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 [Russian Federal Nuclear Center 'All-Russian Research Institute of Experimental Physics', Sarov, Nizhnii Novgorod region (Russian Federation)

    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. Research on advanced chemical and discharge oxygen-iodine lasers

    NASA Astrophysics Data System (ADS)

    Kodymová, Jarmila; Jirásek, Vít; Schmiedberger, Josef; Spalek, Otomar; Censký, Miroslav

    2009-02-01

    Generation of singlet oxygen and atomic iodine for operation of the chemical or discharge oxygen-iodine laser (COIL/DOIL) is described, employing novel methods and device configurations proposed in our laboratory. A centrifugal spray generator of singlet oxygen was developed, based on the conventional reaction between chlorine and basic hydrogen peroxide. Recent results of theoretical and experimental investigation of the generator parameters are presented. A new conception of the discharge generator of singlet oxygen was initiated, based on a combined DC arc jet and RF discharge techniques. Principle of the generator currently developed and constructed is described. A new device configuration was designed for the alternative method of atomic iodine generation using a radiofrequency discharge decomposition of iodine compounds like CH3I or CF3I. Some recent experimental results of this research are also presented.

  3. 20-Kw nitrogen diluent chemical oxygen-iodine laser

    NASA Astrophysics Data System (ADS)

    Yang, Tientsai T.; Bhowmik, Anup; Burde, David H.; Clark, Roy; Carroll, S.; Dickerson, Robert A.; Eblen, J.; Gylys, Vytas T.; Hsia, Y. C.; Humphreys, Richard H., Jr.; Moon, L. F.; Hurlock, Steve C.; Tomassian, A.

    2002-09-01

    A new Chemical Oxygen-Iodine Laser (COIL) has been developed and demonstrated at chlorine flow rates up to 1 gmol/s. The laser employs a cross flow jet oxygen generator operating with no diluent. The generator product flow enters the laser cavity at Mach 1 and is accelerated by mixing with 5 gmol/s, Mach 5 nitrogen diluent in an ejector nozzle array. The nitrogen also serves as the carrier for iodine. Vortex mixing is achieved through the use of mixing tabs at the nitrogen nozzle exit. Mixing approach design and analysis, including CFD analysis, led to the preferred nozzle configuration. The selected mixing enhancement design was tested in cold flow and the results are in good agreement with the CFD predictions. Good mixing was achieved within the desired cavity flow length of 20 cm and pressure recovery about 90 Torr was measured at the cavity exit. Finally, the design was incorporated into the laser and power extraction as high as 20 kw was measured at the best operating condition of 0.9 gmol/s. Stable resonator mode footprints showed desieable intensity profiles, which none of the sugar scoop profiles characteristic of the conventional COIL designs.

  4. 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.

  5. 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 [Institute of Physics, Czech Academy of Sciences, Prague (Czech Republic); Jakubec, I [Institute of Inorganic Chemistry, Czech Academy of Sciences, Rez (Czech Republic)

    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)

  6. Efficient operation of a chemically pumped oxygen iodine laser utilizing dilute hydrogen peroxide

    Microsoft Academic Search

    S. Yoshida; H. Fujii; T. Sawano; M. Endo; T. Fujioka

    1987-01-01

    A chemically pumped oxygen iodine laser system has been operated employing 35 wt pct H2O2 rather than commonly used 90 wt pct H2O2. Laser power as high as 40 W has been extracted. The maximum overall efficiency of 20.7 percent, which is almost 25 percent higher than the previously reported best data, has been achieved.

  7. Cutting performance of a chemical oxygen-iodine laser on aerospace and industrial materials

    Microsoft Academic Search

    William P. Latham; Kip R. Kendrick; James A. Rothenflue; Aravinda Kar; David L. Carroll

    2000-01-01

    A chemical oxygen-iodine laser (COIL) was used for cutting aluminum, titanium, inconel and copper plates. The laser was operated with a stable resonator having an intracavity aperture to produce a circular COIL beam with very few transverse modes. The multimode focal spot diameter was calculated to be 0.24 mm. The new aluminum cut was of particularly high kerf edge quality.

  8. Performance of a high-efficiency 5-cm gain length supersonic chemical oxygen-iodine laser

    Microsoft Academic Search

    Tilghman L. Rittenhouse; Stephen P. Phipps; Charles A. Helms

    1999-01-01

    The Air Force Phillips Laboratory has developed a small-scale supersonic chemical oxygen-iodine laser (COIL) test stand (VertiCOIL) to rapidly evaluate emerging potential technology improvements. VertiCOIL was designed to address issues relevant to military and commercial applications such as long run time, high-efficiency operation, and compact design. VertiCOIL demonstrated an overall chemical efficiency of nearly 27%, one of the highest chemical

  9. Experimental Analysis of the Materials Processing Performance of a Chemical Oxygen-Iodine Laser (COIL)

    Microsoft Academic Search

    D. L. Carroll; J. A. Rothenflue; W. P. Latham

    1996-01-01

    A chemical oxygen-iodine laser (COIL) was used for cutting aluminum and carbon steel, and for depositing a ceramic coating on a substrate. Cut depths of 20 mm were obtained in aluminum and 41 mm in carbon steel using an N2 gas assist and 5-6 kW of power on target. The same laser at the same power level produced a cut

  10. GENETIC ALGORITHMS AND OPTIMIZING CHEMICAL OXYGEN-IODINE LASERS

    Microsoft Academic Search

    David L. Carroll

    1996-01-01

    This paper presents results from the first known application of the genetic algorithm (GA) technique for optimizing the performance of a laser system (chemical, solid-state, or gaseous). The effects of elitism, single point and uniform crossover, creep mutation, different random number seeds, population size, niching and the number of children per pair of parents on the performance of the GA

  11. Spray generator of singlet oxygen for a chemical oxygen-iodine laser

    Microsoft Academic Search

    V. Jirásek; J. Hrubý; O. Špalek; M. ?enský; J. Kodymová

    2010-01-01

    A spray type of singlet oxygen generator for driving the Chemical Oxygen-Iodine Laser was developed. Singlet oxygen, O2(1?g), is generated by a fast reaction of chlorine with basic hydrogen peroxide solution in the form of a dense spray. A mathematical\\u000a model of this reaction system showed that O2(1?g) can be generated in this system with a high yield (0.70–0.80), high

  12. Mode locking of a CW supersonic chemical oxygen-iodine laser

    Microsoft Academic Search

    Stephen P. Phipps; Charles A. Helms; R. James Copland; Wolfgang Rudolph; Keith A. Truesdell; Gordon D. Hager

    1996-01-01

    This paper presents the results of the first mode-locking experiments on a supersonic chemical oxygen-iodine laser (COIL). Mode locking has been achieved using an acoustooptic modulator (AOM) and lasing demonstrated on the TEM00 modes with a small intracavity aperture. A dc magnetic field was used to increase the number of axial modes and a peak power of 2.5 kW has

  13. LASERS: Efficient chemical oxygeniodine laser with a high total pressure of the active medium

    NASA Astrophysics Data System (ADS)

    Zagidullin, M. V.; Nikolaev, V. D.; Svistun, M. I.; Khvatov, N. A.; Heiger, G. D.; Madden, T. J.

    2001-01-01

    A new concept of obtaining a high total pressure of the active medium of a chemical oxygeniodine laser (OIL) is proposed and verified. The nozzle unit of the laser consists of the alternating vertical arrays of cylindrical nozzles to produce high-pressure nitrogen jets, plane slotted nozzles for the flow of O2(1?) oxygen, and vertical arrays of cylindrical nozzles to inject the N2 — I2 mixture between the first two streams. For a molar chlorine flow rate of 39.2 mmol s-1, the output power was 700 W and the chemical efficiency was 19.7 %. The combined use of the ejector nozzle unit proposed to obtain the active medium and a super-sonic diffuser allows a significant simplification of the ejection system for the exhaust active medium of the OIL.

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

    PubMed

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

    2006-06-01

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

  15. Proceedings of the International Conference on Lasers `95, eds. V.J. Corcoran and T.A. Goldman, STS Press, McLean VA, 1996, pp. 225-231. OPTIMIZING HIGH PRESSURE CHEMICAL OXYGEN-IODINE LASERS

    E-print Network

    Carroll, David L.

    Press, McLean VA, 1996, pp. 225-231. OPTIMIZING HIGH PRESSURE CHEMICAL OXYGEN-IODINE LASERS David L laser model was baselined to existing oxygen-iodine research assessment and device improvement chemical* by N2. I. Introduction The typical chemical oxygen-iodine laser (COIL) utilizes an energy transfer from

  16. High-performance chemical oxygen-iodine laser using nitrogen diluent for commercial applications

    SciTech Connect

    Carroll, D.L.; King, D.M.; Fockler, L.; Stromberg, D.; Solomon, W.C.; Sentman, L.H.; Fisher, C.H.

    2000-01-01

    A chemical oxygen-iodine laser (COIL), the VertiCOIL device, was transferred from the Air Force Research Laboratory (AFRL) to the University of Illinois at Urbana-Champaign (UIUC) and made operational. The performance of the high-power VertiCOIL laser was measured with nitrogen diluent. New nozzle designs were investigated and implemented to optimize nitrogen performance. Nitrogen diluent chemical efficiencies of 23% were achieved; these are the highest reported chemical efficiencies with room-temperature nitrogen diluent. A long duration, high chemical efficiency test was demonstrated with nitrogen diluent; a chemical efficiency of 18.5% at 30 mmol/s of chlorine was maintained for 45 min. The highest performance was obtained with new iodine injector blocks and a larger throat height. The new iodine injector blocks moved the injectors closer to the throat by 0.7 cm and the throat height was increased from 0.897 to 1.151 cm (0.353 to 0.453 in). The performance enhancements were in qualitative agreement with the system design predictions of the Blaze II chemical laser model. Three-dimensional computational fluid dynamics calculations using the general aerodynamic simulation program code confirmed the principle design change of moving the iodine injectors closer to throat. Several researchers have suggested that COIL has a significant future as an industrial laser and have identified decommissioning and decontamination (D and D) of nuclear facilities as an important market for COIL.

  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(a1?) are significant dissociation intermediates.

  18. Parametric study of an efficient supersonic chemical oxygen-iodine laser\\/jet generator system operating without buffer gas

    Microsoft Academic Search

    D. Furman; B. D. Barmashenko; S. Rosenwaks

    1998-01-01

    A detailed experimental study of an efficient supersonic chemical oxygen-iodine laser is presented. The laser is energized by a jet-type singlet oxygen generator, operated without primary buffer gas and applies simple nozzle geometry and transonic mixing of iodine and oxygen. Output power of 190 W with chemical efficiency of 18% was obtained in a 5-cm gain length for Cl2 flow

  19. Experimental study of cutting thick aluminum and steel with a chemical oxygen-iodine laser using an N2 or O2 gas assist

    Microsoft Academic Search

    David L. Carroll; James A. Rothenflue

    1997-01-01

    A chemical oxygen-iodine laser (COIL) was used for cutting aluminum and carbon steel. Cut depths of 20 mm were obtained in aluminum and 41 mm in carbon steel using an N2 gas assist and 5 - 6 kW of power on target. The same laser at the same power level produced a cut depth of 65 mm in carbon steel

  20. CONTROL OF LASER RADIATION PARAMETERS: Enhancement of the efficiency and control of emission parameters of an unstable-resonator chemical oxygen—iodine laser

    NASA Astrophysics Data System (ADS)

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

    2007-07-01

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

  1. How many O2(1?) molecules are consumed per dissociated I2 in chemical oxygen-iodine lasers?

    NASA Astrophysics Data System (ADS)

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

    2006-07-01

    Direct measurements of the dissociation of I2 molecules at the optical axis of a supersonic chemical oxygen-iodine laser (COIL) as a function of I2 flow rate were carried out. This enabled us to determine the number of consumed O2(?1) molecules per dissociated I2 molecule. The number depends on the experimental conditions: it is 4.2±0.4 for typical conditions and I2 densities applied for the operation of the COIL, but increases at lower I2 densities. Possible dissociation mechanisms consistent with our results are discussed and the importance of dissociating I2 prior to its mixing with O2(?1) is stressed.

  2. Review of the simple model for metal cutting with the chemical oxygen-iodine laser

    Microsoft Academic Search

    William P. Latham; Aravinda Kar

    2000-01-01

    The COIL has drawn considerable attention owing to its short, fiber-deliverable wavelength, scalability to very high powers, and nearly diffraction-limited optical quality. These unique abilities make it an ideal candidate for rapid cutting of thick metals and other laser materials processing applications. Cutting experiments have been conducted at the Air Force Research Laboratory Chemical Laser Facility for a number of

  3. Experimental study of cutting thick aluminum and steel with a chemical oxygen-iodine laser using an N2 or O2 gas assist

    Microsoft Academic Search

    David L. Carroll; James A. Rothenflue

    1997-01-01

    A chemical oxygen-iodine laser (COIL) was used for cutting aluminum and carbon steel. Cut depths of 20 mm were obtained in aluminum and 41 mm in carbon steel using an N2 gas assist and 5-6 kW of power on target. The same laser at the same power level produced a cut depth of 65 mm in carbon steel with an

  4. Role of N2 molecules in pulse discharge production of I atoms for a pulsed chemical oxygen-iodine laser

    NASA Astrophysics Data System (ADS)

    Kochetov, I. V.; Napartovich, A. P.; Vagin, N. P.; Yuryshev, N. N.

    2011-09-01

    A pulsed electric discharge is the most effective means to turn chemical oxygen-iodine laser (COIL) operation into the pulse mode by fast production of iodine atoms. Experimental studies and numerical simulations are performed on a pulsed COIL initiated by an electric discharge in a mixture CF3I : N2 : O2(3X) : O2(a 1?g) flowing out of a chemical singlet oxygen generator. A transverse pulsed discharge is realized at various iodide pressures. The model comprises a system of kinetic equations for neutral and charged species, the electric circuit equation, the gas thermal balance equation and the photon balance equation. Reaction rate coefficients for processes involving electrons are repeatedly re-calculated by the electron Boltzmann equation solver when the plasma parameters are changed. The processes accounted for in the Boltzmann equation include direct and stepwise excitation and ionization of atoms and molecules, dissociation of molecules, electron attachment processes, electron-ion recombination, electron-electron collisions and second-kind collisions. The last processes are particularly important because of a high singlet oxygen concentration in gas flow from the singlet oxygen chemical generator. A conclusion is drawn about satisfactory agreement between the theory and the experiment.

  5. 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(a?g1) 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'?2u3), I2(A?1u3), and O2(a?g1,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(X?g +1,v).

  6. 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' 3? 2u), I II(A 3? 1u) and O II(a1? 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(X1? + 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(1?). The loss of O II(1?) 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.

  7. 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.

  8. Mechanism of pulse discharge production of iodine atoms from CF3I molecules for a chemical oxygen-iodine laser

    NASA Astrophysics Data System (ADS)

    Kochetov, I. V.; Napartovich, A. P.; Vagin, N. P.; Yuryshev, N. N.

    2009-03-01

    The pulsed chemical oxygen-iodine laser (COIL) development is aimed at many new applications. Pulsed electric discharge is most effective in turning COIL operation into the pulse mode by instant production of iodine atoms. A numerical model is developed for simulations of the pulsed COIL initiated by an electric discharge. The model comprises a system of kinetic equations for neutral and charged species, electric circuit equation, gas thermal balance equation and the photon balance equation. Reaction rate coefficients for processes involving electrons are found by solving the electron Boltzmann equation, which is re-calculated in a course of computations when plasma parameters changed. The processes accounted for in the Boltzmann equation include excitation and ionization of atoms and molecules, dissociation of molecules, electron attachment processes, electron-ion recombination, electron-electron collisions, second-kind collisions and stepwise excitation of molecules. The last processes are particularly important because of a high singlet oxygen concentration in gas flow from the singlet oxygen chemical generator. Results of numerical simulations are compared with experimental laser pulse waveforms. It is concluded that there is satisfactory agreement between theory and the experiment. The prevailing mechanism of iodine atom formation from the CF3I donor in a very complex kinetic system of the COIL medium under pulse discharge conditions, based on their detailed numerical modelling and by comparing these results both with experimental results of other authors and their own experiments, is established. The dominant iodine atom production mechanism for conditions under study is the electron-impact dissociation of CF3I molecules. It was proved that in the conditions of the experiment the secondary chemical reactions with O atoms play an insignificant role.

  9. 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 ?s, 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.

  10. Proceedings of the International Conference on Lasers '98, ed. V.J. Corcoran, STS Press, McLean VA, 1999, in press. PERFORMANCE OF A HIGH POWER CHEMICAL OXYGEN-IODINE LASER

    E-print Network

    Carroll, David L.

    . If successful, this will be the first major advance in high power laser cutting technology since and deactivate the large numbers of nuclear reactor power stations now in place world-wide. Figure 1 shows, 1999, in press. PERFORMANCE OF A HIGH POWER CHEMICAL OXYGEN-IODINE LASER USING NITROGEN DILUENT D

  11. g... production in flowing ArO2 surface-wave microwave discharges: Possible use for oxygen-iodine laser excitation

    E-print Network

    Guerra, Vasco

    O2,,a 1 g... production in flowing Ar­O2 surface-wave microwave discharges: Possible use for oxygen-iodine be effectively used for the oxygen-iodine laser excitation. It is demonstrated that at pressures higher than 10 chemical oxygen-iodine laser operates on the electronic transition of the iodine atom at 1315 nm, where

  12. Gain recovery in an electric oxygen-iodine laser J. W. Zimmerman,1,a

    E-print Network

    Carroll, David L.

    Gain recovery in an electric oxygen-iodine laser J. W. Zimmerman,1,a G. F. Benavides,2 A. D. Palla online 14 January 2009 Recent investigations of an electric oxygen-iodine laser system have shown American Institute of Physics. DOI: 10.1063/1.3064163 The electrically driven oxygen-iodine laser Electri

  13. Development of the electric discharge oxygen-iodine laser

    NASA Astrophysics Data System (ADS)

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

    2007-05-01

    In the hybrid electric discharge Oxygen-Iodine laser (ElectricOIL), the desired O II(a1?) is produced using a low-to-medium pressure electric discharge. The discharge production of atomic oxygen, ozone, and other excited species adds higher levels of complexity to the post-discharge kinetics which are not encountered in a classic purely chemical O II(a1?) generation system. Experimental studies over the past six years using electric discharges have demonstrated O II(a) yields greater than 20%, gain, and cw laser power. Several modeling studies have also been performed for ElectricOIL and similar systems. As the development of this type of iodine laser continues, the roles of oxygen atoms and NO/NO II are found to be very significant in both the discharge region and downstream of the discharge region. A series of O II(1?) emission, I* emission, O-atom titrations, gain, and O II(1?) yield, NO II* emission, and laser power measurements have been taken to explore the complex phenomena that are being observed. As the overall system is better understood improvements are being made in laser power and efficiency.

  14. 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 [School of Physics and Optoelectronic Technology, Dalian University of Technology, Dalian 116024 (China); Duo Liping; Li Guofu [Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116024 (China)

    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.

  15. Numerical study of He/CF3I pulsed discharge used to produce iodine atom in chemical oxygen-iodine laser

    NASA Astrophysics Data System (ADS)

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

    2013-04-01

    The pulsed discharge for producing iodine atoms from the alkyl and perfluoroalky iodides (CH3I, CF3I, 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 CF3I-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 CF3I 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 CF3I is needed to obtain the maximum iodine atom concentration.

  16. 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.

  17. Cutting Performance of a Chemical Oxygen-Iodine Laser William P. Latham, James A. Rothenflue, and Charles A. Helms

    E-print Network

    Carroll, David L.

    that the cutting capability of a 1 kW COIL is equivalent to a 1 kW Nd:YAG laser and about 2.5 times better than a 1, copper, nickel, and titanium. The experimental data are also compared with a simple scaling law

  18. Discharge-driven electric oxygen-iodine laser superlinear enhancement via increasing g0L

    E-print Network

    Carroll, David L.

    Discharge-driven electric oxygen-iodine laser superlinear enhancement via increasing g0L G. F the development of an electric oxygen-iodine laser with higher output using a larger product of gain and gain length, g0L. A factor of 4.4 increase in laser power output on the 1315 nm atomic iodine transition

  19. Evolution of the electric discharge oxygen-iodine laser David L. Carrolla

    E-print Network

    Carroll, David L.

    Evolution of the electric discharge oxygen-iodine laser David L. Carrolla , Gabriel F. Benavidesa and modeling have led to a continuing evolution of the Electric Oxygen-Iodine Laser (ElectricOIL) system. This continuous wave (cw) laser operating on the 1315 nm transition of atomic iodine is pumped by the production

  20. Mixing effects in postdischarge modeling of electric discharge oxygen-iodine laser experiments

    E-print Network

    Carroll, David L.

    Mixing effects in postdischarge modeling of electric discharge oxygen-iodine laser experiments; accepted 16 May 2006; published online 26 July 2006 In an electric discharge oxygen-iodine laser, laser action at 1315 nm on the I 2 P1/2 I 2 P3/2 transition of atomic iodine is obtained by a near resonant

  1. Development of the electric discharge oxygen-iodine laser David L. Carrolla

    E-print Network

    Carroll, David L.

    Development of the electric discharge oxygen-iodine laser David L. Carrolla , Joseph T. Verdeyena ABSTRACT In the hybrid electric discharge Oxygen-Iodine laser (ElectricOIL), the desired O2(a1. As the development of this type of iodine laser continues, the roles of oxygen atoms and NO/NO2 are found to be very

  2. Recent Electric Oxygen-Iodine Laser Experiments and Modeling David L. Carrolla

    E-print Network

    Carroll, David L.

    Recent Electric Oxygen-Iodine Laser Experiments and Modeling David L. Carrolla , Gabriel F and modeling have led to a continuing evolution of the Electric Oxygen-Iodine Laser (ElectricOIL) system. A new with BLAZE-V shows that an iodine pre-dissociator can have a dramatic impact upon gain and laser performance

  3. 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 [Samara Branch of the P.N. Lebedev Physics Institute, Russian Academy of Sciences, Samara (Russian Federation)

    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)

  4. Enhancement of electric oxygen-iodine laser performance using a rectangular discharge and longer gain length

    E-print Network

    Carroll, David L.

    Enhancement of electric oxygen-iodine laser performance using a rectangular discharge and longer transition of atomic iodine via a 50% increase in gain length, flow rates, and discharge power. O2 a 1 of Physics. doi:10.1063/1.3269811 The electrically driven oxygen-iodine laser Electri- cOIL that was first

  5. Systematic development of the electric discharge oxygen-iodine laser David L. Carrolla

    E-print Network

    Carroll, David L.

    1 Systematic development of the electric discharge oxygen-iodine laser David L. Carrolla , Gabriel have led to continued improvements in the hybrid Electric Oxygen-Iodine Laser (ElectricOIL) system molecular iodine injection and partially pre-dissociated iodine are presented. A gain of 0.17% cm-1

  6. Enhancement of electric oxygen-iodine laser performance using larger mode volume resonators

    E-print Network

    Carroll, David L.

    Enhancement of electric oxygen-iodine laser performance using larger mode volume resonators Brian S iodine via a 100% increase in the resonator mode volume. O2 a1 is produced by a single rf.4130, 140.4780, 230.5750. The electrically driven oxygen-iodine laser (Electric- OIL) that was first

  7. Super-linear Enhancement of the Electric Oxygen-Iodine Laser David L. Carrolla

    E-print Network

    Carroll, David L.

    Super-linear Enhancement of the Electric Oxygen-Iodine Laser David L. Carrolla , Brian S. Woodardb., Urbana, Illinois, 61801, United States ABSTRACT Continuing experiments with Electric Oxygen-Iodine Laser output on the 1315-nm transition of atomic iodine. The peak output power observed was 538 W. Keywords

  8. Electric Oxygen-Iodine Laser Performance Enhancement using Larger Discharge and Resonator Mode Volumes

    E-print Network

    Carroll, David L.

    Electric Oxygen-Iodine Laser Performance Enhancement using Larger Discharge and Resonator Mode transition of atomic iodine for only a 50% increase in gain length (5.1 cm to 7.6 cm), flow rates that significantly higher power was available in the electric oxygen-iodine laser gas flow which could be extracted

  9. Gain and continuous-wave laser power enhancement with a multiple discharge electric oxygen-iodine laser

    E-print Network

    Carroll, David L.

    Gain and continuous-wave laser power enhancement with a multiple discharge electric oxygen-iodine transition of atomic iodine via an increase in flow rates and pressure using multiple discharges in an electric oxygen-iodine laser. O2 a 1 is produced by two parallel radio-frequency-excited electric

  10. Experimental Effects of Atomic Oxygen on the Development of an Electric Discharge Oxygen Iodine Laser

    E-print Network

    Carroll, David L.

    Experimental Effects of Atomic Oxygen on the Development of an Electric Discharge Oxygen Iodine of the electric discharge iodine laser continues, the role of oxygen atoms downstream of the discharge region of atomic iodine where the O2(a1 ) was produced in a flowing electric discharge. Excess atomic oxygen

  11. Oxygen Discharge and Post-Discharge Kinetics Experiments and Modeling for the Electric Oxygen-Iodine Laser System

    E-print Network

    Carroll, David L.

    Oxygen Discharge and Post-Discharge Kinetics Experiments and Modeling for the Electric Oxygen-Iodine/2) transition of atomic iodine has been obtained by a near resonant energy transfer from O2(a1 ) produced using a low-pressure oxygen/helium/nitric oxide discharge. In the electric discharge oxygen-iodine laser

  12. Mixing effects in postdischarge modeling of electric discharge oxygen-iodine laser experiments

    NASA Astrophysics Data System (ADS)

    Palla, Andrew D.; Carroll, David L.; Verdeyen, Joseph T.; Solomon, Wayne C.

    2006-07-01

    In an electric discharge oxygen-iodine laser, laser action at 1315nm on the I(P1/22)?I(P3/22) transition of atomic iodine is obtained by a near resonant energy transfer from O2(a?1) which is produced using a low-pressure electric discharge. The discharge production of atomic oxygen, ozone, and other excited species adds higher levels of complexity to the postdischarge kinetics which are not encountered in a classic purely chemical O2(a?1) generation system. Mixing effects are also present. In this paper we present postdischarge modeling results obtained using a modified version of the BLAZE-II gas laser code. A 28 species, 105 reaction chemical kinetic reaction set for the postdischarge kinetics is presented. Calculations were performed to ascertain the impact of a two stream mixing mechanism on the numerical model and to study gain as a function of reactant mass flow rates. The calculations were compared with experimental data. Agreement with experimental data was improved with the addition of new kinetics and the mixing mechanism.

  13. REVIEW: Excited states in the active media of oxygeniodine lasers

    NASA Astrophysics Data System (ADS)

    Azyazov, V. N.

    2009-11-01

    A review of investigations of kinetic processes in active media oxygeniodine lasers (OILs) performed in the last decade is presented. The mechanisms of pumping and quenching of electronically and vibrationally excited O2 and I2 molecules are considered, and dissociation mechanisms of I2 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.

  14. Comparing the efficiency of supersonic oxygen-iodine laser with different mixing designs

    NASA Astrophysics Data System (ADS)

    Vyskubenko, Boris A.; Adamenkov, A. A.; Bakshin, V. V.; Efremov, V. I.; Ilyin, S. P.; Kolobyanin, Yu. V.; Krukovsky, I. M.; Kudryashov, E. A.; Moiseyev, V. B.

    2003-11-01

    The paper presents experimental studies of supersonic oxygen-iodine laser (OIL) using twisted-flow singlet oxygen generator (SOG) over a wide range of the singlet oxygen pressures and the buffer gas flow rates. The experiments used different designs of the nozzle unit and mixing system for singlet oxygen and iodine gas with the carrier gas (such as nitrogen or helium). For a wide range of the key parameters, the study looked at the efficiency of supersonic OIL with variation of the singlet oxygen pressure. The measurements were made for different positions of the iodine injection plane with respect to the critical cross-section (both in the subsonic part of the nozzle and in the supersonic flow). The gas pressure at the nozzle unit entry was varied from 50 to 250 Torr. The total pressure loss have been found for different mixing designs. Experimental curves are given for energy performance and chemical efficiency of the supersonic OIL as a function of the key parameters. Comparison is made between the calculated and experimental data. For the optimum conditions of OIL operation, chemical efficiency of 25-30% has been achieved.

  15. Cutting performance of a chemical oxygen-iodine laser on aerospace and industrial materials William P. Latham, Kip R. Kendrick, James A. Rothenflue

    E-print Network

    Carroll, David L.

    for cutting aluminum, titanium,inconel and copper plates. The laser was operated with a stable resonator model. Using thermophysical data for aluminum, titanium, inconel and copper, this theory agrees very in industry for commercial cutting, welding and ablation applications [1]. Traditionally, CO2 and Nd

  16. 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)

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

    NASA Astrophysics Data System (ADS)

    Mezhenin, A. V.; Azyazov, V. N.

    2012-12-01

    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 ?. It is shown that the simplified two-level laser model satisfactorily predicts the output characteristics of OILs with a stable resonator at ?d <= 7. Efficient energy extraction from the OIL active medium is achieved in the case of ?d = 5 - 7, ? = 4 - 8.

  18. Discharge formation systems for generating atomic iodine in a pulse-periodic oxygen-iodine laser

    NASA Astrophysics Data System (ADS)

    Aksinin, V. I.; Antsiferov, S. A.; Velikanov, S. D.; Gerasimov, A. Yu; Gostev, I. V.; Kazantsev, S. Yu; Kalinovskii, V. V.; Konovalov, V. V.; Kononov, I. G.; Mikhalkin, V. N.; Podlesnykh, S. V.; Sevryugin, I. V.; Firsov, K. N.

    2014-01-01

    Generation characteristics of a pulse-periodic oxygen-iodine laser with the electro-discharge production of atomic iodine were compared with inductively stabilised edged or anisotropic- resistive cathodes used for ignition of the volume discharge. The discharge was initiated by the radiation of a barrier discharge from the side of a grid anode. It was found that at equal specific electrical energy depositions to the gas-discharge plasma, the system with the anisotropic-resistive cathode provides a more stable and uniform volume discharge with the possibility of varying the composition and pressure of working mixtures over a wide range and a greater specific extraction of laser energy is observed (up to 2.4 J L-1). At a high pulse repetition rate of laser pulses (50 - 100 Hz) and long duration of the pulse trains (longer than a minute) the surface of anisotropic-resistive cathode became eroded.

  19. Application of vortex-flow dc glow discharge for atomic iodine production for oxygen-iodine laser

    Microsoft Academic Search

    Pavel A. Mikheyev; Alexander A. Shepelenko

    2004-01-01

    The possibility to produce atomic iodine decomposing methyl iodide with the help of the vortex-flow DC glow discharge for use in oxygen-iodine laser has been investigated experimentally. Number density of iodine atoms had been measured via absorption of single frequency tunable semiconductor laser radiation at 1.315 mum. Two cases were studied: (1) the products of discharge in oxygen decomposed methyl

  20. Advances in the RF atomic iodine generator for oxygen-iodine laser

    NASA Astrophysics Data System (ADS)

    Jirásek, Vít; Schmiedberger, Josef; ?enský, Miroslav; Kodymová, Jarmila

    2010-09-01

    Recent advances in the RF atomic iodine generator for oxygen-iodine lasers are presented. The generator is based on the RF discharge dissociation of a suitable iodine donor immediately before its injection to the flow of singlet oxygen. The discharge is ignited directly in the iodine injector, and the configuration is ready for the laser operation. The dissociation fraction was derived from the atomic iodine number density measured at a presupposed position of laser resonator. The dissociation fraction and the fraction of RF power spent on the dissociation (discharge dissociation efficiency) were measured for the following donors: CH3I, CF3I and HI. A significant improvement of the discharge stability was achieved by increasing the cross-sectional area of the exit injection holes and employing a tangential inlet of working gas into the discharge chamber. The flow rates 0.15 mmol/s and 0.19 mmol/s of produced atomic iodine were achieved using the HI and CF3I, respectively. The atomic iodine number density in the supersonic flow attained 4.22 × 1014 cm-3. The dissociation efficiency was substantially better for HI than for studied organic iodides.

