra, R.J.; Koch, T.H.

    1983-01-15

    The chemical stabilization of coumarin 1, 7-diethylamino-4-methylcoumarin, in a nitrogen laser pumped dye laser and coumarin 311, 7-dimethylamino-4-methylcoumarin, under cw conditions with sulfur-free radical chain transfer agents, are described. The mechanism for stabilization involves encounter of triplet coumarin and ground state coumarin with subsequent radical formation and radical disproportionation catalyzed by the chain transfer agents. The output of the coumarin 1 dye laser decreased 10% when the dye solution was stabilized with cysteine hydrochloride over a 12-h period. The output of the unstabilized dye laser decreased 50% during a similar period of operation.

  2. 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.

  3. 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.

  4. Efficiency of pulsed-discharge-initiated HF chemical lasers

    NASA Astrophysics Data System (ADS)

    Chuchem, D.; Amit, M.

    1993-05-01

    In the pulsed HF chemical laser the reactants, typically SF6 and H2 diluted in He, are premixed in the laser cavity. The laser pumping reaction, F + H2 yields HF* + H, occurs following the production of free neutral F atoms from the SF6 host molecule. One method commonly employed in `cracking' the F atom host molecule is dissociative electron attachment during pulsed electrical discharge. Typically, this pulsed discharge is produced when a low-inductance storage capacitor, C1, is charged to high voltage, and discharged through a two electrode gap in the laser cavity with a low-inductance circuit. The introduction of a high-voltage switch into this circuit is necessary because the laser gap threshold breakdown voltage is usually too low to achieve appreciable efficiency. The efficiency of this process is improved by introducing an intermediate capacitor, C2, into the circuit. Generally this efficiency improvement is explained by the observation that the C2-laser circuit has a much lower inductance than the C1-laser circuit because the C1-laser circuit must include a high-voltage switch. Thus, in this capacity, C2 is called a `speed-up' capacitor. In this paper we present data to show that for voltages above the discharge threshold region, and various C1/C2 ratios, there is a direct correlation between laser output energy, and the energy transferred to the C2 capacitor.

  5. Laser-chemical finishing of micro forming tools

    NASA Astrophysics Data System (ADS)

    Stephen, Andreas; Gerhard, Christoph; Vollertsen, Frank

    2011-03-01

    In this contribution, we report on a laser-chemical removal method for precise machining of micro forming tools. Thereby, a focused machining laser beam is guided coaxially to an etchant jet stream. Since the material removal is caused by laser-induced chemical reactions using this method, machining is achieved at low laser powers. Hence, material stressing involving micro cracks and further parasitic effects can be avoided. Due to these advantages, this method offers a suitable technique for the finishing of precision micro tools. Several experiments have been performed at rotary swaging jaws made of Stellite 21 in order to chamfer the edged transition section between the operating sphere and the tool flank. The influence of both different laser powers and work piece traverse speeds has been investigated. For this purpose, several parallel laser paths were applied along the edged transition section when varying the process parameters. Here, the incident laser beam is subjected to different angles of incidence. Due to reflection effects, the process parameters have to be matched with respect to the particular angle of incidence during the machining. In this vein, the edged transition section of rotary swaging jaws was chamfered at radii in the range of 120 μm.

  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. Laser-Assisted Chemical Polishing of Silicon (112) Wafers

    NASA Astrophysics Data System (ADS)

    Dandekar, Niru; Chivas, Robert; Silverman, Scott; Kou, Xiaolu; Goorsky, Mark

    2012-10-01

    Pulsed laser-assisted chemical etching (PLACE) offers an advanced, novel substrate preparation method for molecular beam epitaxy (MBE) growth of mercury cadmium telluride on silicon (112) wafers. By controlling the laser fluence, the chemical etch process is refined into a final polish step. PLACE offers surface roughness on the order of chemical mechanical polishing standards and has been verified by 488-nm Raman and high-resolution x-ray diffraction as causing no surface or subsurface damage. To the contrary, experiments show that using PLACE not only alters the surface chemically but also removes subsurface damage through recrystallization reaching micron depths. The process occurs in a modular vacuum chamber that could conceivably be transferred between tools so that vacuum is not broken between polishing and MBE deposition. PLACE can achieve ultra-high-purity and fine dimensional control since it is a dry process relying on pyrolytic vapor-phase reactions initiated, and constrained, by a pulsed laser. Since the process is a function of laser fluence and optics, it is imminently scalable to 6-inch wafer sizes and beyond.

  8. Laser spectroscopy of chemically reactive species

    SciTech Connect

    Wu, Ming; Sears, T.J.

    1993-02-01

    We report the observation of stimulated emission pumping spectra in the NCO radical formed in a supersonic free jet expansion by the reaction between photolytically generated CN radicals and O{sub 2}. The spectra give rotationally resolved information on high lying vibrational levels that are difficult or impossible to detect by conventional single photon spectroscopic techniques. These new data provide detailed insight into the Renner-Teller, spin-orbit and Fermi-resonance coupling in the molecule. They also provide a solid basis for future state-selected chemical and dynamical studies involving this important radical species.

  9. A tunable MWIR laser remote sensor for chemical vapor detection

    NASA Astrophysics Data System (ADS)

    Bunn, Thomas L.; Noblett, Patricia M.; Otting, William D.

    1998-01-01

    The Air Force vision for Global Virtual Presence suggests a need for active remote sensing systems that provide both global coverage and the ability to detect multiple gaseous chemical species at low concentration from a significant standoff distance. The system will need to have acceptable weight, volume, and power characteristics, as well as a long operating lifetime for integration with various surveillance platforms. Laser based remote sensing systems utilizing the differential absorption lidar (DIAL) technique are promising for long range chemical sensing applications. Recent advancements in pulsed, diode pumped solid state laser (DPSSL) technology and in tunable optical parametric oscillators (OPO) make broadly tunable laser transmitters possible for the DIAL system. Also the characteristic narrow spectral bandwidth of these laser devices provides high measurement sensitivity and spectral selectivity with the potential to avoid interfering species. Rocketdyne has built and tested a tunable, midwave infrared (MWIR) DIAL system using DPSSL/OPO technology. The key to the system is a novel tuning and line narrowing technology developed for the OPO. The tuning system can quickly adjust to the desired wavelength and precisely locate a narrow spectral feature of interest. Once the spectral feature is located, a rapid dither tuning technique is employed. The laser pulses are tuned ``on'' and ``off'' the spectral resonance of a molecule with precise and repeatable performance as required to make the DIAL measurement. To date, the breadboard system has been tested by measuring methane, ethane, and sulfur dioxide in a calibrated gas cell at a range of 60 meters.

  10. Chemical and structural changes in blood undergoing laser photocoagulation.

    PubMed

    Black, John F; Barton, Jennifer Kehlet

    2004-01-01

    The treatment of cutaneous vascular lesions (port wine stains etc.) using lasers has been guided by theories based on the "cold" or room-temperature optical properties of the hemoglobin target chromophore. We have recently presented evidence showing that under the influence of laser irradiation, the optical properties of blood in vitro are time and temperature dependent. Such complications are not currently subsumed into the in vivo theory. Here, we study the time-domain optical properties of blood undergoing photocoagulation in vitro using two newly developed time-resolved techniques. We also study the asymptotic effect of laser photocoagulation on the chemical and structural properties of the components of the blood matrix. We present evidence showing that the photocoagulation process involves significant changes in the optical absorption and scattering properties of blood, coupled with photothermally induced chemical and structural changes. We demonstrate the first use of a laser to deliberately generate magnetic resonance imaging contrast in vitro. We show that this technique offers significant potential advantages to in vivo intravenous chemical contrast agent injection. PMID:15339203

  11. Nozzle design in cw hydrogen fluoride chemical laser

    SciTech Connect

    Hua, W.; Jiang, Z.; Zhao, Y.

    1996-12-31

    Different geometry nozzles used in CW Hydrogen Fluoride chemical laser are investigated. Four geometry parameters, including throat width, area ratio, axis length and base width, are considered. The flow properties, laser outcoupling power and small signal gain (SSG) of a Fabry-Perot resonator are calculated. The results show that when throat width and area ratio increase, the power and SSG peak will decrease in varying degree; they also varied when axis length changed; larger base width is related to lower cavity pressure, and smaller base width is related higher cavity pressure.

  12. Kinetic studies of laser chemical vapor deposition of titanium nitride

    NASA Astrophysics Data System (ADS)

    Chen, Xiangli; Mazumder, Jyoti

    1994-09-01

    TiN films have been deposited on Ti-6Al-4V substrates by a cw CO2 laser chemical vapor deposition process with TiCl4, H2, and N2. Pulsed dye laser induced fluorescence spectroscopy is used to obtain transient gas phase Ti atomic concentration above the substrate. Multi-wavelength pyrometry is applied to measure the surface temperature during deposition. Film growth rates and compositions are obtained by stylus profilometry and Auger electron spectroscopy. Relationships between the growth rate and TiCl4, H2, and N2 partial pressures are established, from which the rate-controlling reactions and activation energy are obtained.

  13. ARTICLES: Electron-beam-controlled chemical hydrogen-iodine laser

    NASA Astrophysics Data System (ADS)

    Bel'dyugin, Igor'M.; Vysotskiĭ, Yu P.; Stepanov, A. A.; Shcheglov, V. A.

    1987-02-01

    A study is made of the feasibility of constructing a hydrogen-iodine laser with electron-beam-controlled excitation, emitting as a result of the 2P1/2→2P3/2 magnetic-dipole transition in atomic iodine (λ = 1.315 μ). The necessary iodine atoms are produced in an H2-Ar-I2 mixture as a result of a fast chemical reaction H + I2→HI + I initiated by an electric discharge. An analysis of the main processes combined with a calculation of the distribution function of electrons is used in a numerical modeling of such a laser. It is found that the specific input energy required in a hydrogen-laser is fairly high, 250-300 J·liter-1·atm-1, and that there are optimal values of this input energy and of the initial temperature of the mixture.

  14. 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

  15. 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.

  16. 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.

  17. Distributed feedback quantum cascade laser arrays for chemical sensing

    NASA Astrophysics Data System (ADS)

    Lee, Benjamin Guocian

    Quantum cascade lasers (QCLs) are unipolar semiconductor lasers based on intersubband transitions in heterostructures. The emission wavelengths of mid-infrared QCLs span from 3 to 24 mum and cover the "fingerprint" region of molecular absorption. This makes QCLs particularly interesting for spectroscopic applications. Single-mode emission is required for most spectroscopic applications. To achieve single-mode emission, QCLs can be made as distributed feedback (DFB) lasers or integrated with an external cavity (EC). EC-QCLs are widely tunable but are cumbersome and complex to build; they require high quality anti-reflection coatings, well-aligned external optical components including a grating for tuning, and piezoelectric controllers. DFB-QCLs are very compact and can be readily micro-fabricated, but a single DFB-QCL has limited tunability of ˜ 10 cm-1. In this thesis, I developed arrays of DFB-QCLs as widely-tunable, single-mode laser sources, and I demonstrated their applications to chemical sensing. I demonstrated a DFB-QCL array with 32 single-mode lasers on a single chip, emitting in a range over 85 cm-1 near 9mum wavelength, operated pulsed at room temperature. The DFB-QCL array can be continuously tuned, since the separation in nominal emission frequencies is small enough that we can use temperature tuning to span the frequency gaps between adjacent lasers in the array. To show the applications for chemical sensing, absorption spectroscopy was performed using the DFB-QCL array; the absorption spectra of several fluids were obtained, with results that were comparable to conventional Fourier transform infrared spectrometers. Achieving overlapped beams at extended distances can be important for a number of applications envisioned for DFB-QCL arrays, particularly remote sensing. Using the technique of spectral beam combining, the total angular divergence of the DFB-QCL array was reduced to less than 2 milliradians, which is 40 times better than without beam combining. Using the beam-combined array, absorption spectroscopy was performed at a distance of 6 m from the laser chip. An ultra-broadband DFB-QCL array was developed to further increase the coverage and tuning range. The array emitted in a range over 220 cm -1 near 9 mum wavelength, operated pulsed at room temperature.

  18. 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.

  19. Chemical kinetic performance losses for a hydrogen laser thermal thruster

    NASA Technical Reports Server (NTRS)

    Mccay, T. D.; Dexter, C. E.

    1985-01-01

    Projected requirements for efficient, economical, orbit-raising propulsion systems have generated investigations into several potentially high specific impulse, moderate thrust, advanced systems. One of these systems, laser thermal propulsion, utilizes a high temperature plasma as the enthalpy source. The plasma is sustained by a focused laser beam which maintains the plasma temperature at levels near 20,000 K. Since such temperature levels lead to total dissociation and high ionization, the plasma thruster system potentially has a high specific impulse decrement due to recombination losses. The nozzle flow is expected to be sufficiently nonequilibrium to warrant concern over the achievable specific impluse. This investigation was an attempt at evaluation of those losses. The One-Dimensional Kinetics (ODK) option of the Two-Dimensional Kinetics (TDK) Computer Program was used with a chemical kinetics rate set obtained from available literature to determine the chemical kinetic energy losses for typical plasma thruster conditions. The rates were varied about the nominal accepted values to band the possible losses. Kinetic losses were shown to be highly significant for a laser thermal thruster using hydrogen. A 30 percent reduction in specific impulse is possible simply due to the inability to completely extract the molecular recombination energy.

  20. Laser-assisted chemical vapor deposition of nickel and laser cutting in integrated circuit restructuring

    NASA Astrophysics Data System (ADS)

    Remes, J.; Moilanen, H.; Leppävuori, S.

    1997-01-01

    Laser-assisted chemical vapor deposition (LCVD) of nickel from Ni(CO)4 has been utilised for the restructuring of integrated circuit (IC) interconnections. Nickel lines were deposited on a SiO2 passivated IC to achieve new local interconnections between integrated circuit structures. Depositions were carried out over the pressure range of 0.2 to 2.2 mbar of pure Ni(CO)4 buffered in 0 to 800 mbar He. Argon ion laser wavelengths of 488 and 514.5 nm, laser power of 50-150 mW and a laser scan speed of 80 μm/s were utilised for the deposition. The morphology and chemical contents of the deposited interconnection microstructures was examined by AFM, optical microscopy and LIMA. The resistivity of the deposited lines was found to be close to the nickel bulk resistivity. The utilisation of Nd: YAG and XeCl excimer lasers in the cutting of Al and Mo conductor lines for integrated circuit modification is also described.

  1. 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.

  2. Synthesis of diamond by laser-induced chemical vapor deposition

    NASA Astrophysics Data System (ADS)

    Kitahama, Katsuki; Hirata, Kazuhiko; Nakamatsu, Hirohide; Kawai, Shichio; Fujimori, Naoji; Imai, Takahiro; Yoshino, Hiroshi; Doi, Akira

    1986-09-01

    Diamond has been obtained by ArF excimer laser-induced chemical vapor deposition. The reaction was carried out by use of C2H2 diluted with H2 as a source gas and at the pressure range of 8-75 Torr. The products were characterized by scanning electron microscopy and reflection electron diffraction. Deposits prepared in the temperature range of 40-800 °C, which were measured by the thermocouple attached to the substrate, show several lines of diamond in the reflection electron diffraction photographs. The fact that the laser beam must be concentrated for the diamond formation to occur strongly suggests that the reaction proceeds through a multiple photon process.

  3. Laser-induced chemical vapor deposition of titanium diboride

    NASA Astrophysics Data System (ADS)

    Elders, J.; v. Voorst, J. D. W.

    1994-01-01

    This paper investigates the CO(sub 2) laser induced chemical vapor deposition of titanium diboride by the H(sub 2) reduction of TiCl(sub 4) and BCl(sub 3), wherein the limitation on heat diffusion induces dendritic growth on alumina, while at higher temperatures the deposition becomes mass diffusion limited in addition to being heat diffusion limited. Variations in the hydrogen concentration has a big impact on the apparent activation energy, the growth rate, and the morphology - resulting in retarded growth, and smooth, dense morphology at high H(sub 2) concentrations. The 193 nm wavelength of the ArF excimer laser responsible for dissociating titanium tetrachloride, can increase the growth rate by a factor of two. High deposition temperatures probably enhance the growth rate is enhanced due to increased crystal growth, presumably due to the partly dissociated titanium tetrachloride.

  4. Numerical modeling of pyrolytic laser-induced chemical vapor deposition

    NASA Astrophysics Data System (ADS)

    Koutlas, G. N.; Vlachos, N. S.

    2003-03-01

    Laser chemical vapor deposition (LCVD) is a technique to deposit thin films of oxidation, corrosion, and wear resistant as well as electronic, optoelectronic, and superconductor materials. In order to understand the underlying mechanisms of such a process we have developed a numerical model using computational fluid dynamics (CFD). The Navier-Stokes equations governing the flow, heat transfer, and chemical reactions of the gases are solved numerically while the temperature distribution in the substrate is determined by solving the corresponding heat conduction equation. The present CFD model provides an opportunity to assess the important parameters concerning the LCVD process, such as the gas flow field, temperature distribution, concentration of reactants/products, and deposition height. Indicative results are presented for the deposition of titanium carbide upon AISI 1060 carbon. These results provide understanding of the LCVD process and enable its optimization.

  5. ARTICLES: Numerical analysis of a chain-reaction H2-Cl2 chemical laser

    NASA Astrophysics Data System (ADS)

    Mankelevich, Yu A.; Rakhimov, Aleksandr T.; Suetin, N. V.; Feoktistov, V. A.; Filippov, S. S.

    1987-02-01

    A kinetic model is developed for a chemical laser utilizing the chains reaction between Cl2 and vibrationally excited hydrogen. Numerical calculations are made of the influence of the degree of excitation of the H2, and of the pressure, chemical composition, and temperature of the mixture on the lasing characteristics of this laser. It is shown that in spite of slightly inferior energy parameters, compared with HF lasers the system under study has better characteristics than known HCl laser systems.

  6. Combustion Research Program: Flame studies, laser diagnostics, and chemical kinetics

    SciTech Connect

    Crosley, D.R.

    1992-09-01

    This project has comprised laser flame diagnostic experiments, chemical kinetics measurements, and low pressure flame studies. Collisional quenching has been investigated for several systems: the OH radical, by H{sub 2}0 in low pressure flames; the rotational level dependence for NH, including measurements to J=24; and of NH{sub 2} at room temperature. Transition probability measurements for bands involving v{prime} = 2 and 3 of the A-X system of OH were measured in a flame. Laser-induced fluorescence of vinyl radicals was unsuccessfully attempted. RRKM and transition state theory calculations were performed on the OH + C{sub 2}H{sub 4} reaction, on the t-butyl radical + HX; and transition state theory has been applied to a series of bond scission reactions. OH concentrations were measured quantitatively in low pressure H{sub 2}/N{sub 2}O and H{sub 2}/O{sub 2} flames, and the ability to determine spatially precise flame temperatures accurately using OH laser-induced fluorescence was studied.

  7. Laser Cleaning of Undyed Silk: Indications of Chemical Change

    NASA Astrophysics Data System (ADS)

    von Lerber, K.; Strlic, M.; Kolar, J.; Krüger, J.; Pentzien, S.; Kennedy, C.; Wess, T.; Sokhan, M.; Kautek, Wolfgang

    Three different undyed, unweighed silk fabrics (new clean, new soiled, and naturally aged) were cleaned with a computer-controlled Q-switched Nd:YAG laser at 532nm in 30 combinations of fluence and pulse numbers. They were studied for chemical change by viscometry, X-ray diffraction, and FIB-SIMS in combination with temperature calculations. While physical changes only occurred above the tested parameters, chemical changes could be detected as low as 0.2 J cm?2 with four pulses. Yellowing was observed at lower and bleaching at higher fluence/pulse number combinations. Melting was observed in naturally aged silk cleaned with 64 pulses at 4.2 J cm?2. The temperature reached at 0.1 J cm?2 is sufficient to evaporate carbon. Excess energy is transferred into the silk substrate causing thermal degradation. Different chemical processes leading to chain scission and to crosslinking seem to occur simultaneously, even at low fluence and pulse number. An increase in pulse numbers also leads to increasing damage.

  8. Laser chemical etching of waveguides and quasi-optical devices

    NASA Astrophysics Data System (ADS)

    Drouet D'Aubigny, Christian Yann Pierre

    2003-11-01

    The terahertz (THz) frequency domain, located at the frontier of radio and light, is the last unexplored region of the electromagnetic spectrum. As technology becomes available, THz systems are finding applications to fields ranging all the way from astronomical and atmospheric remote sensing to space telecommunications, medical imaging, and security. In Astronomy the THz and far infrared (IR) portion of the electromagnetic spectrum (λ = 300 to 10 μm) may hold the answers to countless questions regarding the origin and evolution of the Universe, galaxy, star and planet formation. Over the past decade, advances in telescope and detector technology have for the first time made this regime available to astronomers. Near THz frequencies, metallic hollow waveguide structures become so small, (typically much less than a millimeter), that conventional machining becomes extremely difficult, and in many cases, nearly impossible. Laser induced, micro-chemical etching is a promising new technology that can be used to fabricate three dimensional structures many millimeters across with micrometer accuracy. Laser micromachining of silicon possesses a significant edge over more conventional techniques. It does not require the use of masks and is not confined to crystal planes. A non-contact process, it eliminates tool wear and vibration problems associated with classical milling machines. At the University of Arizona we have constructed the first such laser micromachining system optimized for the fabrication of THz and far IR waveguide and quasi-optical components. The system can machine structures up to 50 mm in diameter, down to a few microns accuracy in a few minutes and with a remarkable surface finish. A variety of THz devices have been fabricated using this technique, their design, fabrication, assembly and theoretical performance is described in the chapters that follow.

  9. Laser-based instrumentation for detection of chemical-warfare agents

    SciTech Connect

    Quigley, G.P.; Radziemski, L.J.; Sander, R.K.; Hartford, A. Jr.

    1981-01-01

    Several laser-based techniques are being developed for remote, point, and surface contamination detection of chemical warfare agents. These techniques include optoacoustic spectroscopy, laser-induced breakdown spectroscopy, and synchronous detection of laser-induced fluorescence. Detection limits in the part-per-million to part-per-billion regime have been demonstrated.

  10. Laser mass spectrometry of chemical warfare agents using ultrashort laser pulses

    NASA Astrophysics Data System (ADS)

    Weickhardt, C.; Grun, C.; Grotemeyer, J.

    1998-12-01

    Fast relaxation processes in excited molecules such as IC, ISC, and fragmentation are observed in many environmentally and technically relevant substances. They cause severe problems to resonance ionization mass spectrometry because they reduce the ionization yield and lead to mass spectra which do not allow the identification of the compound. By the use of ultrashort laser pulses these problems can be overcome and the advantages of REMPI over conventional ionization techniques in mass spectrometry can be regained. This is demonstrated using soil samples contaminated with a chemical warfare agent.

  11. 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)

  12. Laser Chemical Vapor Deposition of Titanium Nitride and Process Diagnostics with Laser-Induced Fluorescence Spectroscopy.

    NASA Astrophysics Data System (ADS)

    Chen, Xiangli

    TiN films have been deposited on Ti-6Al-4V substrates by a cw CO_2 laser chemical vapor deposition (LCVD) process with TiCl_4, H_2, and N_2. Pulsed dye laser induced fluorescence (LIF) spectroscopy is used to obtain transient gas phase Ti atomic concentration above the substrate. Multi-wavelength pyrometry is applied to measure the surface temperature during deposition. Film thickness profiles are obtained by stylus profilometry, and film compositions are analyzed by Auger Electron Spectroscopy (AES). Very high film growth rates are found in the order of 1 mum/sec. The dependencies of the film growth rate on partial pressure ratio N _2:H_2, TiCl _4 partial pressure, total chamber pressure, and laser power are studied, and empirical relationships between the growth rate and TiCl_4, H_2, and N_2 partial pressures are established. The results suggest that the deposition is mainly due to chemical reactions on the substrate surface that is initiated by laser heating. The time change of Ti atomic concentration above the center of the deposition area measured by LIF is found to behave in the same way as the film thickness when experimental conditions are varied. Therefore, the LIF signal can be used as an in situ diagnostic tool for process monitoring and control. Possible surface reaction pathways and the rate-controlling steps are suggested. The apparent activation energy is found to be (115.0 +/- 10.7) kJ/mol for a substrate center temperature of 1339 K to 1515 K, a total pressure of 600 Torr, a partial pressure ratio N_2:H_2 of 3:1, and a TiCl_4 partial pressure of 27 Torr. AES analyses indicate that all the TiN _{rm x} films are in the range x = 0.8 +/- 0.1, with one exception of x = 0.6 for the lowest total pressure (Total = 100 Torr, N_2:H_2 = 3:1, TiCl_4 = 27 Torr, Laser Power = 400 W). Films are obtained with Cl atomic concentration as low as <0.5%, and O and C atomic concentrations as low as <1%. Finally, suggestions are made for improved numerical modeling based on the new findings.

  13. Metal film deposition by laser breakdown chemical vapor deposition

    NASA Astrophysics Data System (ADS)

    Jervis, T. R.

    1985-01-01

    Dielectric breakdown of gas mixtures can be used to deposit homogeneous thin films by chemical vapor deposition with appropriate control of flow and pressure conditions to suppress gas phase nucleation and particle formation. Using a pulsed CO2 laser operating at 10.6 microns where there is no significant resonant absorption in any of the source gases, we have succeeded in depositing homogeneous films from several gas phase precursors by gas phase laser pyrolysis. Nickel and molybdenum from the respective carbonyls and tungsten from the hexafluoride have been examined to date. In each case the gas precursor is buffered to reduce the partial pressure of the reactants and to induce breakdown. The films are spectrally reflective and uniform over a large area. Films have been characterized by Auger electron spectroscopy, X-ray diffraction, pull tests, and resistivity measurements. The highest quality films have resulted from the nickel depositions. Detailed X-ray diffraction analysis of these films yields a very small domain size (approx. 50 A) consistent with rapid quenching from the gas phase reaction zone. This analysis also shows nickel carbide formation consistent with the temperature of the reaction zone and the Auger electron spectroscopy results which show some carbon and oxygen incorporation (8% and 1% respectively). Gas phase transport and condensation of the molybdenum carbonyl results in substantial carbon and oxygen contamination of the molybdenum films requiring heated substrates, a requirement not consistent with the goals of the program to maximize the quench rate of the deposition. Results from tungsten deposition experiments representing a reduction chemistry instead of the decomposition chemistry involved in the carbonyl experiments are also reported.

  14. Diode laser spectroscopy for on-line chemical analysis

    NASA Astrophysics Data System (ADS)

    Bomse, David S.; Hovde, D. Christian; Oh, Daniel B.; Silver, Joel A.; Stanton, Alan C.

    1992-08-01

    Diode laser spectroscopy provides exceptional sensitivity and selectivity for real-time characterization of reacting systems and gas streams. High frequency wavelength modulation techniques achieve species detection limits that are routinely in the ppm range and can reach sub-ppb levels under favorable conditions. Narrow laser linewidths guarantee selective detection of key species even in the presence of myriad other components. Diode laser spectroscopy is also relatively immune from interference by black body radiation or chemiluminescence. Prototype diode-laser based systems have been demonstrated successfully for trace gas detection in turbulent, high temperature particle-laden streams, for oxygen quantitation in flames, for free radical characterization in a plasma etching reactor and for greenhouse gas flux measurements in air. We also discuss the availability of laser wavelengths, compatibility with fiber optics, cost safety and expectations for new laser development.

  15. 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

  16. 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

  17. Laser-induced chemical liquid phase deposition of copper from aqueous solutions without reducing agents

    SciTech Connect

    Kochemirovsky, V A; Tumkin, I I; Logunov, L S; Safonov, S V; Menchikov, Leonid G

    2012-08-31

    Laser-induced chemical liquid phase deposition of copper without a traditional reducing agent has been used for the first time to obtain conductive patterns on a dielectric surface having a reducing ability. It is shown that phenol-formaldehyde binder of the dielectric (glass fibre) can successfully play the role of a reducing agent in this process. The resulting copper sediments have low electrical resistance and good topology. (interaction of laser radiation with matter. laser plasmas)

  18. 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.

  19. Detection of chemically-induced dysplasia in rat urinary bladder with laser-induced fluorescence

    NASA Astrophysics Data System (ADS)

    Schomacker, Kevin T.; Flotte, Thomas J.; Deutsch, Thomas F.

    1994-05-01

    The ability of laser-induced fluorescence (LIF) to detect flat dysplasia has not been carefully studied. A multiexcitation wavelength LIF system was used to develop an algorithm to detect chemically-induced dysplasia in the rat urinary bladder.

  20. The effect of the cw hydrogen/deuterium fluoride chemical laser with different diluents

    SciTech Connect

    Jiang, Z.; Hua, W.; Chen, J.; Zhao, Y.