  1. Singlet oxygen generation in gas discharge for oxygen-iodine laser pumping

    NASA Astrophysics Data System (ADS)

    Lopaev, D. V.; Braginsky, O. V.; Klopovsky, K. S.; Kovalev, A. S.; Mankelevich, Yu. A.; Popov, N. A.; Rakhimov, A. T.; Rakhimova, T. V.; Vasilieva, A. N.

    2004-09-01

    The possibility of development of effective discharged singlet oxygen (SO) generator (DSOG) for oxygen-iodine laser (OIL) is studied in detail. Researches of kinetics of oxygen atoms and oxygen molecules in the lowest metastable singlet states have been carried out in the different discharges and its afterglow (DC discharges, E-beam controlled discharge and RF discharges) in both CW and pulsed mode in a wide range of conditions (pressures, gas mixtures, energy deposits etc.). The models developed for all the discharges have allowed us to analyze SO generation and loss mechanisms and to find out the key-parameters controlling the highest SO yield. It is shown that in addition to spatial plasma uniformity at low E/N and high specific energy deposit per oxygen molecule, DSOG must be oxygen atom free to avoid fast three-body quenching of SO by atomic oxygen with increasing pressure and thereby to provide pressure scaling (in tens Torrs) for applying to real OIL systems.

  2. Active medium gain study of electric-discharge oxygen-iodine laser

    NASA Astrophysics Data System (ADS)

    Kolobyanin, Yuriy; Adamenkov, Yuriy; Vyskubenko, Boris; Goryachev, Leonid; Ilyin, Sergey; Kalashnik, Anatoliy; Rakhimova, Tatiana; Rogozhnikov, Georgiy

    2007-05-01

    The paper reports on experimental studies of the active medium gain in supersonic electric-discharge oxygen-iodine laser (DOIL) based on traveling mw discharge. The measurements have included: absolute concentration, yield, and energy efficiency of production of SO in pure oxygen and oxygen-helium mixes at an oxygen partial pressure 3 to 15 Torr. For the gas flow to get rid of atomic oxygen, both heterogeneous mercury oxide coatings of the tube walls and homogeneous additives to the work mix, such as nitrogen oxide, have been used. The active medium of DOIL was formed using a nozzle array of the type of ejector sized as 10*50 mm2. The singlet oxygen-helium mix was supplied through three rows of sonic cylindrical nozzles, while the iodine-carrier gas mix - through two rows of supersonic conical nozzles with a half-opening angle of 10°(arc). The gas-phase iodine was produced in a quartz cell filled with iodine crystals. Room-temperature iodine vapors were picked up with a carrier gas (nitrogen or helium) and thus delivered into the nozzle array. The active medium was investigated by the high-resolution laser diode spectroscopy approach that used the laser type Vortex 6025 purchased from New Focus, Inc. The laser medium gain factor was determined by the intra-cavity approach having a sensitivity about 1*10 -6 cm -1. The static temperature of the medium was determined from the measurements of gain half-width. The gain of the active medium of electric-discharge OIL has been investigated. The DOIL in use was operating on a mix composed as O II:He=1:1 at a total pressure of 6 Torr and flowrate - about 1 mmol/s. With helium as an iodine carrier gas at a flowrate ~3 mmol/s, we have recorded a positive gain in the DOIL medium.

  3. 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

  4. 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 [Samara Branch of the P.N. Lebedev Physical Institute, Russian Academy of Sciences, Samara (Russian Federation)

    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)

  5. 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.

  6. 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 [A M Prokhorov General Physics Institute, Russian Academy of Sciences, Moscow (Russian Federation)

    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)

  7. 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. [Moscow State University, Skobeltsyn Institute of Nuclear Physics (Russian Federation)

    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.

  8. Enhanced performance of an electric oxygen-iodine laser D. L. Carrolla

    E-print Network

    Carroll, David L.

    . This continuous wave (cw) laser operating on the 1315 nm transition of atomic iodine is pumped by the production led to improvements in O2(a) production and efficiency. A 95% enhancement in cw laser power demonstration of gain and lasing from an air- helium discharge [Woodard, 2008a]. Computational modeling

  9. Design and operation of a supersonic flow cavity for a non-self-sustained electric discharge pumped oxygen iodine laser

    Microsoft Academic Search

    A. Hicks; S. Tirupathi; N. Jiang; Yu Utkin; W. R. Lempert; J. W. Rich; I. V. Adamovich

    2007-01-01

    The paper presents results of a high-pressure, non-self-sustained crossed discharge-M = 3 supersonic laser cavity operation. A stable and diffuse pulser-sustainer discharge in O2-He flows is generated at pressures of up to P0 = 120 Torr and discharge powers of up to 2.1 kW. The reduced electric field in the dc sustainer discharge ranges from 0.6 × 10-16 to 1.2

  10. Performance of a Multistream Injection Chemical OxygenIodine Laser with Starlet Ejectors

    E-print Network

    Carroll, David L.

    recovery performance. The ejector- mixing nozzle concept put forward by the Russian Lebedev Physical of experiments concerning sonic flow from tubes with V-shaped slots cut into the ends. Our interest

  11. 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%.

  12. 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(1?)/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(B3?0) 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.

  13. 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.

  14. 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.

  15. Gain and continuous-wave laser power enhancement with a secondary discharge to predissociate molecular iodine

    E-print Network

    Carroll, David L.

    molecular iodine in an electric oxygen-iodine laser G. F. Benavides,1 J. W. Zimmerman,2 B. S. Woodard,2 D. L and 38% enhancement in continuous-wave laser power on the 1315 nm transition of atomic iodine through the addition of a secondary discharge to predissociate the molecular iodine in an electric oxygen-iodine laser

  16. Ultrafast Laser Spectroscopyof Chemical Reactions

    E-print Network

    Zewail, Ahmed

    Ultrafast Laser Spectroscopyof Chemical Reactions - Joseph L. Kneeand AhmedH. Zewail California of chemical physics is to understand how chemi- cal reactions complete their journey from reactants to prod at the molecular level. The making of new bonds (and the breaking of old ones) in elementary chemical reactions

  17. Chemical Sensing With Laser Spectroscopy

    Microsoft Academic Search

    Sune Svanberg

    1995-01-01

    SUMMARY Laser spectroscopic techniques constitute powerful tools for chemical sensing. Atoms and molecules can be identified and quantified by their specific spectral signatures and the strength of the signals. A wide variety of methods for establishing spectroscopic contact with the species exist: absorption, emission, fluorescence, Raman scattering, acousto-optic, and opto-galvanic phenomena can be employed. Extreme sensitivity and specificity characterise the

  18. Gain measurements in a non-self-sustained electric discharge pumped oxygen-iodine laser cavity

    Microsoft Academic Search

    A. Hicks; K. Fredrickson; S. Tirupathi; Y. G. Utkin; W. R. Lempert; J. W. Rich; I. V. Adamovich; K. L. Galbally-Kinney; W. J. Kessler; W. T. Rawlins; P. A. Mulhall; S. J. Davis

    2007-01-01

    The paper presents results of singlet delta oxygen yield (SDO) measurements in a high-pressure, non-self-sustained discharge and small signal gain measurements on the 1315 nm iodine atom transition in the M=3 supersonic cavity downstream of the discharge. The results demonstrate operation of a stable pulser-sustainer discharge in O2-He flows at pressures of up to 120 torr and discharge powers of

  19. Spatial and recovery measurements of gain in an electric oxygen-iodine laser

    E-print Network

    Carroll, David L.

    an air-helium discharge [Woodard, 2008a]. Computational modeling of the discharge and post, allowing analysis of the production of various discharge species [O2(a1 ), O2(b1 ), O atoms, and O3 a comprehensive topical review of discharge production of O2(a) and various ElectricOIL studies. The highest gain

  20. Laser Induced Chemical Liquid Phase Deposition (LCLD)

    SciTech Connect

    Nanai, Laszlo; Balint, Agneta M. [University of Szeged, JGYPK, Department of General and Environmental Physics H-6725 Szeged, Boldogasszony sgt. 6 (Hungary); West University of Timisoara, Faculty of Physics, Department of Physics, Bulv. V. Parvan 4, Timisoara 300223 (Romania)

    2012-08-17

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

  1. Alpha high-power chemical laser program

    Microsoft Academic Search

    Anthony J. Cordi; Henry Lurie; David W. Callahan; Matthew Thomson

    1993-01-01

    Alpha is a megawatt-class ground demonstration of a hydrogen fluoride, continuous wave, space-based chemical laser. The laser operates in the infrared at 2.8 microns. The basic device consists of a cylindrical combustion chamber that exhausts radially outward through circumferential nozzles into an annular lasing area. An annular ring resonator is used to extract the laser energy from this area. Technical

  2. Alpha high-power chemical laser program

    Microsoft Academic Search

    Richard Ackerman; David Callahan; Anthony J. Cordi; Henry Lurie; Matthew Thomson

    1995-01-01

    Alpha is a megawatt-class hydrogen fluoride, continuous wave, space based chemical laser brassboard which demonstrates and validates technology for space-based applications. It consists of a cylindrical gain generator that exhausts radially outward through circumferential nozzles forming an annular lasing media and an annular ring resonator, which extracts the laser energy. Technical innovations first demonstrated on Alpha include: (1) use of

  3. 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.

  4. Chemical analysis for excimer laser systems

    Microsoft Academic Search

    R. C. Heaton; P. H. Hemberger; W. F. Sandoval

    1987-01-01

    Analytical methods and procedures used to determine fluorine, krypton, xenon, and argon in fill gases for excimer lasers are described. Fluorine was determined by gas chromatography, mass spectrometry, and wet chemical (iodine liberation) methods. The noble gases were determined by gas chromatography and mass spectrometry, and attempts to identify impurities were made using mass spectrometry. Analytical results for 26 gas

  5. HCL or DCL chemical laser using laser induced chemistry

    SciTech Connect

    Merritt, J.A.

    1980-05-13

    A chemical HCL or DCL laser is obtained by irradiating CoCl2+H2/D2 in admixture with the P54 line of a CO2 laser. The irradiation is accomplished in a laser cavity provided with appropriate brewster windows, mirrors, and coupling means. The CoCl2 is mixed with H2 or D2 in a properly conditioned system without reacting. The irradiating by the P54 line of a CO2 laser dissociates the CoCl2 to form CO+2Cl* (Cl*-atom in an excited state). The Cl* atom then reacts with H2/D2 present to produce HCL or DCL in an excited vibrational state. The halogen containing molecule then lases.

  6. Alpha high-power chemical laser program

    NASA Astrophysics Data System (ADS)

    Cordi, Anthony J.; Lurie, Henry; Callahan, David W.; Thomson, Matthew

    1993-06-01

    Alpha is a megawatt-class ground demonstration of a hydrogen fluoride, continuous wave, space-based chemical laser. The laser operates in the infrared at 2.8 microns. The basic device consists of a cylindrical combustion chamber that exhausts radially outward through circumferential nozzles into an annular lasing area. An annular ring resonator is used to extract the laser energy from this area. Technical firsts include: (1) use of aluminum combustion chamber/nozzle ring modules, (2) diamond turned, water-cooled optics made of molybdenum for low thermal distortion with good heat transfer, (3) use of uncooled silicon mirrors in a megawatt-class laser system, (4) an optical bench made of aluminum honeycomb, and (5) active controls to adjust alignment of selected mirrors and the optical bench.

  7. Alpha high-power chemical laser program

    NASA Astrophysics Data System (ADS)

    Ackerman, Richard A.; Callahan, David; Cordi, Anthony J.; Lurie, Henry; Thomson, Matthew

    1995-03-01

    Alpha is a megawatt-class hydrogen fluoride, continuous wave, space based chemical laser brassboard which demonstrates and validates technology for space-based applications. It consists of a cylindrical gain generator that exhausts radially outward through circumferential nozzles forming an annular lasing media and an annular ring resonator, which extracts the laser energy. Technical innovations first demonstrated on Alpha include: (1) use of extruded aluminum components, (2) diamond turned, annular optics made of molybdenum, (3) uncooled silicon mirrors, (4) light weight optical benches, and (5) active alignment. Alpha first lased in 1989, and has repeatably demonstrated megawatt-class power and excellent beam quality. Using Alpha, TRW has demonstrated the use of low weight uncooled mirrors in very high power lasers to reduce system jitter. They have performed flawlessly and beam jitter levels were significantly reduced.

  8. 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

  9. Chemical analysis for excimer laser systems

    SciTech Connect

    Heaton, R.C.; Hemberger, P.H.; Sandoval, W.F.

    1987-09-01

    Analytical methods and procedures used to determine fluorine, krypton, xenon, and argon in fill gases for excimer lasers are described. Fluorine was determined by gas chromatography, mass spectrometry, and wet chemical (iodine liberation) methods. The noble gases were determined by gas chromatography and mass spectrometry, and attempts to identify impurities were made using mass spectrometry. Analytical results for 26 gas cylinders are reported. Limitations of the methods are discussed and recommendations for future efforts are presented.

  10. Long pulse chemical laser. Final technical report

    SciTech Connect

    Bardon, R.L.; Breidenthal, R.E.; Buonadonna, V.R. [and others] [Boeing Aerospace Co., Seattle, WA (United States)

    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.

  11. 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.

  12. 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.

  13. Remote Chemical Sensing Using Quantum Cascade Lasers

    SciTech Connect

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

    2004-01-20

    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.

  14. Remote chemical sensing by laser optical pumping

    SciTech Connect

    Stevens, C.G.; Magnotta, F.

    1996-08-01

    We are exploring a new approach to remote chemical identification that promises higher precision than can be achieved by conventional DIAL approaches. This technique also addresses and potentially solves the problem of detecting a target gas in the presence of an interfering gas or gases. This new approach utilizes an eye-safe infrared optical pumping pulse to deplete the population of a specific rotational level(s) and then sends probe pulses at the same or different wavelengths to interrogate the bleaching of the absorption. We have experimentally measured optical saturation fluence level at atmospheric pressure for HCl, and find this level to be {approximately}1 mJ/cm{sup 2}, significantly below eye-safe limits in agreement with calculations. Calculations have been performed on other molecules of interest with similar results. In the laboratory, using time-delay-replicated pulses at a single frequency we have made absorption measurements with precision levels routinely approaching 0.1% after averaging 200 laser pulses. These results as well as those of two other pulse experiments will be presented. 5 refs., 9 figs., 1 tab.

  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. Synchronization: from pendulum clocks to chaotic lasers and chemical oscillators

    E-print Network

    Potsdam, Universität

    Synchronization: from pendulum clocks to chaotic lasers and chemical oscillators MICHAEL ROSENBLUM Christiaan Huygens reported on his observation of synchronization of two pendulum clocks which he had briefly described in his memoirs Horologium Oscillatorium (The Pendulum Clock, or Geome- trical

  17. Chemical and Laser Sciences Division annual report 1989

    SciTech Connect

    Haines, N. (ed.)

    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.

  18. Laser cutting with chemical reaction assist

    DOEpatents

    Gettemy, Donald J. (Los Alamos, NM)

    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.

  19. 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.

  20. Chemical HF laser initiated by an excimer XeCl laser

    SciTech Connect

    Borisov, V.; Gordon, E.; Matyushenko, V.; Sizov, V.; Khristoforov, O.

    1982-02-01

    Measurements were made of the energy and time characteristics of a chemical HF laser initiated by radiation from an excimer XeCl laser (lambda = 308 nm). Various compositions of the mixture in the chemical laser were employed. When the mixture composition was F/sub 2/:H/sub 2/:O/sub 2/:He = 10:3.25:1:36 the efficiency (measured relative to the energy deposited in the active region of the HF laser) was approx.550% when the initial concentration of the F atoms was approx.5 x 10/sup 15/ cm/sup -3/. The degree of initiation and the efficiency were deduced from the experimental measurements of the energy of the excimer laser beam absorbed in the active region of the chemical laser.

  1. Laser separation of chemically strengthened glass

    NASA Astrophysics Data System (ADS)

    Abramov, Anatoli A.; Black, Matthew L.; Scott Glaesemann, G.

    A laser method for separating the strengthened glass and the effect of this process on edge quality and strength are reported. We have shown, for the first time to our knowledge, that developed laser based cutting technique enables clean full separation of the strengthened glass sheets having high level of ion exchange without spontaneous cracking or shattering. Nearly 'flaw-free' edge was achieved after optimization of the laser cutting parameters and after defining of an optimum range of the central tension inside the glass. As a result, high strength of the edge of > 500 MPa is demonstrated for the first time.

  2. Chemical pumping of pure rotational HF lasers

    Microsoft Academic Search

    John H. Smith; Dean W. Robinson

    1981-01-01

    Pure rotational laser oscillation has been observed in HF following flash photolysis of various mixtures of trifluoromethyl halide, acetylenic compound, and argon in the ration of 1:1:100. Specifically, mixtures of CF3I+C2H2, CF3I+CH3C2H, and CF3Br+C2H2 exhibit different patterns of laser intensity, and, further, are markedly different from patterns generated by the known photoelimination system CH2CF2. The above systems show laser intensity

  3. Chemical pumping of pure rotational HF lasers

    Microsoft Academic Search

    J. H. Smith; D. W. Robinson

    1981-01-01

    In the reported investigation, pure rotational laser oscillation has been observed in HF, following flash photolysis of various mixtures of trifluoromethyl halide, acetylenic compound, and argon in the ratio of 1:1:100. Specifically, mixtures of CF3I + C2H2, CF3I + CH3C2H, and CF3Br + C2H2 exhibit different patterns of laser intensity, and, further, are markedly different from patterns generated by the

  4. Modulated laser beam relaxation spectrometry of laser-induced chemical vapor deposition

    Microsoft Academic Search

    Paul B. Comita; Toivo T. Kodas

    1987-01-01

    The surface chemical reactions occurring during the laser-assisted deposition of gold from dimethyl gold hexafluoroacetylacetonate were studied using a photothermal modulation technique. A modulated argon ion laser was used to heat an area roughly 1 mm in diameter on an alumina substrate. Products of the photothermal reaction along with reactants were sampled through a 150×150 ?m orifice located at the

  5. 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.

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

    Microsoft Academic Search

    CRAIG M. TARVER

    2004-01-01

    Recent high-power laser deposition experiments on octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX) and 1,3,5-triamino-2,4,6-trinitrobenzene (TATB) produced ignition times from milliseconds to seconds. Global chemical kinetic thermal decomposition models for HMX and TATB developed to predict thermal explosion experiments lasting seconds to days are applied to these laser ignition experimental data. Excellent agreement was obtained for TATB, while the calculated ignition times were longer than

  7. VoIume57, ncmber 3 -CAL PHYSICSLEITERS 1 Augst 1978 INFEWRED LASER INDUCED CHEMIC_AL REACTIONS

    E-print Network

    Miller, William H.

    VoIume57, ncmber 3 -CAL PHYSICSLEITERS 1 Augst 1978 INFEWRED LASER INDUCED CHEMIC_AL REACTIONS X)even if the reactants are infrared izctive. It is well-known that an infrared laser can accei- erate chemical reactions state. This letter points out that infrared Iaserscan en- hance chemical reactions even if they are far

  8. Photonic metamaterials by direct laser writing and silver chemical vapour

    E-print Network

    LETTERS Photonic metamaterials by direct laser writing and silver chemical vapour deposition online: 11 May 2008; doi:10.1038/nmat2197 Metamaterials are artificial materials that--unlike natural metamaterials4,5 has been fabricated by electron-beam lithography and evaporation of metal films, both of which

  9. A UV laser source for biological and chemical sensing

    NASA Astrophysics Data System (ADS)

    Tiihonen, Mikael; Pasiskevicius, Valdas; Laurell, Fredrik; Hammarstrom, Per; Lindgren, Mikael

    2004-01-01

    Optical parametric oscillator (OPO) and sum-frequency mixing (SFM) devices are useful tools for constructing ultraviolet (UV) laser sources for fluorescence spectroscopy. Here, a compact UV-laser sources based on frequency conversion of an actively Q-switched Nd:YAG laser is presented. The second harmonic generation from a Nd:YAG laser was utilized as pump radiation for a periodically poled KTiOPO4 nanosecond optical parametric oscillator. The OPO-signal and the remaining pump were spatially mode-matched for Type I SFM in a ?-barium borate (BBO) crystal and UV radiation at 293 nm could be generated. This corresponds to a conversion efficiency of 2% with respect to the 532 nm harmonic radiation. The wavelength region accessible with this UV source is useful for chemical and biological sensing. Excitation of tryptophan at 293 nm for detection of fluorescence emission in ovalbumin and transthyretin was demonstrated.

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

    SciTech Connect

    Tarver, C M

    2004-03-02

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

  11. 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.

  12. 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

  13. Chemically driven pulsed and continuous visible laser amplifiers and oscillators

    NASA Astrophysics Data System (ADS)

    Gole, J. L.; Shen, K. K.; Wang, H.; Grantier, D.

    1992-07-01

    Procedures are outlined for developing the first visible chemical laser amplifiers and oscillators. Two approaches are discussed to the formation of electronically inverted atomic and diatomic configurations based on highly efficient near resonant intermolecular energy transfer and highly efficient and selective fast direct chemical reaction. Using a very near-resonant energy transfer from selectively formed metastable states of SiO and GeO to select metal atoms, Tl, Ga, Na, and K atom laser amplifiers are formed at 535, 417, 569, 818, and 581 nm wavelengths. The concepts employed to create amplification and oscillation in these systems are also applicable to the efficient energy transfer pumping of potential amplifying transitions in the Pb, Cu, and Sn receptor atoms. It is then sought to develop and scale chemically driven visible and UV lasers. The amplifiers to be produced use the highly efficient and selective formation of alkali dimer (M2 = Na2, Li2) excited states from the alkali trimer-halogen atom M3 - X reactions (X = Cl, Br, I). Optical gains through stimulated emission is demonstrated in select regions close to 527, 492, and 460 nm with potential extension to approximately the 412.5, 365, and 350 nm regions.

  14. Proceedings of the International Conference on Lasers 2000, eds. V.J. Corcoran and T.A. Corcoran, STS Press, McLean VA, 2001, pp. 265-272.

    E-print Network

    Carroll, David L.

    Generation by RF Discharge D. M. King, D. L. Carroll, and J. K. Laystrom CU Aerospace 2004 South Wright oxygen-iodine laser (COIL) singlet oxygen generator (SOG) based on discharge excitation of molecular/s and an O2 partial pressure of 3.0 Torr. Theory indicates that O2(1 D) concentrations should be 4-10 times

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

    NASA Astrophysics Data System (ADS)

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

    2004-10-01

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

  16. Space-Based Chemical Lasers in strategic defense

    SciTech Connect

    Wildt, D. (SDIO, Washington, DC (United States))

    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. Figures of merit for high-energy laser-window materials: thermal lensing and thermal stresses

    NASA Astrophysics Data System (ADS)

    Klein, Claude A.

    2007-01-01

    The selection of a suitable laser-window material involves considerations relating to "thermal lensing," that is, the process of beam distrotion caused by thermally induced phase-aberrations, in addition to issues relating to the stress field generated by beam-induced temperature gradients. The purpose of this paper is to obtain improved figures of merit (FoM) for ranking high-energy laser-window materials in regard to thermal lensing and thermal stresses. We address this task in the following manner: (a) We provide proper analytical expressions for describing how beam-induced optical distortions and beam-induced hoop stresses control the allowable beam fluence; (b) We re-evaluate the role of axial stresses, which may lead to failure through compressive yielding or thermal shock, and derive appropriate FoMs based on allowable irradiances; (c) We illustrate the procedure through FoM evaluations of six window-material candidates for operation at the chemical oxygen-iodine laser wavelength (1.315 µm). This methodology confirms that low-absorption, impurity-free fused silica is the window material of choice for contemplated high-energy laser systems operating in the near-infrared.

  18. Surface melting of metal deposits during laser-induced chemical vapor deposition with a modulated continuous-wave laser

    Microsoft Academic Search

    Paul B. Comita; Peter E. Price; Toivo T. Kodas

    1990-01-01

    Thermal laser-induced chemical vapor deposition of gold crystals on alumina substrates has been studied using a modulated Ar+ laser. Deposition of gold from dimethylgold hexafluoroacetylacetonate is accompanied by surface melting of the deposit when the laser source is modulated. Time-resolved reflectance measurements have been used to study the time evolution of the surface reflectance during growth with both modulated and

  19. Production of radioactive Ag ion beams with a chemically selective laser ion source

    NASA Astrophysics Data System (ADS)

    Jading, Y.; Catherall, R.; Jokinen, A.; Jonsson, O. C.; Kugler, E.; Lettry, J.; Ravn, H. L.; Tengblad, O.; Kautzsch, T.; Klöckl, I.; Kratz, K.-L.; Scheerer, F.; Fedoseyev, V. N.; Mishin, V. I.; van Duppen, P.; Wöhr, A.; Walters, W. B.

    1996-04-01

    We have developed a chemically selective laser ion source at the CERN-ISOLDE facility in order to study neutron-rich Ag nuclides. A pulsed laser system with high repetition rate has been used based on high-power copper-vapour pump lasers and dye lasers. With this source significant reductions of the isobaric background has been achieved.

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

    SciTech Connect

    Mustafa, Mohd Ubaidillah; Juremi, Nor Rashidah Md.; Mohamad, Farizan; Wibawa, Pratama Jujur [Microelectronic and Nanotechnology-Shamsudin Research Centre, Faculty of Electrical and Electronic Engineering, University Tun Hussein Onn Malaysia (Malaysia); Agam, Mohd Arif; Ali, Ahmad Hadi [Faculty of Science, Art and Heritage, University Tun Hussein Onn Malaysia (Malaysia)

    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.

  1. Study of factors influencing the effective delivery of O2(1delta) into the resonator of the oxygen-iodine laser

    NASA Astrophysics Data System (ADS)

    Krukowski, I. M.; Halin, A. L.

    1994-08-01

    Experimental studies have been performed on the processes: chlorine utilization in the bubbler type singlet oxygen generator, the quenching of O2(1(Delta) ) in the OIL path, the propagation of the gas mixture O2 + O2 (1(Delta) ) + H2O throughout forward flow-type water vapor trap.

  2. 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.

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

    SciTech Connect

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

    1982-01-01

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

  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. 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.

  6. Free-Electron Lasers, Thermal Diffusion, Chemical Kinetics, and Surgery

    NASA Astrophysics Data System (ADS)

    Edwards, Glenn; Hutson, M. Shane

    2001-11-01

    Experiments demonstrate that the Mark-III FEL is a particularly effective tool for etching soft matter with remarkably little damage surrounding the site when tuned to wavelengths near 6.45 microns. Based on these observatons, human neuorsurgical and ophthalmic procedures were developed and have been performed successfully. A thermodynamic model was proposed to account for the wavelength dependence; however, the dynamics have not been well understood. We have theoretically investigated thermal diffusion and chemical kinetics in a system of alternating layers of protein and water as heated by a Mark-III FEL. The model is representative of cornea and the exposure conditions are comparable to previous experimental FEL investigations. A substantial temperature enhancement develops in the surface layer on the ten-nanosecond time scale. We consider the onset of both the helix-coil transition and chemical bond breaking of collagen in terms of the thermal, chemical, and structural properties of the system as well as laser wavelength and pulse structure.

  7. 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.

  8. Use of unstable resonators in CW chemical lasers with radial flow of a gas mixture

    Microsoft Academic Search

    A. A. Stepanov; V. A. Shcheglov

    1982-01-01

    Theoretical studies have shown that the ring variant of a CW chemical laser has possibly a great potential in connection with applications involving the use of gasdynamic lasers. However, as a consequence of the employed geometrical design, it is difficult to construct an optical resonator which would ensure an effective utilization of the available energy and produce a laser beam

  9. Annular resonators for high-power chemical lasers

    NASA Astrophysics Data System (ADS)

    Wade, Richard C.

    1993-08-01

    Resonators capable of extracting highly coherent energy from DF and HF chemical laser annular gain media have been under investigation for weapon application since 1974. This survey article traces the background of interest in these devices, describes the various concepts that have been experimentally and analytically investigated, and discusses the issues associated with their operation. From the discussion of issues, preferred concepts are selected. Applicability of these concepts to high-power operation is addressed through discussions of past and ongoing high-power demonstration programs and the issues facing their application to weapon sized devices capable of strategic and tactical missions such as ballistic missile defense (BMD), theater missile defense (TMD), and anti satellite (ASAT).

  10. Chemical By-Products Produced By CO2 And Nd:YAG Laser Interaction With Tissue

    NASA Astrophysics Data System (ADS)

    Kokosa, John M.; Doyle, Daryl J.

    1988-06-01

    The interaction of CW CO2 and Nd:YAG laser light with animal tissue produces large quantities of smoke which has been of concern to laser surgeons. Analysis of the chemical constituents present in smoke produced by CO2 and Nd:YAG laser interaction with samples of beef liver were very similar. A significant quantity of benzene and lesser quantities of polycyclic aromatic hydrocarbons (PAH's) were found to be present. Since these chemicals are classified as carcinogens, adequate smoke exhaust devices should be used during all laser surgical procedures for the protection of patients and operating room personnel.

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

    NASA Astrophysics Data System (ADS)

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

    2010-09-01

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

  12. Materials for high-energy laser windows: oxyfluoride glass vs. fusion-cast CaF2

    NASA Astrophysics Data System (ADS)

    Klein, Claude A.

    2005-05-01

    The process of selecting suitable materials for high-energy laser windows involves considerations realting to (a) the flexural strength, (b) the thermal stresses, and (c) the optical distortion. Optical distortion ocnsiderations strongly favor low-absorbtion materials ythat exhibit a negitive thermo-optic coefficient (dn/dT) in conjunction with minimal stress-birefringence (qd\\overline -q? ~=0). For this reason, calcium floride has been the primary candidate for many years, but the efforts to strengthen this material have not been successful. Recently, a new glass compostion-oxyfloride glass (OFG)-has been promoted as an ideal solution in the sense that it will allow fabricating large "athermal" windows for operation at the chemical oxygen-iodine laser wavelength. It is, therefore, of interest to properly assess the merits of OFG in comparison to CaF2, which we do here on the basis of available (Dec '04) property data for fusion-cast CaF2 and OFG. Oxyfloride glass was found to be deficient in regard to thermal diffusivity, which may lead to excessive coating-induced compressive stresses, and stress- birefringence, which rules out creating a distortion-free window. It is suggested that future efforts should be directed at strengthening CaF2 in view of this material's exceptionally low absorbtion and almost no stress-birefringence

  13. 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.

  14. Dynamic structure elucidation of chemical reactivity by laser pulses and X-ray probes.

    PubMed

    Bartlett, Stuart A; Hamilton, Michelle L; Evans, John

    2015-04-14

    Visualising chemical reactions by X-ray methods is a tantalising prospect. New light sources provide the prospect for studying atomic, electronic and energy transfers accompanying chemical change by X-ray spectroscopy and inelastic scattering. Here we assess how this adventure can illuminate inorganic and catalytic chemistry. In particular X-ray inelastic scattering provides a means of exploiting X-ray free electron lasers, as a parallel to laser Raman spectroscopy. PMID:25741902

  15. CONTROL OF LASER RADIATION PARAMETERS: Computational and experimental study of a Q-switched cw chemical HF/DF laser

    NASA Astrophysics Data System (ADS)

    Aleksandrov, Boris S.; Kuprenyuk, V. I.; Maksimov, Yurii P.; Mashendzhinov, Viktor I.; Rodionov, A. Yu; Rotinyan, Mikhail A.; Sudarikov, V. V.; Tret'yakov, Nikolai E.; Fedorov, Igor'A.; Etsina, Alla L.

    2007-06-01

    The energy and temporal parameters of radiation from a cw chemical medium-size HF/DF laser mechanically Q-switched by a mirror rotating at a frequency of up to 1 kHz are calculated and studied experimentally. The peak power of laser pulses in the repetitively pulsed regime exceeds the cw output power of the HF laser at least by a factor of four. The average power in the repetitively pulses regime is lower than that in the cw regime, but it increases (approximately doubles) with increasing modulation frequency. The time of the complete recovery of the gain profile in the active medium is measured to be 6-7 ?s. Two numerical models are developed which describe the dynamics of Q-switched HF and DF lasers. Some specific features of the operation of these lasers are analysed with the help of these models.

  16. Microstructure and chemical bond evolution of diamond-like carbon films machined by femtosecond laser

    NASA Astrophysics Data System (ADS)

    Wang, Jing; Wang, Chunhui; Liu, Yongsheng; Cheng, Laifei; Li, Weinan; Zhang, Qing; Yang, Xiaojun

    2015-06-01

    Femtosecond laser is of great interest for machining high melting point and hardness materials such as diamond-like carbon, SiC ceramic, et al. In present work, the microstructural and chemical bond evolution of diamond-like carbon films were investigated using electron microscopy and spectroscopy techniques after machined by diverse femtosecond laser power in air. The results showed the machining depth was essentially proportional to the laser power. The well patterned microgrooves and ripple structures with nanoparticles were formed distinctly in the channels. Considering the D and G Raman band parameters on the laser irradiation, it revealed a conversion from amorphous carbon to nanocrystalline graphite after laser treated with increasing laser power. X-ray photoelectron spectroscopy analysis showed a great decrease of sp3/sp2 after laser treatment.

  17. 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

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

    SciTech Connect

    Kim, Chang-hwan; Yoh, Jack J. [School of Mechanical and Aerospace Engineering, Seoul National University, 599 Kwanakro, Kwanakgu, Seoul, Korea 151-742 (Korea, Republic of)

    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.

  19. PhysicoChemical Dynamics of Nanoparticle Formation during Laser Decontamination

    Microsoft Academic Search

    2004-01-01

    Laser-ablation based decontamination is a new and effective approach for simultaneous removal and characterization of contaminants from surfaces (e.g., building walls, ground floors, etc.). The scientific objectives of this research are to: (1) characterize particles generated during laser decontamination, (2) develop a technique for simultaneous cleaning and verification, and (3) develop a model for predicting particle generation. The research will

  20. 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.

  1. 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

    ?The 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 ?m). 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.

  2. 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(a1?)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(a1?) 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(a1?) 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(a1?) 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(a1?) 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(b1?) at lower pressure. Since all necessary conditions have been met, a 30% conversion rate of O II to O II(a1?) has been achieved. Fortuitously, neither excited O atom production nor O II(b1?) 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(a1?) line. Energy normally partitioned to O II(b1?) and apparently O atoms now feeds into O II(a1?) 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(a1?) 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.

  3. 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.

  4. Preparation of ?-Al2O3 films by laser chemical vapor deposition

    NASA Astrophysics Data System (ADS)

    Gao, Ming; Ito, Akihiko; Goto, Takashi

    2015-06-01

    ?- and ?-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 ?-Al2O3 films, whereas the Nd:YAG and InGaAs lasers produced ?-Al2O3 films when used at a high total pressure. ?-Al2O3 films had a cauliflower-like structure, while the ?-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 ?-Al2O3 nucleation in the gas phase at high total pressure, which explains the cauliflower-like structure of nanoparticles observed.

  5. PhysicoChemical Dynamics of Nanoparticle Formation during Laser Decontamination

    Microsoft Academic Search

    2005-01-01

    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

  6. 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.

  7. 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.

  8. 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

  9. 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.

  10. Open-air laser-induced chemical vapor deposition of silicon carbide coatings

    Microsoft Academic Search

    Christopher J. Jensen; Wilson K. S. Chiu

    2006-01-01

    This study demonstrates the open-air deposition of amorphous hydrogenated silicon carbide (a-SiC:H) by laser-induced chemical vapor deposition (LCVD) using an enclosureless (open-air) reactor system. Films are deposited on fused quartz substrates using the precursor gas trimethylsilane (TrMS). Based on Auger electron spectroscopy (AES), Fourier transform infrared absorption spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS), the film's chemical composition and microstructure

  11. 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.

  12. Laser Induced Breakdown Spectroscopy for Chemical Mapping of Materials

    Microsoft Academic Search

    V. Piñon; M. P. Mateo; G. Nicolas

    2012-01-01

    Analytical techniques able to perform spatially-resolved analysis are highly demanded in the surface analysis and material science fields. Comparing with other analytical techniques usually employed, Laser Induced Breakdown Spectroscopy (LIBS) offers several advantages such as simplicity and robustness of the instrumentation which permits on-line and in-situ measurements. None or minimal sample preparation is required and the analysis of any sample

  13. 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.

  14. 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

  15. Laser-assisted chemical cleaning of thin oxide films on carbon steel surfaces

    NASA Astrophysics Data System (ADS)

    Lim, Hyunkyu; Kim, Dongsik

    2003-11-01

    This paper introduces a novel laser chemical process for removing thin oxide films on low-carbon steel surfaces by combining laser-induced shock waves and chemical etching technique that is used in the conventional oxide-scale removal process. In the proposed process, a Q-switched Nd:YAG laser (wavelength 1064 nm, FWHM 6 ns) pulse is focused onto the liquid surface and subsequently induces optical breakdown in the acid solution, producing intense pressure waves. The pressure waves act as a non-contact oxide-film breaker and increases the removal rate. It has been demonstrated that the novel process leads to substantial enhancement of the oxide-film removal, compared with the conventional solvent-based cleaning technique. The removal rate has been measured quantitatively employing an optical microscope, a scanning electron microscope, and energy-dispersive X-ray analysis. Parametric study has been performed to reveal the effect of pressure pulse, laser pulse number, acid concentration, reaction time on the efficiency of scale removal. It is shown that the laser-assisted process can lower the acid concentration, with the cleaning efficiency unchanged or even improved. The results demonstrates a technical feasibility of utilizing the method for industrial applications that required enhanced scale-removal rate or reduced use of toxic chemicals.

  16. 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.

  17. Growth of carbon nanotubes by open-air laser-induced chemical vapor deposition

    Microsoft Academic Search

    Kinghong Kwok; Wilson K. S. Chiu

    2005-01-01

    Carbon nanotubes have remarkable mechanical, electronic and electrochemical properties, but the full potential for application will be realized only if the growth of high quantity and quality carbon nanotubes can be optimized and well controlled. In this study, carbon nanotubes have been successfully grown on fused quartz rods by a novel open-air laser-induced chemical vapor deposition (LCVD) technique with gold

  18. Overview of the SDI (Strategic Defense Initiative) Program in short wavelength chemical lasers

    SciTech Connect

    Jones, C.R.

    1988-01-01

    Advanced chemical lasers promise to be effective space-based weapons against responsive threats. In this program, we are developing both CW and pulsed concepts for achieving this goal. Certain approaches may also be appropriate as ground-based weapons and fusion drivers. 12 refs., 1 fig., 5 tabs.

  19. Sensing chemically excited metastable populations by CO2 laser gain measurements

    Microsoft Academic Search

    D. J. Benard

    1976-01-01

    For chemical laser applications it is desirable to populate metastable states which are not easily detected except in connection with a subsequent transfer of energy to a more efficient emitter. The vibrational states of the carbon dioxide molecule make it possible to monitor the transitions of a molecule which can be nonselectively excited by transfer over a broad range of

  20. 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.

  1. Monte Carlo simulation of laser induced chemical vapor deposition Yehuda Zeiri, Uzi Atzmony, and Joseph Bloch

    E-print Network

    Zeiri, Yehuda

    Monte Carlo simulation of laser induced chemical vapor deposition Yehuda Zeiri, Uzi Atzmony 21 September 1989; accepted for publication 30 November 1990) We have used a Monte Carlo method developed a Monte Carlo procedure which was used to simulate the LICVD process. The beam inten- sities used

  2. Laser assisted chemical vapor deposition synthesis of carbon nanotubes and their characterization

    E-print Network

    Wang, Zhong L.

    small quantities. The majority of high quality carbon nano- tubes have been prepared using either is best visualized as a planar sheet of carbon atoms (graphene) wrapped into a tube, fallsLaser assisted chemical vapor deposition synthesis of carbon nanotubes and their characterization S

  3. Kinetics and reaction mechanisms of laser-assisted chemical vapor deposition of polycrystalline silicon dots from silane

    Microsoft Academic Search

    Y. Pauleau; D. Tonneau

    2002-01-01

    Polycrystalline silicon dots have been deposited on silicon-coated SiO2 substrates from silane irradiated with a continuous wave (cw) argon ion laser and a cw CO2 laser. Various experimental configurations were adopted for laser-assisted chemical vapor deposition of Si dots. The cw argon ion laser was focused either directly on the surface of absorbent polycrystalline Si films acting as substrates (front

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

    SciTech Connect

    Jung Park, Han; Diebold, Gerald J. [Department of Chemistry, Brown University, Providence, Rhode Island 02912 (United States)] [Department of Chemistry, Brown University, Providence, Rhode Island 02912 (United States)

    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.

  5. Facilities: NHMFL 9.4 Tesla Fourier Transform Ion Cyclotron Resonance Mass Spectrometer Citation: Atmospheric Pressure Laser-Induced Acoustic Desorption Chemical Ionization Mass Spectrometry

    E-print Network

    Weston, Ken

    : Atmospheric Pressure Laser-Induced Acoustic Desorption Chemical Ionization Mass Spectrometry for Analysis of atmospheric pressure laser-induced acoustic desorption chemical ionization (AP/ LIAD-CI) source. The laser a powerful new approach for the analysis of saturated hydrocarbon mixtures: atmospheric pressure laser

  6. 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.

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

    PubMed

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

    2015-03-01

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

  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. 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

  10. 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)

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

    SciTech Connect

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

    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.

  12. 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.

  13. 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.

  14. F2-laser ablation of Fabry-Perot cavities in optical fibres: chemical sensors

    NASA Astrophysics Data System (ADS)

    Machavaram, V. R.; Badcock, R. A.; Fernando, G. F.

    2012-03-01

    The authors have previously reported on the micro-machining of intrinsic fibre Fabry-Perot cavities in fused silica optical fibres using a 157 nm excimer laser. The current paper reports on a technique for estimating the depth of the cavity by measuring the transmitted light intensity during the micro-machining of optical fibres using a 157 nm laser. Single and multiple cavities were created in silica and sapphire optical fibres and the feasibility of using micro-machined cavities for monitoring chemicals is demonstrated.

  15. 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.

  16. Excimer laser induced surface chemical modification of polytetrafluoroethylene

    NASA Astrophysics Data System (ADS)

    Révész, K.; Hopp, B.; Bor, Z.

    1997-02-01

    Polytetrafluoroethylene has a notoriously non adhesive and non reactive character. Its successful surface photochemical modification was performed by irradiating the polytetrafluoroethylene/liquid triethylamine interface with an ArF excimer laser ( ?=193 nm). Due to the photochemical treatment the polytetrafluoroethylene surface became more hydrophilic. The water receding contact angle decreased from 94° to 43°. The reaction cross section was determined from the decrease of the contact angles. It was found to be as high as 6.4×10 -18 cm 2. XPS measurements evidenced the removal of fluorine from the polytetrafluoroethylene, incorporation of alkyl carbon and nitrogen. Photochemical dissociation path of the triethylamine makes probable that it bonded to the fluoropolymer backbone via the ?-carbon atom of an ethyl group. A radical, or a photoinduced electron transfer mechanism was suggested to describe this reaction. A selective area electroless plating of silver was performed after pretreating the sample with patterned photomodification. The increased adhesion of the sample was proved by gluing with epoxy resin. As a result of the surface modification the tensile strength of gluing increased by 210× and reached 24% of the value characteristic for the bulk material.

  17. 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.

  18. 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 ?m, CTE:YAG laser, wavelength 2.7 ?m, Nd:YAG laser, wavelength 1.06 ?m, and alexandrite laser, wavelength 0.75 ?m) 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.

  19. Chemical H/sub 2//F/sub 2/ laser initiated by an excimer lamp

    SciTech Connect

    Gordon, E.V.; Matyushenko, V.I.; Pavlenko, V.S.; Sizov, V.D.

    1985-01-01

    A chemical hydrogen--fluorine (H/sub 2//F/sub 2/) laser was operated for the first time by transverse initiation with incoherent radiation from a pulsed electric-discharge excimer lamp with XeCl, XeF, and KrF molecules. This laser operated only when superradiance of the excimer mixtures was suppressed. Estimates indicated that the technical efficiency of the excimer lamp was 5%, which was 10 times higher than the efficiency of an excimer laser which was used to construct it. A study was made of feasibility of constructing a system in which excimer molecules and vibrationally excited HF molecules would form in the same region in space.

  20. Middle infrared active coherent laser spectrometer for standoff detection of chemicals.

    PubMed

    Macleod, Neil A; Rose, Rebecca; Weidmann, Damien

    2013-10-01

    Using a quantum cascade laser emitting at 7.85 ?m, a middle infrared active coherent laser spectrometer has been developed for the standoff detection of vapor phase chemicals. The first prototype has been tested using diffuse target backscattering at ranges up to ~30 m. Exploiting the continuous frequency tuning of the laser source, spectra of water vapor, methane, nitrous oxide, and hydrogen peroxide were recorded. A forward model of the instrument was used to perform spectral unmixing and retrieve line-of-sight integrated concentrations and their one-sigma uncertainties. Performance was found to be limited by speckle noise originating from topographic targets. For absorbers with large absorption cross sections such as nitrous oxide (>10(-19) cm(2)·molecule(-1)), normalized detection sensitivities range between 14 and 0.3 ppm·m·Hz(-1/2), depending on the efficiency of the speckle reduction scheme implemented. PMID:24081032

  1. 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 [Laser Physics Application Section, Raja Ramanna Centre for Advanced Technology, Indore 452013, MP (India)

    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.

  2. 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

  3. Microstructure of metastable metallic alloy films produced by laser breakdown chemical vapor deposition and ion implantation

    Microsoft Academic Search

    S. K. Menon; T. R. Jervis; M. Nastasi

    1986-01-01

    Thin films produced by laser breakdown chemical vapor deposition from nickel and iron carbonyls and by implanting Ni foils with varying levels of C have been characterized by transmission electron microscopy. Decomposition of Ni(CO)â produces polycrystalline films of fcc Ni and metastable ordered hexagonal NiâC. This metastable phase is identical to that produced by gas carburization, rapid solidification of Ni-C

  4. 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 ?-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 ?-diketonates which are evaporated nonselectively and with high rates by laser flash evaporation.

  5. Photothermal laser fabrication of micro- and nanostructured chemical templates for directed protein immobilization.

    PubMed

    Schröter, Anja; Franzka, Steffen; Hartmann, Nils

    2014-12-16

    Photothermal patterning of poly(ethylene glycol) terminated organic monolayers on surface-oxidized silicon substrates is carried out using a microfocused beam of a CW laser operated at a wavelength of 532 nm. Trichlorosilane and trimethoxysilane precursors are used for coating. Monolayers from trimethoxysilane precursors show negligible unspecific protein adsorption in the background, i.e., provide platforms of superior protein repellency. Laser patterning results in decomposition of the monolayers and yields chemical templates for directed immobilization of proteins at predefined positions. Characterization is carried out via complementary analytical methods including fluorescence microscopy, atomic force microscopy, and scanning electron microscopy. Appropriate labeling techniques (fluorescent markers and gold clusters) and substrates (native and thermally oxidized silicon substrates) are chosen in order to facilitate identification of protein adsorption and ensure high sensitivity and selectivity. Variation of the laser parameters at a 1/e(2) spot diameter of 2.8 ?m allows for fabrication of protein binding domains with diameters on the micrometer and nanometer length scale. Minimum domain sizes are about 300 nm. In addition to unspecific protein adsorption on as-patterned monolayers, biotin-streptavidin coupling chemistry is exploited for specific protein binding. This approach represents a novel facile laser-based means for fabrication of protein micro- and nanopatterns. The routine is readily applicable to femtosecond laser processing of glass substrates for the fabrication of transparent templates. PMID:25397891

  6. Volume 197, number 4,5 CHEMICAL PHYSICS LETTERS 18 September 1992 Laser-induced molecular stabilization and trapping

    E-print Network

    Chu, Shih-I

    and photodis- sociation rates of H: molecular ions in intense laser fields at 775 nm and report a novel new reported elsewhere for a shorter (UV) wave- length case at 266 nm [ 91, In this Letter, we reportVolume 197, number 4,5 CHEMICAL PHYSICS LETTERS 18 September 1992 Laser-induced molecular

  7. 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.

  8. 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)

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

    NASA Astrophysics Data System (ADS)

    Kwa?niak, P.; Pura, J.; Zwoli?ska, M.; Wieci?ski, P.; Skar?y?ski, H.; Olszewski, L.; Marczak, J.; Garbacz, H.; Kurzyd?owski, 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.

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

    NASA Astrophysics Data System (ADS)

    Petit, E. J.; Caudano, R.

    1992-01-01

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

  11. Estimation of risks by chemicals produced during laser pyrolysis of tissues

    NASA Astrophysics Data System (ADS)

    Weber, Lothar W.; Spleiss, Martin

    1995-01-01

    Use of laser systems in minimal invasive surgery results in formation of laser aerosol with volatile organic compounds of possible health risk. By use of currently identified chemical substances an overview on possibly associated risks to human health is given. The class of the different identified alkylnitriles seem to be a laser specific toxicological problem. Other groups of chemicals belong to the Maillard reaction type, the fatty acid pyrolysis type, or even the thermally activated chemolysis. In relation to the available different threshold limit values the possible exposure ranges of identified substances are discussed. A rough estimation results in an exposure range of less than 1/100 for almost all substances with given human threshold limit values without regard of possible interactions. For most identified alkylnitriles, alkenes, and heterocycles no threshold limit values are given for lack of, until now, practical purposes. Pyrolysis of anaesthetized organs with isoflurane gave no hints for additional pyrolysis products by fragment interactions with resulting VOCs. Measurements of pyrolysis gases resulted in detection of small amounts of NO additionally with NO2 formation at plasma status.

  12. Sub-millisecond post exposure bake of chemically amplified resists by CO2 laser heat treatment

    NASA Astrophysics Data System (ADS)

    Jung, Byungki; Sha, Jing; Paredes, Florencia; Ober, Christopher K.; Thompson, Michael O.; Chandhok, Manish; Younkin, Todd R.

    2010-04-01

    Chemically amplified photoresists require a post exposure bake (PEB), typically on a hot plate at 90-150°C for 30-120 seconds, to catalytically deprotect the polymer backbone. During PEB, excessive diffusion of the photo-generated acid results in loss of line edge definition, blurring of latent images and changes in the line edge roughness. Both acid diffusion and deprotection are thermally activated processes, with the relative rates affected by the time/temperature profile of the PEB. In this work, we introduce an alternate PEB method involving 500 ?s time scale heating over a temperature range of 130°C to 450°C using a continuous wave CO2 laser. A methodology is developed for characterizing this laser PEB and comparing the behavior with conventional hot plate PEB. The thermal stability of several polymer and photoacid generator (PAG) resist systems were studied and shown to be stable at these high temperatures due to the short heating duration. Sensitivity of resists under hot plate and laser PEB were measured. Under moderate temperatures, the laser PEB sensitivity can exceed that of hot plate PEB by an order of magnitude. Quantitative determination of the acid diffusion was obtained using resist bilayers (PAG loaded / PAG free). Despite the five orders of magnitude difference in PEB time, systems with l-PEB and hot-plate PEB exhibit comparable imaging quality under deep ultraviolet exposure.

  13. Investigation of lamp chemical composition by laser-induced breakdown spectroscopy

    SciTech Connect

    Chen, N.H.; Adler, H.G.; Lapatovich, W.P. [Osram Sylvania, Beverly, MA (United States)

    1998-12-31

    The utilization of laser-induced breakdown spectroscopy (LIBS) as a non-destructive experimental diagnostic for studying lighting devices is discussed. LIBS involves the creation of a small plasma localized at the focus of a pulsed laser beam, and corresponding analysis of the spectrally dispersed radiation from the plasma. LIBS has been used as a method for determining the minority elemental composition of various types of samples. This work is aimed at applying LIBS to the species of interest found in metal halide discharge lamps. A 532 nm, 3 ns FWHM pulse from a Nd:YAG laser was used to produce a localized plasma in the interior of a vitreous silica tube containing mercury and sodium-scandium iodides, while the tube was maintained at operating temperatures in an oven. Spectral features corresponding to Hg, Na, and Sc atomic emission were observed, originating from the evaporated fill chemicals. Time-resolved spectroscopy was used to record emission spectra at delay times on the order of a few microseconds following the laser pulse. At appropriate delay times, the atomic emission lines could be separated from the continuum background. Effective (spatially averaged) plasma temperatures vs. delay time were determined from Boltzmann plots of atomic Sc emission lines. The use of integrated line intensities as an indication of species concentration will be discussed.

  14. A nuclear pumped laser for the Laboratory Microfusion Facility

    NASA Astrophysics Data System (ADS)

    Miley, G. H.

    1989-08-01

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

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

    NASA Astrophysics Data System (ADS)

    Jonavi?ius, 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 15?m, width 5?m, length 35-45 ?m and could provide 300 n?m resistivity measured in a macroscopic way. This proves the techniques potential for creating integrated 3D electric circuits at microscale.

  16. Chemical and explosive detections using photo-acoustic effect and quantum cascade lasers

    NASA Astrophysics Data System (ADS)

    Choa, Fow-Sen

    2013-12-01

    Photoacoustic (PA) effect is a sensitive spectroscopic technique for chemical sensing. In recent years, with the development of quantum cascade lasers (QCLs), significant progress has been achieved for PA sensing applications. Using high-power, tunable mid-IR QCLs as laser sources, PA chemical sensor systems have demonstrated parts-pertrillion- level detection sensitivity. Many of these high sensitivity measurements were demonstrated locally in PA cells. Recently, we have demonstrated standoff PA detection of isopropanol vapor for more than 41 feet distance using a quantum cascade laser and a microphone with acoustic reflectors. We also further demonstrated solid phase TNT detections at a standoff distance of 8 feet. To further calibrate the detection sensitivity, we use nerve gas simulants that were generated and calibrated by a commercial vapor generator. Standoff detection of gas samples with calibrated concentration of 2.3 ppm was achieved at a detection distance of more than 2 feet. An extended detection distance up to 14 feet was observed for a higher gas concentration of 13.9 ppm. For field operations, array of microphones and microphone-reflector pairs can be utilized to achieve noise rejection and signal enhancement. We have experimentally demonstrated that the signal and noise spectra of the 4 microphone/4 reflector system with a combined SNR of 12.48 dB. For the 16-microphone and one reflector case, an SNR of 17.82 was achieved. These successful chemical sensing demonstrations will likely create new demands for widely tunable QCLs with ultralow threshold (for local fire-alarm size detection systems) and high-power (for standoff detection systems) performances.

  17. Pulsed high-pressure chemical HF laser with electric-discharge initiation

    SciTech Connect

    Bosamykin, V.S.; Gordon, E.B.; Gorokhov, V.V.; Karelin, V.I.; Matyushenko, V.I.; Repin, P.B.; Sizov, V.D.

    1982-07-01

    Measurements were made of the energy and time characteristics of the radiation emitted by a chemical HF laser subjected to short-pulse (approx.100 nsec) electric-discharge initiation. A mixture of the composition F/sub 2/:O/sub 2/:SF/sub 6/:H/sub 2/ = 6.5:0.7:15.0:2.0 with a total pressure of 180 Torr had a specific output energy of 17.5 J/liter. The efficiency of conversion of the energy deposited in the discharge was approx.65% and the active volume was approx.0.3 liter.

  18. Shape control of microchannels fabricated in fused silica by femtosecond laser irradiation and chemical etching.

    PubMed

    Vishnubhatla, Krishna Chaitanya; Bellini, Nicola; Ramponi, Roberta; Cerullo, Giulio; Osellame, Roberto

    2009-05-11

    We report on the fabrication of shape-controlled microchannels in fused silica by femtosecond laser irradiation at 600 kHz repetition rate followed by chemical etching. The shape control is achieved by suitable wobbling of the glass substrate during the irradiation process. Cylindrical microchannels with uniform cross-sections are demonstrated with an unprecedented length of 4 mm. Some applications are also addressed: connection of two microchannels with a smaller one, 3D microchannel adapter and fabrication of O-grooves for easy fiber-to-waveguide coupling. PMID:19434202

  19. 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.

  20. Hyperosmotic Chemical Agent's Effect on in vivo Cerebral Blood Flow Revealed by Laser Speckle

    NASA Astrophysics Data System (ADS)

    Cheng, Haiying; Luo, Qingming; Zeng, Shaoqun; Chen, Shangbin; Luo, Weihua; Gong, Hui

    2004-11-01

    We investigated the influence of a hyperosmotic agent (glycerol) on the normal physiological function of tissue by applying the glycerol in vitro and in vivo to rabbit dura mater to assess the changes in the tissue's optical properties. We used a laser speckle imaging technique to study the effect of epidurally applied glycerol on resting cerebral blood flow (CBF). Our results showed that resting CBF decreased as the transparency of the dura mater increased. The challenges for the design of an optical clearing technique were not only the clearing effects and the duration of the action of the chemical agents but also the influence of the glycerol on the tissue's normal physiological function.

  1. Microstructure of metastable metallic alloy films produced by laser breakdown chemical vapor deposition and ion implantation

    SciTech Connect

    Menon, S.K.; Jervis, T.R.; Nastasi, M.

    1986-01-01

    Thin films produced by laser breakdown chemical vapor deposition from nickel and iron carbonyls and by implanting Ni foils with varying levels of C have been characterized by transmission electron microscopy. Decomposition of Ni(CO)/sub 4/ produces polycrystalline films of fcc Ni and metastable ordered hexagonal Ni/sub 3/C. This metastable phase is identical to that produced by gas carburization, rapid solidification of Ni-C melts, and ion implantation of C into Ni at low concentrations. Increasing the H/sub 2/ content in the gas mixture during laser deposition reduces the grain size of the films significantly with grain sizes smaller than 10 nanometers produced. Laser decomposition of Fe(CO)/sub 5/ produces films with islands of fcc gamma-Fe and finely dispersed metastable Fe/sub 3/C (Cementite). In addition, the ferrous oxides Fe/sub 2/O/sub 3/ and Fe/sub 3/O/sub 4/ were found in these samples. Implants of C into pure Ni foils at 77/sup 0/K and at a concentration of 35 at. % produced amorphous layers. Implants at the same dose at room temperature did not produce amorphous layers.

  2. 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.

  3. Double-core-hole spectroscopy for chemical analysis with an intense X-ray femtosecond laser

    PubMed Central

    Berrah, Nora; Fang, Li; Murphy, Brendan; Osipov, Timur; Ueda, Kiyoshi; Kukk, Edwin; Feifel, Raimund; van der Meulen, Peter; Salen, Peter; Schmidt, Henning T.; Thomas, Richard D.; Larsson, Mats; Richter, Robert; Prince, Kevin C.; Bozek, John D.; Bostedt, Christoph; Wada, Shin-ichi; Piancastelli, Maria N.; Tashiro, Motomichi; Ehara, Masahiro

    2011-01-01

    Theory predicts that double-core-hole (DCH) spectroscopy can provide a new powerful means of differentiating between similar chemical systems with a sensitivity not hitherto possible. Although DCH ionization on a single site in molecules was recently measured with double- and single-photon absorption, double-core holes with single vacancies on two different sites, allowing unambiguous chemical analysis, have remained elusive. Here we report that direct observation of double-core holes with single vacancies on two different sites produced via sequential two-photon absorption, using short, intense X-ray pulses from the Linac Coherent Light Source free-electron laser and compare it with theoretical modeling. The observation of DCH states, which exhibit a unique signature, and agreement with theory proves the feasibility of the method. Our findings exploit the ultrashort pulse duration of the free-electron laser to eject two core electrons on a time scale comparable to that of Auger decay and demonstrate possible future X-ray control of physical inner-shell processes. PMID:21969540

  4. Kinetics of laser chemical vapor deposition of carbon and refractory metals

    NASA Astrophysics Data System (ADS)

    Gao, Feng

    2000-10-01

    Three-dimensional laser chemical vapor deposition (3D-LCVD) has been used to grow rods of carbon, tungsten, titanium, and hafnium from a variety of hydrocarbons and metal halide-based precursors. A novel computerized 3D-LCVD system was designed and successfully used in the experiments. A focused Nd:Yag laser beam (lambda = 1.06 mum) was utilized to locally heat up a substrate to deposition temperature. The rods, which grew along the axis of the laser beam, had a typical diameter of 30--80 mum and a length of about 1 mm. The precursors for carbon deposition were the alkynes: propyne, butyne, pentyne, hexyne, and octyne. Propyne gave the highest deposition rate, in excess 3 mm/s at high laser powers (0.45 W) and high partial pressures (3000 mbar). the temperature dependence and pressure dependence were both non-linear functions of the growth rate. the temperature dependence could be separated into two regions---the kinetically limited region, which obeys the Arrhenius relationship, and the transport limited region, which is explained by diffusion of the precursors to the reaction zone. The pressure dependence showed that the reaction order for the different precursors varied from 2.5 for propyne to 1.3 for octyne. The precursors used deposit the refractory metals were tungsten hexafloride, titanium tetraiodide and hafnium chloride. The only successful precursor was tungsten hexafluoride, which readily produced tungsten rods when mixed with hydrogen. Rod diameters typically ranged from 50 mum to 400 mum and the average length of the rods were about 1 mm. Much lower deposition rates, less than 4.5 mum/s were obtained in this case as compared to carbon deposition. By an optimization of the LCVD process, it was possible to deposit high-quality single crystal tungsten rods. They were all oriented in the <100> direction.

  5. 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.

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

    SciTech Connect

    Vaughan, D. (comp.)

    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.

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

    SciTech Connect

    Vaughan, D. [comp.

    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.

  8. Lasing Characteristics of Low-Threshold GaInNAs Lasers Grown by Metalorganic Chemical Vapor Deposition

    Microsoft Academic Search

    Masao Kawaguchi; Tomoyuki Miyamoto; Eric Gouardes; Dietmar Schlenker; Takashi Kondo; Fumio Koyama; Kenichi Iga

    2001-01-01

    We report on the lasing characteristics of low-threshold long-wavelength GaInNAs double quantum well (DQW) lasers grown by metalorganic chemical vapor deposition (MOCVD). We have achieved a threshold current density of 450 A\\/cm2 for a 1.28-mum-emitting laser. This is the lowest value for 1.3-mum-range GaInNAs lasers grown by MOCVD@. We also observed high characteristic temperatures (T0) of 210 K and 130

  9. Functionalized polysiloxane thin films deposited by matrix-assisted pulsed laser evaporation for advanced chemical sensor applications

    Microsoft Academic Search

    E. J. Houser; D. B. Chrisey; M. Bercu; N. D. Scarisoreanu; A. Purice; D. Colceag; C. Constantinescu; A. Moldovan; M. Dinescu

    2006-01-01

    High-quality thin films of fragile chemoselective polymers with precise and accurate thickness, density and chemical integrity are required for advanced chemical sensor applications. While these attributes are difficult to achieve by conventional methods, we have successfully demonstrated the matrix-assisted pulsed laser evaporation (MAPLE) deposition of thin films of especially synthesized fluoro-alcohol substituted carbo-polysiloxane polymer coatings. The quadrupled output of a

  10. Volume 1 IO, number 5 CHEMICAL PHYSICS LETTERS 12 October 1984 PICOSECOND LASER STUDIES ON THE EFFECT OF STRUCTURE AND ENVIRONMENT

    E-print Network

    Eisenthal, Kenneth B.