    1996-12-31

    The He is usually used as diluent in combustion cw hydrogen/deuterium fluoride (HF/DF) chemical lasers. Sometimes the N{sub 2} is also used as diluent in cw HF/DF chemical laser because N{sub 2} is cheaper than the He. It was thought that the efficiency of cw HF/DF laser with N{sub 2} diluent was lower than that of HF/DF laser with He diluent since the molecular weight of N{sub 2} is heavier than that of He. In this paper, the performance of cw DF chemical lasers with He and N{sub 2} diluent was investigated. The small signal gain, power spectral distributions, cavity pressure, power and the efficiency of DF lasers with these two diluents have been calculated using a finite-difference technique for the numerical integration of the steady and unsteady Navier-Stokes equation with reactive flow (compressibility scaling method -- CSM), which was developed in the chemical gas dynamic laboratory of the state institute of applied chemistry in Russia. The numerical results show that the efficiency of DF lasers with Na{sub 2} diluent is not lower than that of the lasers with He diluent.

  1. Fiber ring laser interrogated zeolite-coated singlemode-multimode-singlemode structure for trace chemical detection.

    PubMed

    Lan, X; Huang, J; Han, Q; Wei, T; Gao, Z; Jiang, H; Dong, J; Xiao, H

    2012-06-01

    Zeolite thin films were synthesized on the claddingless multimode portion of a singlemode-multimode-singlemode (SMS) fiber structure to construct a chemical vapor sensor. The zeolite-coated SMS structure was inserted into a fiber ring amplifier to produce a laser line. Combining the strong molecular adsorption capability of the nanoporous zeolite and the high signal-to-noise ratio of the fiber laser, the device was demonstrated for chemical vapor sensing with a low detection limit. PMID:22660100

  2. Time and wavelength domain algorithms for chemical analysis by laser radar

    NASA Technical Reports Server (NTRS)

    Rosen, David L.; Gillespie, James B.

    1992-01-01

    Laser-induced fluorescence (LIF) is a promising technique for laser radar applications. Laser radar using LIF has already been applied to algae blooms and oil slicks. Laser radar using LIF has great potential for remote chemical analysis because LIF spectra are extremely sensitive to chemical composition. However, most samples in the real world contain mixtures of fluorescing components, not merely individual components. Multicomponent analysis of laser radar returns from mixtures is often difficult because LIF spectra from solids and liquids are very broad and devoid of line structure. Therefore, algorithms for interpreting LIF spectra from laser radar returns must be able to analyze spectra that overlap in multicomponent systems. This paper analyzes the possibility of using factor analysis-rank annihilation (FARA) to analyze emission-time matrices (ETM) from laser radar returns instead of excitation-emission matrices (EEM). The authors here define ETM as matrices where the rows (or columns) are emission spectra at fixed times and the columns (or rows) are temporal profiles for fixed emission wavelengths. Laser radar usually uses pulsed lasers for ranging purposes, which are suitable for measuring temporal profiles. Laser radar targets are hard instead of diffuse; that is, a definite surface emits the fluorescence instead of an extended volume. A hard target would not broaden the temporal profiles as would a diffuse target. Both fluorescence lifetimes and emission spectra are sensitive to chemical composition. Therefore, temporal profiles can be used instead of excitation spectra in FARA analysis of laser radar returns. The resulting laser radar returns would be ETM instead of EEM.

  3. 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.

  4. Optimization of shunt isolation processing for silicon solar cells via laser and chemical etching

    NASA Astrophysics Data System (ADS)

    Hao, H. L.; Zhong, S. H.; Zhang, X.; Shen, W. Z.

    2014-08-01

    We employ laser scribing combined with chemical etching process to isolate the shunts in industrial off-spec or non-prime crystalline solar cells. Liquid crystal sheet and Infrared camera measurements have been carried out to reveal the existence of the shunts and hot spot temperature under reverse bias. Following laser scribing with proper laser parameters, chemical etching has been used to further optimize the isolation effect. Through illuminated current-voltage characteristic measurements, the improved open circuit voltage, fill factor and efficiency have been obtained. These results demonstrate that this combined shunt isolation process has great potential for its application in the solar cells.

  5. Near-infrared diode laser spectroscopy in chemical process and environmental air monitoring.

    PubMed

    Martin, Philip A

    2002-07-01

    This review covers the rapidly expanding field of near-infrared tunable diode laser spectroscopy where the availability of new lasers has led to the development of simple and inexpensive spectroscopic systems for the detection and monitoring of gas species. The latest diode lasers and the specific techniques associated with diode laser spectroscopy are described. Specific examples covering chemical vapour deposition reaction diagnostics, remote vehicle emission sensing, balloon-borne atmospheric monitoring and combustion diagnostics then illustrate the technique advantages of rapid, highly selective, in situ monitoring. PMID:12164066

  6. 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)

  7. Surface chemical reaction of laser ablated aluminum sample for detonation initiation

    NASA Astrophysics Data System (ADS)

    Yoh, Jack; Kim, Chang-Hwan; Gojani, Ardian

    2011-06-01

    We explore the evolution of metal plasma generated by high laser irradiances and its effect on the surrounding air by using shadowgraph images after laser pulse termination; hence the formation of laser supported detonation and combustion processes has been investigated. The essence of the paper is in observing initiation of chemical reaction between ablated aluminum plasma and oxygen from air by inducing high power laser pulse (>1000 mJ/pulse) and conduct a quantitative comparison of chemically reactive laser initiated waves with the classical detonation of exploding aluminum (dust) cloud in air. Findings in this work may lead to a new method of initiating detonation from metal sample in its bulk form without the need of mixing nano-particles with oxygen for initiation. Authors thank the financial support from the National Research Foundation of Korea (2009, 2010).

  8. Surface chemical reaction of laser ablated aluminum sample for detonation initiation

    SciTech Connect

    Kim, Chang-hwan; Yoh, Jack J.

    2011-05-01

    We explore the evolution of metal plasma generated by high laser irradiances and its effect on the surrounding air by using shadowgraph images after laser pulse termination; hence the formation of laser supported detonation and combustion processes has been investigated. The essence of the paper is in observing initiation of chemical reaction between ablated aluminum plasma and oxygen from air by inducing high power laser pulse (>1000 mJ/pulse) and conduct a quantitative comparison of chemically reactive laser initiated waves with the classical detonation of exploding aluminum (dust) cloud in air. Findings in this work may lead to a new method of initiating detonation from metal sample in its bulk form without the need of mixing nano-particles with oxygen for initiation.

  9. Predictions of Chemical Species via Diode Laser Spectroscopy

    NASA Technical Reports Server (NTRS)

    Chen, Shin-Juh; Silver, Joel A.; Dahm, Werner J. A.; Piltch, Nancy D.; Salzman, Jack (Technical Monitor)

    2001-01-01

    A technique to predict temperature and chemical species in flames from absorbance measurement of one chemical species is presented. Predicted temperature and mole fractions of methane and water agreed well with measured and published results.

  10. A Topics Course on Chemical Application of Lasers.

    ERIC Educational Resources Information Center

    Coleman, William F.

    1981-01-01

    Describes a topics course offered at the University of New Mexico entitled "Lasers in Chemistry," which is designed for beginning graduate students and advanced undergraduates in all areas of chemistry. (CS)

  11. 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.

  12. 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.

  13. 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.

  14. The effects of motive gas physical properties on the performance of ejector for chemical lasers

    NASA Astrophysics Data System (ADS)

    Jin, Jungkun; Kim, Sehoon; Kwon, Hyuckmo; Kwon, Sejin

    2005-03-01

    Axi-symmetric annular type ejector has been developed as a pressure recovery system for HF/DF chemical laser. Ejector was tested using air as operating gases and low-pressure entrained flow was obtained. In this paper, we changed motive gas since operating gases for chemical laser system are products of chemical reaction. By selection of motive gas, physical properties of operating gas changes, therefore the performance of ejector is different for each motive gas, i.e., specific heat at constant pressure (CP) and average molecular weight (MW) on the effectiveness of ejection. The research was carried out by both numerical analysis using commercial CFD code, FLUENT and experiments.

  15. 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.

  16. Zeeman laser interferometry for detection and chemical analysis

    SciTech Connect

    Johnston, R.G.

    1993-12-01

    Zeeman interferometry has a number of applications for ultrasensitive detection and chemical analysis, including refractive index detection, micro-thermometry, thermooptic spectroscopy, and light scattering.

  17. 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.

  18. Ar ion laser-assisted chemical etching of molybdenum foils in air

    NASA Astrophysics Data System (ADS)

    Koren, G.

    1986-03-01

    Ar ion laser-assisted chemical etching of Mo foils in air is reported. Etching occurred due to local heating by the focused laser beam which induced the Mo oxidation to form the volatile MoO3 at the elevated sample temperature. Holes and slots with slightly tapered walls and a minimum hole diameter of less than 10 μm could be etched in 25-, 50-, and 150-μm-thick foils. The hole diameters increased with increasing laser power and at any given laser power they decreased with increasing sample thickness. Etch-rate measurements as a function of the laser power were performed with static and scanned samples. Threshold powers for etching through the Mo foils were found. They increased with increasing sample thickness. Above these thresholds the etch rates increased rapidly with increasing laser power and rates as high as dz/dt=50 μm/s in the static mode and dV/dt=20×50×300 μm3/s in the scanning mode were obtained in a 50-μm-thick Mo foil under 10-W laser irradiation. Average sample temperatures as functions of the laser power in the scanning mode of operation where thermal equilibrium exists were measured by the use of optical pyrometry. A model which relates the laser power to the etch rate and temperature of the sample is presented and tested for agreement with the experimental results.

  19. 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.

  20. 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.

  1. 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.

  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. Chemical-specific imaging of shallowly buried objects using femtosecond laser pulses.

    PubMed

    Strycker, B D; Wang, K; Springer, M; Sokolov, A V

    2013-07-10

    We demonstrate that objects buried in sand (1 to 4 mm deep) may be selectively imaged according to their chemical composition through spectral analysis of the laser-induced breakdown signal. The signal is generated by loosely focused femtosecond laser pulses having energies ranging from 0.5 to 2.5 mJ. We determine the depth from which a spectral signal may be measured as a function of pulse energy. Having in mind applications to remote sensing, chemical-specific imaging of shallowly buried objects may find use in various fields ranging from space exploration to landmine detection. PMID:23852190

  4. Facial skin rejuvenation: ablative laser resurfacing, chemical peels, or photodynamic therapy? Facts and controversies.

    PubMed

    Hassan, Khaled M; Benedetto, Anthony V

    2013-01-01

    Patients and cosmetic surgeons continue to develop innovative devices and techniques in search of the elusive fountain of youth. Our efforts in the past decade can be distilled to three primary approaches: refinement of existing technologies (ablative lasers); refinement of tried-and-true techniques (chemical peeling); and innovative use of new technologies (photorejuvenation). In this contribution, the authors discuss how these three approaches are used to achieve facial skin rejuvenation. Specifically, the authors compare and contrast the clinical benefits and disadvantages of the ablative fractionated and unfractionated carbon dioxide resurfacing lasers, medium-depth and deep chemical peeling, and the combination of photodynamic therapy with intense-pulsed light. PMID:24160279

  5. 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.

  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. 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.

  8. Chemical Changes Associated with Increased Acid Resistance of Er:YAG Laser Irradiated Enamel

    PubMed Central

    Olea-Mejía, Oscar Fernando; García-Fabila, María Magdalena; Rodríguez-Vilchis, Laura Emma; Sánchez-Flores, Ignacio; Centeno-Pedraza, Claudia

    2014-01-01

    Background. An increase in the acid resistance of dental enamel, as well as morphological and structural changes produced by Er:YAG laser irradiation, has been reported. Purpose. To evaluate the chemical changes associated with acid resistance of enamel treated with Er:YAG laser. Methods. Forty-eight enamel samples were divided into 4 groups (n = 12). Group I (control); Groups II, III, and IV were irradiated with Er:YAG at 100 mJ (12.7 J/cm2), 200 mJ (25.5 J/cm2), and 300 mJ (38.2 J/cm2), respectively. Results. There were significant differences in composition of irradiated groups (with the exception of chlorine) and in the amount of calcium released. Conclusions. Chemical changes associated with an increase in acid resistance of enamel treated with Er:YAG laser showed a clear postirradiation pattern characterized by a decrease in C at.% and an increase in O, P, and Ca at.% and no changes in Cl at.%. An increased Ca/P ratio after Er:YAG laser irradiation was associated with the use of higher laser energy densities. Chemical changes produced by acid dissolution showed a similar trend among experimental groups. Stable or increased Ca/P ratio after acid dissolution was observed in the irradiated groups, with reduction of Ca released into the acid solution. PMID:24600327

  9. Selective wet chemical etching of metallic thin films designed by laser interference metallurgy (LIMET)

    NASA Astrophysics Data System (ADS)

    Catrin, Rodolphe; Gachot, Carsten; Marchand, Günter; Schmid, Ulrich; Mücklich, Frank

    2009-05-01

    The physical and chemical behaviour of materials is strongly correlated with their microstructure. Therefore, much effort is invested in the advanced microstructural design of metallic thin films. Laser Interference Metallurgy (LIMET) is used to locally tune the grain architecture of metallic thin films from the nanoto the microscale. This means a defined size and orientation of the grains with lateral periodicity, by interfering on the sample surface two or more laser beams of a high power nanosecond pulsed Nd:YAG laser. This technique enables the local nucleation and crystallization of amorphous or nanocrystalline metallic thin films, thus combining nano- and microcrystalline regions ordered in periodic line- or lattice-like arrangements in a composite architecture. After having locally modified the microstructure of e-beam evaporated Pt and Au thin films by laser irradiation a wet chemical etching procedure was induced in hot aqua regia. Doing so, a selective etching is achieved without using conventional lithography. Due to the laser-induced recrystallization in periodic structures, these microcrystalline zones of specific oriented grains show a higher resistance against the wet chemical etchant than the as-deposited, nanocrystalline areas, which are completely removed down to the substrate. Therefore, this procedure may have the potential to be an alternative, low cost approach to conventional lithographic techniques and provides a novel method for a straight-forward patterning of metallic thin films.

  10. Laser chemical vapor deposition of Cu and Ni in integrated circuit repair

    NASA Astrophysics Data System (ADS)

    Leppaevuori, Seppo; Remes, Janne; Moilanen, Hannu

    1996-09-01

    Laser-assisted chemical vapor deposition (LCVD) of nickel from Ni(CO)4 and copper from Cu(hfac)tmvs was utilized in the restructuring of an integrated circuit (IC) interconnection. Nickel and copper lines were deposited on passivated ICs by using a focused Ar+ laser beam to achieve new local rewirings on the chip. Nickel line depositions were carried out over the pressure range of 0.2 to 2.2 mbar of Ni(CO)4 buffered in 200 - 800 mbar He. The typical laser beam scan speed was 24 micrometers per second for both metals. The Cu(hfac)tmvs precursor gas partial pressure was 0.3 mbar buffered in 10 mbar He or H2 and typical laser scan speed was 24 micrometers per second. The morphology and chemical contents of the deposited interconnection microstructures was examined by atomic force microscopy (AFM), optical microscopy and laser ionization mass analysis (LIMA). The LIMA analysis indicated that the deposited copper surface was contaminated but the contamination level decreased when the layer was depth profiled. The deposited Ni lines were found to be pure Ni with only traces of carbon contamination. The utilization of XeCl excimer laser in the cutting of Al and Mo conductor lines and passivation contact via opening for IC modification is also described. LCVD method was successful in numerous different IC failure inspection and circuit modification cases.

  11. 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.

  12. Combustion Research Program: Flame studies, laser diagnostics, and chemical kinetics

    SciTech Connect

    Crosley, D.R.

    1991-01-22

    We have made a detailed study of the care that must be taken to correctly measure OH radical concentrations in flames. A large part of these studies has concerned collisional quenching of hydride radical species (OH, NH, and NH{sub 2}), in particular the dependence upon rotational level and collision velocity (temperature). The results on OH and NH have shown unique and interesting behavior from the viewpoint of fundamental molecular dynamics, pointing to quenching often governed by collisions on an anisotropic, attractive surface, whereas NH{sub 2} quenching appears to depend on state-mixing considerations, not dynamic control. This state-specific behavior of these small, theoretically tractable hydrides has direct ramifications for quantitative flame diagnostics. Our other effort in the diagnostic area has been repeated but unsuccessful searches for laser induced fluorescence in the vinyl radical.

  13. Chemical modification of lignocellulosic materials by irradiation with Nd-YAG pulsed laser

    NASA Astrophysics Data System (ADS)

    Botaro, V. R.; dos Santos, C. G.; Arantes Júnior, G.; da Costa, A. R.

    2001-11-01

    Most reports about modification of lignocellulosics are mainly based on chemical modifications such as specific reactions on hydroxyl groups of cellulose. In this work, we describe the irradiation of Whatman 5 filter paper, microcrystalline cellulose and organosolv lignin with Nd-YAG laser pulses at 1064 nm. The chemical and structural properties of the degraded products were investigated by using FTIR and UV spectroscopies, conductimetrical and SEC analyses. While irradiation affects molar mass and polydispersity of lignin, no detrimental effects caused by Nd-YAG laser treatments were observed for cellulose samples. These results demonstrate that Nd-YAG laser can be used as a practical and selective degradation tool, opening a new field for obtaining surface modified natural fibers.

  14. Nanoscale volumetric chemical imaging by soft x-ray laser ablation mass spectrometry

    NASA Astrophysics Data System (ADS)

    Kuznetsov, Ilya; Filevich, Jorge; Woolston, Mark; Gasper, Gerald; Carlton, David; Chao, Weilun; Anderson, Erik; Bernstein, Elliot; Crick, Dean; Rocca, Jorge; Menoni, Carmen

    2014-03-01

    Mass Spectrometry Imaging (MSI) has played an important role in the direct examination of the chemical composition of complex inorganic and organic samples. Typically a visible/ultraviolet laser is used to ablate the sample and create ions that when detected enables the identification of molecular composition. We report the use of soft x-ray (SXR) lasers in the implementation of a novel laser ablation mass spectrometry (XLAMS) nanoprobe that can probe chemical composition from sample regions of a few attoliters volume and with high sensitivity. The concept exploits: i) high focusability, ii) low penetration depth and iii) high photo-ionization efficiency of the 46.9 nm wavelength SXR laser light. In this work we demonstrate the capabilities of XLAMS to realize chemical contrast imaging with ~ 140 nm lateral and ~ 50 nm depth resolution and high sensitivity. The high lateral and depth resolution and high sensitivity of XLAMS imaging method offer great potential for composition imaging of nanofilms and nanostructures and imaging the chemical distribution of dopants and trace elements. This work is supported by NIH/NIAID and NSF grant EEC 0310717.

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

    NASA Astrophysics Data System (ADS)

    Jung Park, Han; Diebold, Gerald J.

    2013-08-01

    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.

  17. Progress toward realization of a KW-class EOIL laser

    NASA Astrophysics Data System (ADS)

    Hill, Alan E.

    2008-02-01

    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 O II into O II(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 O II into O II(a1Δ) operating at substantial oxygen mass flow rates (0.090 moles O II/sec at 50 torr) and 40% electrical efficiency is reported. The O II(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 O II(a1Δ) fractional yield, it is normally mandatory to impart on the order of 100 KJ/mole O II 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 O II(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 also independently tunable. The result is that up to 180 KJ/mole O II gets imparted to the gas by means of the ~6 KW sub-breakdown pump field, while another 2700 watts is applied to the controlled avalanche field. The generator consists of 24 each, 1 cm diameter tubes that are submerged in rapidly circulating cold fluorinert. Heat is efficiently removed so that that the gas temperature, initially 273°K, raises only by 125°K, as evidenced by spectrographic analysis of the fine structure of O II(b1Σ) at lower pressure. Since all necessary conditions have been met, a 30% conversion rate of O II to O II(a1Δ) has been achieved. Fortuitously, neither excited O atom production nor O II(b1Σ) production is visible in the spectra of the higher pressure, best yield runs. Essentially all other spectral lines are dwarfed in comparison the O II(a1Δ) line. Energy normally partitioned to O II(b1Σ) and apparently O atoms now feeds into O II(a1Δ) directly, enabling electrical efficiency to exceed 40%. As a continuation of this work, an I II disassociating mixing section - then subsequently a 20 cm transverse M = 2.5 laser channel - has been coupled to the O II(a1Δ) generator. The effects of titrating NO, NO II, etc. to scavenge O atoms and O 3 atoms is under current investigation. Laser power extraction will commence after having optimized all parameters to achieve maximum gain.

  18. Laser spectroscopy of chemically reactive species. [NCO radical

    SciTech Connect

    Wu, Ming; Sears, T.J.

    1993-01-01

    We report the observation of stimulated emission pumping spectra in the NCO radical formed in a supersonic free jet expansion by the reaction between photolytically generated CN radicals and O[sub 2]. The spectra give rotationally resolved information on high lying vibrational levels that are difficult or impossible to detect by conventional single photon spectroscopic techniques. These new data provide detailed insight into the Renner-Teller, spin-orbit and Fermi-resonance coupling in the molecule. They also provide a solid basis for future state-selected chemical and dynamical studies involving this important radical species.

  19. Change in the surface morphology and chemical composition of some oxide crystals under UV laser irradiation

    SciTech Connect

    Kuzanyan, A S; Badalyan, G R; Kuzanyan, V S; Nikogosyan, V R; Pilosyan, S Kh; Nesterov, V M

    2011-07-31

    The effect of the 248-nm KrF and 355-nm YAG:Nd{sup 3+} laser radiation on the surface morphology and chemical composition of SrTiO{sub 3}, Sr{sub 2}RuO{sub 4}, PbMoO{sub 4}, LiNbO{sub 3}, Y{sub 3}Al{sub 5}O{sub 12}, and Al{sub 2}O{sub 3} crystals has been studied. A relationship between the laser energy density on the sample surface and the surface roughness caused by the irradiation is determined. A technique for determining exactly the geometric surface characteristics is proposed. The effect of the surface roughness on the results of energy-dispersive X-ray (EDX) microanalysis has been investigated. A method for correcting the EDX data for samples with a rough surface has been developed. It is shown that the small variation in the composition of PbMoO{sub 4}, LiNbO{sub 3}, Y{sub 3}Al{sub 5}O{sub 12}, and Al{sub 2}O{sub 3} samples after laser irradiation can be explained by the measurement error, related to the change in the surface roughness. At the same time, the irradiation of SrTiO{sub 3} and Sr{sub 2}RuO{sub 4} crystals by a YAG:Nd laser changes the chemical composition of their surface layers. (interaction of laser radiation with matter)

  20. Chemical and microstructural transformations in lithium iron phosphate battery electrodes following pulsed laser exposure

    NASA Astrophysics Data System (ADS)

    Lutey, Adrian H. A.; Fiorini, Maurizio; Fortunato, Alessandro; Ascari, Alessandro

    2014-12-01

    Multi-layer lithium iron phosphate (LFP) battery electrodes are exposed to nanosecond pulsed laser radiation of wavelength 1064 nm. Test parameters are chosen to achieve characteristic interaction types ranging from partial incision of the active coating layers only to complete penetration of the electrodes with high visual cut quality. Raman spectroscopy is performed on unexposed regions and at points approaching each incision, highlighting changes in chemical composition and microstructure in the heat affected zone (HAZ). Thermogravimetric analysis is performed on the unexposed electrode active materials to distinguish the development of compositional changes under conditions of slow heating below the melting and sublimation temperatures. A brief theoretical description of the physical phenomena taking place during laser exposure is provided in terms of direct ablation during each laser pulse and vaporization or thermal degradation due to conductive heat transfer on a much longer time-scale, with characteristics of the HAZ reported in terms of these changes. For all laser exposures carried out in the study, chemical and microstructural changes are limited to the visible HAZ. Some degree of oxidation and LFP olivine phase degradation is observed in the cathode, while the polycrystalline graphite structure becomes less ordered in the anode. Where complete penetration is achieved, melting of the cathode active layer and combustion of the anode active layer take place near the cut edge due to thermal conduction from the metallic conductive layers. The presented results provide insight into the effects of laser processing on LFP electrode integrity.

  1. 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.

  2. 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.

  3. Personnel protection equipment for use with laser chemicals

    SciTech Connect

    Smith, I.D.; Roepke, J.

    1984-08-01

    The NASA White Sands Test facility (WSTF) recently built the fluid distribution system for the Army's High Energy Laser System Test Facility (HELSTF). As part of the effort, WSTF personnel were required to activate the fluorine system. To insure adequate personnel protection during the fluorine system activation, a project was undertaken to evaluate and qualify personnel protection equipment to be used during the activation (passivation) activity. Previous work in the late 60's and early 70's showed that very few materials were totally satisfactory for use with fluorine. Little if any work has been done to measure the degree of protection afforded against either fluorine gas or hydrofluoric acid (HF), the principal residual reactive material. Two general types of tests were conducted to evaluate materials. These were (1) fluorine and HF gas permeation tests, and (2) high-velocity fluorine gas-impingement tests. The gas permeation tests were designed to exposure one side of the material to the gas at concentrations of up to 27% F2 or 1.5% HF in designed to expose one side of the material to the gas at concentrations of up to 27% F2 or 1.5% HF in GN2 with a gas purge on the opposite side leading to the detection system. The tests showed that all of the materials tested which included ILC Dover Chloropel, glove materials - Neoprene, Viton, leather, butyl rubber, face shield materials, etc., where neither permeated by HF at a 1200 ppm level nor by F2 in GN2 at concentrations as high as 27% by volume. The gas-impingement tests were designed to represent a high-pressure gas leak or the cracking of a B-nut on a system containing residual fluorine gas.

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

    PubMed Central

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

    2015-01-01

    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. PMID:26271602

  5. Feasibility study of a novel pressure recovery system for CO2-COIL based on chemical absorption

    NASA Astrophysics Data System (ADS)

    Li, Qingwei; Jin, Yuqi; Geng, Zicai; Li, Yongzhao; Zhang, Yuelong; Sang, Fengting

    2015-02-01

    A chemical oxygen-iodine laser (COIL) is an electronic transition, low pressure, high throughput system. The use of this laser demands a suitable pressure recovery system. This paper proposed a novel pressure recovery system based on chemical absorption and the feasibility for COIL with CO2 as buffer gas (CO2-COIL) was investigated. The novel pressure recovery system works by chemisorbing the CO2-COIL effluents into two fixed-beds maintained at initial temperature of around 293-323K. Compared with the cryosorption system for N2-COIL based on physical absorption, the novel chemisorptions based pressure recovery system has a simpler logistics and a shorter run-to-run preparation time. Two kinds of solid chemo-sorbents were designed and synthesized. One was used for chemisorbing the oxidizing gases such as O2 ,Cl2 and I2, another was used for chemisorbing the acidic gas such as CO2. The capacities of the two sorbents were measured to be 3.12 mmol(O2)/g and 3.84 mmol (CO2) /g, respectively. It indicated that the synthesized sorbents could effectively chemosorb the CO2-COIL effluents. Secondly, analog test equipment was set up and used to study the feasibility of the novel pressure recovery system used for CO2-COIL. The test results showed that the novel pressure recovery system could maintain the pressure under 6 Torr for tens seconds under the continuous gas flow. It showed that the novel pressure recovery system for CO2-COIL based on chemical absorption is feasible.

  6. A broadband laser plasma x-ray source for application in ultrafast chemical structure dynamics

    SciTech Connect

    Fullagar, Wilfred; Harbst, Michael; Canton, Sophie; Uhlig, Jens; Walczak, Monika; Wahlstroem, Claes-Goeran; Sundstroem, Villy

    2007-11-15

    A plasma source free from characteristic emission lines is described, based on laser irradiation of a water jet in a helium atmosphere. Various key aspects of the laser interaction are presented along with practical characterization of the observed isotropic {approx}4-10 keV x-ray emissions, measurements of which indicate subpicosecond duration. Observations are consistent with a vacuum heating plasma mechanism at the helium-water interface and indicate strong potential for in-house ultrafast chemical structure dynamics application when coupled to contemporary detector developments.

  7. 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.