    /YAG laser (1064 mn, 25-30 ps fwhm) was frequency tripled (355 nm) and qua- drupled (266 nm) to produceVolume 1 IO, number 5 CHEMICAL PHYSICS LETTERS 12 October 1984 PICOSECOND LASER STUDIES by a connecting ethylene bridge. The a'pproach used in the measurement of intersys- tern crossing was laser

  11. Analytical study of the chemical and physical changes induced by KrF laser cleaning of tempera paints.

    PubMed

    Castillejo, Marta; Martin, Margarita; Oujia, Mohamed; Silva, Diego; Torres, Ricardo; Manousaki, Alexandra; Zafiropulos, Vassilis; van den Brink, Oscar F; Heeren, Ron M A; Teule, Rianne; Silva, Alberto; Gouveia, Helena

    2002-09-15

    The cleaning of paintings using UV lasers is a growing field of interest in the practice of conservation. In this work, we have studied the chemical and physical changes induced by KrF excimer laser at 248 nm of tempera paint dosimeter systems. The changes have been evaluated by using a range of analytical techniques. These include profilometry; colorimetry; optical and vibrational spectroscopies, such as laser-induced fluorescence (LIF), laser-induced breakdown spectroscopy (LIBS), Fourier transform Raman (FTR), and infrared (FT-IR); and analytical mass spectrometric techniques, such as direct-temperature-resolved mass spectrometry (DTMS) and matrix-assisted laser desorption and ionization mass spectrometry (MALDI-MS). Integration of the results obtained by these techniques allowed the investigation of the nature and degree of change of the irradiated paint systems. Direct laser irradiation induces various degrees of discoloration that depend strongly on the nature of the pigment. This effect takes place mainly on the surface layer of the sample. Degradation of the binding medium occurs in the presence of inorganic pigments, and in some cases, evidence of alterations in the molecular composition of the pigment has been obtained. Varnished systems do not display this discoloration when a thin protective layer is left on the paint. A laser cleaning strategy for varnished paintings should be based on the partial removal of the varnish, leaving a residual layer that shields the underlying pigments from direct laser exposure. PMID:12349968

  12. 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.

  13. Laser-pulse photolysis studies of chemical reactions in the brain

    NASA Astrophysics Data System (ADS)

    Hess, George P.

    1998-04-01

    Membrane-bound receptor proteins regulate the transmission of signals at the junctions between cells of the mammalian nervous system. Upon binding a specific neurotransmitter these receptor proteins form transient channels through which inorganic ions flow, leading to a change in the transmembrane voltage of a cell. A newly developed laser- pulse photolysis technique, with a microsecond(s) time resolution, allows one to determine the rate constants for both the formation and closing of the transmembrane channel, the dissociation constant for the ligand-binding site that controls channel opening, and the concentration of the receptor in the cell membrane, and gives information about the rate of transient inactivation of the receptor. The technique allows one to determine the binding constants of inhibitors to the closed- and open-channel forms independently. THe use of the chemical kinetic method is illustrated.

  14. Effect of sample compositions on chemical analysis using matrix-assisted laser desorption ionization mass spectrometry

    SciTech Connect

    Schriemer, D.; Dai, Y.; Li, L. [Univ. of Alberta, Edmonton, Alberta (Canada). Dept. of Chemistry

    1996-12-31

    Matrix-assisted laser desorption ionization (MALDI) is an effective ionization technique for mass spectrometry. It takes advantages of some unique properties of certain organic chemicals to provide entrapment, isolation, vaporization, and ionization of the analyte of interest. While the main application of the MALDI technique is currently in the area of biological molecule analysis, it is possible to use this technique for monitoring polymer chemistry such as degradation processes. This is potentially important for studying and developing environmentally degradable polymers. Direct analysis of the analyte in real-world samples is possible with MALDI. However, there is a significant effect of the overall composition of a sample on the detectability and performance of MALDI. Two examples are given to illustrate the positive and negative effects of buffers, salts, and additives on the MALDI sample preparation.

  15. 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 CuCO3?Cu(OH)2, azurite 2CuCO3?Cu(OH)2, yellow ochre (goethite ?-FeOOH, gypsum CaSO4?2H2O), 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.

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

    SciTech Connect

    Van-Hoang Le [J. R. Macdonald Laboratory, Department of Physics, Cardwell Hall, Kansas State University, Manhattan, Kansas 66506 (United States); Department of Physics, University of Pedagogy, 280 An Duong Vuong, Ward 5, Ho Chi Minh City (Viet Nam); Anh-Thu Le; Xie Ruihua; Lin, C. D. [J. R. Macdonald Laboratory, Department of Physics, Cardwell Hall, Kansas State University, Manhattan, Kansas 66506 (United States)

    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.

  17. 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 ?m 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.

  18. Probing Physical and Chemical Properties of Laser Shocked Materials using Ultrafast Dynamic Ellipsometry and Spectroscopies

    NASA Astrophysics Data System (ADS)

    Dang, Nhan

    2013-06-01

    Ultrafast laser techniques allow resolution of shock induced physics and chemistry picoseconds behind the shock front. In this presentation, the 350 ps sustained laser-generated shocks will be shown to combine with ultrafast dynamic ellipsometry to measure the shock state and transient absorption to measure the molecular electronic response to shock loading. Experimental data will be presented on shocked explosive crystals and liquids. Ultrafast dynamic ellipsometry was used to measure the shock and particle velocity as well as the shocked refractive index. Transient absorption spectra of RDX and simple molecular liquids in the spectral region from 440 to 780 nm were measured to map out shock reactivity during the first 350 ps, over shock stress states from 7 to 20 GPa. Additionally, nonlinear spectroscopic probes will be demonstrated to offer the potential to measure even more details of the molecular shock response, such as evolution of chemical species and vibrational temperature. Preliminary results of shocked phenylacetylene obtained using vibrational coherent anti-Stokes Raman spectroscopy (CARS) and the capability of femtosecond stimulated Raman scattering (FSRS) data to measure the nonequilibrium time evolution of mode specific vibrational temperatures on picosecond time scales will be discussed.

  19. Thermal diffusion and chemical kinetics in laminar biomaterial due to heating by a free-electron laser

    Microsoft Academic Search

    M. Shane Hutson; Susanne A. Hauger; Glenn Edwards

    2002-01-01

    We have theoretically investigated the role of thermal diffusion and chemical kinetics as a possible dynamic explanation for the preferential ablative properties of infrared radiation from a free-electron laser ~FEL!. The model is based on a laminar system composed of alternating layers of protein and saline. We have compared exposure to 3 mm where water is the main absorber and

  20. The effect of rotational relaxation rate on the operation of a pulsed H2 + F2 chemical laser

    Microsoft Academic Search

    G. K. Vasilev; E. F. Makarov; A. G. Riabenko; V. L. Talroze

    1976-01-01

    The effect of rotational relaxation rate on the characteristics of an H2 + F2 chemical laser with HF molecules is examined. Two limiting cases are considered: (1) the case of fast rotational relaxation where the relaxation rate is much greater than the rate of processes which disrupt rotational equilibrium, and (2) the case of a frozen rotational relaxation where the

  1. Chemical vapor deposition of highly adherent diamond coatings onto co-cemented tungsten carbides irradiated by high power diode laser.

    PubMed

    Barletta, M; Rubino, G; Valle, R; Polini, R

    2012-02-01

    The present investigation deals with the definition of a new eco-friendly alternative to pretreat Co-cemented tungsten carbide (WC-Co) substrates before diamond deposition by hot filament chemical vapor deposition (HFCVD). In particular, WC-5.8 wt %Co substrates were submitted to a thermal treatment by a continuous wave-high power diode laser to reduce surface Co concentration and promote the reconstruction of the WC grains. Laser pretreatments were performed both in N(2) and Ar atmosphere to prevent substrate oxidation. Diamond coatings were deposited onto the laser pretreated substrates by HFCVD. For comparative purpose, diamond coatings were also deposited on WC-5.8 wt %Co substrates chemically etched by the well-known two-step pretreatment employing Murakami's reagent and Caro's acid. Surface morphology, microstructure, and chemical composition of the WC-5.8 wt %Co substrates after the different pretreatments and the deposition of diamond coatings were assessed by surface profiler, scanning electron microscopy, energy-dispersive X-ray spectroscopy, and X-ray diffraction analyses. Wear performance of the diamond coatings was checked by dry sliding linear reciprocating tribological tests. The worn volume of the diamond coatings deposited on the laser pretreated substrates was always found lower than the one measured on the chemically etched substrates, with the N(2) atmosphere being particularly promising. PMID:22206356

  2. Developments in Theoretical and Applied Mechanics, Vol. XVIII, eds. H. Wilson, R. Batra, C. Bert, A. Davis R. Schapery, D. Stewart, and F. Swinson, School of Engineering, The University of Alabama, 1996, pp. 411-424.

    E-print Network

    Carroll, David L.

    is followed by an energy transfer from other O2(1) molecules to the liberated iodine atoms, thus providing. The typical chemical oxygen-iodine laser (COIL) utilizes an energy transfer from the singlet delta excited the energy for the atomic iodine laser transition of interest. A number of papers have investigated issues

  3. Lasers

    Microsoft Academic Search

    Peter W. Milonni; Joseph H. Eberly

    1988-01-01

    Lasers A comprehensive introduction to the operating principles and applications of lasers. Explains basic principles, including the necessary elements of classical and quantum physics. Provides concise discussions of various laser types including gas, solid state, semiconductor, and free electron lasers, as well as of laser resonators, diffraction, optical coherence, and many applications including holography, phase conjugation, wave mixing, and nonlinear

  4. High performance light trapping structures for Si-based photoelectronics fabricated by hybrid picosecond laser irradiation and chemical corrosion

    NASA Astrophysics Data System (ADS)

    Ji, Lingfei; Lv, Xiaozhan; Wu, Yan; Lin, Zhenyuan; Jiang, Yijian

    2015-03-01

    We propose the fabrication of two types high performance texturized antireflective structures on crystalline (100) silicon (c-Si) surface by hybrid picosecond laser scanning irradiation followed by chemical corrosion. The design and the fabrication with high controllable performance were studied. The hybrid method includes 1064 nm picosecond (ps) laser scanning to form micro-hole array and subsequently short-time alkaline corrosion. After ps laser processing, there is little reconsolidation and heat affect zone on the silicon surface, which is beneficial to achieve the precise chemical corrosion effect. Depending on the laser scanning intervals, scanning times and chemical corrosion time, a variety of surface texture morphologies, even a special micro-nano hierarchical structure in which finer nano-structures formed in the micro units of the texture, were achieved. Observing with SEM, the average diameter of the micro-holes in the micro-nano hierarchica is 25~30 ?m, while the average size of the nano-level ladder-like structures on the micro-hole wall is from dozens to hundreds of nanometers. Comparing to the traditional laser texturing techniques for c-Si solar cell, the whole laser processing was carried out in an open air ambient without using etch mask and SF6/O2 plasma. The results show the reflectance value of the fabricated c-Si surfaces can reach as low as 6% (400 nm~1000 nm). This is a potential method for economical antireflective structures fabrication which is ideal for using in the high-efficiency silicon-based photoelectronic devices.

  5. 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.

  6. 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 ?m to 12 ?m. 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.

  7. Melting and crystallization behavior of low-pressure chemical-vapor-deposition amorphous Si films during excimer-laser annealing

    NASA Astrophysics Data System (ADS)

    Voogt, F. C.; Ishihara, R.; Tichelaar, F. D.

    2004-03-01

    Results are presented of cross-sectional transmission-electron microscopy and time-resolved optical reflectivity investigations into the excimer-laser annealing of low-pressure chemical-vapor-deposition amorphous Si films. It is found that, in the initial stages of the laser pulse, a thin surface layer melts. This is directly followed by explosive crystallization of the film into to small, columnar, and defect-rich grains. As more laser energy is consumed, the Si film melts in from the surface for a second time, eventually leading to complete melting of the film. It is argued that melting along grain boundaries and defects is a crucial step in obtaining large, single-crystalline grains in the super-lateral growth regime.

  8. {ital Ex situ} ellipsometry characterization of excimer laser annealed amorphous silicon thin films grown by low pressure chemical vapor deposition

    SciTech Connect

    Kuo, C.; Hsieh, I.; Schroder, D.K. [Center for Solid State Electronics Research and Department of Electrical Engineering, Arizona State University, Tempe, Arizona 85287-6206 (United States)] [Center for Solid State Electronics Research and Department of Electrical Engineering, Arizona State University, Tempe, Arizona 85287-6206 (United States); Maracas, G.N. [Motorola, Phoenix Corporate Research Laboratory, Tempe, Arizona 85284 (United States)] [Motorola, Phoenix Corporate Research Laboratory, Tempe, Arizona 85284 (United States); Chen, S. [XMR Inc., Fremont, California 94538 (United States)] [XMR Inc., Fremont, California 94538 (United States); Sigmon, T.W. [Lawrence Livermore National Laboratory, L-271, Livermore, California 94551 (United States)] [Lawrence Livermore National Laboratory, L-271, Livermore, California 94551 (United States)

    1997-07-01

    Spectroscopic ellipsometry was used to monitor excimer laser annealed thin ({approximately}100nm) amorphous silicon (a-Si) films grown on quartz substrates by low pressure chemical vapor deposition (LPCVD). The peak position of the imaginary part of the complex dielectric function {epsilon}{sub 2} was used to determine the degree of crystallization of the a-Si. The amplitude of {epsilon}{sub 2} at the Si E{sub 1} transition energy is found to be a good indicator of the polycrystalline silicon (poly-Si) grain size after laser annealing with good correlation between {ital ex situ} ellipsometric data and poly-Si grain sizes being observed. Spectroscopic ellipsometry provides a contactless, nondestructive, and simple technique for monitoring laser annealing both {ital in situ} during the annealing process or {ital ex situ} after annealing. {copyright} {ital 1997 American Institute of Physics.}

  9. Photonic metamaterials by direct laser writing and silver chemical vapour deposition.

    PubMed

    Rill, Michael S; Plet, Christine; Thiel, Michael; Staude, Isabelle; von Freymann, Georg; Linden, Stefan; Wegener, Martin

    2008-07-01

    Metamaterials are artificial materials that--unlike natural substances--enable magnetism to be achieved at optical frequencies. The vast majority of photonic metamaterials has been fabricated by electron-beam lithography and evaporation of metal films, both of which are well-established two-dimensional (2D) technologies. Although stacking of three or four functional layers made using these methods has been reported, a truly 3D fabrication approach would be preferable for 3D photonic metamaterials. Here, we report first steps in this direction by using a combination of direct laser writing and silver chemical vapour deposition--the 3D analogues of electron-beam lithography and evaporation, respectively. The optical characterization of a planar test structure composed of elongated split-ring resonators is in good agreement with theory. Retrieval of the effective optical parameters reveals the importance of bi-anisotropy. Once suitable theoretical blueprints are available, our fabrication approach will enable rapid prototyping of truly 3D photonic metamaterials. PMID:18469820

  10. 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

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

    SciTech Connect

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

    2013-01-01

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

  12. Far infrared chemical lasers. Technical progress report No. 6, September 1, 1979August 31, 1980

    Microsoft Academic Search

    1980-01-01

    Some preliminary experiments in gas laser research are discussed. A new technique for measuring the linewidth of many high J,K rotational lines is presented. The method utilized the Stark effect on optically-pumped molecular gas lasers. Formulas are given for calculating linewidths from experimentally measured electric field strengths. Pure rotational laser oscillation has been observed in HF following flash photolysis of

  13. Enhanced chemical shift of carbon nanotube from laser assisted gas incorporation

    E-print Network

    Lin, Minn-Tsong

    state analysis by scanning photoelectron microscopy SPEM .9,10 After the laser beam irradiates structure of laser modified carbon nanotubes CNTs by scanning photoelectron microscopy. After laser pruning shifts of 0.9 and 0.6 eV in carbon 1s state, respectively. The modification of electronic structure

  14. Optical study of GaN epilayer grown by metalorganic chemical vapor deposition and pulsed laser deposition

    Microsoft Academic Search

    P. Premchander; P. Manoravi; M. Joseph; K. Baskar

    2005-01-01

    Unintentionally doped n-type GaN (0001) epitaxial layers were grown by metalorganic chemical vapor deposition (MOCVD) and pulsed laser deposition (PLD) on sapphire substrates. As-grown GaN films were irradiated with 75MeV high-energy Sn5+ ions at the fluence of 1011cm?2. Both as-grown and irradiated layers were studied by time-resolved photoluminescence (TRPL), photoluminescence (PL) and UV-absorption spectroscopy techniques at room temperature. Surface morphologies

  15. Fabrications of Si Thin-Film Solar Cells by Hot-Wire Chemical Vapor Deposition and Laser Doping Techniques

    Microsoft Academic Search

    Shui-Yang Lien; Dong-Sing Wuu; Hsin-Yuan Mao; Bing-Rui Wu; Yen-Chia Lin; In-Cha Hseih; Ray-Hua Horng

    2006-01-01

    In this paper, we report a novel low-temperature process for fabricating a Si thin-film solar cell on a glass substrate. The cell structure was composed of glass\\/Al\\/p-i-n Si\\/Ag (grid), where the Si intrinsic layer was deposited by hot-wire chemical vapor deposition. All the doped Si layers were produced using a postgrowth laser-doping process. The hot-wire-deposited amorphous, microcrystalline and polycrystalline Si

  16. Chemical Beam Epitaxy (cbe) and Laser-Enhanced CBE of Gallium Arsenide and Indium Gallium Arsenide Using Novel Gas Sources

    Microsoft Academic Search

    Haike Dong

    1995-01-01

    In recent years, chemical beam epitaxy (CBE), or metalorganic molecular beam epitaxy (MOMBE), has been under active development to exploit the advantages of conventional solid-source molecular beam epitaxy (MBE) and metal-organic vapor phase epitaxy (MOVPE). One of the important issues in CBE\\/MOMBE is the selective-area growth by direct writing with an external energy source, e.g., an argon ion laser. The

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

    Microsoft Academic Search

    Pauline Ho; Michael E. Coltrin; William G. Breiland

    1994-01-01

    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

  18. Functionalized polysiloxane thin films deposited by matrix-assisted pulsed laser evaporation for advanced chemical sensor applications

    NASA Astrophysics Data System (ADS)

    Houser, E. J.; Chrisey, D. B.; Bercu, M.; Scarisoreanu, N. D.; Purice, A.; Colceag, D.; Constantinescu, C.; Moldovan, A.; Dinescu, M.

    2006-04-01

    High-quality thin films of fragile chemoselective polymers with precise and accurate thickness, density and chemical integrity are required for advanced chemical sensor applications. While these attributes are difficult to achieve by conventional methods, we have successfully demonstrated the matrix-assisted pulsed laser evaporation (MAPLE) deposition of thin films of especially synthesized fluoro-alcohol substituted carbo-polysiloxane polymer coatings. The quadrupled output of a Nd:YAG laser (265 nm) served as the laser source and depositions were done in a background pressure of N 2. Using various solvents appropriate to solvate this polymer (e.g. tetrahydrofuran, acetone and chloroform) and varying the laser fluence, we optimized the deposition of high-quality thin films on 1 cm 2 double-polished silicon substrates. The best solvent used as matrix was proved to be acetone. Under these conditions, the important functional groups were reproduced and observed by Fourier Transform Infrared Spectroscopy (FTIR) as compared to the drop cast films and the surface roughness was analysed using Atomic Force Microscopy (AFM) and found to be much smoother than conventional wet deposition techniques.

  19. A Study on Fractional Erbium Glass Laser Therapy Versus Chemical Peeling for the Treatment of Melasma in Female Patients

    PubMed Central

    Puri, Neerja

    2013-01-01

    Introduction: Melasma is a commonly acquired hypermelanosis and a common dermatologic skin disease that occurs on sun-exposed areas of face. Aims: To assess the efficacy and safety of non-ablative 1,550 nm Erbium glass fractional laser therapy and compare results with those obtained with chemical peeling. Materials and Methods: We selected 30 patients of melasma aged between 20 years and 50 years for the study. The patients were divided into two groups of 15 patients each. Group I patients were subjected to four sessions of 1,550 nm Erbium glass non-ablative fractional laser at 3 weeks interval. In group II patients, four sessions of chemical peeling with 70% glycolic acid was performed. Results: After 12 weeks of treatment, percentage reduction in Melasma Area and Severity Index (MASI) score was seen in 62.9% in the laser group and 58.7% in the peels group. Conclusion: It was observed that 1,550 nm fractional laser is as effective as 70% glycolic acid peel in reducing MASI score in patients with melasma. PMID:24163531

  20. Quantum cascade laser based techniques for the detection of explosives, chemical warfare agents and toxic industrial chemicals

    Microsoft Academic Search

    C. K. N. Patel

    2007-01-01

    Worldwide occurrence of terrorist activities has made it imperative to use the best available technology for identifying and defeating terrorism involving improvised explosive devices (IED), chemical warfare agents (CWAs) and toxic industrial chemicals (TICs). Early and unequivocal detection of the explosives, CWAs and TICs require highly sensitive measurement techniques that are not confused by the presence of the multitude of

  1. 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 ?m 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 (? ? 190 fs, ? = 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

  2. 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).

  3. Investigation of silicon—germanium metal-oxide-semiconductor field-effect transistors grown by laser-assisted plasma-enhanced chemical vapor deposition

    Microsoft Academic Search

    Ching-Ting Lee; Jian-Gang Lin; Hsin-Ying Lee

    2008-01-01

    SiGe based metal-oxide-semiconductor field-effect transistors (MOSFETs) were fabricated, in which the SiGe channel layer was deposited by using laser-assisted plasma-enhanced chemical vapor deposition (LAPECVD) system. The characteristics were compared with the device without laser assistance.

  4. Lasers

    SciTech Connect

    Eberly, J.H.; Milonni, P.W.

    1988-01-01

    This book explains the operating principles and applications of lasers, including central background material. It incorporates many intuitive explanations and practical examples. Introduces basic principles, including the necessary classical and quantum physics, and provides discussions of specific lasers, laser resonators, and applications, including nonlinear optics.

  5. Modeling of dual emission laser induced fluorescence for slurry thickness measurements in chemical mechanical polishing

    Microsoft Academic Search

    Caprice GrayChris; Chris B. Rogers; Vincent P. Manno; Robert D. White

    2011-01-01

    Dual emission laser induced fluorescence (DELIF) is a technique for measuring the instantaneous thin fluid film thickness\\u000a in dynamic systems. Two fluorophores within the system produce laser induced emissions that are filtered and captured by two\\u000a cameras. The ratio of the images from these cameras is used to cancel the effect of the laser beam profile on the image intensity.

  6. Regeneration technique for basic hydrogen peroxide using potassium superoxide

    Microsoft Academic Search

    Warren L. Dinges; John C. Horrocks; Thomas J. Lonergan

    1994-01-01

    Basic hydrogen peroxide (BHP), the principle fuel for chemical oxygen-iodine lasers, was completely regenerated by the direct addition of potassium superoxide. The researchers successfully returned the reactive hydroperoxide ion, O2H-, to its original molarity. This novel regeneration method is compared with a regeneration technique using potassium hydroxide and hydrogen peroxide. The initial generation of BHP using these standard mixing reagents

  7. Study on Dynamic Alignment Technology of COIL Resonator

    Microsoft Academic Search

    M D Xiong; X J Zou; J H Guo; S N Jia; Z B Zhang

    2006-01-01

    The performance of great power chemical oxygen-iodine laser (COIL) beam is decided mostly by resonator mirror maladjustment and environment vibration. To improve the performance of light beam, an auto-alignment device is used in COIL resonator, the device can keep COIL resonator collimating by adjusting the optical components of resonator. So the coupling model of COIL resonator is present. The multivariable

  8. Fabrication of microcapillaries in fused silica using axicon focusing of femtosecond laser radiation and chemical etchingion/ms

    SciTech Connect

    Yashunin, D A; Malkov, Yu A; Stepanov, A N [Institute of Applied Physics, Russian Academy of Sciences, Nizhnii Novgorod (Russian Federation)

    2013-04-30

    Fabrication of microcapillaries with a diameter of 50 - 80 {mu}m and a length up to 2.5 mm in fused silica by axicon focusing of femtosecond laser radiation and subsequent chemical etching in a 8 % hydrofluoric acid solution is demonstrated. The etching rate is {approx}6 {mu}m min{sup -1}. It is shown that the microcapillaries have optical waveguiding properties, which testifies to the optical quality of the walls of obtained structures. (extreme light fields and their applications)

  9. Enhancing wavelength selection for Quantum Cascade laser based chemical sensors by cavity length variation

    Microsoft Academic Search

    Christina Young; Richard Cendejas; Scott S. Howard; Wendy Sanchez-Vaynshteyn; A. J. Hoffman; K. J. Franz; Yu Yao; B. Mizaikoff; Xiaojun Wang; J. Fan; C. F. Gmachl

    2009-01-01

    Varying quantum cascade laser cavity length results in gain peak selection across a 118 cm-1 range; a result of a change in threshold voltage, and applied electric field as a function of cavity length.

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

    EPA Science Inventory

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

  11. 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 ?m) 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.

  12. Depth profile analysis of the chemical and morphological changes in CO2-laser-irradiated dental enamel

    NASA Astrophysics Data System (ADS)

    Zuerlein, Michael J.; Fried, Daniel; Featherstone, John D. B.

    1999-05-01

    Previous studies have shown that IR irradiation of dental enamel at specific wavelengths results in chemical changes in the mineral phase that reduce the progression of sub- surface caries-like lesions. The inhibition of lesion progression has been correlated to the decomposition of carbonate in the irradiated enamel mineral. The present study investigated loss of the carbonate component as a function of depth with 1 micrometers resolution by measuring the strength of the spectrum in the region of the carbonate absorption bands near 1400 cm-1. Bovine enamel samples were laser treated at ?=9.6 ?m with a pulse duration of either 2 ?s or 100 ?s and at ?=10.6 ?m with a pluse duration of 2 ?s. The depth of treatment was compared with numerical simulation of the temperature rise in enamel due to laser heating. The temperature rise needed to initiate carbonate loss was 400° C, but complete carbonate loss did not occur until surface temperatures were reached which exceeded the melting temperature (800-1200 °C). The depth of the treatment varied depending upon the absorption coefficient, pulse duration, and fluence of the laser irradiation.

  13. 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.

  14. 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, Rafa?; ?enkiewicz, 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.

  15. Three-dimensional laser chemical vapor deposition of nickel-iron alloys

    SciTech Connect

    Maxwell, J.L.; Pegna, J.; Deangelis, D.A.; Messia, D.V. [Rensselaer Polytechnic Inst., Troy, NY (United States). Center for Integrated Electronics and Electronics Manufacturing

    1996-12-31

    A systematic study of the composition of Ni-Fe steel microstructures grown from iron pentacarbonyl and nickel tetracarbonyl by direct laser-induced pyrolysis is presented. The partial pressures of both precursors were varied from 2 to 40 mbar, resulting in needles of iron, nickel, and iron-nickel alloys. An Ar+ laser was employed at incident powers of 100 to 600 mW. Auger Spectroscopy and a microprobe were used to determine the composition of the needles vs. partial pressure and laser power. Composition was also measured along the length of the rods to determine temperature changes during needle growth. This latter effect is useful in modelling the heat flow mechanisms during 3-dimensional laser CVD, as the threshold decomposition temperatures of Fe(CO){sub 5} and Ni(CO){sub 4} differ and the composition of the rods affects their thermal conductivity. In some iron samples, periodic banded structures were observed along the length of the rods, indicative of periodic melting. Axial deposition rates were also measured relative to laser power density, and rates up to 40 {micro}m/s were achieved. Photolysis in the gas phase was observed for the iron-nickel carbonyl mixture, and was largely eliminated with a high-pass UV filter at 420 nm. Additional disassociation of the carbonyl groups produced carbon soot near the reaction zone, but only for high nickel carbonyl concentrations. Convective cooling of the needles during growth was determined to be the primary heat transfer mechanism.

  16. 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

  17. Submicron period grating structures in Ta 2O 5 thin oxide films patterned using UV laser post-exposure chemically assisted selective etching

    Microsoft Academic Search

    S. Pissadakis; A. Ikiades; C. Y. Tai; N. P. Sessions; J. S. Wilkinson

    2004-01-01

    A high-resolution and low-damage method for patterning relief structures in thin Ta2O5 films by chemically assisted UV laser selective etching is presented. The method is based on the initial exposure of the Ta2O5 films to pulsed UV radiation (quadrupled Nd:YAG laser at 266 nm) at fluences below the ablation threshold, for the creation of volume damage in the exposed areas.

  18. High efficiency InGaAs\\/GaAs single-quantum-well lasers using single-step metalorganic chemical vapor deposition

    Microsoft Academic Search

    Hanmin Zhao; Michael H. MacDougal; Newton C. Frateschi; Sabeur Siala; P. D. Dapkus; R. N. Nottenburg

    1994-01-01

    Low-threshold-current single-quantum-well InGaAs\\/GaAs lasers are fabricated by metalorganic chemical vapor deposition on a nonplanar substrate. By taking advantage of the growth rate and doping differences on different crystal facets during the growth, a buried heterostructure laser with natural current blocking p-n-p-n junction is formed by a single growth step. Threshold currents as low as 1.0 mA under pulsed operation and

  19. 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.

  20. 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, 5?-cholestane, cholesta-3,5-diene, squalene, and ?-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

  1. Characterization of nonpolar lipids and steroids by using laser-induced acoustic desorption/chemical ionization, atmospheric pressure chemical ionization, and electrospray ionization mass spectrometry

    SciTech Connect

    Jin, Z.; Daiya, S.; Kenttämaa, Hilkka I.

    2011-01-01

    Laser-induced acoustic desorption (LIAD) combined with ClMn(H{sub 2}O){sup +} 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, 5?-cholestane, cholesta-3,5-diene, squalene, and ?-carotene, were found to solely form the desired water replacement product (adduct-H{sub 2}O) upon reaction with the ClMn(H{sub 2}O){sup +} ions. The steroids, androsterone, dehydroepiandrosterone (DHEA), estrone, estradiol, and estriol, also form abundant adduct-H{sub 2}O ions, but less abundant adduct-2H{sub 2}O 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(H{sub 2}O){sup +} chemical ionization is superior over APCI and ESI for the mass spectrometric characterization of underivatized nonpolar lipids and steroids.

  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.

    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.

  3. Hybrid laser micro\\/nanofabrication of phase change materials with combination of chemical processing

    Microsoft Academic Search

    Y. Lin; M. H. Hong; G. X. Chen; C. S. Lim; L. S. Tan; Z. B. Wang; L. P. Shi; T. C. Chong

    2007-01-01

    Phase change materials have been widely applied in optical data storage technique to produce rewritable versions of compact disks and digital versatile disks random access memory and are still promising for higher capacity optical data storage. In optical data storage system, laser irradiation is used to write and read information in phase change film. The original phase state of phase

  4. Reliability of AlGaAs/GaAs laser diodes grown by metalorganic chemical vapor deposition

    NASA Astrophysics Data System (ADS)

    Dreisewerd, D.; Fritz, W.; Begley, D.; Schwedt, S.; Elliott, G.

    1988-01-01

    The results from an extensive life test of wide stripe laser diodes operating in the 808 nm wavelength region and at a heatsink temperature of -20 C are reported. Devices were mounted p-side down on BeO heatsinks with indium solder. Stringent screening and burn-in criteria were applied to the device population prior to selection for long term test.

  5. Reliability of AlGaAs\\/GaAs laser diodes grown by metalorganic chemical vapor deposition

    Microsoft Academic Search

    D. Dreisewerd; W. Fritz; D. Begley; S. Schwedt; G. Elliott

    1988-01-01

    The results from an extensive life test of wide stripe laser diodes operating in the 808 nm wavelength region and at a heatsink temperature of -20 C are reported. Devices were mounted p-side down on BeO heatsinks with indium solder. Stringent screening and burn-in criteria were applied to the device population prior to selection for long term test.

  6. Laser-induced breakdown spectroscopy (LIBS): a promising versatile chemical sensor technology for hazardous material detection

    Microsoft Academic Search

    Frank C. DeLucia; Alan C. Samuels; Russell S. Harmon; Roy A. Walters; Kevin L. McNesby; Aaron LaPointe; Andrzej W. Miziolek

    2005-01-01

    A series of laboratory experiments have been performed highlighting the potential of laser-induced breakdown spectroscopy (LIBS) as a versatile sensor for the detection of terrorist threats. LIBS has multiple attributes that provide the promise of unprecedented performance for hazardous material detection and identification. These include: 1) real-time analysis, 2) high sensitivity, 3) no sample preparation, and 4) the ability to

  7. DIODE-LASER-BASED MEASUREMENTS OF HYDROGEN FLUORIDE GAS DURING CHEMICAL SUPPRESSION OF FIRES

    EPA Science Inventory

    Near-infrared tunable diode laser (NIR-TDL) spectroscopy is used to quantify HF gas produced during fire suppressant testing of Halon alternatives. Results of comparisons with other techniques for measuring HF gas concentrations are discussed. Measurements of HF gas produced in l...

  8. DIODE LASER-BASED MEASUREMENTS OF HYDROGEN FLUORIDE GAS DURING CHEMICAL SUPPRESSION OF FIRES

    EPA Science Inventory

    Near-infrared tunable diode laser (NIR-TDL) spectroscopy is used to quantify hydrogen fluoride (HF) gas produced during fire-suppressant testing of Halon alternatives. Results of comparisons with other techniques for measuring HF gas concentrations are discussed. Measurements of ...

  9. Far infrared chemical lasers. Technical progress report No. 6, September 1, 1979-August 31, 1980

    SciTech Connect

    Robinson, D. W.

    1980-01-01

    Some preliminary experiments in gas laser research are discussed. A new technique for measuring the linewidth of many high J,K rotational lines is presented. The method utilized the Stark effect on optically-pumped molecular gas lasers. Formulas are given for calculating linewidths from experimentally measured electric field strengths. Pure rotational laser oscillation has been observed in HF following flash photolysis of various mixtures of trifluoromethyl halide, acetylenic compound and argon in the ratio of 1:1:100. The mixed systems show laser intensity at lower rotational levels than could be explained by simple V ..-->.. R collision induced mechanisms (as in the case of CH/sub 2/CF/sub 2/). Further, the intensities in these anomalously low rotational levels appear to be a function of the identity of the electronically excited halide (I* or Br*) produced photolytically. A computer simulation model has been constructed which relaxes nascent HF through V ..-->.. R transfer (formed vibrationally and rotationally excited by elimination) but incorporates an additional pumping mechanism, that of quenching of I* or Br* by these relaxing HF molecules. Most of the experimentally observed laser intensities are explained on the basis of this new pumping mechanism. The observations of intense, amplified spontaneous emission on fifteen far infrared lines from flashlamp pumped H/sub 2/O vapor in the 0.010 to 0.080 torr pressure range is described and explained. A mechanism based on direct optical pumping and collisional redistribution between resonance perturbed levels is presented. The mechanism accounts for experimental dependence of the superfluorescent emissions on pressure and flashlamp energy. Progress is also reported on some preliminary experiments with flashlamp pumping of three new molecules, H/sub 2/CO, NH/sub 3/, and H/sub 2/S.

  10. 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 ?m 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.

  11. Pulsed laser deposition of mesoporous niobium oxide thin films and application as chemical sensors

    Microsoft Academic Search

    Mary E Gimon-Kinsel; Kenneth J Balkus

    1999-01-01

    The pulsed laser deposition (PLD) of a mesoporous niobium oxide, Nb-TMS1, and post-hydrothermal treatment result in mesoporous thin films (90nm–3?m thick) having what appears to be a three-dimensional disordered hexagonal or `wormhole' structure. These films were characterized by FT-IR spectroscopy, X-ray diffraction, scanning electron microscopy and transmission electron microscopy. The mesoporous Nb-TMS1 thin films were employed as the dielectric phase

  12. 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.

  13. 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.

  14. 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. [Department of Electrical Engineering, University of Nebraska-Lincoln, Lincoln, Nebraska 68588 (United States)] [Department of Electrical Engineering, University of Nebraska-Lincoln, Lincoln, Nebraska 68588 (United States)

    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.

  15. A thermo-chemical model of liquid iron oxidation during plasma arc or laser cutting

    NASA Astrophysics Data System (ADS)

    Nemchinsky, Valerian

    2012-11-01

    It is suggested that if liquid iron is in contact with an atmosphere of gaseous oxygen, the chemical reaction of oxidation inside the liquid metal is of a homogeneous type, as opposed to the heterogeneous reaction of oxidation which takes place in a solid metal. A system of equations describing the inter-related chemical and heat processes is formulated and solved numerically. The obtained solution demonstrated the existence of a relatively narrow reaction zone that moves inwards through the metal. It was shown that the temperature in the reaction zone could be rather high as a result of the following sequence of events: a chemical reaction heats the metal, which boosts the oxygen diffusion and the oxygen supply to the reaction zone, which in turn increases the rate of oxidation. Thermal conductivity and depletion of the reagents stop this explosive-like process. Calculations showed that after some initial period, the reaction zone motion follows the parabolic law.

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

    NASA Astrophysics Data System (ADS)

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

    2011-01-01

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

  17. 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.

  18. Chemical characterization of microparticles by laser ablation in an ion trap mass spectrometer

    Microsoft Academic Search

    J. M. Dale; W. B. Whitten; J. M. Ramsey

    1991-01-01

    We are developing a new technique for the chemical characterization of microparticles based upon the use of electrodynamic traps. The electrodynamic trap has achieved widespread use in the mass spectrometry community in the form of the ion trap mass spectrometer or quadrupole ion trap. Small macroscopic particles can be confined or leviated within the electrode structure of a three-dimensional quadrupole

  19. 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. [Los Alamos National Lab., NM (United States). Chemical Science and Technology Div.

    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.

  20. Stability and performance of CDRL-FEL (Chemical Dynamics Research Laboratory-Free Electron Laser)

    SciTech Connect

    Kim, K.J.; Xie, M.

    1990-11-01

    We study the performance of a proposed infrared free electron laser at Lawrence Berkeley Laboratory, which would be a user facility and therefore has a unique set of requirements in intensity, spectrum and stability. The output performance in intensity and spectrum, and methods to optimize the performance, are studied in detail. The effect of the electron beam fluctuation on FEL stability is carefully evaluated to set a tolerance for the accelerator design. Use of intracavity gratings is studied as a means of further improving the spectral purity and stability. 19 refs., 12 figs., 2 tabs.

  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 ?m), 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. Electrical and chemical properties of the XeCl phototriggered laser

    NASA Astrophysics Data System (ADS)

    Harrache, Z.; Belasri, A.

    2004-04-01

    The purpose of this paper is to study, through numerical modeling, the XeCl kinetics and the mechanisms affecting plasma uniformity in high-pressure discharge pumped excimer lasers. In the model, the plasma is represented by a resistance inversely proportional to the electron density. Time variation of the electron density is obtained by integrating the transport equations coupled to the heavy-species kinetics and to the external circuit. A detailed description of the XeCl molecule and of the associated kinetics has been taken into account, together with the effect of the gas mixture composition on power deposition and the spatial uniformity of the plasma. Calculated discharge current and voltage are compared with experimental results. The obtained results indicate clearly that about 50% of the halogen is consumed at the end of the discharge pulse.

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

    NASA Astrophysics Data System (ADS)

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

    2011-02-01

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

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

    SciTech Connect

    Maxwell, James L [Los Alamos National Laboratory; Chavez, Craig A [Los Alamos National Laboratory; Espinoza, Miguel [Los Alamos National Laboratory; Black, Marcie [Los Alamos National Laboratory; Maskaly, Karlene [Los Alamos National Laboratory; Boman, Mats [UPPSALA UNIV

    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.

  6. Room-temperature continuous-wave operation of 1.24-?m GaInNAs lasers grown by metal-organic chemical vapor deposition

    Microsoft Academic Search

    Shunichi Sato; Shiro Satoh

    1999-01-01

    Room-temperature continuous-wave operation is demonstrated for the first time in a GaInNAs-GaAs laser grown by metal-organic chemical vapor deposition. A low-threshold current density of 660 A\\/cm2 and a high characteristic temperature of 113 K emitting at 1.245 ?m is achieved. Emitting at the longest wavelength of 1.225 ?m is also demonstrated in a highly strained GaInAs-GaAs double-quantum-well laser on a

  7. High-temperature characteristic in 1.3-?m-range highly strained GaInNAs ridge stripe lasers grown by metal-organic chemical vapor deposition

    Microsoft Academic Search

    Shunichi Sato; Shiro Satoh

    1999-01-01

    1.3-?m-range highly strained GaInNAs-GaAs double quantum-well ridge stripe lasers with different In contents (37% and 39%) grown by metal-organic chemical vapor deposition are demonstrated. The GaInNAs laser with In content of 37% emitting at 1.294 ?m exhibited both a low threshold current density of 1.0 kA\\/cm2 at 20°C and a high characteristic temperature of 148 K in the temperature range

  8. 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.

  9. 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 ?-Sn and ?-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 ?-Sn, when applied low heating/cooling rates, nanoislands cannot form if the diffusion barrier is larger than 0.35 eV.

  10. 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 [Green Innovation Research Laboratories, NEC Corporation, 34 Miyukigaoka, Tsukuba 305-8501 (Japan); Zhang Hong [School of Physical Science and Technology, Sichuan University, Chengdu 610065 (China); Rubio, Angel [Nano-Bio Spectroscopy group and ETSF Scientific Development Centre, Department Fisica de Materiales, Universidad del Pais Vasco, Avenida de Tolosa 72, E-20018 San Sebastian (Spain)

    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.

  11. Optical study of GaN epilayer grown by metalorganic chemical vapor deposition and pulsed laser deposition

    NASA Astrophysics Data System (ADS)

    Premchander, P.; Manoravi, P.; Joseph, M.; Baskar, K.

    2005-01-01

    Unintentionally doped n-type GaN (0 0 0 1) epitaxial layers were grown by metalorganic chemical vapor deposition (MOCVD) and pulsed laser deposition (PLD) on sapphire substrates. As-grown GaN films were irradiated with 75 MeV high-energy Sn 5+ ions at the fluence of 10 11 cm -2. Both as-grown and irradiated layers were studied by time-resolved photoluminescence (TRPL), photoluminescence (PL) and UV-absorption spectroscopy techniques at room temperature. Surface morphologies of the samples were analyzed by optical microscopy and scanning electron microscopy (SEM). The surface morphologies of the PLD thin films have revealed the presence of GaN nanoparticles. PLD-grown GaN films have shown highest minority carrier lifetime of 20 ns, whereas 1910 ps has been obtained for MOCVD-grown GaN. During high-energy Sn 5+ ion irradiation at 10 11 cm -2 fluences, the lifetime decreased to 1880 ps and 16 ns for MOCVD-and PLD-grown samples, respectively. Near band-edge emission (NBE) was observed at 3.40 eV by room temperature PL measurement for all the GaN samples. UV-absorption edge was observed at 3.41 eV for MOCVD and 3.40 eV for PLD-grown samples, respectively. The irradiation process has reduced the absorption band edge for both MOCVD-and PLD-grown GaN.

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

    NASA Astrophysics Data System (ADS)

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

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

  13. 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.

  14. BRIEF COMMUNICATIONS: Dynamic method for measurement of rate constants of heterogeneous chemical reactions taking place under the action of laser radiation

    NASA Astrophysics Data System (ADS)

    Kirichenko, N. A.; Luk'yanchuk, B. S.; Sapetski?, A. N.

    1981-10-01

    A new dynamic method is proposed for determination of the rate constants of heterogeneous reactions. This involves measuring the temperature and its derivative during laser heating of solid targets, and also the finite thickness of the layer of the chemical compound being formed. The method can be used to find the rate constants obeying an arbitrary kinetic law and differs from traditional methods of measurement in being more accurate and less laborious.

  15. A Strategy to Locate Cysteine Residues in Proteins by Specific Chemical Cleavage Followed by Matrix-Assisted Laser Desorption\\/Ionization Time-of-Flight Mass Spectrometry

    Microsoft Academic Search

    Jiang Wu; Douglas A. Gage; J. Throck Watson

    1996-01-01

    A simple methodology has been developed to characterize the number and location of free cysteine and cystine groups in peptides and proteins, using chemical modification and matrix-assisted laser desorption\\/ionization time-of flight mass spectrometry (MALDI-TOF MS). This new approach employs a specific reaction between free sulfhydryls and 2-nitro-5-thiocyanobenzoic acid (NTCB) to selectively cyanylate cysteine thiols. The N-terminal peptide bond of the

  16. 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.

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

    PubMed

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

    2014-04-11

    A new approach for the analysis of the cyanobacterial microcystins (MCs) in environmental water matrices has been developed. It offers a cost efficient alternative method for the fast quantification of total MCs using mass spectrometry. This approach permits the quantification of total MCs concentrations without requiring any derivatization or the use of a suite of MCs standards. The oxidation product 2-methyl-3-methoxy-4-phenylbutyric acid (MMPB) was formed through a Lemieux oxidation and represented the total concentration of free and bound MCs in water samples. MMPB was analyzed using laser diode thermal desorption-atmospheric pressure chemical ionization coupled to tandem mass spectrometry (LDTD-APCI-MS/MS). LDTD is a robust and reliable sample introduction method with ultra-fast analysis time (<15 s sample(-1)). Several oxidation and LDTD parameters were optimized to improve recoveries and signal intensity. MCs oxidation recovery yield was 103%, showing a complete reaction. Internal calibration with standard addition was achieved with the use of 4-phenylbutyric acid (4-PB) as internal standard and showed good linearity (R(2)>0.999). Limits of detection and quantification were 0.2 and 0.9 ?g L(-1), respectively. These values are comparable with the WHO (World Health Organization) guideline of 1 ?g L(-1) for total microcystin-LR congener in drinking water. Accuracy and interday/intraday variation coefficients were below 15%. Matrix effect was determined with a recovery of 91%, showing no significant signal suppression. This work demonstrates the use of the LDTD-APCI-MS/MS interface for the screening, detection and quantification of total MCs in complex environmental matrices. PMID:24745740

  18. Determination of metformin in mouse, rat, dog and human plasma samples by laser diode thermal desorption/atmospheric pressure chemical ionization tandem mass spectrometry.

    PubMed

    Swales, John G; Gallagher, Richard; Peter, Raimund M

    2010-11-01

    A simple, rapid and robust high-throughput assay for the quantitative analysis of metformin in plasma from different species using laser diode thermal desorption interfaced with atmospheric chemical pressure ionization tandem mass spectrometry (LDTD-APCI-MSMS) was developed for use in a pharmaceutical discovery environment. In order to minimize sample preparation a generic protein precipitation method was used to extract metformin from the plasma. Laser diode thermal desorption is a relatively new sample introduction method, the optimization of the instrumental parameters are presented. The method was successfully applied to spiked mouse, rat, dog and human plasma samples and was subsequently used to determine the oral pharmacokinetics of metformin after dosing to male rats in order to support drug discovery projects. The deviations for intra-assay accuracy and precision across the four species were less than 30% at all calibration and quality control levels. PMID:20547025

  19. Hexagonal Truncated Pyramidal Light Emitting Diodes through Wafer Bonding of ZnO to GaN, Laser Lift-off, and Photo Chemical Etching

    NASA Astrophysics Data System (ADS)

    Thompson, Daniel B.; Murai, Akihiko; Iza, Michael; Brinkley, Stuart; DenBaars, Steven P.; Mishra, Umesh K.; Nakamura, Shuji

    2008-05-01

    We report on a hexagonal pyramidal light emitting diodes (LEDs) produced by direct wafer bonding of a metal organic chemical vapor deposition (MOCVD) grown GaN LED on sapphire to a n-type ZnO wafer, laser lift off, and photochemical etching of the nitrogen face of the GaN LED. Laser lift off was used to remove the sapphire of the GaN wafer, exposing the Nitrogen face for roughening, in the form of microcones, as well as allowing deposition of metal contacts to the nitrogen face of the GaN LED. Contacts to the ZnO allow for the creation of a vertical current path. Selective etching was used to form truncated hexagonal pyramids of the ZnO.

  20. 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

  1. 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.

  2. Laser Skin Renewal

    MedlinePLUS

    ... away. Fractional ablative laser resurfacing – Pinpoint laser beams peel away many small areas of skin. Fractional non- ... renewal exist. Topical cosmeceuticals, microdermabrasion, and lunchtime chemical peels provide very mild improvement. Botulinum toxin (Botox®) can ...

  3. Production of iodine atoms by dissociating CH3I and HI in a dc glow discharge in the flow of argon

    Microsoft Academic Search

    P. A. Mikheyev; A. A. Shepelenko; A. I. Voronov; N. V. Kupryayev

    2004-01-01

    The production of iodine atoms by means of glow discharge in gas flow, with a view to using them in chemical oxygen-iodine lasers, was studied. A dc glow discharge was sustained between coaxial electrodes in the vortex flow of argon, used as the carrier gas, with the addition of iodine-containing molecular precursors CH3I and HI. In the experiments a high

  4. Metalorganic chemical vapor deposition of GaInNAs lattice matched to GaAs for long-wavelength laser diodes

    Microsoft Academic Search

    Shunichi Sato; Shiro Satoh

    1998-01-01

    The crystal growth of GaInNAs lattice matched to GaAs by metalorganic chemical vapor deposition using dimethylhydrazine as the nitrogen source is described for realizing long-wavelength laser diodes. It was found that the crystalline quality of GaInNAs on AlGaAs is improved by inserting a GaAs spacer layer between GaInNAs and AlGaAs. The photoluminescence spectra of GaAs\\/Ga0.9In0.1NyAs1?y\\/GaAs-DH was measured at room temperature

  5. Experimental verification of the chemical sensitivity of two-site double core-hole states formed by an x-ray free-electron laser.

    PubMed

    Salén, P; van der Meulen, P; Schmidt, H T; Thomas, R D; Larsson, M; Feifel, R; Piancastelli, M N; Fang, L; Murphy, B; Osipov, T; Berrah, N; Kukk, E; Ueda, K; Bozek, J D; Bostedt, C; Wada, S; Richter, R; Feyer, V; Prince, K C

    2012-04-13

    We have performed x-ray two-photon photoelectron spectroscopy using the Linac Coherent Light Source x-ray free-electron laser in order to study double core-hole (DCH) states of CO2, N2O, and N2. The experiment verifies the theory behind the chemical sensitivity of two-site DCH states by comparing a set of small molecules with respect to the energy shift of the two-site DCH state and by extracting the relevant parameters from this shift. PMID:22587249

  6. Long-wavelength strain-compensated GaAsSb quantum-well heterostructures laser grown by metalorganic chemical vapor deposition

    NASA Astrophysics Data System (ADS)

    Noh, M. S.; Dupuis, R. D.; Bour, D. P.; Walter, G.; Holonyak, N.

    2003-09-01

    We report data on strain-compensated GaAsSb double-quantum-well lasers having a type-I band alignment and grown by metalorganic chemical vapor deposition on GaAs substrates. In order to compensate for strain effects and to establish a type-I band alignment, tensile-strained higher-band-gap GaAsP quantum-well barriers have been employed. A lasing wavelength of ?˜1.200 ?m from a 500 ?m long device at 1.15Ith has been achieved at room temperature in pulsed-mode operation. The maximum output power was 20 mW for the same device. A low threshold current density of 608.0 A/cm2 was obtained for 1370 ?m long and 60 ?m stripe lasers. The calculated internal quantum efficiency and internal loss were 33.8% and 8.4 cm-1, respectively. We also calculated an infinite cavity length threshold current density of 265 A/cm2. From these data, a gain constant G0˜1728 cm-1 and transparency current density of 135 A/cm2 were calculated. The result showed that the strain-compensated GaAsSb quantum wells are promising active materials for 1.3 ?m vertical-cavity surface-emitting lasers.

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

    SciTech Connect

    Panchenko, Aleksei N; Orlovskii, Viktor M; Tarasenko, Viktor F; Baksht, E Kh [Institute of High Current Electronics, Siberian Branch, Russian Academy of Sciences, Tomsk (Russian Federation)

    2003-05-31

    The amplitude - time and spectral characteristics of laser radiation and discharge characteristics in mixtures of SF{sub 6} with hydrogen and hydrocarbons at a high lasing efficiency are investigated. Lasing efficiencies of {approx}10 % with respect to the deposited energy are obtained under the pumping from capacitive and inductive energy storage units. It is shown that, during a pump pulse, the maximum efficiencies are achieved at high values of the parameter E/p in the laser gap. When profiled electrodes and UV preionisation are used, a specific output energy of a nonchain HF laser of {approx}140 J L{sup -1} atm{sup -1} and a lasing efficiency of {approx}4.5 % with respect to the stored energy were obtained. It is shown that the emission spectrum of a nonchain HF laser operating at high lasing efficiencies becomes significantly wider and cascade lasing is realised on the {nu}(3-2) {yields} {nu}(2-1) {yields} {nu}(1-0) vibrational transitions at several rotational lines. (lasers)

  8. Pulsed laser photolysis and quantum chemical-statistical rate study of the reaction of the ethynyl radical with water vapor

    NASA Astrophysics Data System (ADS)

    Carl, Shaun A.; Minh Thi Nguyen, Hue; Elsamra, Rehab M. I.; Tho Nguyen, Minh; Peeters, Jozef

    2005-03-01

    The rate coefficient of the gas-phase reaction C2H+H2O?products has been experimentally determined over the temperature range 500-825K using a pulsed laser photolysis-chemiluminescence (PLP-CL) technique. Ethynyl radicals (C2H) were generated by pulsed 193nm photolysis of C2H2 in the presence of H2O vapor and buffer gas N2 at 15Torr. The relative concentration of C2H radicals was monitored as a function of time using a CH * chemiluminescence method. The rate constant determinations for C2H+H2O were k1(550K)=(2.3±1.3)×10-13cm3s-1, k1(770cm3s-1, and k1(825cm3s-1. The error in the only other measurement of this rate constant is also discussed. We have also characterized the reaction theoretically using quantum chemical computations. The relevant portion of the potential energy surface of C2H3O in its doublet electronic ground state has been investigated using density functional theory B3LYP /6-311++G(3df,2p) and molecular orbital computations at the unrestricted coupled-cluster level of theory that incorporates all single and double excitations plus perturbative corrections for the triple excitations, along with the 6-311++G(3df,2p) basis set [(U)CCSD(T)/6-311++G(3df,2p)] and using UCCSD(T )/6-31G(d,p) optimized geometries. Five isomers, six dissociation products, and sixteen transition structures were characterized. The results confirm that the hydrogen abstraction producing C2H2+OH is the most facile reaction channel. For this channel, refined computations using (U)CCSD(T)/6-311++G(3df,2p)//(U)CCSD(T)/6-311++G(d,p) and complete-active-space second-order perturbation theory/complete-active-space self-consistent-field theory (CASPT2/CASSCF) [B. O. Roos, Adv. Chem. Phys. 69, 399 (1987)] using the contracted atomic natural orbitals basis set (ANO-L) [J. Almlöf and P. R. Taylor, J. Chem. Phys.86, 4070 (1987)] were performed, yielding zero-point energy-corrected potential energy barriers of 17kJmol-1 and 15kJmol-1, respectively. Transition-state theory rate constant calculations, based on the UCCSD(T) and CASPT2/CASSCF computations that also include H-atom tunneling and a hindered internal rotation, are in perfect agreement with the experimental values. Considering both our experimental and theoretical determinations, the rate constant can best be expressed, in modified Arrhenius form as k1(T)=(2.2±0.1)×10-21T3.05exp[-(376±100)/T]cm3s-1 for the range 300-2000K. Thus, at temperatures above 1500K, reaction of C2H with H2O is predicted to be one of the dominant C2H reactions in hydrocarbon combustion.

  9. In situ measurement of crystallization of oxide thin films during irradiation with pulsed UV laser in chemical solution deposition process

    NASA Astrophysics Data System (ADS)

    Shinoda, Kentaro; Nakajima, Tomohiko; Tsuchiya, Tetsuo

    2013-12-01

    The epitaxial and polycrystalline growth of lanthanum strontium manganite films on single crystalline strontium titanate and lanthanum aluminate substrates, respectively, under the irradiation with XeCl lasers in the excimer laser-assisted metal organic deposition (ELAMOD) process have been previously reported. In order to investigate the growth phenomena, we monitored the thermal radiation from the sample surfaces irradiated with a pulsed ultraviolet laser in situ with near-infrared sensors. The cooling of the lanthanum strontium manganite films on strontium titanate substrates was significantly slower than that of films on lanthanum aluminate substrates. A similar behavior was also observed by the numerical simulation study. This difference in the cooling decay curves may play an important role in the mode by which crystal growth occurs in the ELAMOD process.

  10. International Conference on Lasers '82, New Orleans, LA, December 13-17, 1982, Proceedings

    Microsoft Academic Search

    R. C. Powell

    1983-01-01

    Subjects are discussed which are related to phase conjugation, laser chemistry, laser induced ionization, free electron lasers and masers, applications of lasers in nuclear physics, solid state laser materials, laser applications of collisions and dissociation phenomena, excimer lasers, tunable coherent UV radiation, laser assisted collisions, cavities and propagation, chemically pumped iodine atom lasers, lasers in medicine, blue-green and metal vapor

  11. 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.

  12. Effect of 980-nanometer diode laser on root canal permeability after dentin treatment with different chemical solutions.

    PubMed

    Marchesan, Melissa Andréia; Brugnera-Junior, Aldo; Ozorio, José Estevam; Pécora, Jesus Djalma; Sousa-Neto, Manoel D

    2008-06-01

    This study evaluated the effect of 980-nm diode laser at different parameters on root canal dentin permeability associated with different irrigants. Seventy-five canines were sectioned at 15 mm from the apex, prepared mechanically up to #40 .02 instrument, and irrigated with 2 mL distilled water. Final irrigation (10 mL) was used as follows: (1) distilled water; (2) 1% NaOCl; (3) 17% ethylenediaminetetraacetic acid + a cationic surfactant cetyltrimethylammonium bromide (EDTAC). Laser was applied at 1.5 or 3.0 W as either continuous wave or pulsed wave (100 Hz). The teeth were then processed histochemically, the percentage of copper ion penetration into the dentin of the canal walls was counted, and the data were analyzed statistically with the Tukey-Kramer test (alpha < .01). When laser was associated with water, an increase in permeability was found, whereas permeability decreased when associated with EDTAC. Dentin permeability after laser irradiation was directly dependent on the solution used for final irrigation. PMID:18498899

  13. 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.

  14. Observation of whispering gallery modes in the mid-Infrared with a Quantum Cascade Laser: possible applications to nanoliter chemical

    E-print Network

    Jensen, Grant J.

    Observation of whispering gallery modes in the mid-Infrared with a Quantum Cascade Laser: possible coupling scheme for mid-infrared is described. Future applications of WGM resonators as hyphenated inline chromatography sensors are discussed. KEY WORD LIST Mid Infrared CaF2 Whispering Gallery Mode, Quantum Cascade

  15. 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 [Fachbereich Chemie, Physikalische Chemie, Philipps-Universitaet Marburg, Hans-Meerwein-Strasse, D-35032 Marburg (Germany)

    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.

  16. 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.

  17. Chemical characterization of single particles by laser ablation/desorption in a quadrupole ion trap mass spectrometer

    SciTech Connect

    Dale, J.M.; Yang, M.; Whitten, W.B.; Ramsey, J.M. (Oak Ridge National Lab., TN (United States))

    1994-10-15

    Particles are introduced into the center of the space surrounded by the hyperbolic electrode surfaces of a quadrupole ion trap mass spectrometer. Ions are desorbed or ablated from the surfaces of the particles with laser pulses from a Nd:YAG laser as the particles fall through the trap. The ions are trapped and subsequently mass analyzed using the mass-selective instability mode of operation of the ion trap. Desorption experiments were performed with approximately 100 [mu]m silicon carbide particles with an average of a few nanograms of adsorbed trimethylphenyl-ammonium chloride, tetraphenylphosphonium bromide, or 2,4,6-trinitrotoluene per particle. A conservative detection limit of 0.7 fm per particle was determined for tetraphenylphosphonium bromide. Ablation experiments were performed with approximately 50 [mu]m nickel particles for isotope ratio measurements with good agreement between accepted and average experimental values. 22 refs., 5 figs., 1 tab.

  18. 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.

  19. 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.

  20. Effect of chemical and Er:YAG laser treatment on bond strength of root canal resin-based sealers.

    PubMed

    Akisue, Eduardo; Araki, Angela Toshie; Michelotto, André Luiz Costa; Moura-Netto, Cacio; Gavini, Giulio

    2013-01-01

    Different treatments of dentin walls, as laser irradiation, prior to obturation can influence the adhesion ability of endodontic sealers. Therefore, the objective of this study was to compare in vitro the shear bond strength of four resin-based sealers to dentin treated with citric acid solution or erbium: yttrium, aluminum, garnet (Er:YAG) irradiation. A total of 240 slices with 1.6 mm of thickness were cut using middle third of 84 teeth. Each slice was widened using a #45 taper.06 rotary K3 instrument. The sample was divided into groups according to dentin pretreatment (15 % citric acid or Er:YAG laser) and sealer used (AH Plus, Acroseal, EndoREZ, or RealSeal). Shear bond strength was measured using a universal materials testing machine. As results, significant differences were found when comparing sealers between all groups (p < 0.05) by Kruskal-Wallis test, regardless of the pretreatment used. Comparing pretreatments, 15 % citric acid solution had better outcomes than Er:YAG laser, with significant differences in all groups, except for Acroseal groups (p < 0.05). It was concluded that RealSeal and 15 % citric acid solution achieved the best results regarding the sealer and pretreatment used, respectively. PMID:22710741

  1. 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

  2. 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

  3. ARPA-NRL laser program. Semiannual technical report to Defense Advanced Research Projects Agency, 1 January 1974--30 June 1974. Memorandum report

    Microsoft Academic Search

    J. R. Airey; L. Champagne; N. Djeu; J. K. Hancock; N. Harris

    1975-01-01

    The ARPA-NRL Laser Program is concerned with the development of laser technology in three project areas: Chemical Infrared Lasers, Electrical Infrared Lasers and Electronic State Lasers. The Chemical Infrared Laser Program is focussed on DF-CO supersonic transfer laser experiments designed to evaluate chemical augmentation of gas dynamic lasers. Augmentation has been observed but is limited by deactivation processes. The temperature

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

    PubMed

    Cayzac, Witold; Frank, Alexander; Schumacher, Dennis; Roth, Markus; Blazevi?, 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 mm(2) large and 20??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 (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(3)-10(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 ?EE ? 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. PMID:23635189

  5. Characteristics of a pulsed chemical laser utilizing an H/sub 2/--F/sub 2/ mixture and initiated by radiation from an XeCl excimer laser

    SciTech Connect

    Gordon, E.B.; Matyushenko, V.I.; Sizov, V.D.