  8. An intra-cavity device with a discharge-drived CW DF chemical laser

    NASA Astrophysics Data System (ADS)

    Yan, Baozhu; Liu, Wenguang; Zhou, Qiong; Yuan, Shengfu; Lu, Qisheng

    2015-05-01

    The performance parameters of reflecting mirrors such as absorption coefficient or thermal distortion determine the beam quality of the output laser, so the quality of mirrors is one of the most important factors affecting the capability of the whole laser system. At the present time, there was obviously insufficient in test methods for the mirrors performance. The reflection coefficient, absorption coefficient and scattering coefficient of mirrors could be measured by a lot of test methods such as cavity ring-down method, photothermal deflection method, surface thermal lens method and laser calorimetry. But these methods could not test under high power density radiation. So the test data and results could not indicate the real performance in a real laser system exactly. Testing in a real laser system would be expensive and time consuming. Therefore, the test sequence and data would not be sufficient to analyze and realize the performance of mirrors. To examine the performance of mirrors under high power density radiation, the working principle of intra-cavity was introduced in this paper. Utilizing an output mirror with a low output coupling ratio, an intra-cavity could produce high-power density laser in the resonant cavity on the basis of a relatively small scale of gain medium, and the consumption and cost were very low relatively. Based on a discharge-drived CW DF chemical laser, an intra-cavity device was established. A laser beam of 3kw/cm2 was achieved in the resonant cavity. Two pieces of 22.5 degree mirrors and two pieces of 45 degree mirrors could be tested simultaneously. Absorption coefficient and thermal distortion were measured by calorimetry and Hartmann wavefront sensor respectively. This device was simple, convenient, low-maintenance, and could work for a long time. The test results would provide support for process improvement of mirrors.

  9. Closed-loop control of laser assisted chemical vapor deposition growth of carbon nanotubes

    NASA Astrophysics Data System (ADS)

    van de Burgt, Yoeri; Bellouard, Yves; Mandamparambil, Rajesh; Haluska, Miro; Dietzel, Andreas

    2012-08-01

    Laser-assisted chemical vapor deposition growth is an attractive mask-less process for growing locally aligned nanotubes in selected places on temperature sensitive substrates. An essential parameter for a successful and reproducible synthesis of nanotubes is the temperature during growth. Here, we demonstrate a temperature feedback control mechanism based on the dynamic, in situ monitoring of the infrared radiation coupled with reflectivity information. With the information provided by these sensors, an infrared laser, focused on a silicon substrate covered with aluminum-oxide and iron catalyst layers, can be controlled. The growth takes place in a gaseous mixture of argon (carrier gas), hydrogen (process gas), and ethylene (carbon-containing gas). Scanning electron microscopy and Raman spectroscopy analysis demonstrate the excellent reproducibility of the closed-loop control process over multiple experiments. Furthermore, we developed a unique method to identify the onset for catalyst formation and activation by monitoring the fluctuation of the reflected laser beam.

  10. 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.

  11. The impact of several atomic and molecular laser spectroscopic techniques for chemical analysis

    NASA Astrophysics Data System (ADS)

    Omenetto, N.

    1988-07-01

    Several laser-based methods, namely laser induced fluorescence, laser enhanced ionisation and thermal lensing spectrophotometry are discussed with respect to their capabilities of approaching the extremely high detection sensitivity which is nowadays required in many fields of application, notably in high purity materials, in biomedicine and in the nuclear industry. The discussion is restricted to atomisers operated at atmospheric pressure, i.e., combustion flames, plasmas and graphite furnaces. It is shown that the analytical limit of detection can be in the range of femtograms and that double-resonance excitation possesses significant advantages over single-resonance excitation, both in terms of signal-to-noise ratio and spectral selectivity. In addition, the combination of the fluorescence and ionisation techniques represents a remarkable diagnostic tool. In the nuclear field, the suitability of the technique of thermal lensing for the direct determination and chemical speciation of very low levels of uranium in water is discussed.

  12. 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

  13. 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.

  14. 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.

  15. Remote chemical monitoring in an industrial environment using eyesafe IR laser radar technologies

    NASA Astrophysics Data System (ADS)

    Pasmanik, Guerman A.; Shklovsky, E. J.; Freidman, Gennady I.; Lozhkarev, Vladimir V.; Matveyev, Alexander Z.; Shilov, Alexander A.; Yakovlev, Ivan V.; Peterson, Darrel G.; Partin, Judy K.

    1997-07-01

    The brief description of new lidar prototype for remote chemical monitoring and profiling in the 8 - 12 micron range is given. The lidar includes a Nd:YAG laser (1 J per pulse) source, optical parametrical oscillator (0.2 J per pulse), and four-wave Raman emitter (20 mJ output per pulse). The receiver consists of the hydrogen SRS cells, pumped by an additional OPO pulse. Sensitivity of this receiver reaches approximately 1000 photons per pixel. The applications of this lidar for remote detection of chemicals in atmosphere will also be discussed.

  16. 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.

  17. Laser structuring and modification of polymer surfaces for chemical and medical microcomponents

    NASA Astrophysics Data System (ADS)

    Bremus-Koebberling, Elke A.; Meier-Mahlo, Ulrike; Henkenjohann, Oliver; Beckemper, Stefan; Gillner, Arnold

    2004-10-01

    In the production of micro devices the surface properties become more and more important for chemistry, biotechnology and medical technology with respect to wetting properties and chemical composition of the surface. Typical applications are implants as well as micro fluidic systems or miniaturized devices for DNA- and proteome analysis (biochips). In this paper newly designed laser technologies based on UV-laser treatment of polymers for surface processing are described to manipulate wetting properties, cell growth and immobilization of functional molecules with high spatial resolution. Depending on the processing parameters and used polymers either hydrophobic or hydrophilic properties can be enhanced (i.e. laser induced lotus/anti-lotus effect). Enhanced roughness and changes of the chemical composition have also influence on cell growth on polymer surfaces. Thus guiding aids for cells e.g. on medical implants can be generated by laser irradiation. Due to photo oxidation processes while UV-treatment in air, functional groups are created that are suited for covalent bonding of (bio)moelcules onto the surfaces. A second process for the locally selective immobilization of anchor molecules based on azide functionalized templates suitable for further modification steps is presented by means of irradiating polymers under solutions of these linkers.

  18. 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%.

  19. Chemical vapor synthesis of nanocrystalline perovskites using laser flash evaporation of low volatility solid precursors

    NASA Astrophysics Data System (ADS)

    Winterer, Markus; Srdic, Vladimir V.; Djenadic, Ruzica; Kompch, Alexander; Weirich, Thomas E.

    2007-12-01

    One key requirement for the production of multinary oxide films by chemical vapor deposition (CVD) or nanocrystalline multinary oxides particles by chemical vapor synthesis (CVS) is the availability of precursors with high vapor pressure. This is especially the case for CVS where much higher production rates are required compared to thin films prepared by CVD. However, elements, which form low valent cations such as alkaline earth metals, are typically only available as solid precursors of low volatility, e.g., in form of β-diketonates. This study describes laser flash evaporation as precursor delivery method for CVS of nanocrystalline perovskites. Laser flash evaporation exploits the nonequilibrium evaporation of solid metal organic precursors of low vapor pressure by absorption of the infrared radiation of a CO2 laser. It is shown that stoichiometric, nanocrystalline particles consisting of SrZrO3 and SrTiO3 can be formed from corresponding mixtures of β-diketonates which are evaporated nonselectively and with high rates by laser flash evaporation.

  20. 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

  1. 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

  2. Modeling of HF chemical laser flowfields using the Direct Simulation Monte Carlo method

    SciTech Connect

    McGregor, R.D.; Haflinger, D.E.; Lohn, P.D.; Sollee, J.L.; Behrens, H.W.; Duncan, W.A. U.S. Army, Missile Command, Redstone Arsenal, Al )

    1992-07-01

    A methodology, based on the Direct Simulation Monte Carlo (DSMC) approach, has been developed to screen injector concepts for high-energy chemical lasers. This methodology involves modeling the associated complex three-dimensional, reacting, multispecies flowfields and has been validated by comparison with experimental measurements. The method enables screening of new high-performance injector concepts and has the potential of greatly minimizing idea-to-implementation time and cost. 5 refs.

  3. 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).

  4. Ambient diode laser desorption dielectric barrier discharge ionization mass spectrometry of nonvolatile chemicals.

    PubMed

    Gilbert-López, Bienvenida; Schilling, Michael; Ahlmann, Norman; Michels, Antje; Hayen, Heiko; Molina-Díaz, Antonio; García-Reyes, Juan F; Franzke, Joachim

    2013-03-19

    In this work, the combined use of desorption by a continuous wave near-infrared diode laser and ionization by a dielectric barrier discharge-based probe (laser desorption dielectric barrier discharge ionization mass spectrometry (LD-DBDI-MS)) is presented as an ambient ionization method for the mass spectrometric detection of nonvolatile chemicals on surfaces. A separation of desorption and ionization processes could be verified. The use of the diode laser is motivated by its low cost, ease of use, and small size. To achieve an efficient desorption, the glass substrates are coated at the back side with a black point (target point, where the sample is deposited) in order to absorb the energy offered by the diode laser radiation. Subsequent ionization is accomplished by a helium plasmajet generated in the dielectric barrier discharge source. Examples on the application of this approach are shown in both positive and negative ionization modes. A wide variety of multiclass species with low vapor pressure were tested including pesticides, pharmaceuticals and explosives (reserpine, roxithromycin, propazine, prochloraz, spinosad, ampicillin, dicloxacillin, enrofloxacin, tetracycline, oxytetracycline, erythromycin, spinosad, cyclo-1,3,5,7-tetramethylene tetranitrate (HMX), and cyclo-1,3,5-trimethylene trinitramine (RDX)). A comparative evaluation revealed that the use of the laser is advantageous, compared to just heating the substrate surface. PMID:23419061

  5. 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 in relation to our ultimate goal of a universal compact chemical sensor platform.

  6. On the possibility of simultaneous emission of an autonomous cw HF-DF chemical laser in two spectral ranges

    SciTech Connect

    Bashkin, A S; Gurov, L V; Katorgin, B I; Petrova, S N; Polinovsky, D V

    2008-05-31

    The efficiencies of different fuel compositions used in the combustion chamber of an autonomous cw chemical HF-DF laser for obtaining high specific energy parameters during simultaneous lasing in HF and DF molecules in two spectral ranges are theoretically analysed. It is shown that mirrors with the reflectance above 99% in these spectral ranges can be manufactured in principle. (lasers)

  7. 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. PMID:23020398

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

    NASA Astrophysics Data System (ADS)

    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 mm3) consisting of SiC, Ni/NiOx, 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 H2 gas ambient due to the higher thermal conductivity, temperatures up to 1000°C were achieved even in 200 Torr H2. 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.

  9. 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.

  10. 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

  11. Characterizing effects and benefits of beam defocus on high energy laser performance under thermal blooming and turbulence conditions for air-to-ground engagements

    NASA Astrophysics Data System (ADS)

    Long, Scott N.

    2008-10-01

    This dissertation makes contributions towards knowledge of optimizing of laser weapon performance when operating in the air-to-ground (ATG) regime in thermal blooming conditions. Wave optics modeling techniques were used to represent laser weapon performance in a high fidelity sense to allow progress to be made toward improving lower-fidelity scaling laws that can be used in systems level analysis which has need for better representations of thermal blooming. Chemical-oxygen iodine laser (COIL) based weapon systems that operate near the ground will experience thermal blooming due to atmospheric absorption if output power is sufficiently high. The thermal lens in the ATG case is predominantly in the far-field of the optical system which puts the problem outside the envelope for most classical phase correction techniques. Focusing the laser beyond the target (defocus) in the air-to-ground regime is shown to improve irradiance at the target and can be thought of as reducing the thermal blooming distortion number, ND, rather than phase correction. Improvement is shown in a baseline scenario presented and all variations from it explored herein. The Breaux ND is examined for potential use in a defocus scaling law, and a correction factor due to Smith (1977), developed for a different context, is proposed to address deficiencies. Optimal defocus settings and expected improvement are presented as a function of Breaux ND. Also, the generally negative interaction between turbulence and thermal blooming is investigated and shown to further limit performance potential of ATG laser weapons. This negative interaction can impact the weapon design trade space and operational methods for minimizing the interaction and thermal blooming are explored in a case study.

  12. 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)

  13. 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.

  14. Chemical reactions of excited nitrogen atoms for short wavelength chemical lasers. Final technical report

    SciTech Connect

    Not Available

    1989-12-15

    Accomplishments of this program include the following: (1) Scalable, chemical generation of oxygen atoms by reaction of fluorine atoms and water vapor. (2) Production of nitrogen atom densities of 1 {times} 10{sup 1}5 cm{sup {minus}3} with 5% electrical efficiency by injecting trace amounts of fluorine into microwave discharged nitrogen. (3) Production of cyanide radicals by reaction of high densities of N atoms with cyanogen. (4) Production of carbon atoms by reaction of nitrogen atoms with cyanogen or with fluorine atoms and hydrogen cyanide. (5) Confirmation that the reaction of carbon atoms and carbonyl sulfide produces CS(a{sup 3} {Pi}{sub r}), as predicted by conservation of electron spin and orbital angular momenta and as proposed by others under another SWCL program. (6) Production of cyanide radicals by injection of cyanogen halides into active nitrogen and use as spectroscopic calibration source. (7) Demonstration that sodium atoms react with cyanogen chloride, bromide and iodide and with cyanuric trifluoride to produce cyanide radicals. (8) Demonstration of the potential utility of the fluorine atom plus ammonia reaction system in the production of NF(b{sup l}{Sigma}{sup +}) via N({sup 2}D) + F{sub 2}.

  15. Laser-induced shock wave removal of chemical-mechanical polishing slurries from silicon wafers

    NASA Astrophysics Data System (ADS)

    Lee, J. M.; Cho, S. H.; Park, J. G.; Lee, S. H.; Han, Y. P.; Kim, S. Y.

    2003-02-01

    A new dry cleaning methodology named laser-induced shock cleaning has been applied to remove the chemical-mechanical polishing (CMP) slurries from silicon wafer surfaces. After CMP process using the slurries, the slurry particles should be removed from the surface in order to avoid the circuit failure and enhance the yield. The well-distributed remaining silica particles were attempted to remove from the surface by using laser-induced plasma shock waves. In order to evaluate the cleaning performance quantitatively, the number of particles on the wafer surfaces were measured by surface scanner before and after cleaning. It was found that most of the silica particles on the wafer surface were removed after the treatment of laser-induced shock waves. The average removal efficiency of the particles was 99% over. It was found that cleaning performance is strongly dependent on a gap distance between laser focus and the surface and a suitable control of the gap is crucial for the successful removal of the particles.

  16. 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.

  17. 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 gas by means of the 6 KW sub-breakdown pump field, while another 2700 watts is applied to the controlled avalanche field. The generator consists of 24 each, 1 cm diameter tubes that are submerged in rapidly circulating cold fluorinert. Heat is efficiently removed so that that the gas temperature, initially 273°K, raises only by 125°K, as evidenced by spectrographic analysis of the fine structure of O2(b1Σ) at lower pressure. Since all necessary conditions have been met, a 30% conversion rate of O2 to O2(a1Δ) has been achieved. Fortuitously, neither excited O atom production nor O2(b1Σ) production is visible in the spectra of the higher pressure, best yield runs. Essentially all other spectral lines are dwarfed in comparison the O2(a1Δ) line. Energy normally partitioned to O2(b1Σ) and apparently O atoms now feeds into O2(a1Δ) directly, enabling electrical efficiency to exceed 40%. As a continuation of this work, an I2 disassociating mixing section - then subsequently a 20 cm transverse M = 2.5 laser channel - has been coupled to the O2(a1Δ) generator. The effects of titrating NO, NO2, etc. to scavenge O atoms and O3 atoms is under current investigation. Laser power extraction will commence after having optimized all parameters to achieve maximum gain. Power extraction has been delayed due to substantial mechanical equipment failure; however, the apparatus has now been fully restored. Also, several modes of potential discharge instabilities peculiar to high O2(a1Δ) concentrations have been discovered. These phenomenon and their means of prevention will be discussed.

  18. Laser nanolithography and chemical metalization for the manufacturing of 3D metallic interconnects

    NASA Astrophysics Data System (ADS)

    Jonavičius, Tomas; RekštytÄ--, Sima; Žukauskas, Albertas; Malinauskas, Mangirdas

    2014-03-01

    We present a developed method based on direct laser writing (DLW) and chemical metallization (CM) for microfabrication of three-dimensional (3D) metallic structures. Such approach enables manufacturing of free­-form electro conductive interconnects which can be used in integrated electric circuits such micro-opto-electro mechanical systems (MOEMS). The proposed technique employing ultrafast high repetition rate laser enables efficient fabrication of 3D microstructures on dielectric as well as conductive substrates. The produced polymer links out of organic-inorganic composite matrix after CM serve as interconnects of separate metallic contacts, their dimensions are: height 15μm, width 5μm, length 35-45 μm and could provide 300 nΩm resistivity measured in a macroscopic way. This proves the techniques potential for creating integrated 3D electric circuits at microscale.

  19. Chemical analysis of a-CNx thin films synthesized by nanosecond and femtosecond pulsed laser deposition

    NASA Astrophysics Data System (ADS)

    Szörényi, T.; Fogarassy, E.; Fuchs, C.; Hommet, J.; Le Normand, F.

    An ArF excimer laser (22 ns, 193 nm) and a hybrid dye/excimer laser system (500 fs, 248 nm) are used to deposit amorphous carbon nitride films at room temperature by ablation of a graphite target in nitrogen atmosphere. The chemical composition and structure of the films is characterized by X-ray photoelectron spectroscopy. In the nanosecond case, the nitrogen content increases with reactive gas pressure up to 45 atomic%, while in the subpicosecond case it remains below 7 at.%. When processed with nanosecond pulses, the films' nitrogen content steeply increases with fluence up to a maximum. The target-to-substrate distance has only minor influence on the amount of nitrogen incorporated into the films. The dependence of the carbon-carbon and carbon-nitrogen bond configurations on the processing parameters is also given.

  20. 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

  1. 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.

  2. 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

    2016-03-01

    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.

  3. Chemical speciation in laser-desorption and impact-induced vapor in minerals

    NASA Astrophysics Data System (ADS)

    Shen, A. H.; Dundas, C. M.; Ahrens, T. J.; Beauchamp, J. L.

    2002-12-01

    Knowledge of the chemical species in vapors produced by hypervelocity impact on spacecraft impact detectors as well as planetary surfaces have applications ranging from determination of the composition of cosmic dust to the effects on atmospheres and climates of large impactors. Direct study of resulting atomic, molecular and ionic species is best accomplished via mass spectrometry. Pulsed laser desorption can be used to approximate small impacts on solid surfaces. We conducted pulsed laser desorption-ionization experiments using two different instruments: (1) a Caltech-built Time-of-Flight Mass Spectrometer (TOFMS) similar to that on board the Cassini spacecraft and (2) a commercial Matrix Assisted Laser Desorption Ionization TOFMS made by Applied Biosystems (Model, Voyager-DE Pro). Minerals included in this study were calcite, dolomite, gypsum, anhydrite, olivine, kamacite, brucite, serpentine, and pyrrhotite. We collected only positive ions. A nitrogen laser (337 nm wavelength, 4 μsec pulse width, and 300 mJ) with power density ranging from 1.0x107 to 1.3x109 W/cm2 induced vaporization and ionization. The results can be summarized as: (1) from kamacite and pyrrhotite, only 54Fe+, 56Fe+, 57Fe+ (both kamacite and pyrrhotite) and 58Ni+, 60Ni+ (kamacite only) as well as contamination ions such as 23Na+ and 39K+, 41K+were observed; (2) Ca-containing minerals (calcite, dolomite, gypsum and anhydrite) produced vapors containing 40Ca+ ions, and, at higher laser power, both 40Ca+ as well as CaO+ ions; (3) Mg-containing minerals (dolomite, olivine, brucite and serpentine) produced vapors containing MgO+ ion; (4) for all hydrous minerals, neither H+ nor H3O+ were observed in the vapor; (5) in the vapors of silicate minerals (olivine and serpentine), SiO+ was observed only from serpentine but not from olivine.

  4. Fabrication of highly ultramicroporous carbon nanofoams by SF6-catalyzed laser-induced chemical vapor deposition

    NASA Astrophysics Data System (ADS)

    Hattori, Yoshiyuki; Shuhara, Ai; Kondo, Atsushi; Utsumi, Shigenori; Tanaka, Hideki; Ohba, Tomonori; Kanoh, Hirofumi; Takahashi, Kunimitsu; Vallejos-Burgos, Fernando; Kaneko, Katsumi

    2016-05-01

    We have developed a laser-induced chemical vapor deposition (LCVD) method for preparing nanocarbons with the aid of SF6. This method would offer advantages for the production of aggregates of nanoscale foams (nanofoams) at high rates. Pyrolysis of the as-grown nanofoams induced the high surface area (1120 m2 g-1) and significantly enhanced the adsorption of supercritical H2 (16.6 mg g-1 at 77 K and 0.1 MPa). We also showed that the pyrolized nanofoams have highly ultramicroporous structures. The pyrolized nanofoams would be superior to highly microporous nanocarbons for the adsorption of supercritical gases.

  5. 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.

  6. 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.

  7. Laser chemical vapor deposition of millimeter scale three-dimensional shapes

    NASA Astrophysics Data System (ADS)

    Shaarawi, Mohammed Saad

    2001-07-01

    Laser chemical vapor deposition (LCVD) has been successfully developed as a technique to synthesize millimeter-scale components directly from the gas phase. Material deposition occurs when heat generated by the interaction of a laser beam with a substrate thermally decomposes the gas precursor. Selective illumination or scanning the laser beam over portions of a substrate forms the single thin layer of material that is the building block of this process. Sequential scanning of the laser in a pre-defined pattern on the substrate and subsequent deposit causes the layers to accumulate forming the three-dimensional shape. The primary challenge encountered in LCVD shape forming is the synthesis of uniform layers. Three deposition techniques are studied to address this problem. The most successful technique, Active Surface Deposition, is based on the premise that the most uniform deposits are created by measuring the deposition surface topology and actively varying the deposition rate in response to features at the deposition surface. Defects observed in the other techniques were significantly reduced or completely eliminated using Active Surface Deposition. The second technique, Constant Temperature Deposition, maintains deposit uniformity through the use of closed-loop modulation of the laser power to sustain a constant surface temperature during deposition. The technique was successful in depositing high quality graphite tubes >2 mm tall from an acetylene precursor and partially successful in depositing SiC + C composite tubes from tetramethylsilane (TMS). The final technique, Constant Power Deposition, is based on the premise that maintaining a uniform power output throughout deposition would result in the formation of uniform layers. Constant Power Deposition failed to form coherent shapes. Additionally, LCVD is studied using a combination of analytic and numerical models to gain insight into the deposition process. Thermodynamic modeling is used to predict the phase content for the various deposition conditions observed during deposition. Rod deposition from TMS is examined in terms of a numerical model that incorporates transport phenomena and chemical reactions to simulate steady state deposition. Predictions about deposition rates, phase content and morphological features made by the models compared favorably with experimental results.

  8. CdS thin films prepared by laser assisted chemical bath deposition

    NASA Astrophysics Data System (ADS)

    Garcia, L. V.; Mendivil, M. I.; Garcia Guillen, G.; Aguilar Martinez, J. A.; Krishnan, B.; Avellaneda, D.; Castillo, G. A.; Das Roy, T. K.; Shaji, S.

    2015-05-01

    In this work, we report the preparation and characterization of CdS thin films by laser assisted chemical bath deposition (LACBD). CdS thin films were prepared from a chemical bath containing cadmium chloride, triethanolamine, ammonium hydroxide and thiourea under various deposition conditions. The thin films were deposited by in situ irradiation of the bath using a continuous laser of wavelength 532 nm, varying the power density. The thin films obtained during deposition of 10, 20 and 30 min were analyzed. The changes in morphology, structure, composition, optical and electrical properties of the CdS thin films due to in situ irradiation of the bath were analyzed by atomic force microscopy (AFM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and UV-vis spectroscopy. The thin films obtained by LACBD were nanocrystalline, photoconductive and presented interesting morphologies. The results showed that LACBD is an effective synthesis technique to obtain nanocrystalline CdS thin films having good optoelectronic properties.

  9. 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.

  10. 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.

  11. 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-of-flight mass spectrometer designed for in-situ investigations in planetary space research, J. Mass Spectrom., in press. [4] Neuland, M.B., Meyer, S., Mezger, K., Riedo, A., Tulej, M., Wurz, P., Probing the Allende meteorite with a miniature Laser-Ablation Mass Analyser for space application, Planetary and Space Science, Special Issue: Terrestrial Planets II, submitted

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

    NASA Astrophysics Data System (ADS)

    Haque, Moez

    Three-dimensional (3D) patterning inside optical fiber was shown to be a powerful tool for embedding refractive index and microfluidic structures inside the flexible glass fiber for enabling novel sensing opportunities with lab-in-fibers (LIFs). A femtosecond laser was tightly focused into optical fibers using an oil-immersion lens to eliminate extreme optical aberrations from the cladding-air interface. The laser interactions were then optimized to bring ˜12 nm rms surfaces for the first time inside the fiber cladding by precisely conforming planar nanograting structures when assembled by the writing laser. Further, the unprecedented integration of cladding waveguides, X-couplers, fiber Bragg gratings (FBGs), microholes, mirrors, optofluidic resonators, and microfluidic reservoirs defined the building blocks for facile interconnection of inline core-waveguide devices with fiber cladding optofluidics. Laser templating was restricted to the single mode fiber (SMF) cladding or formed inside all-fused silica coreless optical fibers to meet with buried laser-formed waveguides that were fused to SMFs for novel seamless inline probing while avoiding undesired concave surface profiles and negative lensing losses associated with writing optofluidic templates across the germanium-doped SMF core waveguide. With these components, more advanced, integrated, and multiplexed fiber microsystems were demonstrated for fluorescence detection, Fabry Perot interferometer (FPI) refractometry, and simultaneous sensing of refractive index, temperature, and bending strain. Tapered access ports were found to minimize fiber mechanical weakening and thereby avoid fiber breakage during optofluidic sensing. Optical resonator arrays (ORAs) were then explored to deepen fringe contrasts beyond that available with a single FPI for opening new prospects for fiber inline pass-band optical filters and broadband reflectors. Finally, wavefront splitting interferometers (WSIs) were targeted to improve 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.

  13. Fabrication of high-aspect ratio, micro-fluidic channels and tunnels using femtosecond laser pulses and chemical etching

    NASA Astrophysics Data System (ADS)

    Bellouard, Yves; Said, Ali; Dugan, Mark; Bado, Philippe

    2004-05-01

    We present novel results obtained in the fabrication of high-aspect ratio micro-fluidic microstructures chemically etched from fused silica substrates locally exposed to femtosecond laser radiation. A volume sampling method to generate three-dimensional patterns is proposed and a systematic SEM-based analysis of the microstructure is presented. The results obtained gives new insights toward a better understanding of the femtosecond laser interaction with fused silica glass (a-SiO2).

  14. 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.

  15. 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.

  16. Morphology and chemical composition analysis on multi-pulsed CO2 laser ablation of HgCdTe crystals

    NASA Astrophysics Data System (ADS)

    Tang, Wei; Guo, Jin; Shao, Jun-feng; Wang, Ting-feng

    2013-09-01

    In order to study deeply damage mechanism of HgCdTe crystal irradiated by multi-pulsed CO2 laser and obtain the characteristics of surface morphological and chemical composition changes. Firstly, Irradiation effect experiment is conducted on the Hg0.826Cd0.174Te crystal by pulsed CO2 laser, which has a pulse width of 200ns and repetition frequency ranges from 1 Hz to 100 kHz. Then morphological and chemical composition changes of Hg0.826Cd0.174Te crystal is measured by field emission scanning electron microscope (FESEM) and damage threshold is obtained by morphology method. Finally, the impact of laser power density on morphological and chemical composition changes is analyzed. The research results show that: damage threshold of Hg0.826Cd0.174Te crystal which is irradiated by multi-pulsed CO2 laser is 950 W/cm2. The crystal surface melting phenomenon is very obvious, the obvious crack which is caused by thermal stress is not found in the surface, and a large number of bulges and pits are taken shape in the laser ablation zone. Chemical composition changes of the crystal are obvious, and a lot of O element is found in the laser ablation zone. With the increase of laser irradiation power, the content of Hg element decrease rapidly, the content of Cd, Te and O element raise by degrees, and chemical composition changes of the crystal are more and more obvious. When the irradiation power density is 1.8kW/cm2, the surface becomes smooth in the ablation zone due to the impact of laser impulse force, and the content of the chemical compositions is that Hg accounts for 0.23%, Cd accounts for 21.38%, Te accounts for 26.27%, and O accounts for 52.12%. The conclusions of the study have a reference value for the Hg0.826Cd0.174Tecrystal in the application of making infrared detector and pulsed CO2 laser in the aspect of laser processing.

  17. Studies of elementary processes and coupling involved in the D2/F2 chemical laser

    NASA Astrophysics Data System (ADS)

    Tardy, D. C.