    1982-11-01

    A study was made of the influence of the active mixture composition on the energy and temporal characteristics of an HF laser, for various diluents (He, Kr, Xe, N/sub 2/, SF/sub 6/). An efficiency of 1500%, measured relative to the ultraviolet initiation energy deposited in the mixture, was achieved utilizing an F/sub 2/:O/sub 2/:H/sub 2/:SF/sub 6/ = 7.5:0.75:2.5:3.5 mixture at p = 110 Torr. The specific output energy increased in proportion both to the initiation energy (i.e., keeping the efficiency constant) and to the concentration of the fuel mixture (for a given initiation energy). An output energy of 38 J/liter was achieved for an F/sub 2/:O/sub 2/:H/sub 2/:SF/sub 6/ = 25:2.5:2.5:20 mixture (p = 0.5 atm) with a concentration of atoms created by the ultraviolet radiation of (F)/sub 0/approx.2 x 10/sup 16/ cm/sup -3/.

  6. THE JOURNAL OF CHEMICAL PHYSICS 135, 044317 (2011) Effect of diatomic molecular properties on binary laser pulse optimizations

    E-print Network

    Brown, Alex

    2011-01-01

    THE JOURNAL OF CHEMICAL PHYSICS 135, 044317 (2011) Effect of diatomic molecular properties control of diatomics for molecular quantum computing. © 2011 American Institute of Physics. [doi:10- ing trends in the fidelities were attributed to the intrinsic molecular properties and not the choice

  7. The influence of the gas environment on morphology and chemical composition of surfaces micro-machined with a femtosecond laser

    NASA Astrophysics Data System (ADS)

    Lehr, Jorge; de Marchi, Fabrizio; Matus, Luke; MacLeod, Jennifer; Rosei, Federico; Kietzig, Anne-Marie

    2014-11-01

    We investigated the influence of different gas environments on the fabrication of surfaces, homogeneously covered with equally sized and spaced micro-structures. Two types of structures have been successfully micro-machined with a femtosecond laser on titanium surfaces in various atmospheres. The surface chemistry of samples machined in oxygen and helium shows TiO2, while machining in nitrogen leads to an additional share of TiN. The actual surface structure was found to vary significantly as a function of the gas environment. We found that the ablated particles and their surface triggered two consecutive events: The optical properties of the gas environment became non-isotropic which then led to the pulse intensity being redistributed throughout the cross section of the laser beam. Additionally, the effective intensity was further reduced for TiN surfaces due to TiN's high reflectivity. Thus, the settings for the applied raster-scanning machining method had to be adjusted for each gas environment to produce comparable structures. In contrast to previous studies, where only noble gases were found suitable to produce homogeneous patches, we obtained them in an oxygen environment.

  8. XeCl laser action at medium fluences on biological tissues: fluorescence study and simulation with a chemical solution.

    PubMed

    Berthier, J P; Raynal, E; Kimel, S; Avrillier, S; Ollivier, J P

    1990-05-01

    A rat heart, isolated and perfused, was irradiated with a XeCl excimer laser at 308 nm. The evolution of the fluorescence spectrum was measured. For an incident energy E greater than 4 kJ m-2 per pulse the fluorescence changed with time in a complex and spectrally non-uniform way. The proposed interpretation is that the radiation acts on the cellular respiratory chain. Buffered solutions of NADH, cytochrome c and FAD, which play a role in the respiratory chain, were irradiated in order to simulate the in vivo findings. The conclusion of this study is that XeCl radiation introduces a modification in the functioning of the respiratory chain: it accelerates electron transfer, but this quickly leads to an interruption of the respiratory chain. PMID:2115919

  9. 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.

  10. 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, E-mail: ryang73@ustc.edu; Gudipati, Murthy S., E-mail: gudipati@jpl.nasa.gov [Science Division, Jet Propulsion Laboratory, California Institute of Technology, Mail Stop 183-301, 4800 Oak Grove Drive, Pasadena, California 91109 (United States)

    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.

  11. Fast epitaxial growth of a-axis- and c-axis-oriented YBa 2Cu 3O 7? ? films on (1 0 0) LaAlO 3 substrate by laser chemical vapor deposition

    Microsoft Academic Search

    Pei Zhao; Akihiko Ito; Rong Tu; Takashi Goto

    2011-01-01

    a-axis- and c-axis-oriented YBa2Cu3O7?? (YBCO) films were epitaxially grown on (100) 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 158W (the deposition temperatures from 951 to 1087K). The a-axis-oriented YBCO film showed in-plane epitaxial growth of YBCO [001]\\/\\/LAO [001], and

  12. High quality SiO 2 gate insulator suitable for poly-Si TFTs on plastic substrates employing inductively coupled plasma-chemical vapor deposition with N 2O plasma treatment and excimer laser annealing

    Microsoft Academic Search

    Sang-Myeon Han; Moon-Young Shin; Joong-Hyun Park; Min-Koo Han

    2006-01-01

    Electrical characteristics, such as capacitance–voltage characteristics (C–V) and break-down field, of SiO2 films deposited on plastic substrates by inductively coupled plasma chemical vapor deposition at 150°C were improved by excimer laser annealing and N2O plasma pre-treatment. Excimer laser annealing at an energy density of 250mJ\\/cm2 produced a flat-band voltage of the SiO2 film shifted close to 0V while the effective

  13. Strained-layer InGaAs-GaAs-AlGaAs buried-heterostructure quantum-well lasers by three-step selective-area metalorganic chemical vapor deposition

    Microsoft Academic Search

    Timothy M. Cockerill; David V. Forbes; Jonathan A. Dantzig; James J. Coleman

    1994-01-01

    Strained-layer InxGa1-xAs-GaAs-AlyGa1-yAs buried-heterostructure (BH) quantum-well lasers have been fabricated using three-step selective area atmospheric pressure metal-organic chemical vapor deposition. Selective-area epitaxy is used to produce BH lasers involving only GaAs on GaAs regrowth, eliminating the detrimental effects associated with exposed AlyGa1-yAs found in other fabrication methods. Additionally, selective-area epitaxy provides inplane bandgap energy control to fabricate BH devices with different

  14. 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

  15. 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 [Institut fuer Kernphysik, Technische Universitaet Darmstadt, Schlossgartenstr. 9, 64289 Darmstadt (Germany); Blazevic, Abel; Wamers, Felix; Traeger, Michael; Berdermann, Eleni; Voss, Bernd; Hessling, Thomas [GSI Helmholtzzentrum fuer Schwerionenforschung, Planckstr. 1, 64291 Darmstadt (Germany)

    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.

  16. Industrial laser use expanding in the USSR

    NASA Astrophysics Data System (ADS)

    Velikhov, Y. P.

    1985-04-01

    The effect of lasers on industrial procedures and the economy is discussed. Some applications of lasers in industry which are considered are laser thermal technology, laser control of industrial processes and large scale chemical production. Lasers are applied in such fields as biology, environmental protection, construction and irrigation works, communications, computer technology, printing and image recording and processing. Lasers also have applications toward the problem of controlling thermonuclear reactions. Objectives of laser application studies are outlined.

  17. 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.

  18. Theoretical study of the dynamics and kinetics of the O + CS ? CO + S chemical laser reaction, where CO shows a very high vibrational excitation.

    PubMed

    Gamallo, Pablo; Francia, Rafael; Martínez, Rodrigo; Sayós, Ramón; González, Miguel

    2012-12-01

    The dynamics and kinetics of the O((3)P) + CS(X(1)?(+)) ? CO(X(1)?(+)) + S((3)P) chemical laser reaction was studied theoretically in detail for the first time, as a function of collision energy (0.0388-2.0 eV) and rovibrational excitation of CS. This was made using the quasi-classical trajectory (QCT) method and employing the best ab initio analytical ground potential energy surface (1(3)A' PES) available. A broad set of properties was determined, including scalar and vector properties, and the reaction mode. The behaviors observed and the considerable formation of OCS collision complexes were interpreted from some characteristics of the PES (early barrier, shallow minimum in the exit channel, and high exoergicity (mainly channeled into CO vibration; up to ?81% of the available energy)) and the kinematics. The QCT vibrational and rotational CO populations and the vector properties show a quite good agreement with experiments, but the QCT rate constants disagree. To better account for the kinetics, we performed CASPT2/aug-cc-pVTZ ab initio calculations on the stationary points along the minimum energy path of the ground and first excited (1(3)A'') PESs. The transition state theory, which can be satisfactorily applied here, leads to rate constants (100-2000 K) that are quite close to the measured ones, where comparison is possible (150-300 K). We expect that these results will encourage further theoretical and experimental developments. PMID:23131012

  19. Reactions of laser-ablated U atoms with HF: infrared spectra and quantum chemical calculations of HUF, UH, and UF in noble gas solids.

    PubMed

    Vent-Schmidt, Thomas; Andrews, Lester; Riedel, Sebastian

    2015-03-19

    Reactions of laser-ablated U atoms with HF produce HUF as the major product and UH and UF as minor products, which are identified from their argon and neon matrix infrared spectra. Our assignment of HUF is confirmed by the observation of DUF and close agreement with observed and calculated vibrational frequencies and deuterium shifts in the vibrational frequencies. Our previous observation of the UH diatomic molecule from argon matrix experiments with H2, HD, and D2 as reagents is confirmed through its present observation with HF and DF, and with recent higher level quantum chemical calculations. The HF reaction provides a lower concentration of F in the system and thus simplifies the fluorine chemistry relative to similar U atom reactions with F2, and the new matrix identification of UF here is consistent with recent high level calculations on UF. In addition, we find evidence for the higher oxidation state secondary reaction products UHF2, UHF3, and UH2F2. PMID:25080179

  20. Fast epitaxial growth of a-axis- and c-axis-oriented YBa 2Cu 3O 7- ? 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-? (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 ?m h-1, about 2-1000 times higher than that of metalorganic chemical vapor deposition.

  1. Laser-assisted electrochemistry

    SciTech Connect

    Glenn, D.F.

    1995-05-01

    The effect of laser irradiation on electrodeposition processes has been investigated. These studies demonstrated that the addition of laser irradiation to an electroplating process can dramatically enhance plating rates and current efficiencies, as well as improve the morphology of the resultant electrodeposit. During the course of these investigations, the mechanism for the laser enhancement of electrodeposition processes was determined. Experimental evidence was obtained to show that laser irradiation of the substrate results in increased metal ion concentrations at the surface of the electrode due to a laser-induced Soret effect. The laser-induced Soret effect has important implications for laser-assisted electrochemical processing. The increase in the surface concentration of ions allows efficient electrodeposition from dilute solutions. As such, laser- assisted electrodeposition may develop into an environmentally conscious manufacturing process by reducing waste and limiting worker exposure to toxic chemicals.

  2. Laser demonstration and performance characterization of optically pumped Alkali Laser systems

    Microsoft Academic Search

    Clifford V. Sulham

    2010-01-01

    Diode Pumped Alkali Lasers (DPALs) offer a promising approach for high power lasers in military applications that will not suffer from the long logistical trails of chemical lasers or the thermal management issues of diode pumped solid state lasers. This research focuses on characterizing a DPAL-type system to gain a better understanding of using this type of laser as a

  3. Laser ablation: LIBS and ICPMS

    SciTech Connect

    Russo, Richard E.; Gonzalez, Jhanis; Liu, Chunyi

    2006-08-29

    Laser ablation has become a dominant technology for directsolid sampling chemical analysis. Commonly used detection modalitiesinclude LIBS (laser induced breakdown spectroscopy) for directspectroscopic analysis from the laser-induced plasma at the samplesurface,and ICPMS (inductively coupled plasma mass spectroscopy) in whichthe ablated aerosol is transported and excited in a secondary source.Each measurement approach dictates the laser parameters required foroptimum performance. Fundamental and experimental research studies haveled to significant improvements in performance metrics for laser ablationsolid sampling chemical analysis using both LIBS and ICPMS.

  4. TilE JOURNAL OF CHEMICAL PHYSICS VOLUME 51, NUMBER 12 15 DECEMBER 1969 Dissociation Energy of Li2 from Laser-Excited Fluorescence*

    E-print Network

    Zare, Richard N.

    Grant GP- 8570 and by the Advanced Research Projects Agency of the De- partment of Defense monitored from Laser-Excited Fluorescence* R. VELASCO, t CH. OTTINGER,i AND R. N. ZARE§ Joint Institutejor of the argon ion laser, have been observed and analyzed. Based on a short Birge-Sponer extrapolation

  5. Instabilities and structure formation in laser processing

    SciTech Connect

    Baeuerle, D.; Arenholz, E.; Arnold, N.; Heitz, J.; Kargl, P.B. [Johannes-Kepler-Univ. Linz (Austria). Angewandte Physik

    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.

  6. Introduction to laser plasma diagnostics

    Microsoft Academic Search

    A. A. Hauer; H. A. Baldis

    1988-01-01

    This report reviews optical and X-ray techniques for the diagnosis of laser-produced plasmas. Emphasis is placed on the parameter regimes (e.g., laser irradiance greater than 10 to the 12th power watts\\/sq cm) appropriate to the laser fusion field. We also include, however, material related to other laser-plasma work such as chemical analysis. This work is intended to be an introduction

  7. Lasers '81

    SciTech Connect

    Collins, C.B.

    1982-01-01

    Progress in lasers is discussed. The subjects addressed include: excimer lasers, surface spectroscopy, modern laser spectroscopy, free electron lasers, cavities and propagation, lasers in medicine, X-ray and gamma ray lasers, laser spectroscopy of small molecules and clusters, optical bistability, excitons, nonlinear optics in the X-ray and gamma ray regions, collective atomic phenomena, tunable IR lasers, far IR/submillimeter lasers, and laser-assisted collisions. Also treated are: special applications, multiphoton processes in atoms and small molecules, nuclear pumped lasers, material processing and applications, polarization, high energy lasers, laser chemistry, IR molecular lasers, laser applications of collision and dissociation phenomena, solid state laser materials, phase conjugation, advances in laser technology for fusion, metal vapor lasers, picosecond phenomena, laser ranging and geodesy, and laser photochemistry of complex molecules.

  8. Laser diode thermal desorption atmospheric pressure chemical ionization tandem mass spectrometry applied for the ultra-fast quantitative analysis of BKM120 in human plasma.

    PubMed

    Lanshoeft, Christian; Heudi, Olivier; Leuthold, Luc Alexis; Schlotterbeck, Götz; Elbast, Walid; Picard, Franck; Kretz, Olivier

    2014-09-01

    A sensitive and ultra-fast method utilizing the laser diode thermal desorption ion source using atmospheric pressure chemical ionization coupled to tandem mass spectrometry (LDTD-APCI-MS/MS) was developed for the quantitative analysis of BKM120, an investigational anticancer drug in human plasma. Samples originating from protein precipitation (PP) followed by salting-out assisted liquid-liquid extraction (SALLE) were spotted onto the LazWell™ plate prior to their thermal desorption and detection by tandem mass spectrometry in positive mode. The validated method described in this paper presents a high absolute extraction recovery (>90 %) for BKM120 and its internal standard (ISTD) [D8]BKM120, with precision and accuracy meeting the acceptance criteria. Standard curves were linear over the range of 5.00 to 2000 ng mL(-1) with a coefficient of determination (R (2)) >0.995. The method specificity was demonstrated in six different batches of human plasma. Intra- and inter-run precision as well as accuracy within ±20 % at the lower limit of quantification (LLOQ) and ±15 % (other levels) were achieved during a three-run validation for quality control (QC) samples. The post-preparative stability on the LazWell™ plate at room temperature was 72 h and a 200-fold dilution of spiked samples was demonstrated. The method was applied successfully to three clinical studies (n?=?847) and cross-checked with the validated LC-ESI-MS/MS reference method. The sample analysis run time was 10 s as compared to 4.5 min for the current validated LC-ESI-MS/MS method. The resultant data were in agreement with the results obtained using the validated reference LC-ESI-MS/MS assay and the same pharmacokinetic (PK) parameters were calculated for both analytical assays. This work demonstrates that LDTD-APCI-MS/MS is a reliable method for the ultra-fast quantitative analysis of BKM120 which can be used to speed-up and support its bioanalysis in the frame of the clinical trials. PMID:24958346

  9. 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.

  10. A Modular Control Platform for a Diode Pumped Alkali Laser

    Microsoft Academic Search

    J. Shapiro; S. Teare

    2008-01-01

    Many of the difficulties of creating compact, high power laser systems can be overcome if the heat dissipating properties of chemical lasers can be combined with the efficiency of diode lasers. Recently, the novel idea of using solid state diode lasers to pump gaseous gain media, such as is done in diode pumped alkali lasers (DPALs), has been proposed and

  11. Heterogeneous losses of externally generated I atoms for OIL

    NASA Astrophysics Data System (ADS)

    Torbin, A. P.; Mikheyev, P. A.; Ufimtsev, N. I.; Voronov, A. I.; Azyazov, V. N.

    2012-01-01

    Usage of an external iodine atom generator can improve energy efficiency of the oxygen-iodine laser (OIL) and expand its range of operation parameters. However, a noticeable part of iodine atoms may recombine or undergo chemical bonding during transportation from the generator to the injection point. Experimental results reported in this paper showed that uncoated aluminum surfaces readily bounded iodine atoms, while nickel, stainless steel, Teflon or Plexiglas did not. Estimations based on experimental results had shown that the upper bound of probability of surface iodine atom recombination for materials Teflon, Plexiglas, nickel or stainless steel is ?rec <= 10-5.

  12. 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.

  13. DARPA-NRL laser program. Report to Defense Advanced Research Projects Agency

    Microsoft Academic Search

    J. R. Airey; R. Burnham; L. Champagne; N. Dejeu; J. Eversole

    1976-01-01

    The DARPA-NRL Laser Program is concerned with the development of laser technology in three project areas: chemical infrared lasers, electrical infrared lasers and electronic-state lasers. The chemical infrared laser program includes studies of pulsed HCl laser systems and molecular energy transfer processes. Data have been collected which suggests that intramolecular energy transfer occurs in SF6 at a rate 1,000 times

  14. THE JOURNAL OF CHEMICAL PHYSICS VOLUME 51, NUMBER 12 15 DECEMBER 1969 Spectroscopy of Na2 Using Laser-Induced Fluorescence*

    E-print Network

    Zare, Richard N.

    , National Institute of Health Grant GM 11123-04, and by the Advanced Research Projects Agency of the Department of Defense monitored by Army Research Office-Durham under Contract DA-31-124-ARO-D-139. t JILA of the argon-ion laser. *This cooperative project was supported by National Science Foundation Grant GP-8095

  15. Excimer laser refractive surgery.

    PubMed Central

    Manche, E E; Carr, J D; Haw, W W; Hersh, P S

    1998-01-01

    Excimer laser photorefractive keratectomy and excimer laser in situ keratomileusis are relatively new treatment modalities that can be used to correct refractive errors of the eye. They are most commonly used to correct myopia (nearsightedness) but can also be used to correct hyperopia (farsightedness) and astigmatism. The excimer laser alters the refractive state of the eye by removing tissue from the anterior cornea through a process known as photoablative decomposition. This process uses ultraviolet energy from the excimer laser to disrupt chemical bonds in the cornea without causing any thermal damage to surrounding tissue. The modified anterior corneal surface enables light to be focused on the retina, thereby reducing or eliminating the dependence on glasses and contact lenses. We discuss in detail all aspects of excimer laser refractive surgery--techniques, indications and contraindications, clinical outcomes, and complications. PMID:9682628

  16. 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...

  17. Surface engineering using excimer lasers

    Microsoft Academic Search

    Anthony J. Pedraza; Douglas H. Lowndes

    1998-01-01

    Excimer laser irradiation of insulators produces structural and chemical modifications in the near-surface region of these materials. These changes have lead to the usage of excimer lasers to engineer the surface of insulators for various applications, as illustrated in four examples presented here: (1) Laser-enhanced bonding of deposited metallic films. A very strong bonding between metallic films and Al2O3 can

  18. Engineering Light: Quantum Cascade Lasers

    SciTech Connect

    Claire Gmachl

    2010-03-17

    Quantum cascade lasers are ideal for environmental sensing and medical diagnostic applications. Gmachl discusses how these lasers work, and their applications, including their use as chemical trace gas sensors. As examples of these applications, she briefly presents results from her field campaign at the Beijing Olympics, and ongoing campaigns in Texas, Maryland, and Ghana.

  19. Laser technology application in gravure printing

    Microsoft Academic Search

    Hong H. Xiao

    1994-01-01

    Laser technology has found its new application in the gravure printing industry. The argon gas laser is used as a light source. The beam is controlled by a graphic software and used to expose a printing cylinder coated with photosensitive material. After the chemical process, the artwork is thus etched onto the cylinder and ready to reproduce pages. The laser

  20. 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

  1. Investigation of statistics strategies for improving the discriminating power of laser-induced breakdown spectroscopy for chemical and biological warfare agent simulants

    Microsoft Academic Search

    Chase A. Munson; Frank C. De Lucia; Thuvan Piehler; Kevin L. McNesby; Andrzej W. Miziolek

    2005-01-01

    Laser-induced breakdown spectroscopy spectra of bacterial spores, molds, pollens and nerve agent simulants have been acquired. The performance of several statistical methodologies–linear correlation, principal components analysis, and soft independent model of class analogy–has been evaluated for their ability to differentiate between the various samples. The effect of data selection (total spectra, peak intensities, and intensity ratios) and pre-treatments (e.g., averaging)

  2. Chemical analysis of archeological materials in submarine environments using laser-induced breakdown spectroscopy. On-site trials in the Mediterranean Sea

    NASA Astrophysics Data System (ADS)

    Guirado, S.; Fortes, F. J.; Lazic, V.; Laserna, J. J.

    2012-08-01

    The main aim of this work is to demonstrate the capability of laser-induced breakdown spectroscopy (LIBS) for the recognition and identification of archeological materials submerged in sea water at depths up to 30 m. For this purpose, a remote LIBS instrument based on a fiber optic cable to deliver the laser beam energy has been evaluated. An air flux was applied to create a sample-air interface prior to laser ablation. This flux prevents the contact of sea water with the sample surface during the analysis. In this way, good quality LIBS spectra were obtained. Parametric studies in the laboratory such as gas flow pressure, beam focal conditions and angle of incidence, among others, were performed to optimize the best conditions for field analysis. Finally, real samples such as different bronzes containing a high oxidation degree were analyzed underwater in the Mediterranean Sea. The dependence of LIBS signal with the analysis depth was also studied. Results obtained in these field trials confirmed the capability of remote LIBS for in-situ analysis of underwater archeological samples.

  3. Chemical Peels

    MedlinePLUS

    ... to Choose the Best Skin Care Products Chemical Peels Uses for Chemical Peels Learn more about specific conditions where chemical peels ... skin Sagging skin Wrinkles What is a chemical peel? A chemical peel is a technique used to ...

  4. Multi-purpose InGaAsP buried heterostructure laser diodes for uncooled digital, analog, and wireless applications grown by molecular beam epitaxy and metal-organic chemical-vapor deposition

    NASA Astrophysics Data System (ADS)

    Pickrell, G. W.; Zhang, H. L.; Ren, H. W.; Zhang, D.; Xue, Q.; Um, J.; Lin, H. C.; Anselm, K. A.; Makino, T.; Hwang, W. Y.

    2009-02-01

    Using a combination of molecular beam epitaxy (MBE) and metal-organic, chemical-vapor deposition (MOCVD), highperformance, buried-heterostructure, distributed feedback (DFB), laser diodes are being manufactured for multiple, uncooled (-20 to 85 °C and -40 to 95 °C) product lines. MBE is used to grow the active regions and the p-type cladding layers, while MOCVD is used for the Fe-doped blocking layers. Multi-wafer growths are used to reduce device costs. Devices, employing the same basic active region design, have been fabricated operating at wavelengths from 1490 to 1610 nm for applications including coarse wavelength division multiplexing (CWDM) OC-48 digital, analog return path, and 2.2 GHz (3G) wireless code division multiple access (W-CDMA). These devices show good linearity (analog return path and wireless) and high-speed operation (digital). Accelerated lifetime testing of these devices shows excellent reliability with a median lifetime of 17 years at 90 °C.

  5. Gas lasers

    Microsoft Academic Search

    A K Nath

    1988-01-01

    The important gas lasers which find wide applications in material processing are the CO2 laser, the argon-ion laser and the excimer lasers. This paper briefly describes the basic concepts and the technology of\\u000a these lasers.

  6. Laser satellite power systems: concepts and issues

    SciTech Connect

    Walbridge, E.W.

    1982-01-01

    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 a laser beam. The laser SPS is an alternative to the microwave SPS. Lasers and how they work are described, as are the types of lasers - electric discharge, direct and indirect solar pumped, free electron, and closed-cycle chemical - that are candidates for application in a laser SPS. The advantages of a laser SPS over the microwave alternative are pointed out. One such advantage is that, for the same power delivered to the utility busbar, land requirements for a laser system are much smaller (by a factor of 21) than those for microwave system. The four laser SPS concepts that have been presented in the literature are described and commented on. Finally key issues for further laser SPS research are discussed.

  7. Laser satellite power systems - Concepts and issues

    NASA Astrophysics Data System (ADS)

    Walbridge, E. W.

    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 a laser beam. The laser SPS is an alternative to the microwave SPS. Lasers and how they work are described, as are the types of lasers - electric discharge, direct and indirect solar pumped, free electron, and closed-cycle chemical - that are candidates for application in a laser SPS. The advantages of a laser SPS over the microwave alternative are pointed out. One such advantage is that, for the same power delivered to the utility busbar, land requirements for a laser system are much smaller (by a factor of 21) than those for a microwave system. The four laser SPS concepts that have been presented in the literature are described and commented on. Finally key issues for further laser SPS research are discussed.

  8. 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...

  9. Using Chalcogenide Glass to Optimize Quantum Cascade Laser

    E-print Network

    Petta, Jason

    Using Chalcogenide Glass to Optimize Quantum Cascade Laser Performance Josh McNeur Professor Craig) is technologically important for chemical and biological testing Mid-infrared semi-conductor lasers thus have become popular #12;Quantum Cascade Lasers Quantum Cascade (QC) Lasers Electrons waterfall down series of quantum

  10. Laser bumping for flip chip and TAB applications

    Microsoft Academic Search

    D. Metzger; U. Beutler; J. Eldring; H. Reichl

    1994-01-01

    An important aspect in microelectronics and packaging technologies is single chip bumping. A laser bumping method is suggested both for flip chip and TAB (tape automated bonding) applications. Laser chemical vapor deposition with an organometallic gold compound was used to deposit gold bumps from the vapor phase. With a computer controlled laser deposition system the laser bumping process was performed.

  11. Applied atomic collision physics. Volume 3 - Gas lasers

    Microsoft Academic Search

    E. W. McDaniel; W. L. Nighan

    1982-01-01

    The theoretical basis, development, functional principles, and applications of gas lasers are detailed. Energy transfer, direct excitation, photodissociation, chemical, and excimer lasers are described. Attention is given to the theory of lasers, the production of excited states, and the kinetics and spectroscopy of excited states, as well as techniques for the extraction of laser energy. Various aspects of charged particle

  12. Chemical Changes

    NSDL National Science Digital Library

    Mr. Jolley

    2005-10-25

    In this activity you will learn what a chemical change is. The first step to understanding chemical changes is to recognize the difference between chemical properties and physical properties. Click here for an example: Chemical and Physical Changes What are the signs of a chemical reaction occuring? Signs of Chemical Change What variables affect a chemical reaction? Variables ...

  13. 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.

  14. 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.

  15. Laser removal of sludge from steam generators

    DOEpatents

    Nachbar, Henry D. (Ballston Lake, NY)

    1990-01-01

    A method of removing unwanted chemical deposits known as sludge from the metal surfaces of steam generators with laser energy is provided. Laser energy of a certain power density, of a critical wavelength and frequency, is intermittently focused on the sludge deposits to vaporize them so that the surfaces are cleaned without affecting the metal surface (sludge substrate). Fiberoptic tubes are utilized for laser beam transmission and beam direction. Fiberoptics are also utilized to monitor laser operation and sludge removal.

  16. Laser-evoked coloration in polymers

    Microsoft Academic Search

    H. Y. Zheng; David Rosseinsky; G. C. Lim

    2005-01-01

    Laser-evoked coloration in polymers has long been a major aim of polymer technology for potential applications in product surface decoration, marking personalised images and logos. However, the coloration results reported so far were mostly attributed to laser-induced thermal–chemical reactions. The laser-irradiated areas are characterized with grooves due to material removal. Furthermore, only single color was laser-induced in any given polymer

  17. Laser-evoked coloration in polymers

    Microsoft Academic Search

    H. Y. Zheng; David Rosseinsky; G. C. Lim

    2005-01-01

    Laser-evoked coloration in polymers has long been a major aim of polymer technology for potential applications in product surface decoration, marking personalised images and logos. However, the coloration results reported so far were mostly attributed to laser-induced thermal chemical reactions. The laser-irradiated areas are characterized with grooves due to material removal. Furthermore, only single color was laser-induced in any given

  18. Laser technology application in gravure printing

    NASA Astrophysics Data System (ADS)

    Xiao, Hong H.

    1994-05-01

    Laser technology has found its new application in the gravure printing industry. The argon gas laser is used as a light source. The beam is controlled by a graphic software and used to expose a printing cylinder coated with photosensitive material. After the chemical process, the artwork is thus etched onto the cylinder and ready to reproduce pages. The laser exposure process, and the cylinder engraving processes will also be discussed. The samples of laser exposed images will be presented.

  19. 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.

  20. Chemical Peels

    MedlinePLUS

    ... Diseases and treatments A - D Chemical peel Chemical peels Also called chemexfoliation , derma peeling Do you wish ... cost of cosmetic treatments. Learn more about chemical peels: Is a chemical peel the right choice for ...

  1. Chemical Mechanical Planarization- Chemical

    NSDL National Science Digital Library

    This website includes an animation which illustrates the chemical action of slurry in the chemical-mechanical planarization process. Objective: Explain the mechanical and chemical steps in the CMP process. This simulation is from Module 068 of the Process & Equipment III Cluster of the MATEC Module Library (MML). Find this animation under the section "Process & Equipment III." To view other clusters or for more information about the MML visit http://matec.org/ps/library3/process_I.shtmlKey Phrase: MATEC Animation

  2. 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.

  3. RF discharge generation of I atoms in CH3I and CF3I for COIL/DOIL

    NASA Astrophysics Data System (ADS)

    Schmiedberger, Josef; Jirásek, Vít; Censký, Miroslav; Picková, Irena; Kodymová, Jarmila

    2008-10-01

    A cw/pulsed radiofrequency discharge coupled by electrodes in coaxial arrangement was used to dissociate iodine atoms from CH3I or CF3I molecules diluted in a carrier gas (a mixture of Ar and He). The discharge chamber was arranged directly inside an iodine injector (made of aluminum) to minimize the recombination of generated atomic iodine and enabling an increased assistance of UV light for a photo-dissociation enhancement of I atoms production. The effluent of the discharge chamber/iodine injector was injected into the flow of N2 downstream the nozzle throat. Measurements of I atoms concentration distribution at different distances from the injection and in two directions across cavity were done by means of absorption measurements at the wavelength of 1315 nm. Dependences of atomic iodine concentration on main RF discharge parameters and flow mixing conditions were measured. This novel method could be an alternative to the chemical generation of atomic iodine and also an efficient alternative to other electric discharge methods of I atoms generation for chemical oxygen-iodine laser (COIL) and discharge oxygen-iodine laser (DOIL).

  4. The metal-organic chemical vapor deposition growth and properties of InAsSb mid-infrared (3-6-?m) lasers and LEDs

    Microsoft Academic Search

    Robert M. Biefeld; Steven R. Kurtz; Andrew A. Allerman

    1997-01-01

    We describe the metal-organic chemical vapor deposition (MOCVD) growth of AlAs1-xSbx cladding layers and InAsSb-InAs multiple-quantum well (MQW) and InAsSb-InAsP strained-layer superlattice (SLS) active regions for use in mid-infrared emitters. The AlAs1-xSbx cladding layers were successfully doped p- or n-type using diethylzinc or tetraethyltin, respectively. By changing the layer thickness and composition of SLSs and MQWs, we have prepared structures

  5. 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., E-mail: cfk23@cam.ac.uk [Department of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge CB2 3RA (United Kingdom)

    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.

  6. Laser clock

    SciTech Connect

    Facklam, R.L.

    1983-05-26

    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 detects a beat frequency and convert it to a clock signal.

  7. Surface properties of femtosecond laser ablated PMMA.

    PubMed

    Marco, Carmela De; Eaton, Shane M; Suriano, Raffaella; Turri, Stefano; Levi, Marinella; Ramponi, Roberta; Cerullo, Giulio; Osellame, Roberto

    2010-08-01

    The effects of femtosecond laser ablation on the physical and chemical properties at the surface of poly methylmethacrylate (PMMA) were studied. Femtosecond laser microfabrication caused the initially wetting behavior of PMMA to become nonwetting, mainly because of the laser-induced surface porosity at the submicroscale. Static and dynamic contact angle measurements along with morphological characterization revealed that after the laser irradiation, the system lies in an intermediate regime between those theorized by Wenzel and Cassie-Baxter. Spectroscopic analysis did not evidence any significant variation in the chemical properties of the processed polymeric surfaces. PMID:20735111

  8. Development of selective laser treatment techniques using mid-infrared tunable nanosecond pulsed laser.

    PubMed

    Ishii, Katsunori; Saiki, Masayuki; Hazama, Hisanao; Awazu, Kunio

    2010-01-01

    Mid-infrared (MIR) laser with a specific wavelength can excite the corresponding biomolecular site to regulate chemical, thermal and mechanical interactions to biological molecules and tissues. In laser surgery and medicine, tunable MIR laser irradiation can realize the selective and less-invasive treatments and the special diagnosis by vibrational spectroscopic information. This paper showed a novel selective therapeutic technique for a laser angioplasty of atherosclerotic plaques and a laser dental surgery of a carious dentin using a MIR tunable nanosecond pulsed laser. PMID:21096133

  9. The fabrication of vertically aligned and periodically distributed carbon nanotube bundles and periodically porous carbon nanotube films through a combination of laser interference ablation and metal-catalyzed chemical vapor deposition.

    PubMed

    Yuan, Dajun; Lin, Wei; Guo, Rui; Wong, C P; Das, Suman

    2012-06-01

    Scalable fabrication of carbon nanotube (CNT) bundles is essential to future advances in several applications. Here, we report on the development of a simple, two-step method for fabricating vertically aligned and periodically distributed CNT bundles and periodically porous CNT films at the sub-micron scale. The method involves laser interference ablation (LIA) of an iron film followed by CNT growth via iron-catalyzed chemical vapor deposition. CNT bundles with square widths ranging from 0.5 to 1.5 µm in width, and 50-200 µm in length, are grown atop the patterned catalyst over areas spanning 8 cm(2). The CNT bundles exhibit a high degree of control over square width, orientation, uniformity, and periodicity. This simple scalable method of producing well-placed and oriented CNT bundles demonstrates a high application potential for wafer-scale integration of CNT structures into various device applications, including IC interconnects, field emitters, sensors, batteries, and optoelectronics, etc. PMID:22551592

  10. Extraction of pure spectral signatures and corresponding chemical maps from EPR imaging data sets: identifying defects on a CaF2 surface due to a laser beam exposure.

    PubMed

    Abou Fadel, Maya; Zhang, Xin; de Juan, Anna; Tauler, Roma; Vezin, Hervé; Duponchel, Ludovic

    2015-04-01

    A calcium fluoride (CaF2) plate was exposed to pulsed laser irradiations inducing surface morphological and ionization changes on its surface. More precisely surface damages mainly correspond to intrinsic defects. Electron paramagnetic resonance (EPR) hyperspectral imaging is a powerful technique able to characterize the defects formed on the CaF2 surface. Indeed, EPR hyperspectral images provide spatial and spectral information about the sample studied. In fact, these images possess a great potential to obtain accurate and reliable knowledge about the chemical composition and the distribution of the component due to the presence of the spatial aspect. However, the complexity of such hyperspectral data sets imposes the use of advanced chemometric tools to extract valuable information on the considered physicochemical system. Therefore, Multivariate Curve Resolution-Alternating Least Squares (MCR-ALS) is proposed to identify and locate the different constituents in the images. The originality of this work is that it reports on the application of MCR-ALS, for the first time, on electron paramagnetic resonance (EPR) imaging data sets that will furnish the distribution maps and the spectral signatures of all components present in the sample. The results show the identification of different intrinsic defects on a CaF2 sample from the sole information in the raw image measurements and, therefore, confirm the potential of this methodology and the important role of spatial information contained in the image. PMID:25730682

  11. Laser surface modification of PEEK

    NASA Astrophysics Data System (ADS)

    Riveiro, A.; Soto, R.; Comesaña, R.; Boutinguiza, M.; del Val, J.; Quintero, F.; Lusquiños, F.; Pou, J.

    2012-09-01

    Polyether-ether-ketone (PEEK) is a synthetic thermoplastic polymer with excellent mechanical and chemical properties, which make it attractive for the field of reconstructive surgery. Nevertheless, this material has a poor interfacial biocompatibility due to its large chemical stability which induces poor adhesive bonding properties. The possibilities of enhancing the PEEK adhesive properties by laser treatments have been explored in the past. This paper presents a systematic approach to discern the role of laser irradiation wavelength on the surface modification of PEEK under three laser wavelengths (? = 1064, 532, and 355 nm) with the aim to determine the most adequate processing conditions to increase the roughness and wettability, the main parameters affecting cell adhesion characteristics of implants. Overall results show that the ultraviolet (? = 355 nm) laser radiation is the most suitable one to enhance surface wettability of PEEK.

  12. 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.

  13. Gas lasers.

    PubMed

    Bloom, A L

    1966-10-01

    A review is given of the present status of gas discharge lasers, with particular attention to developments reported in 1965 and early 1966. Following a brief history, gas lasers are classified by types-neutral atom, ion, and molecular-and a comparison is given of the properties of the various types. A short discussion is given of noise and coherence properties. Detailed descriptions are given of three recent developments of particular interest-the CO(2) laser, the argon-ion laser, and pulsed self-terminating lasers. Finally, brief mention is made of the most important present applications of gas lasers. PMID:20057585

  14. Laser Analyzer

    NASA Technical Reports Server (NTRS)

    1993-01-01

    Dopant level analysis is important to the laser system designer because it allows him to model the laser's performance. It also allows the end user to determine what went wrong when a laser fails to perform as expected. Under a Small Business Innovation Research (SBIR) contract, Scientific Materials Corporation has developed a process for producing uniform laser rods in which the amount of water trapped in the crystal during growth is reduced. This research led to the formation of a subsidiary company, Montana Analytical Services, which conducts analysis of laser rods for dopant ion concentrations. This is a significant advance in laser technology.

  15. DARPA-NRL laser program: semiannual technical report to Defense Advanced Research Projects Agency -- 1 July 1975 to 31 December 1975. Memorandum report

    Microsoft Academic Search

    J. R. Airey; R. Burnham; L. Champagne; N. Djeu; J. Eversole

    1976-01-01

    The DARPA-NRL Laser Program is concerned with the development of laser technology in three project areas: chemical infrared lasers, electrical infrared lasers and electronic-state lasers. The chemical infrared laser program includes studies of pulsed HCl laser systems and molecular energy transfer processes. Data have been collected which suggests that intramolecular energy transfer occurs in SF at a rate 1,000 times

  16. Page 1Laser Safety Training Laser Institute of America Laser Safety Laser Institute of America

    E-print Network

    Farritor, Shane

    Page 1Laser Safety Training © Laser Institute of America 1 Laser Safety © Laser Institute of America Laser Safety: Hazards, Bioeffects, and Control Measures Laser Institute of America Gus Anibarro Education Manager 2Laser Safety © Laser Institute of America Laser Safety Overview Laser Safety Accidents

  17. Laser polishing of niobium for SRF applications

    SciTech Connect

    Zhao, Liang; Klopf, J. Michael [JLAB; Reece, Charles E. [JLAB; Kelley, Michael [W& M

    2013-09-01

    Smooth interior surfaces are desired for niobium SRF cavities, now obtained by buffered chemical polish (BCP) and/or electropolish (EP). Laser polishing is a potential alternative, having advantages of speed, freedom from chemistry and in-process inspection. Here we show that laser polishing can produce smooth topography with Power Spectral Density (PSD) measurements similar to that obtained by EP. We studied the influence of the laser power density and laser beam raster rate on the surface topography. These two factors need to be combined carefully to smooth the surface without damaging it. Computational modeling was used to simulate the surface temperature and explain the mechanism of laser polishing.

  18. Laser Telecommunication timeLaser beam

    E-print Network

    La Rosa, Andres H.

    Telecommunication Experiment This picture represents how human voice (sound signals) is converted by the modulatorLaser Telecommunication Experiment Laser time Laser beam intensity timeLaser beam Laser battery (modulating signal) #12;Laser Telecommunication Experiment A diagram of our laser telecommunication kit. LASER

  19. Fs-laser processing of polydimethylsiloxane

    SciTech Connect

    Atanasov, Petar A., E-mail: paatanas@ie.bas.bg; Nedyalkov, Nikolay N. [Institute of Electronics, Bulgarian Academy of Sciences, 72 Tsarigradsko Shose, Sofia 1784 (Bulgaria); Valova, Eugenia I.; Georgieva, Zhenya S.; Armyanov, Stefan A.; Kolev, Konstantin N. [Rostislaw Kaischew Institute of Physical Chemistry, Bulgarian Academy of Sciences, Acad. G. Bonchev Str., Block 11, Sofia 1113 (Bulgaria); Amoruso, Salvatore; Wang, Xuan; Bruzzese, Ricardo [CNR-SPIN, Dipartimento di Scienze Fisiche, Universita degli Studi di Napoli Federico II, Complesso Universitario di Monte S. Angelo, Via Cintia, I-80126 Napoli (Italy); Sawczak, Miroslaw; ?liwi?ski, Gerard [Photophysics Department, The Szewalski Institute, Polish Academy of Sciences, 14 Fiszera St, 80-231 Gda?sk (Poland)

    2014-07-14

    We present an experimental analysis on surface structuring of polydimethylsiloxane films with UV (263?nm) femtosecond laser pulses, in air. Laser processed areas are analyzed by optical microscopy, SEM, and ?-Raman spectroscopy. The laser-treated sample shows the formation of a randomly nanostructured surface morphology. ?-Raman spectra, carried out at both 514 and 785?nm excitation wavelengths, prior and after laser treatment allow evidencing the changes in the sample structure. The influence of the laser fluence on the surface morphology is studied. Finally, successful electro-less metallization of the laser-processed sample is achieved, even after several months from the laser-treatment contrary to previous observation with nanosecond pulses. Our findings address the effectiveness of fs-laser treatment and chemical metallization of polydimethylsiloxane films with perspective technological interest in micro-fabrication devices for MEMS and nano-electromechanical systems.

  20. Chemical Emergencies

    MedlinePLUS

    ... the case of a terrorist attack with a chemical weapon. Some hazardous chemicals have been developed by military ... there are no guarantees of safety during a chemical emergency, you can take actions to protect yourself. You ...

  1. Development of mid-IR lasers for Laser Remote Sensing

    NASA Technical Reports Server (NTRS)

    Soibel, Alexander; Mansour, Kamjou; Spiers, Gary; Forouhar, Siamak

    2005-01-01

    There is an existing need in JPL and in NASA for development of mid-IR lasers, such as Quantum Cascade (QC) lasers, for in-situ and remote laser spectrometers. Mid-IR, compact, low power consumption laser spectrometers have a great potential for detection and measurements of planetary gases and biological important biomarker molecules such as H20, H202, CH4, and many additional chemical species on Mars and other Solar system planets. Another potential application of QC lasers for future NASA mission is in high power remote Laser Reflectance Spectrometers (LRS). In LSR instrument, mid-infrared lasers will act as the illumination source for conducting active mid-IR reflectance spectroscopy of solid-surfaced objects in the outer Solar System. These spectrometers have the potential to provide an incredible amount of information about the compositions of surfaces in the outer Solar System. In this work, we will discuss our current effort at JPL to advance QC lasers to a level that the laser performance, operational requirements and reliability be compatible with the instruments demands for space exploration applications.

  2. Laser-induced chemistry: an advanced tool for micro structuring, synthesis, and modification of materials

    Microsoft Academic Search

    Simeon Metev; Andreas Stephen; Joerg Schwarz; Carsten Wochnowski

    2004-01-01

    Laser-induced technological chemical processes can significantly contribute to the development of new methods for micro treatment of materials and hence to the broadening of the application spectrum of laser microtechnology. In this paper three typical laser-activated chemical technological methods in liquids, gases and solids and their possible applications are presented and discussed: (1) Laser-induced liquid-phase jet-chemical etching of metals. In

  3. Selective thermo\\/photochemical treatment of materials--a new trend in laser microtechnology

    Microsoft Academic Search

    Simeon Metev; Andreas Stephen; Jorg Schwarz; Carsten Wochnowski

    2003-01-01

    Laser-induced technological chemical processes can significantly contribute to the development of new methods for micro treatment of materials and hence to the broadening of the application spectrum of laser microtechnology. In this paper three typical laser-activated chemical technological methods in liquids, gases and solids and their possible applications are presented and discussed: 1) Laser-induced liquid-phase jet-chemical etching of metals. In

  4. Laser stimulated thermoluminescence

    Microsoft Academic Search

    A. Abtahi; P. Bräunlich; P. Kelly; J. Gasiot

    1985-01-01

    Experimental and computational methods are presented for the complete characterization of the thermoluminescence response obtained from thermoluminescent phosphors upon exposure to localized Gaussian laser heating beams. A number of different phosphor configurations are described as examples. These include LiF:Mg,Ti (TLD-100, Harshaw Chemical Corporation) in form of chips, which are widely used in the dosimetry of ionizing radiation, and thin-layer dosimeters

  5. Compact Quantum Cascade Laser Transmitter

    SciTech Connect

    Anheier, Norman C.; Hatchell, Brian K.; Gervais, Kevin L.; Wojcik, Michael D.; Krishnaswami, Kannan; Bernacki, Bruce E.

    2009-04-01

    ): In this paper we present design considerations, thermal and optical modeling results, and device performance for a ruggedized, compact laser transmitter that utilizes a room temperature quantum cascade (QC) laser source. The QC laser transmitter is intended for portable mid-infrared (3-12 µm) spectroscopy applications, where the atmospheric transmission window is relatively free of water vapor interference and where the molecular rotational vibration absorption features can be used to detect and uniquely identify chemical compounds of interest. Initial QC laser-based sensor development efforts were constrained by the complications of cryogenic operation. However, improvements in both QC laser designs and fabrication processes have provided room-temperature devices that now enable significant miniaturization and integration potential for national security, environmental monitoring, atmospheric science, and industrial safety applications.

  6. 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.

  7. Newer Trends in Laser Tattoo Removal

    PubMed Central

    Shah, Swapnil D; Aurangabadkar, Sanjeev J

    2015-01-01

    Q switched lasers are the current gold standard for laser tattoo removal. Though these systems are generally quite effective in clearing tattoos & have an established safety record, certain limitations exist while following the standard protocol. To overcome these limitation newer techniques such as multipass method, combination treatments with chemical agent and other laser have been introduced. These methods help in faster, less painful and complication free tattoo removal. PMID:25949019

  8. CW laser pumped emerald laser

    Microsoft Academic Search

    M. L. Shand; S. T. Lai

    1984-01-01

    A CW laser-pumped emerald laser is reported. A 34 percent output power slope efficiency is observed with longitudinal pumping by a krypton laser in a nearly concentric cavity. The laser has been tuned from 728.8 to 809.0 nm. Losses in emerald are larger than those of alexandrite determined in a similar cavity. The present data also indicate that the excited

  9. CW laser pumped emerald laser

    SciTech Connect

    Shand, M.L.; Lai, S.T.

    1984-02-01

    A CW laser-pumped emerald laser is reported. A 34 percent output power slope efficiency is observed with longitudinal pumping by a krypton laser in a nearly concentric cavity. The laser has been tuned from 728.8 to 809.0 nm. Losses in emerald are larger than those of alexandrite determined in a similar cavity. The present data also indicate that the excited state absorption minimum is shifted from that of alexandrite. 13 references.

  10. CW laser pumped emerald laser

    NASA Astrophysics Data System (ADS)

    Shand, M. L.; Lai, S. T.

    1984-02-01

    A CW laser-pumped emerald laser is reported. A 34 percent output power slope efficiency is observed with longitudinal pumping by a krypton laser in a nearly concentric cavity. The laser has been tuned from 728.8 to 809.0 nm. Losses in emerald are larger than those of alexandrite determined in a similar cavity. The present data also indicate that the excited state absorption minimum is shifted from that of alexandrite.

  11. Laser device

    DOEpatents

    Scott, Jill R. (Idaho Falls, ID); Tremblay, Paul L. (Idaho Falls, ID)

    2007-07-10

    A laser device includes a target position, an optical component separated a distance J from the target position, and a laser energy source separated a distance H from the optical component, distance H being greater than distance J. A laser source manipulation mechanism exhibits a mechanical resolution of positioning the laser source. The mechanical resolution is less than a spatial resolution of laser energy at the target position as directed through the optical component. A vertical and a lateral index that intersect at an origin can be defined for the optical component. The manipulation mechanism can auto align laser aim through the origin during laser source motion. The laser source manipulation mechanism can include a mechanical index. The mechanical index can include a pivot point for laser source lateral motion and a reference point for laser source vertical motion. The target position can be located within an adverse environment including at least one of a high magnetic field, a vacuum system, a high pressure system, and a hazardous zone. The laser source and an electro-mechanical part of the manipulation mechanism can be located outside the adverse environment. The manipulation mechanism can include a Peaucellier linkage.

  12. Laser device

    DOEpatents

    Scott, Jill R.; Tremblay, Paul L.

    2004-11-23

    A laser device includes a target position, an optical component separated a distance J from the target position, and a laser energy source separated a distance H from the optical component, distance H being greater than distance J. A laser source manipulation mechanism exhibits a mechanical resolution of positioning the laser source. The mechanical resolution is less than a spatial resolution of laser energy at the target position as directed through the optical component. A vertical and a lateral index that intersect at an origin can be defined for the optical component. The manipulation mechanism can auto align laser aim through the origin during laser source motion. The laser source manipulation mechanism can include a mechanical index. The mechanical index can include a pivot point for laser source lateral motion and a reference point for laser source vertical motion. The target position can be located within an adverse environment including at least one of a high magnetic field, a vacuum system, a high pressure system, and a hazardous zone. The laser source and an electro-mechanical part of the manipulation mechanism can be located outside the adverse environment. The manipulation mechanism can include a Peaucellier linkage.

  13. Diatomic Cesium in a Diode-Pumped Alkali Laser System

    Microsoft Academic Search

    Jamey Christy; Eric Martinez; Tanner Oakes; Jake Smith; Kendrick Walter

    2008-01-01

    Abstract Diode Pumped Alkali Laser (DPAL) systems combine the positive characteristics of chemical and diode lasers. These systems create a laser that is compact and ecient, while working well at high temperatures and high powers. In conjunction with the Air Force Research Laboratory (AFRL), an attempt was made to improve DPAL technology by using a diatomic alkali metal as a

  14. Ultrashort-pulse laser generated nanoparticles of energetic materials

    DOEpatents

    Welle, Eric J. (Niceville, NM); Tappan, Alexander S. (Albuquerque, NM); Palmer, Jeremy A. (Albuquerque, NM)

    2010-08-03

    A process for generating nanoscale particles of energetic materials, such as explosive materials, using ultrashort-pulse laser irradiation. The use of ultrashort laser pulses in embodiments of this invention enables one to generate particles by laser ablation that retain the chemical identity of the starting material while avoiding ignition, deflagration, and detonation of the explosive material.

  15. Laser-supported detonation waves and pulsed laser propulsion

    SciTech Connect

    Kare, J. (Lawrence Livermore National Laboratory, Livermore, California 94550 (United States))

    1990-07-30

    A laser thermal rocket uses the energy of a large remote laser, possibly ground-based, to heat an inert propellant and generate thrust. Use of a pulsed laser allows the design of extremely simple thrusters with very high performance compared to chemical rockets. The temperatures, pressures, and fluxes involved in such thrusters (10{sup 4} K, 10{sup 2} atmospheres, 10{sup 7} w/cm{sup 2}) typically result in the creation of laser-supported detonation (LSD) waves. The thrust cycle thus involves a complex set of transient shock phenomena, including laser-surface interactions in the ignition of the LSD wave, laser-plasma interactions in the LSD wave itself, and high-temperature nonequilibrium chemistry behind the LSD wave. The SDIO Laser Propulsion Program is investigating these phenomena as part of an overall effort to develop the technology for a low-cost Earth-to-orbit laser launch system. We will summarize the Program's approach to developing a high performance thruster, the double-pulse planar thruster, and present an overview of some results obtained to date, along with a discussion of the many research question still outstanding in this area.

  16. Laser-supported detonation waves and pulsed laser propulsion

    SciTech Connect

    Kare, J.T.

    1989-01-01

    A laser thermal rocket uses the energy of a large remote laser, possibly ground-based, to heat an inert propellant and generate thrust. Use of a pulsed laser allows the design of extremely simple thrusters with very high performance compared to chemical rockets. The temperatures, pressures, and fluxes involved in such thrusters (10{sup 4} K, 10{sup 2} atmospheres, 10{sup 7} w/cm{sup 2}) typically result in the creation of laser-supported detonation (LSD) waves. The thrust cycle thus involves a complex set of transient shock phenomena, including laser-surface interactions in the ignition if the LSD wave, laser-plasma interactions in the LSD wave itself, and high-temperature nonequilibrium chemistry behind the LSD wave. The SDIO Laser Propulsion Program is investigating these phenomena as part of an overall effort to develop the technology for a low-cost Earth-to-orbit laser launch system. We will summarize the program's approach to developing a high performance thruster, the double-pulse planar thruster, and present an overview of some results obtained to date, along with a discussion of the many research questions still outstanding in this area. 16 refs., 7 figs.

  17. Nanochemical effects in femtosecond laser ablation of metals

    SciTech Connect

    Vorobyev, A. Y.; Guo, Chunlei [The Institute of Optics, University of Rochester, Rochester, New York 14627 (United States)] [The Institute of Optics, University of Rochester, Rochester, New York 14627 (United States)

    2013-02-18

    We study chemical energy released from the oxidation of aluminum in multipulse femtosecond laser ablation in air and oxygen. Our study shows that the released chemical energy amounts to about 13% of the incident laser energy, and about 50% of the ablated material is oxidized. The ablated material mass per laser pulse is measured to be on the nanogram scale. Our study indicates that femtosecond laser ablation is capable of inducing nanochemical reactions since the femtosecond laser pulse can controllably produce nanoparticles, clusters, and atoms from a solid target.

  18. Development of a new multi-residue laser diode thermal desorption atmospheric pressure chemical ionization tandem mass spectrometry method for the detection and quantification of pesticides and pharmaceuticals in wastewater samples.

    PubMed

    Boisvert, Michel; Fayad, Paul B; Sauvé, Sébastien

    2012-11-19

    A new solid phase extraction (SPE) method coupled to a high throughput sample analysis technique was developed for the simultaneous determination of nine selected emerging contaminants in wastewater (atrazine, desethylatrazine, 17?-estradiol, ethynylestradiol, norethindrone, caffeine, carbamazepine, diclofenac and sulfamethoxazole). We specifically included pharmaceutical compounds from multiple therapeutic classes, as well as pesticides. Sample pre-concentration and clean-up was performed using a mixed-mode SPE cartridge (Strata ABW) having both cation and anion exchange properties, followed by analysis by laser diode thermal desorption atmospheric pressure chemical ionization coupled to tandem mass spectrometry (LDTD-APCI-MS/MS). The LDTD interface is a new high-throughput sample introduction method, which reduces total analysis time to less than 15s per sample as compared to minutes with traditional liquid-chromatography coupled to tandem mass spectrometry (LC-MS/MS). Several SPE parameters were evaluated in order to optimize recovery efficiencies when extracting analytes from wastewater, such as the nature of the stationary phase, the loading flow rate, the extraction pH, the volume and composition of the washing solution and the initial sample volume. The method was successfully applied to real wastewater samples from the primary sedimentation tank of a municipal wastewater treatment plant. Recoveries of target compounds from wastewater ranged from 78% to 106%, the limit of detection ranged from 30 to 122ng L(-1) while the limit of quantification ranged from 90 to 370ng L(-1). Calibration curves in the wastewater matrix showed good linearity (R(2)?0.991) for all target analytes and the intraday and interday coefficient of variation was below 15%, reflecting a good precision. PMID:23140957

  19. Laser cleaning on Roman coins

    NASA Astrophysics Data System (ADS)

    Drakaki, E.; Karydas, A. G.; Klinkenberg, B.; Kokkoris, M.; Serafetinides, A. A.; Stavrou, E.; Vlastou, R.; Zarkadas, C.

    Ancient metal objects react with moisture and environmental chemicals to form various corrosion products. Because of the unique character and high value of such objects, any cleaning procedure should guarantee minimum destructiveness. The most common treatment used is mechanical stripping, in which it is difficult to avoid surface damage when employed. Lasers are currently being tested for a wide range of conservation applications. Since they are highly controllable and can be selectively applied, lasers can be used to achieve more effective and safer cleaning of archaeological artifacts and protect their surface details. The basic criterion that motivated us to use lasers to clean Roman coins was the requirement of pulsed emission, in order to minimize heat-induced damages. In fact, the laser interaction with the coins has to be short enough, to produce a fast removal of the encrustation, avoiding heat conduction into the substrate. The cleaning effects of three lasers operating at different wavelengths, namely a TEA CO2 laser emitting at 10.6 ?m, an Er:YAG laser at 2.94 ?m, and a 2?-Nd:YAG laser at 532 nm have been compared on corroded Romans coins and various atomic and nuclear techniques have also been applied to evaluate the efficiency of the applied procedure.

  20. 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. Reliable fuel ignition is provided over a wide range of fuel conditions by using a single remote excitation light source for one or more small lasers located proximate to one or more fuel combustion zones. In the embodiment of the invention claimed herein, 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 combined with either the first portion after a delay before injection into the ignitor laser.

  1. Chemical Communication

    NSDL National Science Digital Library

    0000-00-00

    A concise lesson about chemical communication in insects covering both semio and info chemicals. The site includes a short video of grape root borer moths using sex pheromone. Further links on the take the user to visual and auditory communication.

  2. 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 capable of producing alternating beams of light having different wavelengths is used in tandem with one or more ignitor lasers to provide a compact, durable, engine deployable fuel ignition laser system. Reliable fuel ignition is provided over a wide range of fuel conditions by using the single remote excitation light source for pumping one or more small lasers located proximate to one or more fuel combustion zones with alternating wavelengths of light.

  3. Injection lasers

    SciTech Connect

    Salter, S.R.; Smith, D.R.

    1982-10-19

    Apparatus for stabilizing output characteristics of an injection laser has a light sensitive device for producing an electrical signal indicative of the D.C. Output light level of the laser. The electrical signal is compared with a reference signal to produce a further signal which is applied to D.C. Bias control means for the laser. The D.C. Bias control means responds to the further signal to adjust the D.C. Bias level such that the D.C. Light output level remains substantially at a predetermined level. The means or peak output of the laser can be controlled in a similar manner.

  4. Micromachining soda-lime glass by femtosecond laser pulses

    NASA Astrophysics Data System (ADS)

    Jia, Wei; Yu, Jian; Chai, Lu; Wang, Ching-Yue

    2015-06-01

    The physical process of forming a modified region in soda-lime glass was investigated using 1 kHz intense femtosecond laser pulses from a Ti: sapphire laser at 775 nm. Through the modifications induced by the femtosecond laser radiation using selective chemical etching techniques, we fabricated reproducible and defined microstructures and further studied their morphologies and etching properties. Moreover, a possible physical mechanism for the femtosecond laser modification in soda-lime glass was proposed.

  5. Chemical sensor

    NASA Technical Reports Server (NTRS)

    Rauh, R. David (Inventor)

    1990-01-01

    A sensor for detecting a chemical substance includes an insertion element having a structure which enables insertion of the chemical substance with a resulting change in the bulk electrical characteristics of the insertion element under conditions sufficient to permit effective insertion; the change in the bulk electrical characteristics of the insertion element is detected as an indication of the presence of the chemical substance.

  6. Laser-evoked coloration in polymers

    NASA Astrophysics Data System (ADS)

    Zheng, H. Y.; Rosseinsky, David; Lim, G. C.

    2005-05-01

    Laser-evoked coloration in polymers has long been a major aim of polymer technology for potential applications in product surface decoration, marking personalised images and logos. However, the coloration results reported so far were mostly attributed to laser-induced thermal-chemical reactions. The laser-irradiated areas are characterized with grooves due to material removal. Furthermore, only single color was laser-induced in any given polymer matrix. To induce multiple colors in a given polymer matrix with no apparent surface material removal is most desirable and challenging and may be achieved through laser-induced photo-chemical reactions. However, little public information is available at present. We report that two colors of red and green have been produced on an initially transparent CPV/PVA samples through UV laser-induced photo-chemical reactions. This is believed the first observation of laser-induced multiple-colors in the given polymer matrix. It is believed that the colorants underwent photo-effected electron transfer with suitable electron donors from the polymers to change from colorless bipyridilium Bipm 2+ to the colored Bipm + species. The discovery may lead to new approaches to the development of laser-evoked multiple coloration in polymers.

  7. Heterodyne laser spectroscopy system

    SciTech Connect

    Wyeth, R.W.; Paisner, J.A.; Story, T.

    1989-03-28

    A heterodyne laser spectroscopy system utilizes laser heterodyne techniques for purposes of laser isotope separation spectroscopy, vapor diagnostics, processing of precise laser frequency offsets from a reference frequency and the like, and provides spectral analysis of a laser beam.

  8. Laser/plasma chemical processing of substrates

    DOEpatents

    Gee, James M. (Albuquerque, NM); Hargis, Jr., Philip J. (Albuquerque, NM)

    1986-01-01

    A process for the modification of substrate surfaces is described, wherein etching or deposition at a surface occurs only in the presence of both reactive species and a directed beam of coherent light.