    1986-12-01

    The performance of a H2/D2 chemical laser is a function of the nascent energy disposal parameters for the F + H2 (D2) and H (D) + F2 chemical reactions and the vibrational relaxation of HF (DF). Chemiluminescence Mapping (CM) in which chemical components are observed by their spectral and time resolution is a technique which is capable of providing fundamental information on both nascent energy distributions for bimolecular exchange reactions and vibrational relaxation. Knowledge of the reactants (atoms or ions) and residence times must be known in order to interpret the data. Using a double floating probe the ion content flowing from a microwave discharge of hydrogen was found to be less than .0000018 of the total flow, thus ion molecule reactions are unimportant. The interpretation of CM experiments requires realistic modeling to deconvolute the experimental data. Both types of CM experiments provide nascent vibrational energy distributions. CM-LP experiments also provide total reaction rate constants and microscopic relaxation rate constants. In addition to the F + H2(D2) benchmark reactions, experimental results for H(D)+F2, F+ HBr, and F+CH2Cls are discussed and compared to other studies when available.

  18. 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 uniformity in tests with polyurethane substrate, however, it was found to have no effect in improving the overall deposition rate compared to H2S-free deposition process. Deposition on other selected substrates, such as ultra-fine polymer foam, carbon nanofoam and multi-wall carbon nanotubes, was demonstrated. The HPDL system shows good promise for large-scale industrial application as the cost of HPDL energy continues to decrease.

  19. 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.

  20. Spherical silicon-shell photonic band gap structures fabricated by laser-assisted chemical vapor deposition

    NASA Astrophysics Data System (ADS)

    Wang, H.; Yang, Z. Y.; Lu, Y. F.

    2007-02-01

    Laser-assisted chemical vapor deposition was applied in fabricating three-dimensional (3D) spherical-shell photonic band gap (PBG) structures by depositing silicon shells covering silica particles, which had been self-assembled into 3D colloidal crystals. The colloidal crystals of self-assembled silica particles were formed on silicon substrates using the isothermal heating evaporation approach. A continuous wave Nd:YAG laser (1064nm wavelength) was used to deposit silicon shells by thermally decomposing disilane gas. Periodic silicon-shell/silica-particle PBG structures were obtained. By removing the silica particles enclosed in the silicon shells using hydrofluoric acid, hollow spherical silicon-shell arrays were produced. This technique is capable of fabricating structures with complete photonic band gaps, which is predicted by simulations with the plane wave method. The techniques developed in this study have the potential to flexibly engineer the positions of the PBGs by varying both the silica particle size and the silicon-shell thickness. Ellipsometry was used to investigate the specific photonic band gaps for both structures.

  1. 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.

  2. 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.

  3. Core-shell photonic band gap structures fabricated using laser-assisted chemical vapor deposition

    NASA Astrophysics Data System (ADS)

    Wang, H.; Lu, Y. F.

    2008-01-01

    Laser-assisted chemical vapor deposition (LCVD), in combination with three-dimensional (3D) self-assembly of colloidal silica particles, was used to fabricate 3D core-shell photonic band gap (PBG) structures. Self-assembled multilayer silica particles were formed on silicon substrates using the isothermal heating evaporation approach. A continuous-wave CO2 laser (10.6 μm wavelength) was used as the energy source in the LCVD to fabricate a silica-core-silicon-shell PBG structure. This technique is capable of fabricating structures with various PBGs by adjusting the silica particle size and Si-shell thickness using different LCVD parameters. This capability enables us to engineer positions and widths of PBGs by flexibly controlling the particle size and shell thicknesses. In the fabricated PBG structures, face-centered cubic structures consist of silica-core-silicon-shell "effective atoms." A series of PBG structures with designed PBGs was obtained under different experimental conditions. Incidence-angle-resolved spectroscopic ellipsometry was used to identify specific PBGs. The refractive indices of the effective atoms with different Si-shell thicknesses were calculated using the Bruggeman composite model. The plain-wave expansion method was used to simulate the photonic dispersion diagrams, which supported the experimental results.

  4. Theoretical analysis of dynamic chemical imaging with lasers using high-order harmonic generation

    SciTech Connect

    Van-Hoang Le; Anh-Thu Le; Xie Ruihua; Lin, C. D.

    2007-07-15

    We report theoretical investigations of the tomographic procedure suggested by Itatani et al. [Nature (London) 432, 867 (2004)] for reconstructing highest occupied molecular orbitals (HOMOs) using high-order harmonic generation (HHG). Due to the limited range of harmonics from the plateau region, we found that even under the most favorable assumptions, it is still very difficult to obtain accurate HOMO wave functions using the tomographic procedure, but the symmetry of the HOMOs and the internuclear separation between the atoms can be accurately extracted, especially when lasers of longer wavelengths are used to generate the HHG. Since the tomographic procedure relies on approximating the continuum wave functions in the recombination process by plane waves, the method can no longer be applied upon the improvement of the theory. For future chemical imaging with lasers, we suggest that one may want to focus on how to extract the positions of atoms in molecules instead, by developing an iterative method such that the theoretically calculated macroscopic HHG spectra can best fit the experimental HHG data.

  5. 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. PMID:26480354

  6. Luminescence properties of SiOxNy irradiated by IR laser 808 nm: The role of Si quantum dots and Si chemical environment

    NASA Astrophysics Data System (ADS)

    Ruggeri, Rosa; Neri, Fortunato; Sciuto, Antonella; Privitera, Vittorio; Spinella, Corrado; Mannino, Giovanni

    2012-01-01

    We investigated optical, structural, and chemical properties of SiOxNy layers irradiated by CW IR laser during a time lapse of few milliseconds. We observed tunable photoluminescence signal at room temperature in the range 750-950 nm, without Si/SiO2 phase separation, depending on the IR laser power irradiation. Furthermore, no photoluminescence signal was recorded when the IR laser power density was high enough to promote phase separation forming Si quantum dots. By chemical analysis the source of the luminescence signal has been identified in a change of silicon chemical environment induced by IR laser annealing inside the amorphous matrix.

  7. 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.

  8. 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.

  9. Synthesis of nanostructured carbon materials by open-air laser-induced chemical vapor deposition

    NASA Astrophysics Data System (ADS)

    Kwok, Kinghong

    Elemental carbon in the sp2 hybridization state can form a great variety of graphitic and amorphous structures. Carbon nanotube is a well-known form of graphitic carbon that has remarkable mechanical, electronic and electrochemical properties with applications ranging from reinforced composite materials to micro-scale electronic devices. Pyrolytic carbon film with turbostratic structure is a form of amorphous carbon that possesses excellent barrier properties against diffusion of moisture and hydrogen, and is used as hermetic coating for optical fibers operating under harsh environments. Current deposition techniques for these novel carbon materials are limited in production rate, quality and reproducibility, thereby restricting their usage for advanced applications. In this dissertation, an open-air laser-induced chemical vapor deposition technique is proposed and investigated for the rapid growth of high quality carbon nanotubes and nanometer thick pyrolytic carbon films. The first part of the thesis focuses on the open-air synthesis of carbon nanotubes on stationary and moving fused quartz substrates. The second part will study the deposition of pyrolytic carbon film on various optical components including optical fibers. Optical microscopy, high-resolution transmission and scanning electron microscopy, Raman and Auger electron spectroscopy, as well as x-ray energy-dispersive spectrometry, scanning white-light interferometry and thermal pyrometry are used to investigate the deposition rate, morphology, microstructure and chemical composition of the deposited carbon materials.

  10. Chemical stabilization of laser dyes. Final report, 1 July 1981-1 October 1984

    SciTech Connect

    Koch, T.H.

    1984-11-01

    Coumarin laser dyes upon excitation degrade to produce products which absorb at the lasing wavelength. This results in attenuation of dye laser output. Modes of degradation of coumarin dye lasers under both anaerobic and aerobic conditions were determined and methods of stabilization of dye lasers were established.

  11. 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.

  12. 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.

  13. 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 liquid. This capability, deployed at airports and other public places, will go a long way towards increasing public safety and minimizing inconveniences faced in airline travel.

  14. 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 general science of Laser Chemical Vapor Deposition and to elucidate the practicality of fabricating ceramic-metal composites using the process.

  15. 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.

  16. Chemical stabilization of laser dyes. Final report, 1 April 1987-31 March 1990

    SciTech Connect

    Koch, T.H.

    1990-04-10

    Irradiation of ethanol solutions of coumarin laser dye lasers produces products which absorb at the lasing wavelength. This results in attenuation of dye laser output through interference of stimulated emission. A major photoprocess which produces material which absorbs at the lasing wavelength is dye sensitized solvent oxidative oligomerization, producing aldehydic and ketonic products. A dye laser stabilization technique is removal of these carbonyl compounds as they are formed by reduction with a polymer bound borohydride reducing agent.

  17. Fast growth of branched nickel monosilicide nanowires by laser-assisted chemical vapor deposition.

    PubMed

    Gao, Y; Zhou, Y S; Qian, M; Xie, Z Q; Xiong, W; Luo, H F; Jiang, L; Lu, Y F

    2011-06-10

    Branched nickel monosilicide (NiSi) nanowires (NWs), for the first time, have been synthesized on Ni foams by laser-assisted chemical vapor deposition using disilane precursor molecules. Studies indicate that 600 °C is the threshold temperature for the growth of a large number of branched NiSi NWs with 100-500 nm long branches extending from the main stems. Below the threshold temperature, unbranched NiSi NWs were obtained. The density of the branched NiSi NWs is relatively higher in comparison to that of the unbranched ones. The growth rate of the branched NiSi NWs at 700 °C is estimated up to 10 µm min(-1). High-resolution transmission electron microscopy and energy-dispersive x-ray spectroscopy of the branched NiSi NWs suggest that the formation of these branched nanostructures is ascribed to the Ni-dominant diffusion process. These NiSi NWs with branched nanostructures could bring them new opportunities in nanodevices. PMID:21474870

  18. Fast growth of branched nickel monosilicide nanowires by laser-assisted chemical vapor deposition

    NASA Astrophysics Data System (ADS)

    Gao, Y.; Zhou, Y. S.; Qian, M.; Xie, Z. Q.; Xiong, W.; Luo, H. F.; Jiang, L.; Lu, Y. F.

    2011-06-01

    Branched nickel monosilicide (NiSi) nanowires (NWs), for the first time, have been synthesized on Ni foams by laser-assisted chemical vapor deposition using disilane precursor molecules. Studies indicate that 600 °C is the threshold temperature for the growth of a large number of branched NiSi NWs with 100-500 nm long branches extending from the main stems. Below the threshold temperature, unbranched NiSi NWs were obtained. The density of the branched NiSi NWs is relatively higher in comparison to that of the unbranched ones. The growth rate of the branched NiSi NWs at 700 °C is estimated up to 10 µm min - 1. High-resolution transmission electron microscopy and energy-dispersive x-ray spectroscopy of the branched NiSi NWs suggest that the formation of these branched nanostructures is ascribed to the Ni-dominant diffusion process. These NiSi NWs with branched nanostructures could bring them new opportunities in nanodevices.

  19. 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

  20. 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.

  1. Examination of quantum cascade laser source for a MEMS-scale photoacoustic chemical sensor

    NASA Astrophysics Data System (ADS)

    Heaps, David A.; Pellegrino, Paul M.

    2006-05-01

    Photoacoustic spectroscopy is a useful monitoring technique that is well suited for trace gas detection. The technique also possesses favorable detection characteristics when the system dimensions are scaled to a micro-system design. The objective of present work is to incorporate two strengths of the Army Research Laboratory (ARL), Quantum Cascade Laser (QCL) source development and chemical and biological sensing into a monolithic micro-electromechanical systems (MEMS) photoacoutic trace gas sensor. Past examination of a one quarter scale photoacoustic (PA) macro-cell has indicated a pathway to incorporate a photoacoustic resonance structure in a micro-mechanical platform. Initial studies involve the incorporation of a QCL source operating @ ~3.45 μm into the PA macro-cell system as a means to discern proper operational characteristics in relation to the photoacoustic cell design. Results will be presented describing beam conditioning, modulation control and wavelength selection associated with the QCL source. Some preliminary information regarding MEMS-scale designs based off of hybrid concept, involving commercially available microphone and fully fabricated MEMS photoacoustic resonator will be described.

  2. Effects of specific heat ratio on a simulated chemical-laser-cavity flow. Master's thesis

    SciTech Connect

    Botts, C.D.

    1990-12-01

    Mixing of primary cold flow air and secondary helium to control the ratio of specific heats for the medium flowing through a simulated chemical laser nozzle/lasing cavity was accomplished. The effects of a range of mixture specific heat ratios on flowfield behavior were examined using static pressure ports in the test cavity. Schlieren photography and high speed filming aided description of the flow dynamics. Results indicated that boundary layer effects became evident in the nozzles as specific heat ratios increased. Large pressure fluctuations were observed in the cavity when helium was introduced into the flow to raise the specific heat ratio. This unstable behavior was attributed to the helium mass flow into the mixer and the mixer design itself. Use of the air/helium mixer brought about the pressure fluctuations earlier in a test run than with than with the mixer removed under the same conditions. Favorable pressure conditions for lasing were achieved for at least two seconds for the supersonic nozzles' design specific heat ratio of 1.51. Adverse pressure behavior was also attributed to three dimensional viscous effects along the cavity walls. (JHD)

  3. Data analysis of multi-laser standoff spectral identification of chemical and biological compounds

    NASA Astrophysics Data System (ADS)

    Farahi, R.; Zaharov, V.; Tetard, L.; Thundat, T.; Passian, A.

    2013-06-01

    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 development 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.

  4. 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.

  5. Chemically assisted femtosecond laser machining for applications in LiNbO3 and LiTaO3

    NASA Astrophysics Data System (ADS)

    Sivarajah, Prasahnt; Werley, Christopher A.; Ofori-Okai, Benjamin K.; Nelson, Keith A.

    2013-09-01

    We introduce and optimize a fabrication procedure that employs both femtosecond laser machining and hydrofluoric acid etching for cutting holes or voids in slabs of lithium niobate and lithium tantalate. The fabricated structures have 3 μm lateral resolution, a lateral extent of at least several millimeters, and cut depths of up to 100 μm. Excellent surface quality is achieved by initially protecting the optical surface with a sacrificial silicon dioxide layer that is later removed during chemical etching. To optimize cut quality and machining speed, we explored various laser-machining parameters, including laser polarization, repetition rate, pulse duration, pulse energy, exposure time, and focusing, as well as scanning, protective coating, and etching procedures. The resulting structures significantly broaden the capabilities of terahertz polaritonics, in which lithium niobate and lithium tantalate are used for terahertz wave generation, imaging, and control. The approach should be applicable to a wide range of materials that are difficult to process by conventional methods.

  6. Organic chemical analysis on a microscopic scale using two-step laser desorption/laser ionization mass spectrometry

    NASA Astrophysics Data System (ADS)

    Kovalenko, L. J.; Philippoz, J.-M.; Bucenell, J. R.; Zenobi, R.; Zare, R. N.

    1991-04-01

    The distribution of PAHs in the Allende meteorite has been measured using two-step laser desorption and laser multiphoton-ionization mass spectrometry. This method enables in situ analysis (with a spatial resolution of 1 mm or better) of selected organic molecules. Results show that PAH concentrations are locally high compared to the average concentration found by analysis of pulverized samples, and are found primarily in the fine-grained matrix; no PAHs were detected in the interiors of individual chondrules at the detection limit (about 0.05 ppm).

  7. Organic chemical analysis on a microscopic scale using two-step laser desorption/laser ionization mass spectrometry

    NASA Technical Reports Server (NTRS)

    Kovalenko, L. J.; Philippoz, J.-M.; Bucenell, J. R.; Zenobi, R.; Zare, R. N.

    1991-01-01

    The distribution of PAHs in the Allende meteorite has been measured using two-step laser desorption and laser multiphoton-ionization mass spectrometry. This method enables in situ analysis (with a spatial resolution of 1 mm or better) of selected organic molecules. Results show that PAH concentrations are locally high compared to the average concentration found by analysis of pulverized samples, and are found primarily in the fine-grained matrix; no PAHs were detected in the interiors of individual chondrules at the detection limit (about 0.05 ppm).

  8. 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 fluorescence detection, Fabry-Perot interferometric refractometry, and simultaneous sensing of refractive index, temperature, and bending strain. The flexible writing technique and multiplexed sensors described here open powerful prospects to migrate the benefits of LOCs into a more flexible and miniature LIF platform for highly functional and distributed sensing capabilities. The waveguide backbone of the LIF inherently provides an efficient exchange of information, combining sensing data that are attractive in telecom networks, smart catheters for medical procedures, compact sensors for security and defense, shape sensors, and low-cost health care products. PMID:25120138

  9. 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.

  10. 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.

  11. 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. PMID:25642789

  12. 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.

  13. Two-coordinate control of the radiation pattern of a chemical non-chain electric-discharge DF laser by using space-time light modulators

    SciTech Connect

    Alekseev, V N; Kotylev, V N; Liber, V I

    2008-07-31

    The results of studies of radiation parameters of a chemical non-chain DF laser (emitting in the range from 3.5 to 4.1 {mu}m) with an intracavity control of the radiation pattern with the help of spatiotemporal modulators based on PLZT electrooptic ceramics are presented. (control of laser radiation parameters)

  14. 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.

  15. Plasma shutter for CO2 TEA laser for high-range resolved mapping of chemical plume

    NASA Astrophysics Data System (ADS)

    Bellecci, Carlo; Gaudio, Pasqualino; Martellucci, Sergio; Richetta, Maria

    1998-12-01

    A plasma shutter has been made for cutting nitrogen tail of energy pulse of TEA CO2 laser. Studies to implement all set-ups has been done using preliminarily a TE CO2 laser source. The system is described and the dependence of the gas break down by energy of the discharge is discussed.

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

    SciTech Connect

    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.

  17. 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.

  18. 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.

  19. Detection of chemical changes in bone after irradiation with Er,Cr:YSGG laser

    NASA Astrophysics Data System (ADS)

    Benetti, Carolina; Santos, Moises O.; Rabelo, Jose S.; Ana, Patrícia A.; Correa, Paulo R.; Zezell, Denise M.

    2011-03-01

    The use of laser for bone cutting can be more advantageous than the use of drill. However, for a safe clinical application, it is necessary to know the effects of laser irradiation on bone tissues. In this study, the Fourier Transform Infrared spectroscopy (FTIR) was used to verify the molecular and compositional changes promoted by laser irradiation on bone tissue. Bone slabs were obtained from rabbit's tibia and analyzed using ATR-FTIR. After the initial analysis, the samples were irradiated using a pulsed Er,Cr:YSGG laser (2780nm), and analyzed one more time. In order to verify changes due to laser irradiation, the area under phosphate (1300-900cm-1), amides (1680-1200cm-1), water (3600-2400cm-1), and carbonate (around 870cm-1 and between 1600-1300cm-1) bands were calculated, and normalized by phosphate band area (1300-900cm-1). It was observed that Er,Cr:YSGG irradiation promoted a significant decrease in the content of water and amides I and III at irradiated bone, evidencing that laser procedure caused an evaporation of the organic content and changed the collagen structure, suggesting that these changes may interfere with the healing process. In this way, these changes should be considered in a clinical application of laser irradiation in surgeries.

  20. 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

  1. 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.

  2. Chemical stabilization of laser dyes. Final report, 1 December 1984-28 February 1987

    SciTech Connect

    Koch, T.H.

    1987-05-07

    Coumarin laser dyes upon excitation degrade to produce products that absorb at the lasing wavelength. This results in attenuation of dye laser output through interference of stimulated emission. The roles of singlet oxygen and excitation intensity on dye degradation were explored. Singlet oxygen is formed but its reactions with the dye do not appear to be a major cause of dye laser output deterioration. High light intensity results in dye-sensitized, solvent oligomerization to yield materials that interfere with dye-stimulated emission. 1, 4-Diazabicyclo2,2,2octane (DABCO)inhibits this oligomerization.

  3. Fabrication of ridge waveguide of 808 nm GaAs-based laser diodes by wet chemical etching

    NASA Astrophysics Data System (ADS)

    Xiang, Li; Degang, Zhao; Desheng, Jiang; Ping, Chen; Zongshun, Liu; Jianjun, Zhu; Ming, Shi; Danmei, Zhao; Wei, Liu; Shuming, Zhang; Hui, Yang

    2015-07-01

    The fabrication of ridge waveguide of 808 nm GaAs-based laser diodes by wet chemical etching is investigated. The etching behavior of GaAs, InGaP and AlGaInP in various solutions is evaluated. As a result, the etching solutions simultaneously corroding InGaP and AlGaInP layers are searched successfully. Effects of etching time and the concentration of mixtures on etching depth and the geometrical shape of ridge are analyzed. It is found that under proper conditions, appropriate etching depth and smooth surfaces can be obtained and the steep degree of pattern can be accepted, especially for wide ridge waveguide laser diodes. Project supported by the National Natural Science Foundation of China (Nos. 61474110, 61377020, 61376089, 61223005, 61176126) and the National Science Fund for Distinguished Young Scholars (No. 60925017).

  4. 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.

  5. PHYSICO-CHEMICAL DYNAMICS OF NANOPARTICLE FORMATION DURING LASER DECONTAMINATION AND CHARACTERIZATION

    EPA Science Inventory

    Improvement of understanding on nanoparticle production during simultaneous laser-based decontamination and characterization is imperative to the acceleration of decommission and deactivation (D&D) missions of US Department of Energy (DOE). Many researchers, mostly in material re...

  6. 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.

  7. Excimer laser ablation mass spectrometry of inorganic solids: Chemical, matrix, and sampling effects on polyatomic ion yields

    SciTech Connect

    Gibson, J.K.

    1995-07-01

    Positive ions formed directly by excimer laser ablation in vacuum of several lanthanide (Ln) and transition metal solid materials---including Ln{sub 2}O{sub 3}, Ln{sub 2}S{sub 3}, LnF{sub 3}, Ta{sub 2}O{sub 5}, ZrO{sub 2}, TiO, and TiO{sub 2}---were identified by time-of-flight mass spectrometry. Variations in ion yields were investigated as a function of the composition of the precursor material, laser irradiance, and ion sampling delay after ablation. The compositions of the observed polyatomic ions reflected the distinctive chemistries of the metal constituents, but the ion yield distributions were not generally indicative of the particular chemical/valence constitution of the target material. For example, the yield of CeO{sup +} relative to Ce{sup +} was substantially greater from the trivalent cerium oxide, Ce{sub 2}(WO{sub 4}){sub 3}(s), than from tetravalent CeO{sub 2}(s). Observed ion distributions apparently reflected the chemical composition of the ablation plume and the degree of gas-phase recombination therein. The observed abundances of polyatomic ions were found to correlate well with their estimated bond strengths. Further obscuring the chemical composition of the progenitor, minor changes in ablation, and sampling parameters---especially irradiance and sampling delay---were often manifested as significant variations in relative ion intensities. {copyright} {ital 1995} {ital American} {ital Vacuum} {ital Society}

  8. Chemical and structural modifications of laser treated WTi surfaces at different ambient conditions

    NASA Astrophysics Data System (ADS)

    Petrović, S.; Peruško, D.; Milovanović, D.; Siketić, Z.; Jakšić, M.; Kovač, J.; Gaković, B.; Milosavljević, M.; Trtica, M.

    2011-11-01

    In this work we have studied the influence of laser modification on the composition and structure of tungsten titanium (WTi) thin films, deposited on n-type (100) silicon wafers. After deposition, the samples were multi-pulse laser irradiated in a nitrogen, oxygen, and helium ambient. The composition of the WTi/Si sample was determined by Elastic Recoil Detection Analysis (ERDA). Surface morphology was monitored by Atomic Force Microscopy (AFM). In the experiment, typical laser output parameters were: wavelength 1064 nm, pulse duration 150 ps, and laser pulse energy 30 mJ. Surface concentrations of W and Ti, as well as the concentration of gas components nitrogen and oxygen were determinated before and after the action of laser radiation in different ambient conditions. The contents of W and Ti decreased after irradiation due to adsorbed gases from the surrounding atmosphere. After surface irradiation in the inert ambient (He), the concentrations of the components were not significantly changed. In other cases, oxygen was the dominant component at the surface, probably due to the high affinity of thin film components. Also, the morphological changes occurred at the surface of WTi, as an increase in the surface roughness and formation of the granular structures are a result of laser-induced surface oxidation and recrystallization.

  9. Highly sensitive refractive index fiber inline Mach-Zehnder interferometer fabricated by femtosecond laser micromachining and chemical etching

    NASA Astrophysics Data System (ADS)

    Sun, Xiao-Yan; Chu, Dong-Kai; Dong, Xin-Ran; Zhou, Chu; Li, Hai-Tao; Luo-Zhi; Hu, You-Wang; Zhou, Jian-Ying; Cong-Wang; Duan, Ji-An

    2016-03-01

    A High sensitive refractive index (RI) sensor based on Mach-Zehnder interferometer (MZI) in a conventional single-mode optical fiber is proposed, which is fabricated by femtosecond laser transversal-scanning inscription method and chemical etching. A rectangular cavity structure is formed in part of fiber core and cladding interface. The MZI sensor shows excellent refractive index sensitivity and linearity, which exhibits an extremely high RI sensitivity of -17197 nm/RIU (refractive index unit) with the linearity of 0.9996 within the refractive index range of 1.3371-1.3407. The experimental results are consistent with theoretical analysis.

  10. 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.

  11. 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.

  12. 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.

  13. 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. PMID:25423046

  14. 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.

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

    PubMed Central

    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

    2014-01-01

    Abstract. 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. PMID:25423046

  16. 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.

  17. Development of Efficient Mid-IR Interband Cascade Lasers for Chemical Sensing

    NASA Technical Reports Server (NTRS)

    Yang, Rui Q.; Hill, Cory J.; Yang, Baohua; Qiu, Yueming; Jan, Darrell

    2006-01-01

    Significant progress has been made: Above room temperature (up to 350K) pulsed operation has been demonstrated. CW operation temperature has been raised up to 237 K. DFB IC lasers have been applied for the detection of trace gases such as CH4, HCl, and H2CO. Devices have been operated continuously over several hundred hours without degradation. Main challenge remains for many potential applications of ICLs. CW operation at room temperature and above with significant output powers. There is still significant room for improvement: Laser design and material quality - many parameters have not been optimized. Device fabrication and thermal management (passivation, better mounting, etc.). Significantly higher output power can be achieved with laser arrays.

  18. (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.

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

    SciTech Connect

    Falco, B.

    1991-01-20

    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.

  20. Laser Control of Chemical Dynamics. I. Control of Electronic Transitions by Quadratic Chirping

    NASA Astrophysics Data System (ADS)

    Zou, S.; Kondorskiy, A.; Mil'nikov, G.; Nakamura, H.

    An effective scheme for the laser control of wavepacket dynamics applicable to systems with many degrees of freedom is discussed. It is demonstrated that specially designed quadratically chirped pulses can be used to achieve fast and near-complete excitation of the wavepacket without significantly distorting its shape. The parameters of the laser pulse can be estimated analytically from the Zhu-Nakamura (ZN) theory of nonadiabatic transitions. The scheme is applicable to various processes, such as simple electronic excitations, pump-dumps, and selective bond-breaking, and, taking diatomic and triatomic molecules as examples, it is actually shown to work well.

  1. 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.

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

    SciTech Connect

    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.

  3. 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.

  4. Combustion Research Program: Flame studies, laser diagnostics, and chemical kinetics. Final report, 15 July 1987--15 June 1992

    SciTech Connect

    Crosley, D.R.

    1992-09-01

    This project has comprised laser flame diagnostic experiments, chemical kinetics measurements, and low pressure flame studies. Collisional quenching has been investigated for several systems: the OH radical, by H{sub 2}0 in low pressure flames; the rotational level dependence for NH, including measurements to J=24; and of NH{sub 2} at room temperature. Transition probability measurements for bands involving v{prime} = 2 and 3 of the A-X system of OH were measured in a flame. Laser-induced fluorescence of vinyl radicals was unsuccessfully attempted. RRKM and transition state theory calculations were performed on the OH + C{sub 2}H{sub 4} reaction, on the t-butyl radical + HX; and transition state theory has been applied to a series of bond scission reactions. OH concentrations were measured quantitatively in low pressure H{sub 2}/N{sub 2}O and H{sub 2}/O{sub 2} flames, and the ability to determine spatially precise flame temperatures accurately using OH laser-induced fluorescence was studied.

  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. Improved AMOLED with aligned poly-Si thin-film transistors by laser annealing and chemical solution treatments

    NASA Astrophysics Data System (ADS)

    Wu, G. M.; Chen, C. N.; Feng, W. S.; Lu, H. C.

    2009-12-01

    Low-temperature polycrystalline silicon (LTPS) thin-film transistors (TFT) were prepared for the active-matrix organic light-emitting displays (AMOLED). The excimer laser annealing (ELA) recrystallization technique was employed with a chemical solution treatment process to improve the TFT characteristic uniformity and the AMOLED display image quality. The characteristics of the poly-Si array thin films were influenced by XeCl ELA optic module design, TFT device channel direction, and laser irradiation overlap ratio. The ELA system module provided aligned poly-Si grain size of 0.3 μm by the homogenization lens design. The chemical solution treatment process included a dilute HF solution (DHF), ozone (O 3) water, and buffer oxide etching solution (BOE). The PMOS TFT showed better field effect mobility of 87.6 cm 2/V s, and the threshold voltage was -1.35 V. The off current ( Ioff) was 1.25×10 -11 A, and the on/off current ratio was 6.27×10 6. In addition, the image quality of the AMOLED display was highly improved using the 2T1C structure design without any compensation circuit.

  7. 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.

  8. Laser photochemical growth of amorphous silicon at low temperatures and comparison with thermal chemical vapor deposition

    SciTech Connect

    Eres, D.; Lowndes, D.H.; Geohegan, D.B.; Mashburn, D.N.

    1987-01-01

    Pulsed ArF (193 nm) excimer laser radiation has been used to dissociate disilane (Si/sub 2/H/sub 6/, resulting in photochemically controlled deposition of amorphous Si thin films. A high stability HeNe (6328 A) laser was used for precise in situ monitoring of film deposition rates, under varying deposition conditions. A helium window purge nearly eliminated Si film deposition on the chamber windows. With the excimer laser beam parallel to the substrate, deposition of amorphous Si can be controlled entirely by the photon fluence (negligible background thermal growth) at temperatures from room temperature up to /approximately/400/degree/C. Reasonable photolytic deposition rate (>1 A/sec) are combined with 'digital' control of film thickness (/approx gt/0.02 A/laser pulse). Activation energies of 1.50 (+-0.1) eV and 0.09 (+-0.02) eV were found for pyrolytic and photolytic deposition, respectively. 15 refs., 3 figs.

  9. Highly uniform and reproducible vertical-cavity surface emitting lasers grown by metalorganic chemical vapor deposition

    SciTech Connect

    Hou, H.Q.; Chui, H.C.; Choquette, K.D.; Hammons, B.E.; Breiland, W.G.; Geib, K.M.

    1996-01-01

    We show that the uniformity of the lasing wavelength of vertical-cavity surface emitting lasers (VCSELs) can be as good as {plus_minus}0.3% across a entire 3 in. wafer in MOCVD growth with a similar run-to-run reproducibility.

  10. Modeling of chemical and mechanical aspects in laser restoration of artworks

    NASA Astrophysics Data System (ADS)

    Fotakis, Costas; Athanassiou, Athanassia; Andreou, Efi; Tornari, Vivi; Bonarou, Antonia; Antonucci, Laura; Anglos, Dmitrios; Georgiou, Savas K.; Zafiropulos, Vassilis

    2002-02-01

    In this paper, investigation of photochemical and photomechanical effects induced in polymer substrates under pulsed UV ablation is presented. The examined laser parameters are the wavelength at 248 nm and 193 nm in the nanosecond regime, and the fluence below and above the ablation threshold. The two polymeric substrates used are PMMA and blends of PMMA and PS.

  11. Characterization of Nonpolar Lipids and Selected Steroids by Using Laser-Induced Acoustic Desorption/Chemical Ionization, Atmospheric Pressure Chemical Ionization, and Electrospray Ionization Mass Spectrometry†

    PubMed Central

    Jin, Zhicheng; Daiya, Shivani; Kenttämaa, Hilkka I.

    2011-01-01

    Laser-induced acoustic desorption (LIAD) combined with ClMn(H2O)+ chemical ionization (CI) was tested for the analysis of nonpolar lipids and selected steroids in a Fourier-transform ion cyclotron resonance mass spectrometer (FT-ICR). The nonpolar lipids studied, cholesterol, 5α-cholestane, cholesta-3,5-diene, squalene, and β-carotene, were found to solely form the desired water replacement product (adduct-H2O) with the ClMn(H2O)+ ions. The steroids, androsterone, dehydroepiandrosterone (DHEA), estrone, estradiol, and estriol, also form abundant adduct-H2O ions, but less abundant adduct-2H2O ions were also observed. Neither (+)APCI nor (+)ESI can ionize the saturated hydrocarbon lipid, cholestane. APCI successfully ionizes the unsaturated hydrocarbon lipids to form exclusively the intact protonated analytes. However, it causes extensive fragmentation for cholesterol and the steroids. The worst case is cholesterol that does not produce any stable protonated molecules. On the other hand, ESI cannot ionize any of the hydrocarbon analytes, saturated or unsaturated. However, ESI can be used to protonate the oxygen-containing analytes with substantially less fragmentation than for APCI in all cases except for cholesterol and estrone. In conclusion, LIAD/ClMn(H2O)+ chemical ionization is superior over APCI and ESI for the mass spectrometric characterization of underivatized nonpolar lipids and steroids. PMID:21528012

  12. Relationship between the chemical and morphological characteristics of human dentin after Er:YAG laser irradiation

    NASA Astrophysics Data System (ADS)

    Silva Soares, Luís Eduardo; Lavesa Martin, Ovídio César; Moriyama, Lilian Tan; Kurachi, Cristina; Martin, Airton Abrahão

    2013-06-01

    The effects of laser etching on dentin are studied by microenergy-dispersive x-ray fluorescence spectrometry (μ-EDXRF) and scanning electron microscopy (SEM) to establish the correlation of data obtained. Fifteen human third molars are prepared, baseline μ-EDXRF mappings are performed, and ten specimens are selected. Each specimen received four treatments: acid etching (control-CG) or erbium:yttrium-aluminum-garnet (Er:YAG) laser irradiation (I-100 mJ, II-160 mJ, and III-220 mJ), and maps are done again. The Ca and P content are significantly reduced after acid etching (p<0.0001) and increased after laser irradiation with 220 mJ (Ca: p<0.0153 and P: p=0.0005). The Ca/P ratio increased and decreased after CG (p=0.0052) and GI (p=0.0003) treatments, respectively. CG treatment resulted in lower inorganic content (GI: p<0.05, GII: p<0.01, and GIII: p<0.01) and higher Ca/P ratios than laser etching (GI: p<0.001, GII: p<0.01, and GIII: p<0.01). The SEM photomicrographies revealed open (CG) and partially open dentin tubules (GI, GII, and GIII). μ-EDXRF mappings illustrated that acid etching created homogeneous distribution of inorganic content over dentin. Er:YAG laser etching (220 mJ) produced irregular elemental distribution and changed the stoichiometric proportions of hydroxyapatite, as showed by an increase of mineral content. Decreases and increases of mineral content in the μ-EDXRF images are correlated to holes and mounds, respectively, as found in SEM images.

  13. Relationship between the chemical and morphological characteristics of human dentin after Er:YAG laser irradiation.

    PubMed

    Soares, Luís Eduardo Silva; Martin, Ovídio César Lavesa; Moriyama, Lilian Tan; Kurachi, Cristina; Martin, Airton Abrahão

    2013-06-01

    The effects of laser etching on dentin are studied by microenergy-dispersive x-ray fluorescence spectrometry (μ-EDXRF) and scanning electron microscopy (SEM) to establish the correlation of data obtained. Fifteen human third molars are prepared, baseline μ-EDXRF mappings are performed, and ten specimens are selected. Each specimen received four treatments: acid etching (control-CG) or erbium:yttrium-aluminum-garnet (Er:YAG) laser irradiation (I-100 mJ, II-160 mJ, and III-220 mJ), and maps are done again. The Ca and P content are significantly reduced after acid etching (p<0.0001) and increased after laser irradiation with 220 mJ (Ca: p<0.0153 and P: p=0.0005). The Ca/P ratio increased and decreased after CG (p=0.0052) and GI (p=0.0003) treatments, respectively. CG treatment resulted in lower inorganic content (GI: p<0.05, GII: p<0.01, and GIII: p<0.01) and higher Ca/P ratios than laser etching (GI: p<0.001, GII: p<0.01, and GIII: p<0.01). The SEM photomicrographies revealed open (CG) and partially open dentin tubules (GI, GII, and GIII). μ-EDXRF mappings illustrated that acid etching created homogeneous distribution of inorganic content over dentin. Er:YAG laser etching (220 mJ) produced irregular elemental distribution and changed the stoichiometric proportions of hydroxyapatite, as showed by an increase of mineral content. Decreases and increases of mineral content in the μ-EDXRF images are correlated to holes and mounds, respectively, as found in SEM images. PMID:23797898

  14. 3D mapping of chemical distribution from melting at lower mantle conditions in the laser-heated diamond anvil cell

    NASA Astrophysics Data System (ADS)

    Dorfman, S. M.; Nabiei, F.; Cantoni, M.; Badro, J.; Gaal, R.; Gillet, P.

    2014-12-01

    The laser-heated diamond anvil cell is a unique tool for subjecting materials to pressures over few hundreds of GPa and temperatures of thousands of Kelvins which enables us to experimentally simulate the inaccessible interiors of planets. However, small sample size, laser profile and thermally conductive diamonds cause temperature gradients of 1000s K over a few microns which also affects chemical and structural distribution of phases in the sample. We have examined samples of San Carlos olivine (Mg,Fe)2SiO3 powder melted in the diamond anvil cell by double-sided and single-sided laser heating for 3-6 minutes to ~3000 K at 35-37 GPa. Moreover, MgO is used as an insulating media in one of the sample. Recovered samples were analyzed by a combination of focused ion beam (FIB) and scanning electron microscope (SEM) equipped with energy dispersive x-ray (EDX) detector. Images and chemical maps were acquired for ~300 slices with ~70 nm depth from each sample, comprising about half of the heated zone. Detailed chemical and structural analysis by transmission electron microscopy (TEM) of lamellas prepared from the remaining section of the samples will also be presented. In all samples the heated zone included (Mg,Fe)SiO3 perovskite-structured bridgmanite (PV) phase and two (Mg, Fe)O phases, one of which, magnesiowüstite (MW), is richer in iron than the other one, ferropericlase (FP). In double-side heated samples we observe a Fe-rich quenched melt core surrounded by MW phase. Our results show that with increasing heating time, Fe migrates to the molten center of the sample. In the single-side heated sample, the Fe-rich MW phase is concentrated in the center of heated zone. In all samples a FP crust was observed around the heated zone. This crust, however, is broken in the upper part (colder part) of the single-side heated sample due the high asymmetrical temperature gradient within the sample. The results confirm the importance of double-side heating and insulating media for generating homogenous central temperature and chemical distribution.

  15. Short wavelength chemical laser demonstration based on N({sup 2}D) chemistry. Final technical report

    SciTech Connect

    Not Available

    1990-01-19

    The overall goal of this project was to demonstrate lasing on the NCl(b{yields}x) transition at 665 nm. Our scheme is based on chemical production of excited nitrogen atoms in the {sup 2}D metastable state and subsequent reaction of N({sup 2}D) with Cl{sub 2} to produce NCl(b). Our intermediate objectives were: (1) demonstrate chemical generation of N({sup 2}D), (2) identify and measure rate constants important to the chemical scheme, and (3) demonstrate production of NCl(b) from the N({sup 2}D) + Cl{sub 2} reaction. The program results and accomplishments are summarized in this report.

  16. Soft x-ray laser ablation mass spectrometry for materials study and nanoscale chemical imaging

    NASA Astrophysics Data System (ADS)

    Kuznetsov, Ilya; Burian, Tomas; Juha, Libor; Soufli, Regina; Filevich, Jorge; Woolston, M.; Bernstein, Elliot R.; Crick, Dean C.; Carlton, D.; Chao, W.; Anderson, E. H.; Rocca, Jorge J.; Menoni, Carmen S.

    2015-09-01

    There are significant advantages for using a compact capillary discharge soft x-ray laser (SXRL) with wavelength of 46.9 nm for mass spectrometry applications. The 26.4 eV energy photons provide efficient single-photon ionization while preserving the structure of molecules and clusters. The tens of nanometers absorption depth of the radiation coupled with the focusing of the laser beam to diameter of ˜100 nm result in the ablation of atto-liter scale craters which in turn enable high resolution mass spectral imaging of solid samples. In this paper we describe results on the analysis of composition depth-profiling of multilayer oxide stack and material studies in photoresists, ionic crystals, and magnesium corrosion products using SXRL ablation mass spectrometry, a method first demonstrated by our group. These materials are used in a variety of soft x-ray applications such as detectors, multilayer optics, and many more.

  17. Scanning Diode Laser Desorption Thin-Layer Chromatography Coupled with Atmospheric Pressure Chemical Ionization Mass Spectrometry

    NASA Astrophysics Data System (ADS)

    Peng, Song; Ahlmann, Norman; Edler, Michael; Franzke, Joachim

    Continuous wave diode laser is applied for desorption of an analyte from a porous surface of a thin-layer plate covered with a graphite suspension. The thermally desorbed analyte molecules are ionized in the gas phase by a corona discharge at atmospheric pressure. Therefore, both essential processes - the desorption and the ionization of analyte molecules, which are often performed in one step - are separated. Reserpine was chosen as model analyte, which is often used for specification of mass spectrometers. No fragmentation was observed because of efficient collisional cooling under atmospheric pressure. The influence of diode laser power and the composition of the graphite suspension were investigated, and a primary optimization was performed. An interface to allow online qualitative and quantitative full plate detection and analysis of compounds separated by thin-layer chromatography is presented.

  18. UV laser ablation of halonaphthalene-doped PMMA: chemical modifications above versus below the ablation threshold

    NASA Astrophysics Data System (ADS)

    Athanassiou, A.; Andreou, E.; Anglos, D.; Georgiou, S.; Fotakis, C.

    Laser-induced fluorescence is employed to monitor the photochemical modifications that bromo- and iodonaphthalene incorporated in PMMA films undergo following ablation at 248 nm. Following irradiation at low fluences with nanosecond pulses, photolysis of the dopants is found to result in the formation of naphthalene-like photoproducts, whereas above the threshold additional products are observed. Based on concentration studies, these are tentatively ascribed to species containing two naphthyl groups. In close correspondence to the formation of the new species, the photolysis yields for both dopants are found to increase sharply above the threshold. Finally, the nature and extent of these photochemical effects is indicated to depend sensitively on the laser pulse width. The mechanistic implications of these results are discussed.

  19. 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 environment, especially from improvised explosive devices (IEDs), and of civilian personnel from terrorist attacks in metropolitan areas.

  20. Chemical sensing with pulsed QC-DFB lasers operating at 15.6 micrometers.

    PubMed

    Kosterev, A A; Curl, R F; Tittel, F K; Rochat, M; Beck, M; Hofstetter, D; Faist, J

    2002-01-01

    Pulsed thermoelectrically cooled QC-DFB lasers operating at 15.6 micrometers were characterized for spectroscopic gas sensing applications. A new method for wavelength scanning based on repetition rate modulation was developed. A non-wavelength-selective pyroelectric detector was incorporated in the sensor configuration giving the advantage of room-temperature operation and low cost. Absorption lines of CO2 and H2O were observed in ambient air, providing information about the concentration of these species. PMID:12599401

  1. 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.

  2. Laser induced chemical vapor phase epitaxial growth of III-V semiconductor films

    NASA Astrophysics Data System (ADS)

    Chu, Shirley S.; Chu, Ting L.

    1991-05-01

    The objective of this project is to investigate the homo- and hetero-epitaxial growth of device quality III-V semiconductor films by the free electron laser (FEL) induced growth at lower temperatures. An ArF excimer laser was used in this investigation. Metalorganic vapor phase epitaxy (MOVPE) is the commonly used technique in the growth of III-V compounds and alloys. The major concern to the use of MOVPE is the hazard involved in using highly toxic arsine and phosphine gases as the group V source materials. Efforts during this period have been focused to the homoepitaxial growth of GaAs and heteroepitaxial growth of InP on GaAs using alternate sources to eliminate the use of arsine and phosphine. Good quality epitaxial GaAs films have been prepared from elemental arsenic for the first time by either conventional substrate heating or laser enhanced processes. The epitaxial GaAs films grown from elemental arsenic are suitable for many GaAs based devices, particularly for large area devices such as solar cells. Significant cost reduction and less stringent safety requirements are major advantages.

  3. 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.

  4. 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. With the current spatial resolution, grain-sized inclusions embedded in the surface (e.g. CAIs, dark inclusions, metal grains) could be identified. Detailed investigations, e.g. differentiation of chondrule components from rims of chondrules can be derived from LMS data. LMS has capabilities for highly sensitive chemical composition measurements of grain sized inclusions and sub-micrometre sized surface layers. The latter information is of considerable interest in the context of space weathering. References [1] P. Wurz, et al., 2009, AIP Conf.Proc. , CP1144:70-75. [2] P. Wurz et al.,2012, Sol. Sys. Res. 46 408-422. [3] U. Rohner, J. Whitby, and P. Wurz, 2003, Meas. Sci. Technol., 14 2159-2164. [4] A. Riedo et al.,2013, J.Anal.Atom.Spectrom. 28(8):1133-1356. [5] A. Riedo, et al., 2013, J. Mass Spectrom.48, 1-15. [6] M.B. Neuland et al.,2014, Planet. Space. Sci. 101, 196-209. [7] V. Grimaudoet al.,2014, Anal. Chem., submitted.

  5. 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 limit of detection for ClO4, was determined to be 14.7 +/- 0.5 wt%/wt for the given experimental conditions. In the second part of this research, the temperature-dependent absorption and emission properties of Tm doped KPb2Cl5 (KPC) and KPb2Br5 (KPB) were evaluated for applications in laser cooling. A Tm doped Y3Al5O12 (YAG) crystal was also included for comparative studies. Under laser pumping, all crystals exhibited broad IR fluorescence at room temperature with a mean fluorescence wavelength of ˜1.82 mum and bandwidth of 0.14 mum (FWHM) for Tm:KPC/KPB and ˜1.79 mum for Tm:YAG. Initial experiments on laser-induced heating/cooling were performed using a combined IR imaging and fluorescence thermometry setup. Employing a continuous-wave laser operating at 1.907 mum, Tm: KPC and Tm: KPB crystals revealed a very small heat load resulting in temperature increase of ˜ 0.3 ( +/- 0.1)°C. The heat loading in Tm:YAG was signicantly larger and resulted in a temperature increase of ˜0.9 (+/-0.1)°C. The results derived from IR imaging were also conrmed by the fluorescence thermometry experiments, which showed only minimal changes in the FIR intensity ratio of the green Er3+ fluorescence lines from Er:KPC.

  6. 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.

  7. 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.

  8. 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)

  9. Optical properties and chemical behavior of Laser-dye Coumarin-500 and the influence of atmospheric corona discharges

    NASA Astrophysics Data System (ADS)

    Keskin, S. Sinan; Aslan, Necdet; Bayrakçeken, Fuat

    2009-03-01

    Structure elucidation of Coumarin-500 Laser-dye in cyclohexane at room temperature has been studied by UV-Vis, Raman, and FTIR spectroscopic techniques. Optical properties and chemical behavior under the influence of atmospheric positive electric pulsed corona discharges were also examined. The effects of UV-Vis irradiation changed some optical parameters, such as decrease in optical density on the absorption spectrum and formation of photoproducts, due to the chromaticity removal. No significant optical changes were observed in the light absorption upon UV-irradiation but large changes in absorption spectrum were observed after positive electric corona discharge treatments, FTIR and Raman spectra in non-polar solvent are recorded and interpreted.

  10. 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.

  11. 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.

  12. 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.

  13. Mitigation of organic laser damage precursors from chemical processing of fused silica.

    PubMed

    Baxamusa, S; Miller, P E; Wong, L; Steele, R; Shen, N; Bude, J

    2014-12-01

    Increases in the laser damage threshold of fused silica have been driven by the successive elimination of near-surface damage precursors such as polishing residue, fractures, and inorganic salts. In this work, we show that trace impurities in ultrapure water used to process fused silica optics may be responsible for the formation of carbonaceous deposits. We use surrogate materials to show that organic compounds precipitated onto fused silica surfaces form discrete damage precursors. Following a standard etching process, solvent-free oxidative decomposition using oxygen plasma or high-temperature thermal treatments in air reduced the total density of damage precursors to as low as <50 cm(-2). Finally, we show that inorganic compounds are more likely to cause damage when they are tightly adhered to a surface, which may explain why high-temperature thermal treatments have been historically unsuccessful at removing extrinsic damage precursors from fused silica. PMID:25606889

  14. Multivariate analysis of laser-induced breakdown spectroscopy chemical signatures for geomaterial classification

    NASA Astrophysics Data System (ADS)

    Gottfried, Jennifer L.; Harmon, Russell S.; de Lucia, Frank C., Jr.; Miziolek, Andrzej W.

    2009-10-01

    A large suite of natural carbonate, fluorite and silicate geological materials was studied using laser-induced breakdown spectroscopy (LIBS). Both single- and double-pulse LIBS spectra were acquired using close-contact benchtop and standoff (25 m) LIBS systems. Principal components analysis (PCA) and partial least squares discriminant analysis (PLS-DA) were used to identify the distinguishing characteristics of the geological samples and to classify the materials. Excellent discrimination was achieved with all sample types using PLS-DA and several techniques for improving sample classification were identified. The laboratory double-pulse LIBS system did not provide any advantage for sample classification over the single-pulse LIBS system, except in the case of the soil samples. The standoff LIBS system provided comparable results to the laboratory systems. This work also demonstrates how PCA can be used to identify spectral differences between similar sample types based on minor impurities.

  15. ARTICLES: Numerical investigation of a purely chemical generator of atomic gaseous hydrogen (deuterium) and of a cw H(D)-O3-CO2 laser utilizing this generator

    NASA Astrophysics Data System (ADS)

    Bashkin, A. S.; Gamzatov, N. M.; Oraevskiĭ, A. N.

    1987-02-01

    A numerical investigation is reported of a generator of atomic gaseous hydrogen (or deuterium) and of a cw low-toxicity H(D)-O3-CO2 laser utilizing this generator. A high nonequilibrium concentration of H (D) atoms is achieved in a supersonic oxygen-hydrogen (or oxygen-deuterium) flame in this generator. Hydrogen (deuterium) combustion regimes convenient for experimental realization and characterized by a molar concentration of atomic hydrogen (deuterium) in the flame by up to ~15%, are identified. Numerical optimization of all the components of a cw laser system in respect of the principal parameters is used to show that a cw D-O3-CO2 laser utilizing this chemical generator of deuterium atoms can have high output characteristics: a specific output power of ~140 W·sec·g-1, a chemical efficiency of ~10%, and an inversion zone of over 30 cm length in the downstream direction.

  16. 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.

  17. An infrared free electron laser system for the proposed Chemical Dynamics Research Laboratory at LBL based on a 500 MHz superconducting linac

    SciTech Connect

    Kim, K.J.; Byrns, R.; Chattopadhyay, S.; Donahue, R.; Edighoffer, J.; Gough, R.; Hoyer, E.; Leemans, W.; Staples, J.; Taylor, B.; Xie, M.

    1992-09-01

    We describe a new design of the Infrared Free Electron Laser (IRFEL) for the proposed Chemical Dynamics Research Laboratory (CDRL) at LBL. The design and choice of parameters are dictated by the unique requirements of the CDRL scientific program. The accelerator system is based on the 500 MHz superconducting cavity technology to achieve a wavelength stability of 10{sup {minus}4}.

  18. An infrared free electron laser system for the proposed Chemical Dynamics Research Laboratory at LBL based on a 500 MHz superconducting linac

    SciTech Connect

    Kim, K.J.; Byrns, R.; Chattopadhyay, S.; Donahue, R.; Edighoffer, J.; Gough, R.; Hoyer, E.; Leemans, W.; Staples, J.; Taylor, B.; Xie, M.

    1992-09-01

    We describe a new design of the Infrared Free Electron Laser (IRFEL) for the proposed Chemical Dynamics Research Laboratory (CDRL) at LBL. The design and choice of parameters are dictated by the unique requirements of the CDRL scientific program. The accelerator system is based on the 500 MHz superconducting cavity technology to achieve a wavelength stability of 10[sup [minus]4].

  19. An infrared free electron laser system for the proposed chemical dynamics research laboratory at LBL based on a 500 MHz superconducting linac

    NASA Astrophysics Data System (ADS)

    Kim, K.-J.; Byrns, R.; Chattopadhyay, S.; Donahue, R.; Edighoffer, J.; Gough, R.; Hoyer, E.; Leemans, W.; Staples, J.; Taylor, B.; Xie, M.

    1994-03-01

    We describe a new design of the Infrared Free Electron Laser (IRFEL) for the proposed Chemical Dynamics Research Laboratory (CDRL) at LBL. The design and choice of parameters are dictated by the unique requirements of the CDRL scientific program. The accelerator system is based on the 500 MHz superconducting cavity technology to achieve a wavelength stability of 10 -4.

  20. An infrared free electron laser system for the proposed Chemical Dynamics Research Laboratory at LBL based on a 500 MHz superconducting linac

    NASA Astrophysics Data System (ADS)

    Kim, K. J.; Byrns, R.; Chattopadhyay, S.; Donahue, R.; Edighoffer, J.; Gough, R.; Hoyer, E.; Leemans, W.; Staples, J.; Taylor, B.

    1992-09-01

    A design of the Infrared Free Electron Laser (IRFEL) for the proposed Chemical Dynamics Research Laboratory (CDRL) at LBL is described. The design and choice of parameters are dictated by the unique requirements of the CDRL scientific program. The accelerator system is based on the 500 MHz superconducting cavity technology to achieve a wavelength stability of 10(exp -4).

  1. Preparation, characterisation and optimisation of lithium battery anodes consisting of silicon synthesised using Laser assisted Chemical Vapour Pyrolysis

    NASA Astrophysics Data System (ADS)

    Veliscek, Ziga; Perse, Lidija Slemenik; Dominko, Robert; Kelder, Erik; Gaberscek, Miran

    2015-01-01

    Suitability of silicon prepared using Laser assisted Chemical Vapour Pyrolysis (LaCVP) as a potential anode material in lithium batteries is systematically investigated. Its compositional, morphological, physical-chemical and electrochemical properties are compared to a current benchmark commercial silicon. Important differences in particle size and particle composition are found which, as shown, affect critically the rheological properties of the corresponding electrode slurries. In order to overcome the rheological problems of prepared nanosilicon, we introduce and optimise a spraying method instead of using the usual casting technique for slurry application. Interestingly, the optimised electrodes show similar electrochemical performance, regardless of the particle size or composition of nanosilicon. This unexpected result is explained by the unusually high resistance of electrochemical wiring in silicon-based electrodes (about 60 Ohm per 1 mg cm-2 of active material loading). Despite that, the optimised material still shows a capacity up to 1200 mA h g-1 at a relatively high loading of 1.6 mg cm-2 and after 20 cycles. On the other hand, by decreasing the loading to below ca. 0.9 mg cm-2 the wiring problems are effectively overcome and capacities close to theoretical values can be obtained.

  2. 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.

  3. 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.

  4. 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)

  5. 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.

  6. 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.

  7. 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.

  8. Slow Passage Through Bifurcation and Limit Points. Asymptotic Theory and Applications in the Areas of Chemical and Laser Instabilities.

    NASA Astrophysics Data System (ADS)

    Georgiou, Miltiades

    We study several new effects of slow passage through bifurcation parameter and limit points. First, we investigate experimental results on slow passage through limit points, recently obtained for the bistable iodate-arsenous acid reaction. We compare these observations with the asymptotic and numerical results obtained from a simple model. The transition near the lower limit point is fast and follows the varepsilon ^{2/3} law predicted by the theory (varepsilon is the ramp rate of the control parameter). By contrast, the jump transition near the upper limit point is slow and follows an varepsilon law which is not predicted by the theory. Our numerical study shows that the values of varepsilon used in the experiments are too large to follow the varepsilon^{2/3} law. Second, we investigate the effect of additive gaussian white noise on the pulsed solutions of a laser with a saturable absorber (LSA). We assume that the noise does not affect the short time inner solution, and concentrate on the long time outer solution. Using asymptotic methods we show that the problem is adequately described by a single nonlinear differential equation with a slowly varying bifurcation parameter. We solve the Langevin equation and we determine the scalings between the delay and the amplitude of the noise. These results agree with the numerical study of the complete laser equations. Finally, we consider the slow passage past a low frequency Hopf bifurcation, in the context of the chemical model of the Brusselator. Using phase plane techniques, we show that the oscillations may disappear as a result of the slowly varying bifurcation parameter. This phenomenon appears if the time scale of the variation of the bifurcation parameter is of the same order as the time scale of the slow part of the relaxation oscillations.

  9. 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.

  10. 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.

  11. Laser-induced fluorescence measurements and kinetic analysis of Si atom formation in a rotating disk chemical vapor deposition reactor

    SciTech Connect

    Ho, P.; Coltrin, M.E.; Breiland, W.G. )

    1994-10-06

    An extensive set of laser-induced fluorescence (LIF) measurements of Si atoms during the chemical vapor deposition (CVD) of silicon from silane and disilane in a research rotating disk reactor are presented. The experimental results are compared in detail with predictions from a numerical model of CVD from silane and disilane that treats the fluid flow coupled to gas-phase and gas-surface chemistry. The comparisons showed that the unimolecular decomposition of SiH[sub 2] could not account for the observed gas-phase Si atom density profiles. The H[sub 3]SiSiH [leftrightarrow] Si + SiH[sub 4] and H[sub 3]SiSiH + SiH[sub 2] [leftrightarrow] Si + Si[sub 2]H[sub 6] reactions are proposed as the primary Si atom production routes. The model is in good agreement with the measured shapes of the Si atom profiles and the trends in Si atom density with susceptor temperature, pressure, and reactant gas mixture. 33 refs., 12 figs., 3 tabs.

  12. 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

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

    PubMed

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

    2012-07-01

    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

  14. 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.

  15. Direct monitoring of chemical transformations by combining thin layer chromatography with nanoparticle-assisted laser desorption/ionization mass spectrometry.

    PubMed

    Chen, Chun-Chi; Yang, Yung-Lin; Ou, Chun-Lin; Chou, Chih-Hung; Liaw, Chih-Chuang; Lin, Po-Chiao

    2013-03-01

    A nanomaterial-assisted method that combines thin layer chromatography (TLC) with matrix-assisted laser desorption/ionization mass spectrometry (MALDI MS) was developed to directly monitor chemical transformations. A substrate-dependent extraction strategy was studied and successfully used to identify target molecules from the depths of a developed TLC plate. By using this strategy, a hydrophobic sample of interest was enriched on the surface of the TLC plate in the presence of acetonitrile, in contrast to using water and methanol to identify hydrophilic samples. The successful enrichment of samples by specific solvents provided stable desorption/ionization efficiencies of compounds of interest and led to very good sensitivity near the attomole scale. The method was then used to monitor 4-dimethylaminopyridine (DMAP)-catalyzed acylation in preparation of bifunctional sulfonamides. The labile DMAP-acyl intermediate and final sulfonamide product were clearly identified on TLC plates without external purification or sample preparation. Furthermore, in combination with collision-induced dissociation (CID) to provide structural information, the technique was successfully used in the natural product discovery of anti-inflammatory flavonoids from Helminthostachys zeylanica, a traditional Chinese herb. The newly proposed method provides a very low background from silica supports or organic matrices in the low molecular weight range (100-1000 Da). The technique may greatly accelerate studies of metabolomics, drug discovery, and organic synthesis. PMID:23330148

  16. 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.

  17. Laser-induced chemical reactions. [H + H/sub 2/; F + H/sub 2/; H + HF; Cl + H/sub 2/; H + HCl; H + LiF

    SciTech Connect

    Orel, A.E.

    1980-12-01

    A classical model for the interaction of laser radiation with a molecular system is derived. This model is used to study the enhancement of a chemical reaction via a collision induced absorption. It was found that an infrared laser will in general enhance the rate of a chemical reaction, even if the reactants are infrared inactive. Results for an illustrative analytically solvable model are presented, as well as results from classical trajectory studies on a number of systems. The collision induced absorption spectrum in these systems can be written as the Fourier transform of a particular dipole correlation function. This is used to obtain the collision induced absorption spectrum for a state-selected, mono-energetic reactive collision system. Examples treated are a one-dimensional barrier problem, reactive and nonreactive collisions of H + H/sub 2/, and a modified H + H/sub 2/ potential energy surface which leads to a collision intermediate. An extension of the classical model to treat laser-induced electronically nonadiabatic collision processes is constructed. The model treats all degrees of freedom, molecular, electronic and radiation, in a dynamically consistent framework within classical mechanics. Application is made to several systems. Several interesting phenomena are discovered including a Franck-Condon-like effect causing maxima in the reaction probability at energies much below the classical threshold, laser de-enhancement of chemical reactions and an isotope effect. In order to assess the validity of the classical model for electronically nonadiabatic process (without a laser field), a model problem involving energy transfer in a collinear atom-diatom system is studied, and the results compared to the available quantum mechanical calculation. The calculations are in qualitative agreement.

  18. Crystalline SiGe films grown on Si substrates using laser-assisted plasma-enhanced chemical vapor deposition at low temperature

    SciTech Connect

    Lee, C.-T.; Cheng, J.-H.; Lee, H.-Y.

    2007-08-27

    Compared with conventional plasma-enhanced chemical vapor deposition, laser-assisted plasma-enhanced chemical vapor deposition (LAPECVD) can be used to deposit crystalline SiGe films on Si substrates at low temperature. In the LAPECVD system, a CO{sub 2} laser with a wavelength of 10.6 {mu}m was utilized to assist the pyrolytical decomposition of SiH{sub 4} and GeH{sub 4} reactant gases. The resultant Si{sub 0.78}Ge{sub 0.22} films were obtained and verified through the use of the Auger electron spectroscopy measurement. As the diffraction pattern of a glancing incident angle X-ray diffraction measurement had indicated, several significant diffraction peaks corresponding to a diamond-cubic structure at (111) (220), and (311) were clearly observed. Crystalline SiGe films were also identified by the electron diffraction pattern of high-resolution transmission electron microscopy images.

  19. 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.

  20. Lasers '92; Proceedings of the International Conference on Lasers and Applications, 15th, Houston, TX, Dec. 7-10, 1992

    NASA Technical Reports Server (NTRS)

    Wang, Charles P. (Editor)

    1993-01-01

    Papers from the conference are presented, and the topics covered include the following: x-ray lasers, excimer lasers, chemical lasers, high power lasers, blue-green lasers, dye lasers, solid state lasers, semiconductor lasers, gas and discharge lasers, carbon dioxide lasers, ultrafast phenomena, nonlinear optics, quantum optics, dynamic gratings and wave mixing, laser radar, lasers in medicine, optical filters and laser communication, optical techniques and instruments, laser material interaction, and industrial and manufacturing applications.

  1. Topical Meeting on Laser Applications to Chemical Analysis III, Salt Lake City, UT, Jan. 27-31, 1992, Proceedings

    NASA Astrophysics Data System (ADS)

    Miziolek, Andrzej W.; Long, S. R.; Crosley, David R.

    1993-02-01

    Various papers on lasers, photonics, and environmental optics are presented. Individual topics addressed include: tunable diode laser ratio measurements of atmospheric constituents employing dual fitting analysis and jump scanning, ultrasensitive spectral trace detection of individual molecular components in an atmospheric binary mixture, applications of a tunable CO2 sideband lasers for high-resolution spectroscopic measurements of atmospheric gases, molecular analysis by ionization of laser-desorbed neutral species, spatially resolved multispecies and temperature analysis in hydrogen flames, intense backward Raman lasers in CH4 and H2, time-resolved emission studies of ArF-laser-produced microplasmas. Also discussed are: measurements of the refractive index of PbEuTe in the 3-10 micron region of the infrared, high-efficiency and compact blue source: intracavity frequency tripling by using LBO and BBO without the influence of birefringence, radiation and collisional energy transfer among the A 2Pi(i) and X 2Sigma(+) states of CN, wager-vapor absorption line measurements in the 940-nm band using a Raman-shifted dye laser, Gaussian-Schell model source in 1D first-order systems with loss or gain. (For individual items see A93-28552 to A93-28566)

  2. 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

  3. ARTICLES: Possible development of chemical lasers utilizing the hydrogen fluorination chain reaction with a thermal branching mechanism

    NASA Astrophysics Data System (ADS)

    Baĭkov, É. U.; Bashkin, A. S.; Oraevskiĭ, A. N.

    1987-01-01

    An analysis is made of the feasibility of pulsed lasing in an H2-F2 laser as a result of thermal dissociation of specially selected RF fluoride molecules. Calculations are used to obtain the dissociation rate constants of RF molecules required for efficient implementation of the proposed operating regime of an H2-F2 laser and various suitable molecules are found. It is found that high values of the specific output energy and the quantum efficiency of lasing can be achieved in an H2-F2 laser utilizing the hydrogen fluorination chain reaction with a thermal branching mechanism.

  4. 1. 5-. mu. m GaInAsP planar buried heterostructure lasers grown using chemical-beam-epitaxial base structures

    SciTech Connect

    Tsang, W.T.; Bowers, J.E.; Burkhardt, E.G.; Ditzenberger, J.A.; Wilt, D.P.; Dutta, N.K.; Napholtz, S.G.; Shen, T.M.; Twu, Y.; Logan, R.A.; and others

    1988-02-15

    GaInAsP/InP double heterostructures grown by chemical-beam epitaxy have been used in conjunction with liquid-phase-epitaxial regrowth to fabricate high-performance buried heterostructure lasers operating at a wavelength of 1.5 ..mu..m. These lasers show room-temperature threshold currents as low as 12 mA, external quantum efficiencies as high as 0.2 mW/mA per facet, and, in general, linear output power up to approx.10 mW/facet. The 3-dB bandwidth at optimal biasing is about 8 GHz and is believed to be limited by the heatsink stud. The relative intensity noise is low, <-150 dB/Hz at 1 GHz for bias currents from 50 mA to above 150 mA.

  5. 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.

  6. 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

  7. Preparation of AlAsSb and mid-infrared (3-5 {mu}m) lasers by metal-organic chemical vapor deposition

    SciTech Connect

    Allerman, A.A.; Biefeld, R.M.; Kurtz, S.R.

    1996-12-31

    Mid-infrared (3-5 {mu}m) infrared lasers and LEDs are being developed for use in chemical sensor systems. As-rich, InAsSb heterostructures display unique electronic properties that are beneficial to the performance of these midwave infrared emitters. The authors have grown AlAs{sub 1{minus}x}Sb{sub x} epitaxial layers by metal-organic chemical vapor deposition using trimethylamine (TMAA) or ethyldimethylamine alane (EDMAA), triethylantimony (TESb) and arsine. They examined the growth of AlAs{sub 1{minus}x}Sb{sub x} using temperatures of 500 to 600 {degrees}C, pressures of 70 to 630 torr, V/III ratios of 1-27, and growth rates of 0.3 to 2.7 {mu}m/hour in a horizontal quartz reactor. The semi-metal properties of a p-GaAsSb/n-InAs heterojunction are utilized as a source for injection of electrons into the active region of lasers. A regrowth technique has been used to fabricate gain-guided lasers using AlAs{sub 1{minus}x}Sb{sub x} for optical confinement with either a strained InAsSb/InAs multi-quantum well (MQW) or an InAsSb/InAsP strained layer superlattice (SLS) as the active region. Under pulsed injection, the InAsSb/InAs MQW laser operated up to 210K with an emission wavelength of 3.8-3.9 {mu}m. Under pulsed optical pumping, the InAsSb/InAsP SLS operated to 240K with an emission wavelength of 3.5-3.7 {mu}m. LED emission has been observed with both active regions in both p-n junction and semi-metal injection structures.

  8. 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.

  9. Design, construction and development of a laser desorption ionization/laser ablation time-of-flight mass spectrometer for chemical analysis with and without surface plasmon resonance

    NASA Astrophysics Data System (ADS)

    Owega, Sandy

    Theoretical modeling of the Wiley-McLaren double-focusing field system (two acceleration fields) provided the critical dimensions for the design and construction of a time-of-flight mass spectrometer (TOFMS) for this research. For optimum resolution, the distances within the acceleration fields, s (0.26 cm) and d (2.60 cm) were determined for a drift tube length D of 42.2 cm. Arcing occurred frequently using our laser desorption ionization (LDI)/laser ablation (LA) technique; five different configurations were designed and evaluated. The third configuration was determined to be the most useful for LDI/LA-TOFMS experiments. The LDI/LA technique was tested for molecular mass and structural reactivity analysis. This LDI/LA technique was successfully applied to dithizone, 1,4,8,11- tetraazocyclotetradecane, dicyclohexyl-18-crown-6 ether, [5]-helicene dendrimer, gramicidin S, substance P, mellitin, PAHs, fullerenes/derivatives, thia fatty esters/acids, and a variety of related compounds. One advantage of the present LDI/LA technique, over conventional ones is that the sample does not need to have appreciable spectral absorption at the laser wavelength. The physical process that occurred during our LDI/LA technique was elucidated with internal standardization and ion association using gramicidin S. The LDI/LA mechanism generating the [M + Ag]+ cation was thought to be electronic-excitation (at low laser fluences) that evolved into a thermal one (at high laser fluences), depending on the silver film thickness. The five configurations were also evaluated for incorporating surface plasmon resonance (SPR) into our LDI/LA technique to ultimately construct a novel SPR- LDI/LA-TOFMS instrument. They indicated that silver surface plasmons have a SPR angle ?r of 44 and an energy of 3.7 eV for a thin silver film thickness of 40 nm. The SPR-LDI/LA technique demonstrated that a lower minimum laser fluence for the production of the silver cluster cations [Agn]+ was required at ? r. SPR was thus confirmed to assist in the electronic-excitation desorption during LDI/LA of a thin silver film with or without deposited samples. The capability to perform SPR- LDI/LA on a molecular weight of 1141 Da from a thin silver film represents a new milestone beyond previous achievements. (Abstract shortened by UMI.)

  10. Femtosecond-laser-produced low-density plasmas in transparent biological media: a tool for the creation of chemical, thermal, and thermomechanical effects below the optical breakdown threshold

    NASA Astrophysics Data System (ADS)

    Vogel, Alfred; Noack, Joachim; Huettmann, Gereon; Paltauf, Guenther

    2002-04-01

    The irradiance threshold for femtosecond optical breakdown in aqueous media is approximately equals 1.0x1013W cm-2. At the breakdown threshold, a plasma with a free electron density of about 1021cm-3 is generated, and the energy density in the breakdown region is sufficiently high to cause the formation of a bubble which can be experimentally observed. We found previously that plasmas with a free electron density <1021cm-3 are formed also in a fairly large irradiance range below the breakdown threshold. The present study investigates the chemical, thermal, and thermomechanical effects produced by these low-density plasmas. We use a rate equation model considering multiphoton ionization and produced by these low-density plasmas. We use a rate equation model considering multiphoton ionization and avalanche ionization to numerically simulate the temporal evolution of the free electron density during the laser pulse for a given irradiance, and to calculate the irradiance dependence of the free-electron density and volumetric energy density reached at the end of the laser pulse. The value of the energy density created by each laser pulse is then used to calculate the temperature distribution in the focal region after application of a single laser pulse and of series of pulses. The results of the temperature calculations yield, finally, the starting point for calculations of the thermoelastic stresses that are generated during the formation of the low-density plasmas. We found that, particularly for short wavelengths, a large 'tuning range' exists for the creation of spatially extremely confined chemical, thermal and mechanical effects via free electron generation through nonlinear absorption. Photochemical effects dominate at the lower end of this irradiance range, whereas at the upper end they are mixed with thermal effects and modified by thermoelastic stresses. Above the breakdown threshold, the spatial confinement is partly destroyed by cavitation bubble formation, and the laser-induced effects become more disruptive. Our simulations revealed that the highly localized ablation of intracellular structures and intranuclear chromosome dissection recently demonstrated by other researchers are probably mediated by free-electron- induced chemical bond breaking and not related to heating or thermoelastic stresses. We conclude that low density plasmas below the optical breakdown threshold can be a versatile tool for the manipulation of transparent biological media and other transparent materials. (enabling, e.g., the generation of optical waveguides in bulk glass). Low density plasmas may, however, also be a potential hazard in multiphoton microscopy and higher harmonic imaging.

  11. Preparation of the c-axis oriented AlN film by laser chemical vapor deposition using a newly proposed Al(acac)3 precursor

    NASA Astrophysics Data System (ADS)

    You, Yu; Ito, Akihiko; Tu, Rong; Goto, Takashi

    2013-02-01

    Highly oriented AlN film was prepared on a c-plane sapphire substrate by laser chemical vapor deposition using a newly proposed aluminum acetylacetonate precursor and ammonia gas as source reactants. The c-axis oriented AlN films were obtained on the c-plane sapphire substrate at deposition temperatures from 900 to 1230 K. AlN film prepared at 1047 K showed an epitaxial relation as (//( [//[. The full width at half maximum (FWHM) of the X-ray rocking curve for AlN (0002) plane increased with increasing deposition temperature. The c-axis lattice parameter decreased with increasing deposition temperature.

  12. Role of stress in the chemical etching of fused silica exposed to low-energy femtosecond laser pulses

    NASA Astrophysics Data System (ADS)

    Champion, Audrey; Bellouard, Yves; Mindaugas, Gecevicius; Beresna, Martynas; Kazansky, Peter G.

    2011-03-01

    Recently, it was demonstrated that femtosecond lasers pulses with energies below the ablation threshold locally enhance the etching rate of fused silica: regions that are exposed to the laser beam are etched faster. This remarkable property has been used for fabricating a variety of micro-structures like fluidic channels, tunnels or more complex devices, like mechanical flexures. The physical effect causing the etching-rate local enhancement is still debated and various hypotheses have been proposed among which localized densification models seem to prevail. In that context, we recently demonstrated that the amount of deposited energy plays a very important role. It was found that for laser repetition rates where no cumulative effects are observed, there exists an optimal amount of energy deposited to achieve the fastest etching rate. These observations suggest that the stress introduced during laser exposure plays an important role in the processing of fused silica with low energy ultrafast pulses. In this paper, we investigate the stress distributions in various laser patterns and how this stress distribution can account for various effects observed during processing such as a local etching enhancement, the occurrence of cracks in dense patterns made of multiple lines and finally, the presence of stress-induced birefringence.

  13. A method to give chemically stabilities of photoelectrodes for water splitting: Compositing of a highly crystalized TiO2 layer on a chemically unstable Cu2O photocathode using laser-induced crystallization process

    NASA Astrophysics Data System (ADS)

    Nishikawa, Masami; Fukuda, Masayuki; Nakabayashi, Yukihiro; Saito, Nobuo; Ogawa, Nobuhiro; Nakajima, Tomohiko; Shinoda, Kentaro; Tsuchiya, Tetsuo; Nosaka, Yoshio

    2016-02-01

    To prevent the self-reduction of the Cu2O photocathode for solar hydrogen production, we developed a compositing process of a highly crystalized TiO2 layer on the Cu2O photocathode using an excimer-laser-assisted metal-organic deposition (ELAMOD) process. The TiO2 layer was successfully crystalized without oxidation of Cu2O to CuO mainly owing to a photothermal effect with nanosecond duration time induced by laser absorption of the TiO2 precursor while the crystallization of the TiO2 layer by usual furnace heating process was accompanied by oxidation of Cu2O which degrade the water reduction ability. On the TiO2/Cu2O photocathode prepared by ELAMOD process, the self-reduction of Cu2O did not occur and then photocurrent due to water reduction was constant with reaction time while on the bare Cu2O photocathode, the photocurrent decreased owing to the occurrence of the self-reduction. This indicated that reaction stability of the photocathode was largely enhanced after compositing of the crystallineTiO2 layer. This ELAMOD process would be applicable for any kinds of chemically unstable photoelectrodes containing non-oxides such as sulfides and phosphides, and therefore any kinds of photoelectrodes would have potentials toward a practical use by improving their chemical stabilities.

  14. 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.

  15. 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.

  16. PARTICLE GENERATION BY LASER ABLATION IN SUPPORT OF CHEMICAL ANALYSIS OF HIGH LEVEL MIXED WASTE FROM PLUTONIUM PRODUCTION OPERATIONS

    EPA Science Inventory

    Methods for compositional analysis of fissile materials and radioactive/toxic wastes are being developed to support characterization prior to treatment and remediation. The need for rapid, real-time, on site characterization of waste at DOE sites has led to deployment of laser ab...

  17. Facile and Chemically Pure Preparation of YVO4:Eu3+ Colloid with Novel Nanostructure via Laser Ablation in Water

    NASA Astrophysics Data System (ADS)

    Wang, Haohao; Odawara, Osamu; Wada, Hiroyuki

    2016-02-01

    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.

  18. Facile and Chemically Pure Preparation of YVO4:Eu(3+) Colloid with Novel Nanostructure via Laser Ablation in Water.

    PubMed

    Wang, Haohao; Odawara, Osamu; Wada, Hiroyuki

    2016-01-01

    A YVO4:Eu(3+) 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

  19. 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.

  20. 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

  1. Optical and laser properties of Tm3+-doped air-cladding fiber fabricated by plasma non-chemical vapor deposition

    NASA Astrophysics Data System (ADS)

    Xia, Changming; Zhou, Guiyao; Liu, Jiantao; Zhang, Wei; Han, Ying; Yuan, Jinhui

    2015-10-01

    Tm3+/Al3+ co-doped silica glass with the composition of 0.08 Tm2O3-0.8 Al2O3-99.12 SiO2 (mol%) is prepared by combining the high-temperature plasma furnace sintering technology and the dried RE-doped granulates. Using the prepared Tm3+/Al3+ co-doped silica glass as the fiber core, the Tm3+/Al3+ co-doped air-cladding fiber is fabricated by the stack-and-draw technology. Optical and laser properties of Tm3+/Al3+ co-doped air-cladding fiber are studied. The experimental results show that the Tm3+/Al3+ co-doped air-cladding fiber can be used as the potential material for the high-power fiber laser operating at 2 μm.

  2. 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.

  3. Tuning the size of aluminum oxide nanoparticles synthesized by laser ablation in water using physical and chemical approaches.

    PubMed

    Al-Mamun, Sharif Abdullah; Nakajima, Reiko; Ishigaki, Takamasa

    2013-02-15

    Colloidal solution of nano-sized spherical Al(2)O(3) particles were produced by nanosecond laser ablation upon irradiation on a corundum target in a distilled water environment. The effects of target inclination along the direction of laser irradiation and defocusing of the laser beam have been investigated in this study. The effect of the pH of the aqueous solution has also been studied. Synthesized particles were analyzed using transmission electron microscopy (TEM) to investigate particle shape and size distributions. Ablated nanoparticles (NPs) were spherical in shape, with the average particle size ranging from 8 to 18 nm in different operating conditions. Target inclination resulted in a decrease in the average particle size. Laser defocusing at the same power and thus with reduced fluence caused a decrease in the average size and standard deviation (SD), whereas defocusing that maintained the same fluence caused the reverse effect. Phase identification of NPs performed with high resolution TEM lattice images and fast Fourier transform indicated both a metastable γ-Al(2)O(3) phase and a stable α-Al(2)O(3) phase. X-ray diffraction analysis was also performed, which showed peaks of both α-Al(2)O(3) and γ-Al(2)O(3) with the presence of α- and γ-AlO(OH) polymorphs in acidic and alkaline solution, respectively. Surface conditions of the ablated particles representing the acidic and alkaline conditions were found to have a significant influence on both the size and crystallographic phase, which indicates it may be possible to induce size and phase transitions by changing the surface chemistry. PMID:23177203

  4. 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

  5. Unusual mechanism for H{sub 3}{sup +} formation from ethane as obtained by femtosecond laser pulse ionization and quantum chemical calculations

    SciTech Connect

    Kraus, Peter M.; Schwarzer, Martin C.; Schirmel, Nora; Urbasch, Gunter; Frenking, Gernot; Weitzel, Karl-Michael

    2011-03-21

    The formation of H{sub 3}{sup +} from saturated hydrocarbon molecules represents a prototype of a complex chemical process, involving the breaking and the making of chemical bonds. We present a combined theoretical and experimental investigation providing for the first time an understanding of the mechanism of H{sub 3}{sup +} formation at the molecular level. The experimental approach involves femtosecond laser pulse ionization of ethane leading to H{sub 3}{sup +} ions with kinetic energies on the order of 4 to 6.5 eV. The theoretical approach involves high-level quantum chemical calculation of the complete reaction path. The calculations confirm that the process takes place on the potential energy surface of the ethane dication. A surprising result of the theoretical investigation is, that the transition state of the process can be formally regarded as a H{sub 2} molecule attached to a C{sub 2}H{sub 4}{sup 2+} entity but IRC calculations show that it belongs to the reaction channel yielding C{sub 2}H{sub 3}{sup +}+ H{sub 3}{sup +}. Experimentally measured kinetic energies of the correlated H{sub 3}{sup +} and C{sub 2}H{sub 3}{sup +} ions confirm the reaction path suggested by theory.

  6. 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.

  7. Laser Research

    NASA Technical Reports Server (NTRS)

    1979-01-01

    Eastman Kodak Company, Rochester, New York is a broad-based firm which produces photographic apparatus and supplies, fibers, chemicals and vitamin concentrates. Much of the company's research and development effort is devoted to photographic science and imaging technology, including laser technology. Eastman Kodak is using a COSMIC computer program called LACOMA in the analysis of laser optical systems and camera design studies. The company reports that use of the program has provided development time savings and reduced computer service fees.

  8. 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

  9. Design of a superconducting linear accelerator for an Infrared Free Electron Laser of the proposed Chemical Dynamics Research Laboratory at LBL

    SciTech Connect

    Chattopadhyay, S.; Byrns, R.; Donahue, R.; Edighoffer, J.; Gough, R.; Hoyer, E.; Kim, K.J.; Leemans, W.; Staples, J.; Taylor, B.; Xie, M.

    1992-08-01

    An accelerator complex has recently been designed at LBL as part of an Infrared Free Electron Laser facility in support of a proposed Chemical Dynamics Research Laboratory. We will outline the choice of parameters and design philosophy, which are strongly driven by the demand of reliable and spectrally stable operation of the FEL for very special scientific experiments. The design is based on a 500 MHz recirculating superconducting electron linac with highest energy reach of about 60 MeV. The accelerator is injected with beams prepared by a specially designed gun-buncher system and incorporates a near-isochronous and achromatic recirculation line tunable over a wide range of beam energies. The stability issues considered to arrive at the specific design will be outlined.

  10. A spectrometer on chemical vapour deposition-diamond basis for the measurement of the charge-state distribution of heavy ions in a laser-generated plasma

    NASA Astrophysics Data System (ADS)

    Cayzac, Witold; Frank, Alexander; Schumacher, Dennis; Roth, Markus; Blažević, Abel; Wamers, Felix; Träger, Michael; Berdermann, Elèni; Voss, Bernd; Hessling, Thomas

    2013-04-01

    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 × 7 mm2 large and 20 μm 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 48Ca 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 103-104 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 Δ E/E ≈ 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.

  11. Investigations of the fabrication and the surface-enhanced Raman scattering detection applications for tapered fiber probes prepared with the laser-induced chemical deposition method.

    PubMed

    Fan, Qunfang; Cao, Jie; Liu, Ye; Yao, Bo; Mao, Qinghe

    2013-09-01

    The process of depositing nanoparticles onto tapered fiber probes with the laser-induced chemical deposition method (LICDM) and the surface-enhanced Raman scattering (SERS) detection performance of the prepared probes are experimentally investigated in this paper. Our results show that the nanoparticle-deposited tapered fiber probes prepared with the LICDM method depend strongly on the value of the cone angle. For small-angle tapered probes the nanoparticle-deposited areas are only focused at the taper tips, because the taper surfaces are mainly covered by a relatively low-intensity evanescent field. By lengthening the reaction time or increasing the induced power or solution concentration, it is still possible to deposit nanoparticles on small-angle tapers with the light-scattering effect. With 4-aminothiophenol as the testing molecule, it was found that for given preparation conditions, the cone angles for the tapered probes with the highest SERS spectral intensities for different excitation laser powers are almost the same. However, such an optimal cone angle is determined by the combined effects of both the localized surface plasmon resonance strength and the transmission loss generated by the nanoparticles deposited. PMID:24085073

  12. 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 technique which provides chemical information in both the mass spectra and chemical images. PMID:24447453

  13. Calcium phosphate thin films synthesized by pulsed laser deposition: Physico-chemical characterization and in vitro cell response

    NASA Astrophysics Data System (ADS)

    Mihailescu, I. N.; Torricelli, P.; Bigi, A.; Mayer, I.; Iliescu, M.; Werckmann, J.; Socol, G.; Miroiu, F.; Cuisinier, F.; Elkaim, R.; Hildebrand, G.

    2005-07-01

    We review the progress made by us using pulsed laser deposition (PLD) of two bioactive calcium phosphates: octacalcium phosphate (OCP) and Mn doped carbonated hydroxyapatite (Mn-CHA). Coatings of these materials well suited for biomimetic medical prostheses and pivots were synthesized on titanium substrates with a pulsed KrF* UV laser source. The best deposition conditions for Mn-CHA thin films were 13 Pa O 2, 400 °C with post heat treatment of 6 h in air enriched with water vapours. The coatings are stoichiometric and crystalline. For OCP, deposition at 150 °C in 50 Pa water vapor atmosphere, post treated by 6 h annealing in hot flux of water vapours, resulted in stoichiometric, but poorly-crystallized films. Degradation tests show different behavior for the OCP and Mn-CHA coatings. In vitro cell growth shows excellent adherence and biocompatibility of osteoblasts and fibroblasts in both OCP and Mn-CHA coatings. Human osteoblasts display normal proliferation and viability, and good differentiation behaviour.

  14. Advanced Diagnostics for COIL and DOIL

    NASA Astrophysics Data System (ADS)

    Davis, Steven J.; Rawlins, W. T.; Lee, Seonkyung; Silva, Michelle L.; Kessler, William J.; Mulhall, Phillip A.

    2004-09-01

    In this paper we discuss the application of sensitive, non-intrusive diagnostic techniques to characterize species in the flow that are critical for chemical oxygen iodine laser (COIL) devices and the electric discharge oxygen iodine laser (DOIL) concept. The key diagnostics include chemiluminescence to detect O2(a,b) and I(2P1/2) and tunable diode laser absorption measurements of I* and temperature. We have characterized variations in O and O2(a) yields with discharge power and oxygen mole fraction. We observe O2(a) yields to increase dramatically with decreasing oxygen mole fraction. We also discuss the application of a novel imaging diagnostic to obtain 2-D images of species concentrations and temperature.

  15. Combustion Research Program: Flame studies, laser diagnostics, and chemical kinetics. Progress report, 15 July 1987--3 December 1990

    SciTech Connect

    Crosley, D.R.

    1991-01-22

    We have made a detailed study of the care that must be taken to correctly measure OH radical concentrations in flames. A large part of these studies has concerned collisional quenching of hydride radical species (OH, NH, and NH{sub 2}), in particular the dependence upon rotational level and collision velocity (temperature). The results on OH and NH have shown unique and interesting behavior from the viewpoint of fundamental molecular dynamics, pointing to quenching often governed by collisions on an anisotropic, attractive surface, whereas NH{sub 2} quenching appears to depend on state-mixing considerations, not dynamic control. This state-specific behavior of these small, theoretically tractable hydrides has direct ramifications for quantitative flame diagnostics. Our other effort in the diagnostic area has been repeated but unsuccessful searches for laser induced fluorescence in the vinyl radical.

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. Defect structure and chemical bonding of p-type ZnO:Sb thin films prepared by pulsed laser deposition

    NASA Astrophysics Data System (ADS)

    Santos-Ortiz, Reinaldo; Jha, Jitendra Kumar; Sun, Wei; Nyandoto, Gilbert; Du, Jincheng; Shepherd, Nigel D.

    2014-11-01

    X-ray photoelectron spectroscopy and x-ray diffraction were used to understand the local environment of Sb in pulsed laser deposited ZnO:Sb films, which switched to p-type electrical conductivity from as-deposited n-type behavior after being annealed at 600 °C under an O2 flow. Tensile in-plane stress was observed in the as-deposited n-type films, and its magnitude increased after the annealing induced p-type switch. This stress can be explained by larger Sb sitting on smaller Zn sites in both the as-deposited and annealed films. Annealing resulted in oxygen incorporation and a more electronegative environment for the cations, as indicated by shifts to higher binding energy of both the Zn2p and Sb3d XPS peaks. The XPS results also show the formation of Sb2O5 in the p-type samples, and indicate a reorganization of the local coordination of Sb. Based on these results and density functional theory computations of the formation and ionization energies of defect complexes, we propose that ≤ft[ S{{b}Zn}-2{{V}Zn} \\right]\\prime acceptor complexes are responsible for the p-type conductivity.

  1. 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. PMID:25712592

  2. 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.

  3. Analysis of trimethoprim, lincomycin, sulfadoxin and tylosin in swine manure using laser diode thermal desorption-atmospheric pressure chemical ionization-tandem mass spectrometry.

    PubMed

    Solliec, Morgan; Massé, Daniel; Sauvé, Sébastien

    2014-10-01

    A new extraction method coupled to a high throughput sample analysis technique was developed for the determination of four veterinary antibiotics. The analytes belong to different groups of antibiotics such as chemotherapeutics, sulfonamides, lincosamides and macrolides. Trimethoprim (TMP), sulfadoxin (SFX), lincomycin (LCM) and tylosin (TYL) were extracted from lyophilized manure using a sonication extraction. McIlvaine buffer and methanol (MeOH) were used as extraction buffers, followed by cation-exchange solid phase extraction (SPE) for clean-up. Analysis was performed by laser diode thermal desorption-atmospheric pressure chemical-ionization (LDTD-APCI) tandem mass spectrometry (MS/MS) with selected reaction monitoring (SRM) detection. The LDTD is a high throughput sample introduction method that reduces total analysis time to less than 15s per sample, compared to minutes when using traditional liquid chromatography (LC). Various SPE parameters were optimized after sample extraction: the stationary phase, the extraction solvent composition, the quantity of sample extracted and sample pH. LDTD parameters were also optimized: solvent deposition, carrier gas, laser power and corona discharge. The method limit of detection (MLD) ranged from 2.5 to 8.3 µg kg(-1) while the method limit of quantification (MLQ) ranged from 8.3 to 28µgkg(-1). Calibration curves in the manure matrix showed good linearity (R(2)≥ 0.996) for all analytes and the interday and intraday coefficients of variation were below 14%. Recoveries of analytes from manure ranged from 53% to 69%. The method was successfully applied to real manure samples. PMID:25059125

  4. 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 ionization. This new technique can thus be potentially employed to undertake in situ analysis of materials imbedded in diverse media, such as cryogenic ices, biological samples, tissues, minerals, etc., by covered with an IR-absorbing laser ablation medium and study the chemical composition and reaction pathways of the analyte in its natural surroundings.

  5. 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 employed to undertake in situ analysis of materials imbedded in diverse media, such as cryogenic ices, biological samples, tissues, minerals, etc., by covered with an IR-absorbing laser ablation medium and study the chemical composition and reaction pathways of the analyte in its natural surroundings. PMID:24628162

  6. 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

    NASA Astrophysics Data System (ADS)

    Yang, Rui; Gudipati, Murthy S.

    2014-03-01

    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 employed to undertake in situ analysis of materials imbedded in diverse media, such as cryogenic ices, biological samples, tissues, minerals, etc., by covered with an IR-absorbing laser ablation medium and study the chemical composition and reaction pathways of the analyte in its natural surroundings.

  7. 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.

  8. Bibliography of Soviet laser developments, number 88, March - April 1987

    NASA Astrophysics Data System (ADS)

    1988-03-01

    This is the Soviet Laser Bibliography for March-April 1987, and is No. 88 in a continuing series on Soviet laser developments. The coverage includes basic research on solid state, liquid, gas, and chemical laser components; nonlinear optics; spectroscopy of laser materials; ultrashort pulse generation; theoretical aspects of advanced lasers; and general laser theory. Laser applications are listed under biological effects; communications systems; beam propagation; adaptive optics; computer technology; holography; laser-induced chemical reactions; measurement of laser parameters; laser measurement applications laser-excited optical effects; laser spectroscopy; beam-target interaction; and plasma generation and diagnostics.

  9. Bibliography of Soviet laser developments, number 64, March -April 1983

    NASA Astrophysics Data System (ADS)

    1984-03-01

    This is the Soviet Laser Bibliography for March-April 1983, and is No. 64 in a continuing series on Soviet laser developments. The coverage includes basic research on solid state, liquid, gas, and chemical lasers; components; nonlinear optics; spectroscopy of laser materials; ultrashort pulse generation; crystal growing; theoretical aspects of advanced lasers; and general laser theory. Laser applications are listed under biological effects; communications; beam propagation; adaptive optics; computer technology; holography; laser-induced chemical reactions; measurement of laser parameters; laser measurement applications; laser-excited optical effects; laser spectroscopy; beam-target interaction; and plasma generation and diagnostics.

  10. Bibliography of Soviet laser developments, number 65, May - June 1983

    NASA Astrophysics Data System (ADS)

    1984-05-01

    This is the Soviet Laser Bibliography for May-June 1983, and is No. 65 in a continuing series on Soviet laser developments. The coverage includes basic research on solid state, liquid gas, and chemical lasers; components; nonlinear optics; spectroscopy of laser materials; ultrashot pulse generation; crystal growing; theoretical aspects of advanced lasers; and general laser theory. Laser applications are listed under biological effects; communications; beam propagation; adaptive optics; computer technology; holography; laser-induced chemical reactions; measurement of laser parameters; laser measurement applications; laser-excited optical effects; laser spectroscopy, beam-target interaction; and plasma generation and diagnostics.

  11. Bibliography of Soviet laser developments: January - February 1988

    NASA Astrophysics Data System (ADS)

    1989-02-01

    This is the Soviet Laser Bibliography for January and February 1988, and is No. 93 in a continuing series on Soviet Laser developments. The coverage includes basic research on solid state, liquid, gas, and chemical lasers; components; nonlinear optics; spectroscopy of laser materials; ultrashort pulse generation; theoretical aspects of advanced lasers; and general laser theory. Laser applications are listed under biological effects; communications systems; beam propagation; adaptive optics; computer technology; holography; laser induced chemical reactions; measurement of laser parameters; laser measurement applications; laser excited optical effects; laser spectroscopy; beam target interaction; and plasma generation and diagnostics.

  12. Bibliography of Soviet laser developments, September-October 1987

    NASA Astrophysics Data System (ADS)

    1988-10-01

    This is the Soviet Laser Bibliography for September to October 1987, and is No. 91 in a continuing series on Soviet laser developments. The coverage includes basic research on solid state, liquid, gas, and chemical lasers; components; nonlinear optics; spectroscopy of laser materials; ultrashort pulse generation; crystal growing; theoretical aspects of advanced lasers; and general laser theory. Laser applications are listed under biological effects; communications systems; beam propagation; adaptive optics; computer technology; holography; laser induced chemical reactions; measurement of laser parameters; laser measurement applications; laser excited optical effects; laser spectroscopy; beam target interaction; and plasma generation and diagnostics.

  13. Bibliography of Soviet laser developments, number 83, May - June 1986

    NASA Astrophysics Data System (ADS)

    1987-09-01

    This is the Soviet Laser Bibliography for May-June 1986, and is No. 83 in a continuing series on Soviet laser developments. The coverage includes basic research on solid state, liquid, gas, and chemical lasers; components; nonlinear optics; spectroscopy of laser materials; ultrashort pulse generation; theoretical aspects of advanced lasers; and general laser theory. Laser applications are listed under biological effects; communications systems; beam propagation; adaptive optics; computer technology; holography; laser-induced chemical reactions; measurement of laser parameters; laser measurement applications; laser-excited optical effects; laser spectroscopy; beam-target interaction; and plasma generation and diagnostics.

  14. Bibliography of Soviet laser developments, number 87, January - February 1987

    NASA Astrophysics Data System (ADS)

    1987-12-01

    This Soviet Laser Bibliography is no. 87 in a continuing series on Soviet Laser developments. The coverage includes basic research on solid state, liquid, gas, and chemical lasers; components; nonlinear optics; spectroscopy of laser materials; ultrashort pulse generation; theoretical aspects of advanced lasers; and general laser theory. Laser applications are listed under biological effects; communications systems; beam propagation; adaptive optics; computer technology; holography; laser induced chemical reactions; measurement of laser parameters; laser measurement applications; laser-excited optical effects; laser spectroscopy; beam-target interaction; and plasma generation and diagnostics.

  15. Bibliography of Soviet Laser Developments, no. 62, November - December 1982

    NASA Astrophysics Data System (ADS)

    1983-10-01

    This is the Soviet Laser Bibliography for November-December 1982, and is No. 62 in a continuing series on Soviet laser developments. The coverage includes basic research on solid state, liquid, gas, and chemical lasers; components; nonlinear optics; spectroscopy of laser materials; ultrashort pulse generation; theoretical aspects of advanced lasers; and general laser theory. Laser applications are listed under biological effects; communications; beam propagation; adaptive optics; computer technology; holography; laser-induced chemical reactions; measurements of laser parameters; laser measurement applications; laser-excited optical effects; laser spectroscopy; beam-target interaction; and plasma generation and diagnostics.

  16. 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.

  17. 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??m in tall and ?0.45??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. PMID:23526837

  18. Metallurgical and chemical characterization of copper alloy reference materials within laser ablation inductively coupled plasma mass spectrometry: Method development for minimally-invasive analysis of ancient bronze objects

    NASA Astrophysics Data System (ADS)

    Walaszek, Damian; Senn, Marianne; Faller, Markus; Philippe, Laetitia; Wagner, Barbara; Bulska, Ewa; Ulrich, Andrea

    2013-01-01

    The chemical composition of ancient metal objects provides important information for manufacturing studies and authenticity verification of ancient copper or bronze artifacts. Non- or minimal-destructive analytical methods are preferred to mitigate visible damage. Laser ablation inductively coupled plasma mass spectrometry (LA-ICPMS) enables the determination of major elements as well as impurities down to lower ppm-levels, however, accuracy and precision of analysis strongly depend on the homogeneity of reference materials used for calibration. Moreover, appropriate analytical procedures are required e.g. in terms of ablation strategies (scan mode, spot size, etc.). This study reviews available copper alloy (certified) reference materials — (C)RMs from different sources and contributes new metallurgical data on homogeneity and spatial elemental distribution. Investigations of the standards were performed by optical and scanning electron microscopy with X-ray spectrometry (SEM-EDX) for the following copper alloy and bronze (certified) reference materials: NIST 454, BAM 374, BAM 211, BAM 227, BAM 374, BAM 378, BAS 50.01-2, BAS 50.03-4, and BAS 50.04-4. Additionally, the influence of inhomogeneities on different ablation and calibration strategies is evaluated to define an optimum analytical strategy in terms of line scan versus single spot ablation, variation of spot size, selection of the most appropriate RMs or minimum number of calibration reference materials.

  19. Energy distribution of interface state density in AlN/ n-GaAs heterostructures formed by laser chemical vapor deposition

    NASA Astrophysics Data System (ADS)

    Li, Xin; Tansley, T. L.; Chin, V. W. L.

    1993-02-01

    AlN/ n-GaAs heterointerface formed by the Laser Chemical Vapor Deposition techniques have been studied by the quasistatic-low-frequency and Terman's-high-frequency methods. The results compare favourably with those obtained from high-low frequency, conductance and DLTS methods. All of these methods give essentially the same results with interface trap densities in the range of 10 12-10 13 eV -1 cm -2 with a "U"-shaped energy distribution having a minimum at about Ec - 0.9 eV. The distribution is analyzed in terms of exponential density-of-state tails derived from conduction and valence band edges in the Disorder Induced Gap State (DIGS) model. The surface Fermi level is pinned at Ec - 0.83 eV by the requirement that depletion and interface charges are equal and opposite, and the charge distribution profile makes this pinned value particularly stable. The surface potential Vs can be moved at most 0.35 eV either side of the pinned level before breakdown occurs in the AlN dielectric film.

  20. Carbamazepine in municipal wastewater and wastewater sludge: ultrafast quantification by laser diode thermal desorption-atmospheric pressure chemical ionization coupled with tandem mass spectrometry.

    PubMed

    Mohapatra, D P; Brar, S K; Tyagi, R D; Picard, P; Surampalli, R Y

    2012-09-15

    In this study, the distribution of the anti-epileptic drug carbamazepine (CBZ) in wastewater (WW) and aqueous and solid phases of wastewater sludge (WWS) was carried out. A rapid and reliable method enabling high-throughput sample analysis for quicker data generation, detection, and monitoring of CBZ in WW and WWS was developed and validated. The ultrafast method (15s per sample) is based on the laser diode thermal desorption-atmospheric pressure chemical ionization (LDTD-APCI) coupled to tandem mass spectrometry (MS/MS). The optimization of instrumental parameters and method application for environmental analysis are presented. The performance of the novel method was evaluated by estimation of extraction recovery, linearity, precision and detection limit. The method detection limits was 12 ng L(-1) in WW and 3.4 ng g(-1) in WWS. The intra- and inter-day precisions were 8% and 11% in WW and 6% and 9% in WWS, respectively. Furthermore, three extraction methods, ultrasonic extraction (USE), microwave-assisted extraction (MAE) and accelerated solvent extraction (ASE) with three different solvent condition such as methanol, acetone and acetonitrile:ethyle acetate (5:1, v/v) were compared on the basis of procedural blank and method recovery. Overall, ASE showed the best extraction efficiency with methanol as compared to USE and MAE. Furthermore, the quantification of CBZ in WW and WWS samples showed the presence of contaminant in all stages of the treatment plant. PMID:22967548

  1. 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.

  2. 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.

  3. 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.

  4. 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 expand the knowledge about the mechanism of the formation of nanoalloys using LASiS and show how to obtain multielement nanoparticles of enormous interest for nanomedicine, plasmonics, magneto-plasmonics and catalysis. PMID:25746398

  5. Bibliography of Soviet laser developments, March-April 1988

    NASA Astrophysics Data System (ADS)

    1990-03-01

    This is the Soviet Laser Bibliography for March to April 1988. The coverage includes basic research on solid state, liquid, gas, and chemical lasers; components; nonlinear; optics; spectroscopy of laser materials; ultrashort pulse generation; theoretical aspects of advanced lasers; and general laser theory. Laser applications are listed under biological effects; communications systems; beam propagation; adaptive optics; computer technology; holography, laser-induced chemical reactions; measurement of laser parameters; laser measurement applications; laser-excited optical effects; laser spectroscopy; beam-target interaction; and plasma generation and diagnostics.

  6. Laser technology for space tasks

    NASA Astrophysics Data System (ADS)

    Brauch, Uwe; Schall, Wolfgang; Spindler, Gerhard; Wittwer, Wolfram; Zeyfang, Eberhard

    1990-04-01

    The possibilities of using lasers for energy supply, transport and debris elimination in space are studied. Laser cutting has been successful for aluminum, titanium and their alloys, and ceramics and composites, for space structures. Optimal photoelectric convectors of laser light to electric energy show a high efficiency, such as thermic lasers, which seem a good alternative to chemical and electrical energy vectors for low Earth orbital stations. For the estimation of the debris size, the focusing of a laser beam with lenses or a little mirror is possible with mean power lasers. It is concluded that laser technology shows a high potential for the future and needs a better development.

  7. FINAL REPORT. PARTICLE GENERATION BY LASER ABLATION IN SUPPORT OF CHEMICAL ANALYSIS OF HIGH LEVEL MIXED WASTE FROM PLUTONIUM PRODUCTION OPERATIONS

    EPA Science Inventory

    We 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 consi...

  8. Controllable high-throughput high-quality femtosecond laser-enhanced chemical etching by temporal pulse shaping based on electron density control

    PubMed Central

    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

  9. Correlation between O/Er Content Ratio and Photoluminescence Intensity of (Er, O)-Doped Hydrogenated Amorphous Si Thin Films Prepared by a Catalytic Chemical Vapor Deposition/Laser Ablation Hybrid Process

    NASA Astrophysics Data System (ADS)

    Sakai, Joe; Masuda, Atsushi; Akiyama, Haruo; Eryu, Osamu; Nakashima, Kenshiro; Matsumura, Hideki

    2004-07-01

    (Er, O)-doped hydrogenated amorphous Si (a-Si:H) thin films were prepared on Si or SiO2 substrates by a novel catalytic chemical vapor deposition (Cat-CVD)/laser ablation hybrid process which simultaneously performs a Cat-CVD of a-Si:H matrices and a doping of laser-ablated (Er, O) from an Er2O3 sintered target. These (Er, O)-doped a-Si:H films showed excellent photoluminescence (PL) properties in spite of the low temperature of the process (200°C during deposition and no postannealing). The Er and O contents of these films were evaluated by Rutherford backscattering and non-Rutherford elastic resonance scattering (NRERS), respectively. It was clarified that the dependence of the (Er, O) content on ambient pressure was not identical for O and Er. Thus, the O/Er content ratio, correlated to the PL intensity, strongly depended on the ambient pressure.

  10. 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.

  11. Growth of ferroelectric Ba0.8Sr0.2TiO3 epitaxial films by ultraviolet pulsed laser irradiation of chemical solution derived precursor layers

    NASA Astrophysics Data System (ADS)

    Queraltó, A.; Pérez del Pino, A.; de la Mata, M.; Arbiol, J.; Tristany, M.; Gómez, A.; Obradors, X.; Puig, T.

    2015-06-01

    Highly crystalline epitaxial Ba0.8Sr0.2TiO3 (BST) thin-films are grown on (001)-oriented LaNiO3-buffered LaAlO3 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-1.

  12. 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.

  13. 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.

  14. Laser use and safety.

    PubMed

    1992-09-01

    This Guidance Article is an update of an article published in a special issue of Health Devices entitled "Lasers in Medicine--An Introduction" (13[8], June 1984). Although surgical lasers have a good overall safety record, they do expose patients, physicians, and other clinical staff to serious risks. Laser hazards can cause injury, disability, or even death: hospital staff have been burned by misdirected laser beams, technicians and maintenance personnel have received eye injuries while working on lasers and have been exposed to hazardous chemicals while changing laser dyes, and patients have died from injuries resulting from fires ignited by laser energy. Laser accidents most commonly result from misdirection of the laser beam. Direct or reflected radiation can burn skin, hair, or, more seriously, the cornea or retina, causing permanent damage. Misdirected laser energy can also cause ignition of surgical drapes, tracheal tubes, or the patient's hair. Also, a frequent by-product of laser-tissue interactions is laser plume, or smoke. Its acrid smell and particulate matter irritate the eyes, nose, and lungs and cause nausea; it is also a suspected vector for transmitting infectious materials, such as the human papilloma virus (HPV) associated with condyloma (a wartlike lesion) and cervical cancer. The risks are not limited to patients and those directly involved in using and maintaining lasers. Many laser procedures are performed in areas outside the controlled environment of the surgical suite; patients in a waiting area or even passersby could conceivably walk into an accessible laser treatment room, such as a doctor's office, and inadvertently be exposed to a direct or reflected beam.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:1428901

  15. [Study of flow properties of wet solids using laser induced photo chemical anemometry]. Quarterly technical progress report, October--December 1990

    SciTech Connect

    Falco, B.

    1991-01-20

    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. [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.

  17. Bibliography of Soviet laser developments, Number 84, July-August 1986

    SciTech Connect

    Not Available

    1987-10-01

    This is the Soviet Laser Bibliography for July-August 1986, and is No. 84 in a continuing series on Soviet laser developments. The coverage includes basic research on solid-state, liquid, gas, and chemical lasers; components; nonlinear optics; spectroscopy of laser materials; ultrashort pulse generation; crystal growing; theoretical aspects of advanced lasers; and general laser theory. Laser applications are listed under biological effects; communications systems; beam propagation; adaptive optics; computer technology; holography; laser-induced chemical reactions; measurement of laser parameters; laser measurement applications; laser-excited optical effects; laser spectroscopy; beam-target interaction; and plasma generation and diagnostics.

  18. Bibliography of Soviet laser developments, Number 77, May-June 1985

    SciTech Connect

    Not Available

    1986-09-01

    This is the Soviet Laser Bibliography for May-June 1985, and is No. 77 in a continuing series on Soviet laser developments. The coverage includes basic research on solid-state, liquid, gas, and chemical lasers; components; nonlinear optics; spectroscopy of laser materials; ultrashort pulse generation; theoretical aspects of advanced lasers; and general laser theory. Laser applications are listed under biological effects; communications systems; beam propagation; adaptive optics; computer technology; holography; laser-induced chemical reactions; measurement of laser parameters; laser measurement applications; laser-excited optical effects; laser spectroscopy; beam-target interaction; and plasma generation and diagnostics.

  19. Bibliography of Soviet laser developments, Number 83, May-June 1986

    SciTech Connect

    Not Available

    1987-09-01

    This is the Soviet Laser Bibliography for May-June 1986, and is No. 83 in a continuing series on Soviet laser developments. The coverage includes basic research on solid-state, liquid, gas, and chemical lasers; components; nonlinear optics; spectroscopy of laser materials; ultrashort pulse generation; theoretical aspects of advanced lasers; and general laser theory. Laser applications are listed under biological effects; communications systems; beam propagation; adaptive optics; computer technology; holography; laser-induced chemical reactions; measurement of laser parameters; laser measurement applications; laser-excited optical effects; laser spectroscopy; beam-target interaction; and plasma generation and diagnostics.

  20. Bibliography of Soviet laser developments, Number 86, November-December 1986

    SciTech Connect

    Not Available

    1987-12-01

    This is the Soviet Laser Bibliography for November-December 1986, and is No. 86 in a continuing series on Soviet laser developments. The coverage includes basic research on solid-state, liquid, gas, and chemical lasers; components; nonlinear optics; spectroscopy of laser materials; ultrashort pulse generation; crystal growing; theoretical aspects of advanced lasers; and general laser theory. Laser applications are listed under biological effects; communications systems; beam propagation; adaptive optics; computer technology; holography; laser-induced chemical reactions; measurement of laser parameters; laser measurement applications; laser-excited optical effects; laser spectroscopy; beam-target interaction; and plasma generation and diagnostics.

  1. Bibliography of Soviet laser developments, Number 75, January-February 1985

    SciTech Connect

    Not Available

    1986-05-01

    This is the Soviet Laser Bibliography for January-February 1985, and is No. 75 in a continuing series on Soviet laser developments. The coverage includes basic research on solid-state, liquid, gas, and chemical lasers; components; nonlinear optics; spectroscopy of laser materials; ultrashort pulse generation; theoretical aspects of advanced lasers; and general laser theory. Laser applications are listed under biological effects; communications systems; beam propagation; adaptive optics; computer technology; holography; laser-induced chemical reactions; measurement of laser parameters; laser measurement applications; laser-excited optical effects; laser spectroscopy; beam-target interaction; and plasma generation and diagnostics.

  2. Bibliography of Soviet laser developments, Number 76, March-April 1985

    SciTech Connect

    Not Available

    1986-06-01

    This is the Soviet Laser Bibliography for March-April 1985, and is No. 76 in a continuing series on Soviet laser developments. The coverage includes basic research on solid-state, liquid, gas, and chemical lasers; components; nonlinear optics; spectroscopy of laser materials; ultrashort pulse generation; theoretical aspects of advanced lasers; and general laser theory. Laser applications are listed under biological effects; communications systems; beam propagation; adaptive optics; computer technology; holography; laser-induced chemical reactions; measurement of laser parameters; laser measurement applications; laser-excited optical effects; laser spectroscopy; beam-target interaction; and plasma generation and diagnostics.

  3. Bibliography of Soviet laser developments, Number 85, September-October 1986

    SciTech Connect

    Not Available

    1987-11-01

    This is the Soviet Laser Bibliography for September-October 1986, and is No. 85 in a continuing series on Soviet laser developments. The coverage includes basic research on solid-state, liquid, gas, and chemical lasers; components; nonlinear optics; spectroscopy of laser materials; ultrashort pulse generation; crystal growing; theoretical aspects of advanced lasers; and general laser theory. Laser applications are listed under biological effects; communications systems; beam propagation; adaptive optics; computer technology; holography; laser-induced chemical reactions; measurement of laser parameters; laser measurement applications; laser-excited optical effects; laser spectroscopy; beam-target interaction; and plasma generation and diagnostics.

  4. Bibliography of Soviet laser developments, Number 82, March-April 1986

    SciTech Connect

    Not Available

    1987-08-01

    This is the Soviet Laser Bibliography for March-April 1986, and is No. 82 in a continuing series on Soviet laser developments. The coverage includes basic research on solid-state, liquid, gas, and chemical lasers; components; nonlinear optics; spectroscopy of laser materials; ultrashort pulse generation; theoretical aspects of advanced lasers; and general laser theory. Laser applications are listed under biological effects; communications systems; beam propagation; adaptive optics; computer technology; holography; laser-induced chemical reactions; measurement of laser parameters; laser measurement applications; laser-excited optical effects; laser spectroscopy; beam-target interaction; and plasma generation and diagnostics.

  5. Bibliography of Soviet laser developments, Number 78, July-August 1985

    SciTech Connect

    Not Available

    1986-12-01

    This is the Soviet Laser Bibliography for July-August 1985, and is No. 78 in a continuing series on Soviet laser developments. The coverage includes basic research on solid-state, liquid, gas, and chemical lasers; components; nonlinear optics; spectroscopy of laser materials; ultrashort pulse generation; theoretical aspects of advanced lasers; and general laser theory. Laser applications are listed under biological effects; communications systems; beam propagation; adaptive optics; computer technology; holography; laser-induced chemical reactions; measurement of laser parameters; laser measurement applications; laser-excited optical effects; laser spectroscopy; beam-target interaction; and plasma generation and diagnostics.

  6. Bibliography of Soviet laser developments, Number 79, September-October 1985

    SciTech Connect

    Not Available

    1987-01-01

    This is the Soviet Laser Bibliography for September-October 1985, and is No. 79 in a continuing series on Soviet laser developments. The coverage includes basic research on solid-state, liquid, gas, and chemical lasers; components; nonlinear optics; spectroscopy of laser materials; ultrashort pulse generation; theoretical aspects of advanced lasers; and general laser theory. Laser applications are listed under biological effects; communications systems; beam propagation; adaptive optics; computer technology; holography; laser-induced chemical reactions; measurement of laser parameters; laser measurement applications; laser-excited optical effects; laser spectroscopy; beam-target interaction; and plasma generation and diagnostics.

  7. Bibliography of Soviet laser developments, Number 74, November-December 1984

    SciTech Connect

    Not Available

    1986-09-01

    This is the Soviet Laser Bibliography for November-December 1984, and is No. 74 in a continuing series on Soviet laser developments. The coverage includes basic research on solid-state, liquid, gas, and chemical lasers; components; nonlinear optics; spectroscopy of laser materials; ultrashort pulse generation; theoretical aspects of advanced lasers; and general laser theory. Laser applications are listed under biological effects; communications systems; beam propagation; adaptive optics; computer technology; holography; laser-induced chemical reactions; measurement of laser parameters; laser measurement applications; laser-excited optical effects; laser spectroscopy; beam-target interaction; and plasma generation and diagnostics.

  8. Bibliography of Soviet laser developments, Number 80, November-December 1985

    SciTech Connect

    Not Available

    1987-03-01

    This is the Soviet Laser Bibliography for November-December 1985, and is No. 80 in a continuing series on Soviet laser developments. The coverage includes basic research on solid-state, liquid, gas, and chemical lasers; components; nonlinear optics; spectroscopy of laser materials; ultrashort pulse generation; theoretical aspects of advanced lasers; and general laser theory. Laser applications are listed under biological effects; communications systems; beam propagation; adaptive optics; computer technology; holography; laser-induced chemical reactions; measurement of laser parameters; laser measurement applications; laser-excited optical effects; laser spectroscopy; beam-target interaction; and plasma generation and diagnostics.

  9. Bibliography of Soviet Laser Developments, Number 63, January-February 1983

    NASA Astrophysics Data System (ADS)

    1984-02-01

    This is the Soviet Laser Bibliography for January-February 1983, and is No. 63 in a continuing series on Soviet laser developments. The coverage includes basic research on solid state, liquid, gas, and chemical lasers; components; nonlinear optics; spectroscopy of laser materials; ultrashot pulse generations; crystal growing; theoretical aspects of advanced lasers; and general laser theory. Laser applications are listed under biological effects; communications; beam propagation; adaptive optics; computer technology; holography; laser-induced chemical reactions; measurement of laser parameters; laser measurement applications; laser-excited optical effects; laser spectroscopy; beam-target interaction; and plasma generation and diagnostics.

  10. Bibliography of Soviet Laser Developments, Number 67, September-October 1983

    NASA Astrophysics Data System (ADS)

    1984-12-01

    This is the Soviet Laser Bibliography for September-October 1983, and is No. 67 in a continuing series on Soviet laser developments. The coverage includes basic research on solid state, liquid, gas, and chemical lasers; components; nonlinear optics; spectroscopy of laser materials; ultrashort pulse generation; crystal growing; theoretical aspects of advanced lasers; and general laser theory. Laser applications are listed under biological effects; communications; beam propagation; adaptive optics; computer technology; holography; laser-induced chemical reactions; measurement of laser parameters; laser measurement applications; laser-excited optical effects; laser spectroscopy; beam-target interaction; and plasma generation and diagnostics.

  11. Measurement and analysis of internal loss and injection efficiency for continuous-wave blue semipolar ( 20 2 ¯ 1 ¯ ) III-nitride laser diodes with chemically assisted ion beam etched facets

    NASA Astrophysics Data System (ADS)

    Becerra, Daniel L.; Kuritzky, Leah Y.; Nedy, Joseph; Saud Abbas, Arwa; Pourhashemi, Arash; Farrell, Robert M.; Cohen, Daniel A.; DenBaars, Steven P.; Speck, James S.; Nakamura, Shuji

    2016-02-01

    Continuous-wave blue semipolar ( 20 2 ¯ 1 ¯ ) III-nitride laser diodes were fabricated with highly vertical, smooth, and uniform mirror facets produced by chemically assisted ion beam etching. Uniform mirror facets are a requirement for accurate experimental determination of internal laser parameters, including internal loss and injection efficiency, which were determined to be 9 cm-1 and 73%, respectively, using the cavity length dependent method. The cavity length of the uncoated devices was varied from 900 μm to 1800 μm, with threshold current densities ranging from 3 kA/cm2 to 9 kA/cm2 and threshold voltages ranging from 5.5 V to 7 V. The experimentally determined internal loss was found to be in good agreement with a calculated value of 9.5 cm-1 using a 1D mode solver. The loss in each layer was calculated and in light of the analysis several modifications to the laser design are proposed.

  12. 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.

  13. 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.

  14. Mixed-layered bismuth-oxygen-iodine materials for capture and waste disposal of radioactive iodine

    DOEpatents

    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.

  15. 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.

  16. Quantitative chemical imaging of element diffusion into heterogeneous media using laser ablation inductively coupled plasma mass spectrometry, synchrotron micro-X-ray fluorescence, and extended X-ray absorption fine structure spectroscopy.

    PubMed

    Wang, H A O; Grolimund, D; Van Loon, L R; Barmettler, K; Borca, C N; Aeschlimann, B; Günther, D

    2011-08-15

    Quantitative chemical imaging of trace elements in heterogeneous media is important for the fundamental understanding of a broad range of chemical and physical processes. The primary aim of this study was to develop an analytical methodology for quantitative high spatial resolution chemical imaging based on the complementary use of independent microanalytical techniques. The selected scientific case study is focused on high spatially resolved quantitative imaging of major elements, minor elements, and a trace element (Cs) in Opalinus clay, which has been proposed as the host rock for high-level radioactive waste repositories. Laser ablation inductively coupled plasma mass spectrometry (LA-ICPMS), providing quantitative chemical information, and synchrotron radiation based micro-X-ray fluorescence (SR-microXRF), providing high spatial resolution images, were applied to study Cs migration into Opalinus clay rock. The results indicate that combining the outputs achievable by the two independent techniques enhances the imaging capabilities significantly. The qualitative high resolution image of SR-microXRF is in good agreement with the quantitative image recorded with lower spatial resolution by LA-ICPMS. Combining both techniques, it was possible to determine that the Opalinus clay sample contains two distinct domains: (i) a clay mineral rich domain and (ii) a calcium carbonate dominated domain. The two domains are separated by sharp boundaries. The spatial Cs distribution is highly correlated to the distribution of the clay. Furthermore, extended X-ray absorption fine structure analysis indicates that the trace element Cs preferentially migrates into clay interlayers rather than into the calcite domain, which complements the results acquired by LA-ICPMS and SR-microXRF. By using complementary techniques, the quantification robustness was improved to quantitative micrometer spatial resolution. Such quantitative, microscale chemical images allow a more detailed understanding of the chemical reactive transport process into and within heterogeneous media to be gained. PMID:21623637

  17. Intracorporeal laser lithotripsy

    PubMed Central

    Papatsoris, Athanasios G.; Skolarikos, Andreas; Buchholz, Noor

    2012-01-01

    Objectives To review the current literature on intracorporeal laser lithotripsy. Methods We searched PubMed for relevant reports up to January 2012, using the keywords ‘laser’, ‘lithotripsy’ and ‘intracorporeal’. Results We studied 125 relevant reports of studies with various levels of evidence. Efficient lithotripsy depends on the laser variables (wavelength, pulse duration and pulse energy) and the physical properties of the stones (optical, mechanical and chemical). The most efficient laser for stones in all locations and of all mineral compositions is the holmium yttrium–aluminium–garnet laser (Ho:YAG). The frequency-doubled double-pulse Nd:YAG laser functions through the generation of a plasma bubble. New laser systems, such as the erbium:YAG and the thulium laser, are under evaluation. Laser protection systems have also been developed for the novel digital flexible ureteroscopes. Although complications are rare, a high relevant clinical suspicion is necessary. Conclusions Laser lithotripsy technology is continuously developing, while the Ho:YAG laser remains the reference standard for intracorporeal lithotripsy. PMID:26558041

  18. 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...

  19. A high-repetition rate scheme for synchrotron-based picosecond laser pump/x-ray probe experiments on chemical and biological systems in solution.

    PubMed

    Lima, Frederico A; Milne, Christopher J; Amarasinghe, Dimali C V; Rittmann-Frank, Mercedes Hannelore; van der Veen, Renske M; Reinhard, Marco; Pham, Van-Thai; Karlsson, Susanne; Johnson, Steven L; Grolimund, Daniel; Borca, Camelia; Huthwelker, Thomas; Janousch, Markus; van Mourik, Frank; Abela, Rafael; Chergui, Majed

    2011-06-01

    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. PMID:21721678

  20. 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.

  1. 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. PMID:23455645

  2. Laser propulsion for orbit transfer - Laser technology issues

    NASA Technical Reports Server (NTRS)

    Horvath, J. C.; Frisbee, R. H.

    1985-01-01

    Using reasonable near-term mission traffic models (1991-2000 being the assumed operational time of the system) and the most current unclassified laser and laser thruster information available, it was found that space-based laser propulsion orbit transfer vehicles (OTVs) can outperform the aerobraked chemical OTV over a 10-year life-cycle. The conservative traffic models used resulted in an optimum laser power of about 1 MW per laser. This is significantly lower than the power levels considered in other studies. Trip time was taken into account only to the extent that the system was sized to accomplish the mission schedule.

  3. Bibliography of Soviet laser developments, Number 66, July-August 1983

    NASA Astrophysics Data System (ADS)

    1984-09-01

    This bibliography is the 66th in a continuing series on Soviet laser developments. The coverage includes basic research on solid state, liquid, gas, and chemical laser; components; nonlinear optics; spectroscopy of laser materials; ultrashort pulse generation; crystal growing; theoretical aspects of advanced lasers; and general laser theory. Laser applications are listed under biological effects; communications; beam propagation; adaptive optics; computer technology; holography; laser-induced chemical reactions; measurement of laser parameters; laser measurement applications; laser-excited optical effects; laser spectroscopy, beam-target interaction, and plasma generation and diagnostics.

  4. 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

  5. 1.12 μm Polarization Controlled Highly Strained GaInAs Vertical-Cavity Surface-Emitting Lasers on GaAs(311)B by Metal Organic Chemical Vapor Deposition

    NASA Astrophysics Data System (ADS)

    Nishiyama, Nobuhiko; Arai, Masakazu; Shinada, Satoshi; Azuchi, Munechika; Matsutani, Akihiro; Miyamoto, Tomoyuki; Koyama, Fumio; Iga, Kenichi

    2001-05-01

    A highly strained GaInAs vertical-cavity surface-emitting laser (VCSEL) emitting at 1.12 μm has been realized on a GaAs(311)B substrate by metal organic chemical vapor deposition (MOCVD) for the first time. The threshold current of an 8 μm oxide aperture device was as low as 0.9 mA@. This device operated at up to 170°C without a heatsink under the CW condition. The polarization direction of the oscillation mode was stable and the orthogonal polarization suppression ratio (OPSR) was 30 dB@. The operating lifetime of over 2000 under room-temperature CW conditions was confirmed without any degradation in spite of high strain of over 2%.

  6. 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...

  7. The determination of the chemical composition profile of the GaAs/AlGaAs heterostructures designed for quantum cascade lasers by means of synchrotron radiation

    NASA Astrophysics Data System (ADS)

    Gaca, JarosŁaw; Wójcik, Marek; Bugajski, Maciej; Kosiel, Kamil

    2011-10-01

    The chemical composition profile of the GaAs/AlGaAs quantum cascade structures grown on (0 0 1) GaAs substrate by molecular beam epitaxy is studied by a synchrotron radiation high-resolution X-ray diffraction. The analysis is carried out for the whole structure as well for its parts. In order to determine some structural parameters, such as: the thickness and chemical composition of each layer making up the investigated structure, the profile of the interface between succeeding layers, and the preservation of the structure periodicity, the experimental X-ray diffraction profiles are compared with simulated ones calculated by means of Darwin dynamical theory of X-ray diffraction. It is shown that this method gives correct chemical composition profiles and allows for the evaluation of the deviations from the designed values of the structural parameters in most investigated cases. Limits of the method are discussed, especially by the determination of the chemical composition profile for thin heterostructures, such as those making active or injector regions.

  8. Engineering Light: Quantum Cascade Lasers

    ScienceCinema

    Claire Gmachl

    2010-09-01

    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.

  9. 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.

  10. High temperature pulsed and continuous-wave operation and thermally stable threshold characteristics of vertical-cavity surface-emitting lasers grown by metalorganic chemical vapor deposition

    NASA Astrophysics Data System (ADS)

    Lu, Bo; Zhou, P.; Cheng, Julian; Malloy, K. J.; Zolper, J. C.

    1994-09-01

    A systematic and comparative study of the temperature performance of vertical-cavity surface-emitting lasers (VCSELs) is presented to discuss how thermal effects govern their temperature range for cw operation. These include the temperature-induced detuning of the lasing mode from the gain peak, thermal self-heating, and thermal runaway. The power dissipation of the VCSELs and the resultant rise in junction temperature have been measured as a function of the mode detuning. It is shown that low power dissipation is achieved by aligning the cavity mode to the gain peak and introducing continuously graded heterointerfaces throughout the VCSEL structure. By selecting the optimal mode detuning, VCSELs have achieved excellent operating characteristics over a broad range of temperatures, including thermally stable threshold voltage and current, and a very wide temperature range for both pulsed (100-580 K) and continuous-wave (100-400 K) operations.

  11. Bibliography of Soviet laser developments, No. 92, November - December 1987

    NASA Astrophysics Data System (ADS)

    1988-12-01

    This bibliography has been compiled under an interagency agreement as a continuing effort to document current Soviet-bloc developments in the quantum electronics field. It includes all significant laser-related articles received by the Agency in that interval. The bulk of the entries come from the approximately 30 periodicals which are known to publish the most significant findings in Soviet laser technology. Citations from the Soviet reference journals (journals of abstracts) are also included. Laser items from the popular or semipopular press are generally omitted. Citation topics include: solid state lasers, liquid lasers, gas lasers, chemical lasers, laser components, nonlinear optics, and laser applications.

  12. 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.

  13. 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.

  14. Laser device

    SciTech Connect

    Mcmahan, W.H.

    1980-10-21

    A means is provided for continuously purging deleterious contaminants including water vapor, ozone and organic vapors from the resonant cavity of lasers where the resonant cavity is characterized by a gap-space between the gain medium and the optical mirror at both ends of the cavity with each of the gapspaces being disposed within an enclosed chamber where the contaminants tend to collect. This is accomplished by connecting the interiors of the gap-space chambers through tubular gas conduits with one or more canisters which contain a chemical desiccant or molecular sieve capable of removing the unwanted gases or vapors. A molecular sieve comprised of zeolite with the appropriate intermolecular spacing is especially preferred.

  15. Method for laser induced isotope enrichment

    DOEpatents

    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.

  16. 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.

  17. Chemical synthesis and crystal growth of AgGaGeS4, a material for mid-IR nonlinear laser applications

    NASA Astrophysics Data System (ADS)

    Rame, J.; Petit, J.; Clement, Q.; Melkonian, J. M.; Viana, B.

    2015-02-01

    AgGaGeS4 compound (AGGS) is a promising nonlinear material for mid-IR applications. The different steps of this materials processing are presented. The chemical synthesis of polycrystals and the single crystal growth process are described. Compounds volatility can induce stoichiometry deviation and reduce the quality of obtained single crystals. Nevertheless, 28 mm diameter and 70 mm length single crystals have been grown by Bridgman-Stockbarger method, cut and polished AGGS crystal is obtained. The crystal has good homogeneity and absorption coefficient of less than 0.1 cm-1 in the 0.5-11.5 μm range which make it usable in nonlinear devices.

  18. Ion beam induced chemical and morphological changes in TiO2 films deposited on Si(1 1 1) surface by pulsed laser deposition

    NASA Astrophysics Data System (ADS)

    Mohanta, R. R.; Medicherla, V. R. R.; Mohanta, K. L.; Nayak, Nimai C.; Majumder, S.; Solanki, V.; Varma, Shikha; Bapna, Komal; Phase, D. M.; Sathe, V.

    2015-01-01

    We have investigated TiO2 films prepared by pulsed laser deposition method on Si(1 1 1) surface using X-ray diffraction (XRD), Raman Spectroscopy, X-ray Photoelectron Spectroscopy (XPS), Atomic Force Microscopy (AFM) and ion beam sputtering techniques. Our XRD data along with Raman indicated that the deposited TiO2 is in anatase phase. The binding energy position of Ti 2p also supports the anatase phase formation. AFM topography of as deposited film indicates the formation of non uniform TiO2 growth with the formation of voids on Si(1 1 1) substrate. After sputtering with argon ion beam, surface erosion occurs and voids have disappeared. The Ti 2p core level of sputtered TiO2 exhibits the formation of Ti2O3, TiO and pure Ti on the surface. High binding energy shoulder of O 1s peak becomes sharp after sputtering. Ti LMM Auger peaks become broader after sputtering but no shift in kinetic energy is observed.

  19. FT-IR, Laser-Raman spectra and quantum chemical calculations of methyl 4-(trifluoromethyl)-1H-pyrrole-3-carboxylate-A DFT approach

    NASA Astrophysics Data System (ADS)

    Sert, Yusuf; Sreenivasa, S.; Doğan, H.; Manojkumar, K. E.; Suchetan, P. A.; Ucun, Fatih

    2014-06-01

    In this study the experimental and theoretical vibrational frequencies of a newly synthesized anti-tumor and anti-inflammatory agent namely, methyl 4-(trifluoromethyl)-1H-pyrrole-3-carboxylate have been investigated. The experimental FT-IR (4000-400 cm-1) and Laser-Raman spectra (4000-100 cm-1) of the molecule in solid phase have been recorded. The theoretical vibrational frequencies and optimized geometric parameters (bond lengths, bond angles and torsion angles) have been calculated using density functional theory (DFT/B3LYP: Becke, 3-parameter, Lee-Yang-Parr and DFT/M06-2X: highly parameterized, empirical exchange correlation function) with 6-311++G(d,p) basis set by Gaussian 03 software, for the first time. The assignments of the vibrational frequencies have been done by potential energy distribution (PED) analysis using VEDA 4 software. The theoretical optimized geometric parameters and vibrational frequencies have been found to be in good agreement with the corresponding experimental data and results in the literature. In addition, the highest occupied molecular orbital (HOMO) energy, the lowest unoccupied molecular orbital (LUMO) energy and the other related molecular energy values of the compound have been investigated using the same theoretical calculations.

  20. Chemical cytometry of thiols using capillary zone electrophoresis-laser induced fluorescence and TMPAB-o-M, an improved fluorogenic reagent.

    PubMed

    Guo, Xiao-Feng; Arceo, Jennifer; Huge, Bonnie Jaskowski; Ludwig, Katelyn R; Dovichi, Norman J

    2016-02-01

    Low molecular weight thiol compounds play crucial roles in many physiological processes. Most methods for determination of thiol compounds are population-averaged; few methods for quantification of thiol compounds in single cells have been reported. We report an ultrasensitive method for determination of thiol compounds in single cells by use of 1,3,5,7-tetramethyl-8-phenyl-(2-maleimide)-difluoroboradiaza-s-indacene (TMPAB-o-M), a fluorogenic probe with useful spectral properties, coupled with capillary zone electrophoresis and laser induced fluorescence detection using a post-column sheath flow cuvette. TMPAB-o-M provides low background, high sensitivity, and excellent reactivity. After optimization of the separation method, we achieved baseline separation of labeled glutathione (GSH), cysteine (Cys), homocysteine, and γ-glutamylcysteine within 11 min, and produced concentration limits of detection from 10 to 20 pM and mass LODs of 65 to 100 zmol. The method was applied for analysis of thiol containing compounds in both cell homogenates and in single HCT-29 and MCF-10A cells. GSH was the main thiol, and Cys was also detected in both cell types. Cells were treated with N-ethylmaleimide, which significantly attenuated thiol levels. PMID:26814594

  1. 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. PMID:26814607

  2. 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.

  3. 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.

  4. 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.

  5. Laser clock

    NASA Astrophysics Data System (ADS)

    Facklam, R. L.

    1984-11-01

    A laser clock includes a linear laser in one embodiment of the clock and a ring laser gyro in the other embodiment. The linear laser is frequency stabilized and utilizes a single active medium in the form of a low pressure gas, such as He-Ne, with a Doppler broadened gain curve. The ring laser gyro is a four frequency laser with a Faraday rotor. Detector and electronic circuitry associated with the laser of each embodiment detect a beat frequency and coverts it to a clock signal.

  6. InAsSb-based mid-infrared lasers (3.5--3.9 {micro}m) and light-emitting diodes with AlAsSb claddings and semi-metal electron injection grown by metal-organic chemical vapor deposition

    SciTech Connect

    Allerman, A.A.; Biefeld, R.M.; Kurtz, S.R.

    1997-10-01

    Mid-infrared (3--5 {micro}m) lasers and LED`s are being developed for use in chemical sensor systems. As-rich, InAsSb heterostructures display unique electronic properties that are beneficial to the performance of these midwave infrared emitters. The metal-organic chemical vapor deposition (MOCVD) growth of AlAs{sub 1{minus}x}Sb{sub x} cladding layers and InAsSb/InAsP superlattice active regions are described. A regrowth technique has been used to fabricate gain-guided, injection lasers using undoped (p-type) AlAs{sub 0.16}Sb{sub 0.84} for optical confinement. In device studies, the authors demonstrate lasers and LEDs utilizing the semi-metal properties of a p-GaAsSb/n-InAs heterojunction as a source for injection of electrons into the active region of emitters. This avoids the difficulties associated with n-type doping of AlAsSb cladding layers required for conventional p-n junction lasers and also provides a means for construction of active regions with multiple gain stages. Gain guided injected lasers employing a strained InAsSb/InAs multi-quantum well active region operated up to 210 K in pulsed mode, with an emission wavelength of 3.8--3.9 {micro}m. A characteristic temperature of 40 K was observed to 140 K and 29 K from 140 K to 210 K. An optically pumped laser with an InAsSb/InAsP superlattice active region is also described. The maximum operating temperature of this 3.7 {micro}m laser was 240 K.

  7. Apatite chemical composition, determined by electron microprobe and laser-ablation inductively coupled plasma mass spectrometry, as a probe into granite petrogenesis

    NASA Astrophysics Data System (ADS)

    Sha, Lian-Kun; Chappell, Bruce W.

    1999-11-01

    Major, minor, and trace element abundances in apatites from various I- and S-type (igneous and sedimentary) granites of the Lachlan Fold Belt have been determined using electron microprobe and laser ablation inductively coupled plasma mass spectrometer. The results show that apatite can accommodate many minor and trace elements, whose concentrations and ratios are relatively sensitive to factors controlling many of the fundamental differences between I- and S-type granites. Apatites from S-type granites generally have higher F but lower Cl contents than those from I-type granites, which is ascribed mainly to the loss of Cl during the weathering processes forming the source rocks of S-type granites, although fractional crystallisation can cause significant enrichment in F as well. High Mn and Fe contents in apatites from S-type granites, and high S and As abundances in apatites from mafic I-type granites, result from different oxygen fugacities and degrees of Al saturation (or aluminosity) between metaluminous mafic I-type magmas and peraluminous S-type and felsic I-type magmas. There are systematic and distinctive differences in absolute rare-earth element (REE) abundances, REE distribution patterns, and element ratios (e.g., La/Y, Sm/Nd, etc.) between apatites from different types of granite. The strong Eu depletion that characterises apatites from S- and felsic I-type granites is interpreted here to be a result of the uniqueness of crystal chemistry of apatite and high Eu 2+/Eu 3+ ratios in S-type and felsic I-type magmas, which are more reduced and peraluminous than mafic I-type magmas. Strong REE (La to Eu) and Th enrichment in apatites from mafic I-type granites and marked Nd depletion in apatites from most S-type and felsic I-type granites are caused by the precipitation and fractionation of monazite in the parental magmas of the latter rocks. Substitution mechanisms are responsible for high Na in apatites from S-type and felsic I-type granites, and for high Si in apatites from mafic I-type granites, and may also have important effects on REE partitioning between apatite and melt. Thus, apatite chemistry can be used as an excellent indicator of granite petrogenesis. The results have important implications for identifying different types of granite and are potentially significant for determining the provenance of sedimentary rocks.

  8. 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.

  9. Chemical Emergencies

    MedlinePlus

    Chemical Emergencies Under certain conditions, chemicals which are normally safe can be poisonous or harmful to your health. A major chemical emergency is an accident that releases a hazardous amount ...

  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. Laser ignition

    DOEpatents

    Early, James W. (Los Alamos, NM); Lester, Charles S. (San Juan Pueblo, NM)

    2002-01-01

    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. The beam from the excitation light source is split with a portion of it going to the ignitor laser and a second portion of it being recombined with the first portion after a delay before injection into the ignitor laser. 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.

  12. The high-power iodine laser

    NASA Astrophysics Data System (ADS)

    Brederlow, G.; Fill, E.; Witte, K. J.

    The book provides a description of the present state of the art concerning the iodine laser, giving particular attention to the design and operation of pulsed high-power iodine lasers. The basic features of the laser are examined, taking into account aspects of spontaneous emission lifetime, hyperfine structure, line broadening and line shifts, stimulated emission cross sections, the influence of magnetic fields, sublevel relaxation, the photodissociation of alkyl iodides, flashlamp technology, excitation in a direct discharge, chemical excitation, and questions regarding the chemical kinetics of the photodissociation iodine laser. The principles of high-power operation are considered along with aspects of beam quality and losses, the design and layout of an iodine laser system, the scalability and prospects of the iodine laser, and the design of the single-beam Asterix III laser.

  13. Classification of Laser Vaccine Adjuvants

    PubMed Central

    Kashiwagi, Satoshi; Brauns, Timothy; Poznansky, Mark C

    2016-01-01

    An immunologic adjuvant, which enhances the magnitude and quality of immune responses to vaccine antigens, has become an essential part of modern vaccine practice. Chemicals and biologicals have been typically used for this purpose, but there are an increasing number of studies that are being conducted on the vaccine adjuvant effect of laser light on the skin. Currently, four different types or classes of laser devices have been shown to systemically enhance immune responses to intradermal vaccination: ultra-short pulsed lasers, non-pulsed lasers, non-ablative fractional lasers and ablative fractional lasers. Aside from involving the application of laser light to the skin in a manner that minimizes discomfort and damage, each type of laser vaccine adjuvant involves emission parameters, modes of action and immunologic adjuvant effects that are quite distinct from each other. This review provides a summary of the four major classes of “laser vaccine adjuvant” and clarifies and resolves their characteristics as immunologic adjuvants. These aspects of each adjuvant’s properties will ultimately help define which laser would be most efficacious in delivering a specific clinical benefit with a specific vaccine. PMID:27104047

  14. Laser propulsion option

    NASA Technical Reports Server (NTRS)

    Humes, Donald H.

    1989-01-01

    The use of laser thrusters with exhaust powers in the 25 MW to 250 MW range can reduce the fuel that would be needed to transport the lunar outpost equipment to low-lunar orbit with a chemical OTV by 57000 Kg to 105000 Kg with no significant penalty in trip time. This would save one or two launches of the heavy-load launch vehicle. Nuclear-electric OTVs would take 40 to 120 times as long to get to the moon and would spend 100 to 1700 times as long in the Van Allen radiation belts as OTVs that have laser thrusters.

  15. [Chemical peel treatments in dermatology].

    PubMed

    Wiest, L G; Habig, J

    2015-10-01

    Chemical peel treatments, which utilize a number of chemical peeling solutions subject to patient indication, are an easy to learn therapeutic technique suited for, in particular, various types of acne, acne scars, actinic keratosis and "sun-damaged skin". Especially the positive and long-lasting results of deep peels in the area of skin rejuvenation are deemed the gold standard against which other techniques, including lasers, must compare themselves. Other benefits of chemical peels include the flexibility to mix and match chemical solutions to custom design the treatment best suited for the desired degree of skin penetration, as well as the relatively low cost. PMID:26373295

  16. 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

  17. Laser therapy

    MedlinePlus

    ... be used for many medical purposes. Because the laser beam is so small and precise, it allows health care providers to safely treat tissue without injuring the surrounding area. Lasers are often used to: Treat varicose veins Improve ...

  18. 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.

  19. 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.

  20. Laser sampling

    NASA Astrophysics Data System (ADS)

    Gorbatenko, A. A.; Revina, E. I.

    2015-10-01

    The review is devoted to the major advances in laser sampling. The advantages and drawbacks of the technique are considered. Specific features of combinations of laser sampling with various instrumental analytical methods, primarily inductively coupled plasma mass spectrometry, are discussed. Examples of practical implementation of hybrid methods involving laser sampling as well as corresponding analytical characteristics are presented. The bibliography includes 78 references.