  9. Gas lasers

    Microsoft Academic Search

    A. L. Bloom

    1966-01-01

    A review is given of the present status of gas discharge lasers, with particular attention to developments reported in 1965 and early 1966. Following a brief history, gas lasers are classified by types--neutral atom, ion, and molecular--and a comparison is given of the properties of the various types. A short discussion is given of noise and coherence properties. Detailed descriptions

  10. Quantum cascade laser investigations of CH{sub 4} and C{sub 2}H{sub 2} interconversion in hydrocarbon/H{sub 2} gas mixtures during microwave plasma enhanced chemical vapor deposition of diamond

    SciTech Connect

    Ma Jie; Cheesman, Andrew; Ashfold, Michael N. R. [School of Chemistry, University of Bristol, Bristol BS8 1TS (United Kingdom); Hay, Kenneth G.; Wright, Stephen; Langford, Nigel; Duxbury, Geoffrey [Department of Physics, University of Strathclyde, John Anderson Building, 107 Rottenrow, Glasgow G4 0NG (United Kingdom); Mankelevich, Yuri A. [Skobel'tsyn Institute of Nuclear Physics, Moscow State University, Leninskie Gory, Moscow 119991 (Russian Federation)

    2009-08-01

    CH{sub 4} and C{sub 2}H{sub 2} molecules (and their interconversion) in hydrocarbon/rare gas/H{sub 2} gas mixtures in a microwave reactor used for plasma enhanced diamond chemical vapor deposition (CVD) have been investigated by line-of-sight infrared absorption spectroscopy in the wavenumber range of 1276.5-1273.1 cm{sup -1} using a quantum cascade laser spectrometer. Parameters explored include process conditions [pressure, input power, source hydrocarbon, rare gas (Ar or Ne), input gas mixing ratio], height (z) above the substrate, and time (t) after addition of hydrocarbon to a pre-existing Ar/H{sub 2} plasma. The line integrated absorptions so obtained have been converted to species number densities by reference to the companion two-dimensional (r,z) modeling of the CVD reactor described in Mankelevich et al. [J. Appl. Phys. 104, 113304 (2008)]. The gas temperature distribution within the reactor ensures that the measured absorptions are dominated by CH{sub 4} and C{sub 2}H{sub 2} molecules in the cool periphery of the reactor. Nonetheless, the measurements prove to be of enormous value in testing, tensioning, and confirming the model predictions. Under standard process conditions, the study confirms that all hydrocarbon source gases investigated (methane, acetylene, ethane, propyne, propane, and butane) are converted into a mixture dominated by CH{sub 4} and C{sub 2}H{sub 2}. The interconversion between these two species is highly dependent on the local gas temperature and the H atom number density, and thus on position within the reactor. CH{sub 4}->C{sub 2}H{sub 2} conversion occurs most efficiently in an annular shell around the central plasma (characterized by 1400CH{sub 4} is favored in the more distant regions where T{sub gas}<1400 K. Analysis of the multistep interconversion mechanism reveals substantial net consumption of H atoms accompanying the CH{sub 4}->C{sub 2}H{sub 2} conversion, whereas the reverse C{sub 2}H{sub 2}->CH{sub 4} process only requires H atoms to drive the reactions; H atoms are not consumed by the overall conversion.

  11. Influence of gas temperature on self-sustained volume discharge characteristics in working mixtures of a repetitively pulsed COIL

    NASA Astrophysics Data System (ADS)

    Aksinin, V. I.; Antsiferov, S. A.; Velikanov, S. D.; Kazantsev, S. Yu; Kalinovskii, V. V.; Konovalov, V. V.; Kononov, I. G.; Mikhalkin, V. N.; Podlesnykh, S. V.; Sevryugin, I. V.; Firsov, K. N.

    2014-02-01

    The influence of gas temperature on the characteristics of a self-sustained volume discharge was studied in the working mixtures of a chemical oxygen - iodine laser with pulsed electricdischarge production of iodine atoms. In experiments, laser working mixtures were modelled by the mixture of air and iodide C2H5I. It was established that mixture heating is accompanied by an increase in the voltage across the discharge plasma and by a decrease in the discharge current. By varying the temperature of the mixture with the iodine content of ~2.7% and initial pressure p=12 Torr from 22 °C to 96 °C, the current amplitude falls by ~12%, and at the instant corresponding to a maximal current the voltage raises by ~22%. Such a change in the discharge characteristics is explained by a higher rate of electron attachment to vibrationally excited iodide molecules at elevated temperatures.

  12. Laser device

    DOEpatents

    Scott, Jill R. (Idaho Falls, ID); Tremblay, Paul L. (Idaho Falls, ID)

    2008-08-19

    A laser device includes a virtual source configured to aim laser energy that originates from a true source. The virtual source has a vertical rotational axis during vertical motion of the virtual source and the vertical axis passes through an exit point from which the laser energy emanates independent of virtual source position. The emanating laser energy is collinear with an orientation line. The laser device includes a virtual source manipulation mechanism that positions the virtual source. The manipulation mechanism has a center of lateral pivot approximately coincident with a lateral index and a center of vertical pivot approximately coincident with a vertical index. The vertical index and lateral index intersect at an index origin. The virtual source and manipulation mechanism auto align the orientation line through the index origin during virtual source motion.

  13. Chemical burns

    PubMed Central

    Cartotto, Robert C.; Peters, Walter J.; Neligan, Peter C.; Douglas, Leith G.; Beeston, Jeff

    1996-01-01

    Objectives To report a burn unit’s experience with chemical burns and to discuss the fundamental principles in managing chemical burns. Design A chart review. Setting A burn centre at a major university-affiliated hospital. Patients Twenty-four patients with chemical burns, representing 2.6% of all burn admissions over an 8-year period at the Ross Tilley Regional Adult Burn Centre. Seventy-five percent of the burn injuries were work-related accidents. Chemicals involved included hydrofluoric acid, sulfuric acid, black liquor, various lyes, potassium permanganate and phenol. Results Fourteen patients required excision and skin grafting. Complications were frequent and included ocular chemical contacts, wound infections, tendon exposures, toe amputation and systemic reactions from absorption of chemical. One patient died from a chemical scald burn to 98% of the body surface area. Conclusions The key principles in the management of chemical burns include removal of the chemical, copious irrigation, limited use of antidotes, correct estimation of the extent of injury, identification of systemic toxicity, treatment of ocular contacts and management of chemical inhalation injury. Individualized treatment is emphasized. PMID:8640619

  14. 1.2-?m GaAsP\\/InGaAs strain compensated single-quantum-well diode laser on GaAs using metal-organic chemical vapor deposition

    Microsoft Academic Search

    Won-Jin Choi; P. Daniel Dapkus; Jack J. Jewell

    1999-01-01

    We demonstrate here 1.2-?m laser emission from a GaAsP-InGaAs strain compensated single-quantum-well (SQW) diode. This development enables the fabrication of vertical-cavity surface-emitting lasers for optical interconnection through Si wafers. Strain compensation and low temperature growth were used to extend the wavelength of emission to the longest yet achieved on a GaAs substrate in this materials system. The minimum threshold density

  15. Chemical Composition

    NASA Astrophysics Data System (ADS)

    May, Willie; Cavanagh, Richard; Turk, Gregory; Winchester, Michael; Travis, John; Smith, Melody; Derose, Paul; Choquette, Steven; Kramer, Gary; Sieber, John; Greenberg, Robert; Lindstrom, Richard; Lamaze, George; Zeisler, Rolf; Schantz, Michele; Sander, Lane; Phinney, Karen; Welch, Michael; Vetter, Thomas; Pratt, Kenneth; Scott, John; Small, John; Wight, Scott; Stranick, Stephan

    Measurements of the chemical compositions of materials and the levels of certain substances in them are vital when assessing and improving public health, safety and the environment, are necessary to ensure trade equity, and are required when monitoring and improving industrial products and services. Chemical measurements play a crucial role in most areas of the economy, including healthcare, food and nutrition, agriculture, environmental technologies, chemicals and materials, instrumentation, electronics, forensics, energy, and transportation.

  16. Chemical Bonds

    NSDL National Science Digital Library

    The Concord Consortium

    2011-12-11

    Electrons are key to forming the two broad categories of chemical bonds: covalent and ionic. Atoms, which have a nucleus surrounded by electrons, are represented in several different ways. In the Chemical Bonds activity, students explore the different kinds of chemical bonds that can form, ranging from non-polar covalent to ionic. In the model depicted above students adjust the electronegativity of two atoms and see the effect it has on electron distribution and bond type.

  17. Gas and metal vapor lasers and applications; Proceedings of the Meeting, Los Angeles, CA, Jan. 22, 23, 1991

    NASA Astrophysics Data System (ADS)

    Kim, Jin J.; Tittel, Frank K.

    Various papers on gas and metal vapor lasers and applications are presented. Individual topics addressed include: high-power copper vapor laser development, modified off-axis unstable resonator for copper vapor laser, industrial applications of metal vapor lasers, newly developed excitation circuit for kHz pulsed lasers, copper vapor laser precision processing, development of solid state pulse power supply for copper vapor laser, multiple spectral structure of the 578.2-nm line for copper vapor laser, adsorption of bromine in CuBr laser, processing of polytetrafluoroethylene with high-power VUV laser radiation, characterization of a subpicosecond XeF(C - A) excimer laser, X-ray preionization for high-repetition-rate discharge excimer lasers. Also discussed are: investigation of microwave-pumped excimer and rare-gas laser transitions, influence of gas composition of XeCl laser performance, output power stabilization of a XeCl excimer laser by HCl gas injection, excimer laser machining of optical fiber taps, diagnostics of a compact UV-preionized XeCl laser with BCl3 halogen donor, blackbody-pumped CO32 lasers using Gaussian and waveguide cavities, chemical problems of high-power sealed-off CO lasers, laser action of Xe and Ne pumped by electron beam, process monitoring during CO2 laser cutting, double-pulsed TEA CO2 laser, superhigh-gain gas laser, high-power ns-pulse iodine laser provided with SBS mirror. (No individual items are abstracted in this volume)

  18. Improving the reliability and modal stability of high power 870 nm AlGaAs CSP laser diodes for applications to free space communication systems

    Microsoft Academic Search

    J. C. Connolly; G. A. Alphonse; D. B. Carlin; M. Ettenberg

    1991-01-01

    The operating characteristics (power-current, beam divergence, etc.) and reliability assessment of high-power CSP lasers is discussed. The emission wavelength of these lasers was optimized at 860 to 880 nm. The operational characteristics of a new laser, the inverse channel substrate planar (ICSP) laser, grown by metalorganic chemical vapor deposition (MOCVD), is discussed and the reliability assessment of this laser is

  19. Quiet Lasers

    E-print Network

    Jacques Arnaud; Laurent Chusseau; Fabrice Philippe

    2009-06-08

    We call "quiet laser" a stationary laser that generates in detectors regular photo-electrons (sub-Poisson statistics). It follows from the law of conservation of energy that this is so when the laser power supply does not fluctuate. Various configurations are analyzed on the basis of the Planck (1907) semi-classical concept: "I am not seeking the meaning of light quanta in the vacuum but rather in places where emission and absorption occur, and I assume that what happens in the vacuum is rigorously described by Maxwell's equations". Exact agreement with Quantum Optics results is noted. Comments welcome!

  20. Laser therapy

    MedlinePLUS

    Laser therapy is a treatment that uses a strong beam of light to cut, burn, or destroy tissue. ... safely treat tissue without injuring the surrounding area. ... eye surgery to improve vision Repairing a detached retina of ...

  1. Ring lasers

    SciTech Connect

    Lindop, A.J.

    1981-01-27

    The invention provides a ring laser having one or more parallelsided prisms, or other refracting device, positioned in the light path of the laser resonant cavity formed by, for example, three mirrors, and including a solenoid or other means for imparting oscillatory translational motion to the prism or prisms or refracting device with a component parallel to the portion of the light path which passes therethrough.

  2. Laser pancreatectomy

    Microsoft Academic Search

    T. Schröder; O. J. Rämö; S. N. Joffe

    1988-01-01

    Summary Total pancreatectomy was performed in dogs (n = 5) and pigs (n = 6) using a contact Nd:YAG laser with a wave length of 1060 nm. The fiber was connected to a laser scalpel, and a 1.0-mm-diameter sapphire tip was used. The power was set at 10–12 W with a pulse time of 9.9 s. The animals were followed

  3. Chemical Composition

    Microsoft Academic Search

    Willie May; Richard Cavanagh; Gregory Turk; Michael Winchester; John Travis; Melody Smith; Paul Derose; Steven Choquette; Gary Kramer; John Sieber; Robert Greenberg; Richard Lindstrom; George Lamaze; Rolf Zeisler; Michele Schantz; Karen Phinney; Michael Welch; Thomas Vetter; Kenneth Pratt; John Scott; John Small; Scott Wight; Stephan Stranick

    2006-01-01

    Measurements of the chemical compositions of materials and the levels of certain substances in them are vital when assessing and improving public health, safety and the environment, are necessary to ensure trade equity, and are required when monitoring and improving industrial products and services. Chemical measurements play a crucial role in most areas of the economy, including healthcare, food and

  4. Chemical geodynamics

    Microsoft Academic Search

    A. Zindler; S. R. Hart

    1986-01-01

    Consideration is given to the following three principal boundary conditions relating to the nature and development of chemical structure in the earth's mantle: (1) inferred scale lengths for mantle chemical heterogeneities, (2) interrelationships of the various isotopic tracers, and (3) the bulk composition of the earth. These boundary conditions are integrated with geophysical constraints in order to evaluate models for

  5. Chemical Reactions

    NSDL National Science Digital Library

    National Science Teachers Association (NSTA)

    2009-05-01

    We don't often stop to think about it, but underlying many of our everyday activities are chemical reactions. From the cooking of an egg to the growth of a child, chemical reactions make things happen. Although many of the reactions that support our lives

  6. Cleaning laser spark spectroscopy for online cleaning quality control method development

    NASA Astrophysics Data System (ADS)

    Mutin, T. Y.; Smirnov, V. N.; Veiko, V. P.; Volkov, S. A.

    2011-02-01

    This work is dedicated to spectroscopic investigations of laser spark during the laser cleaning process. The goal is to proof its analytical possibilities for chemical composition determination for online cleaning quality control. Photographic recordings of laser spark were performed to estimate its parameters. Fiber spectrometer was used to analyze the emission of cleaning process established with fiber laser. Conclusions have been made about fiber laser radiation usability for spectroscopic purpose.

  7. Cleaning laser spark spectroscopy for online cleaning quality control method development

    NASA Astrophysics Data System (ADS)

    Mutin, T. Y.; Smirnov, V. N.; Veiko, V. P.; Volkov, S. A.

    2010-07-01

    This work is dedicated to spectroscopic investigations of laser spark during the laser cleaning process. The goal is to proof its analytical possibilities for chemical composition determination for online cleaning quality control. Photographic recordings of laser spark were performed to estimate its parameters. Fiber spectrometer was used to analyze the emission of cleaning process established with fiber laser. Conclusions have been made about fiber laser radiation usability for spectroscopic purpose.

  8. Laser Angioplasty

    NASA Technical Reports Server (NTRS)

    1990-01-01

    The principal method of dealing with coronary artery blockage is bypass surgery. A non-surgical alternative available to some patients is balloon angioplasty. For several years, medical researchers have been exploring another alternative that would help a wider circle of patients than the balloon treatment and entail less risk than bypass surgery. A research group is on the verge of an exciting development: laser angioplasty with a 'cool' type of laser, called an excimer laser, that does not damage blood vessel walls and offers non-surgical cleansing of clogged arteries with extraordinary precision. The system is the Dymer 200+ Excimer Laser Angioplasty System, developed by Advanced Intraventional Systems. Used in human clinical tests since 1987, the system is the first fully integrated 'cool' laser capable of generating the requisite laser energy and delivering the energy to target arteries. Thirteen research hospitals in the U.S. have purchased Dymer 200+ systems and used them in clinical trials in 121 peripheral and 555 coronary artery cases. The success rate in opening blocked coronary arteries is 85 percent, with fewer complications than in balloon angioplasty. Food and Drug Administration approval for the system is hoped for in the latter part of 1990. * Advanced Intraventional Systems became Spectranetics in 1994 and discontinued the product.

  9. DIODE LASER FREQUENCY STANDARD FOR LASER INTERFEROMETRY

    Microsoft Academic Search

    Janusz Pienkowski

    Diode lasers are becoming increasingly important in length metrology. We demonstrate construction of a simple single-frequency diode laser 632,8 nm, used as a frequency standard in the laser interferometers. We present two different systems applied for frequency stabil ization of diode laser . For diode laser used as the secondar y standard, the system stabilizes diode temperature, the frequ ency

  10. Detection of chemical agent aerosols

    NASA Astrophysics Data System (ADS)

    Fox, Jay A.; Ahl, Jeffrey L.; D'Amico, Francis M.; Vanderbeek, Richard G.; Moon, Raphael; Swim, Cynthia R.

    1999-05-01

    One of the major threats presented by a chemical agent attack is that of a munition exploding overhead and 'raining' aerosols which can contaminate surfaces when they impact. Since contact with these surfaces can be fatal, it is imperative to know when such an attack has taken place and the likely threat density and location. We present the results of an experiment designed to show the utility of a CO2 lidar in detecting such an attack. Testing occurred at Dugway Proving Grounds, Utah and involved the simulation of an explosive airburst chemical attack. Explosions occurred at a height of 30 m and liquid droplets from two chemicals, PEG-200 (polyethylene glycol 200) and TEP (triethylphosphate), were expelled and fell to the ground. The munition was the U.S. Army M9 Simulator, Projectile, Airburst, Liquid (SPAL) system that is designed for chemical warfare training exercises. The instrument that was used to detect the presence of the aerosols was the Laser Standoff Chemical Detector (LSCD) which is a light detection and ranging (LIDAR) system that utilizes a rapidly tunable, pulsed CO2 laser. The LIDAR scanned a horizontal path approximately 5 - 8 m above the ground in order to measure the concentration of liquid deposition. The LIDAR data were later correlated with card data to determine how well the system could predict the location and quantity of liquid deposition on the ground.

  11. Investigation of the Production of O2(a1 ) in Rectangular

    E-print Network

    Carroll, David L.

    and rotational energy, (ii) thermal energy (gas temperature), (iii) energy stored in electronic energy states Oxygen- Iodine Laser (ElectricOIL) system. This continuous wave (cw) laser operating on the 1315 nm transition of atomic iodine is pumped by the production of O2(a) in a radio-frequency (RF) discharge in an O2

  12. ACTIVE MEDIA: Atomic iodine production in a gas flow by decomposing methyl iodide in a dc glow discharge

    Microsoft Academic Search

    P. A. Mikheyev; A. A. Shepelenko; A. I. Voronov; Nikolai V. Kupryaev

    2002-01-01

    The production of atomic iodine for an oxygen --- iodine laser is studied by decomposing methyl iodide in a dc glow discharge in a vortex gas flow. The concentration of iodine atoms in discharge products was measured from the atomic iodine absorption of the radiation of a single-frequency tunable diode laser at a wavelength of 1.315 mum. Atomic iodine concentrations

  13. Laser Safety Introduction

    E-print Network

    McQuade, D. Tyler

    Laser Safety #12;Introduction · A Laser is a device that controls the way energized atoms release photons. · LASER is an acronym for "Light Amplification by Stimulated Emission of Radiation" · The light emitted by a laser is non

  14. Laser Physics and Laser-Tissue Interaction

    PubMed Central

    Welch, A. J.; Torres, Jorge H.; Cheong, Wai-Fung

    1989-01-01

    Within the last few years, lasers have gained increasing use in the management of cardiovascular disease, and laser angioplasty has become a widely performed procedure. For this reason, a basic knowledge of lasers and their applications is essential to vascular surgeons, cardiologists, and interventional radiologists. To elucidate some fundamental concepts regarding laser physics, we describe how laser light is generated and review the properties that make lasers useful in medicine. We also discuss beam profile and spotsize, as well as dosimetric specifications for laser angioplasty. After considering laser-tissue interaction and light propagation in tissue, we explain how the aforementioned concepts apply to direct laser angioplasty and laser-balloon angioplasty. An understanding of these issues should prove useful not only in performing laser angioplasty but in comparing the reported results of various laser applications. (Texas Heart Institute Journal 1989;16:141-9) PMID:15227198

  15. Gas discharge lasers

    Microsoft Academic Search

    A. E. Novik

    1982-01-01

    Gas discharge lasers are discussed with reference to the theoretical principles underlying their operation, costruction and design, performance characteristics, fabrication, and applications. The types of gas discharge lasers considered include lasers operating at atomic and molecular transitions, ion lasers, and pulsed gas discharge lasers. Particular attention is given to the most widely used types of lasers, such as He-Ne, argon-ion,

  16. Unnecessary Chemicals

    ERIC Educational Resources Information Center

    Johnson, Anita

    1978-01-01

    Discusses the health hazards resulting from chemical additions of many common products such as cough syrups, food dyes, and cosmetics. Steps being taken to protect consumers from these health hazards are included. (MDR)

  17. Desktop manufacturing using diode lasers

    NASA Astrophysics Data System (ADS)

    Roychoudhuri, Chandrasekhar

    1998-06-01

    Semiconductor laser diodes, while not yet ready to replace YAG and CO2 lasers from heavy duty machining, are already capable of carrying out a number of manufacturing jobs that require a power density of 100 kw/cm2 or less, and CW power of 100 Watt or less. We present results of cutting cellulose materials, marking plastics, soldering electronic circuit boards, surface (transformation) hardening, chemical vapor phase deposition (by gas breakdown) using fiber coupled CW lasers at 810 nm (60 Watts) and 980 nm (25 Watts). We also present the results of sintering metal powders under different conditions to improve density and hardness, demonstrating that diodes can do an excellent job in solid free-form development (or rapid prototyping).

  18. Advanced laser diodes for sensing applications

    SciTech Connect

    VAWTER,GREGORY A.; MAR,ALAN; CHOW,WENG W.; ALLERMAN,ANDREW A.

    2000-01-01

    The authors have developed diode lasers for short pulse duration and high peak pulse power in the 0.01--100.0 m pulsewidth regime. A primary goal of the program was producing up to 10 W while maintaining good far-field beam quality and ease of manufacturability for low cost. High peak power, 17 W, picosecond pulses have been achieved by gain switching of flared geometry waveguide lasers and amplifiers. Such high powers area world record for this type of diode laser. The light emission pattern from diode lasers is of critical importance for sensing systems such as range finding and chemical detection. They have developed a new integrated optical beam transformer producing rib-waveguide diode lasers with a symmetric, low divergence, output beam and increased upper power limits for irreversible facet damage.

  19. Laser telemetry

    SciTech Connect

    Clark, L.K.; Peron, M.C.

    1982-10-12

    A projectile carries a laser transmitter which directs its output beam to the rear through an aperture in the projectile. The beam is coded (Modulated) in accordance with the start or stop of events or flight conditions being monitored by one or more transducers in the projectile. The beam is initially pulsed at a known reference rate from a thermal battery automatically activated by the launching acceleration of the projectile. Thus, occurrence of an event or condition will change the laser frequency to a new predetermined rate. The beam can be decoded at a receiving station in the vicinity of the launching site.

  20. Laser Boronizing of Stainless Steel with Direct Diode Laser

    NASA Astrophysics Data System (ADS)

    Kusuhara, Takayoshi; Morimoto, Junji; Abe, Nobuyuki; Tsukamoto, Masahiro

    Boronizing is a thermo-chemical surface treatment in which boron atoms are diffused into the surface of a work piece to form borides with the base material. When applied to the metallic materials, boronizing provides wear and abrasion resistance comparable to sintered carbides. However conventional boronizing is carried out at temperatures ranging from 800°C to 1050°C and takes from one to several hours. The structure and properties of the base material is influenced considerably by the high temperature and long treatment time. In order to avoid these drawbacks of conventional boronizing, laser-assisted boronizing is investigated which activates the conventional boronizing material and the work piece with a high density laser power. In this study, effect of laser characteristics was examined on the laser boronizing of stainless steel. After laser boronizing, the microstructure of the boride layer was analyzed with an optical microscope, electron probe micro analyser(EPMA) and X-ray diffractometer (XRD). The mechanical properties of borided layer were evaluated using Vickers hardness tester and sand erosion tester. Results showed that the boride layer was composed of NiB, CrB, FeB and Fe2B, and get wear resistance.

  1. Influence of the element silicon on laser processing

    NASA Astrophysics Data System (ADS)

    Yan, Qi

    2005-01-01

    Laser cutting had been widely used in the material processing field with the increase of the requirements on the quality and work efficiency. As to the laser cutting, there had many factors that could affect the quality of cuts. Among them, the chemical composition played an important role because laser processing was a kind of interaction among laser beam, shielding gas and materials. Compared with the other element, silicon element had a deleterious effect on the laser processing which resulted in cuts with a dross and brittleness in the welded seam. However, many kinds of steel with high amount of silicon need to be processed by laser technology in recent years. In this paper, the influence of silicon element on the quality of laser cutting and laser welding was discussed. Continuous CO2 laser was used to cut and weld materials with different amount of silicon. Results showed that with the increase amount of silicon, the speed of laser cutting and laser welding decreased in order to obtain the good cuts and welds. Silicon had the obvious influence on the laser processing technology and quality. Microstructure of the laser welds for materials with high amount of silicon was also analyzed in this paper.

  2. Laser direct-write microfabrication and patterning

    NASA Astrophysics Data System (ADS)

    Yuan, Dajun

    The ability to generate small structures is central to modern science and technology. In this work, four laser direct-write microfabrication and micropatterning techniques were studied: (a) Laser micromachining of channels in PMMA using a CO2 laser was investigated experimentally and theoretically. Heat transfer models for the channel depth, channel profile, laser power and scanning speed were developed and applied in this work. These models, are in excellent agreement with experimental results, with a maximum deviation of approximately 5% for the range of experimental parameters (laser power, scanning speed) tested. (b) A sub-micrometer resolution laser direct-write polymerization system for 1 creating two-dimensional and three-dimensional structures was developed using a frequency-doubled Nd:YAG laser. Experimental studies and Monte Carlo simulations were conducted to understand the detailed microscale optical scattering, chemical reaction, polymerization, and their influence on critical fabrication parameters. The experimental data are in good agreement with the theoretical model. (c) Direct laser interference was developed for rapid and large area fabrication of two-dimensional and three dimensional periodic structures on photopolymerizable materials with 10ns pulses from a frequency-tripled Nd:YAG laser emitting at 355 nm. Three different photopolymerizable materials were investigated: pentaerythritol triacrylate (PETIA) with photoinitiator N-methyldiethanolamine (N-MDEA); SU-8 with absorber TINUVIN 384-2; and Shipley 1813. (d) A new approach to fabricating nanometer sized cavity arrays on Poly(3,4-ethylene dioxythiophene)-poly(styrenesulfonate) (PEDOT-PSS) thin films using laser-assisted near-field patterning was investigated. Periodic nano-cavity arrays were patterned by combining direct laser interference technology and laser induced near-field technology. An analytical model based on Mie theory was developed, the predicted intensity distributions on the substrate indicate a strong near-field enhancement confined to a very small area (nanometer scale).

  3. Chemical sensors

    SciTech Connect

    Hubbard, C.W.; Gordon, R.L.

    1987-05-01

    The revolution in analytical chemistry promised by recent developments in the field of chemical sensors has potential for significant positive impact on both research and production activities conducted by and for the Department of Energy. Analyses which were, in the past, performed only with a roomful of expensive equipment can now be performed with miniature solid-state electronic devices or small optical probes. Progress in the development of chemical sensors has been rapid, and the field is currently growing at a great rate. In accordance, Pacific Northwest Laboratory initiated a survey of recent literature so that contributors to active programs in research on analytical methods could be made aware of principles and applications of this new technology. This report presents the results of that survey. The sensors discussed here are divided into three types: micro solid-state devices, optical sensors, and piezoelectric crystal devices. The report is divided into three corresponding sections. The first section, ''Micro Solid-State Devices,'' discusses the design, operation, and application of electronic sensors that are produced in much the same way as standard solid-state electronic devices. The second section, ''Optrodes,'' covers the design and operation of chemical sensors that use fiber optics to detect chemically induced changes in optical properties. The final section, ''Piezoelectric Crystal Detectors,'' discusses two types of chemical sensors that depend on the changes in the properties of an oscillating piezoelectric crystal to detect the presence of certain materials. Advantages and disadvantages of each type of sensor are summarized in each section.

  4. Fbis report. Science and technology: China, August 18, 1995

    SciTech Connect

    NONE

    1995-08-18

    ;Contents: Impact of 1996-2010 World`s S&T Progress on China`s Social andEconomic Development; Microstructure of Nanocrystalline Materials; AFM Observation of Surface Nanoscale Lithography on Cadmium Stearate LB FilmStructure; Success in Inserting Anti-Bacteria Peptide Gene Into Rice; Achievements Made in Shandong Academy of Agricultural Sciences; ShanghaiCompletes Satellite/Computer Information Network System; Zhejiag University Holds International Virtual Reality Conference; China Develops First Domestic Automonous Underwater Robot; Reports on Diamond Thin Films; Beijing Telecom Expert Proposes Tactics for Developing `Capital Information Highway`; MPT To Build Jinan-Shijiazhuang- Taiyuan-Yinchuan Fiber Optic Cable; CAS Institute Unveils World-Class Chemical Oxygen-Iodine Laser; Tarium Oil Field Update; Three Largest Natural Gas Fields in Western China; World`s FirstS-Shaped Oil Well Goes Into Operation; China`s Largest Coastal Wind Power Gnerating Field--Nan`ao.

  5. Laser acoustic technology demonstration and equipment field trails

    Microsoft Academic Search

    J. G. Rodriguez; D. M. Tow

    1991-01-01

    A fieldable, noncontacting, laser acoustic method to characterize chemical weapon (CW) containers has been demonstrated. The laser sensor detects the vibrational response of CW containers to acoustic excitation. Laboratory results demonstrated that the vibrational signatures are unique to the fill material of the munition containers. The field trials, at Tooele Utah Army Depot, demonstrated that this noncontacting inspection technique could

  6. Laser optoacoustics

    Microsoft Academic Search

    Vitalii E. Gusev; Aleksandr A. Karabutov

    1991-01-01

    Some problems relevant to optics, acoustics, and physics of solids are analyzed in a systematic manner. Optoacoustic phenomena in various media, including dielectrics, metals, and semiconductors, are examined using a unified methodological approach. Particular attention is given to effects related to the nonlinear nature of optical-acoustic interaction. The problem of the excitation of high-intensity acoustic waves by laser emission is

  7. Exciplex lasers

    SciTech Connect

    Hutchinson, M. H.

    1981-09-29

    A laser contains as a lasing medium a noble gas and a compound including one or more of the hydroxide, nitride, cyanide, acetylide, phenyl, ethyl, phenoxide and ethoxide radicals which form noble gas exciplexes and emit coherent energy on dissociation to the ground state.

  8. Laser system

    Microsoft Academic Search

    H. Karning; F. Prein; K. H. Vierling

    1985-01-01

    A laser system with a folded beam path is disclosed. The beam path is formed by a plurality of mirrors. Mirrors reflect light in a closed loop from one mirror to the other. Electrodes are disposed on opposite sides of the path between the mirrors and form channels through which the path extends. In addition to serving to direct the

  9. Laser Jello

    NSDL National Science Digital Library

    2011-12-06

    In this activity, learners use gelatin as a lens to investigate the properties of laser light. Learners can view total internal reflection of a beam of light and investigate angles of reflection and refraction. Using different colors of gelatin demonstrates its color filtering properties. Use this activity to help learners explore light reflection and refraction, wavelengths, color, and lenses.

  10. Laser Balancing

    NASA Technical Reports Server (NTRS)

    1981-01-01

    Mechanical Technology, Incorporated developed a fully automatic laser machining process that allows more precise balancing removes metal faster, eliminates excess metal removal and other operator induced inaccuracies, and provides significant reduction in balancing time. Manufacturing costs are reduced as a result.

  11. Femtosecond laser ablation of dentin

    NASA Astrophysics Data System (ADS)

    Alves, S.; Oliveira, V.; Vilar, R.

    2012-06-01

    The surface morphology, structure and composition of human dentin treated with a femtosecond infrared laser (pulse duration 500 fs, wavelength 1030 nm, fluences ranging from 1 to 3 J cm-2) was studied by scanning electron microscopy, x-ray diffraction, x-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy. The average dentin ablation threshold under these conditions was 0.6 ± 0.2 J cm-2 and the ablation rate achieved in the range 1 to 2 µm/pulse for an average fluence of 3 J cm-2. The ablation surfaces present an irregular and rugged appearance, with no significant traces of melting, deformation, cracking or carbonization. The smear layer was entirely removed by the laser treatment. For fluences only slightly higher than the ablation threshold the morphology of the laser-treated surfaces was very similar to the dentin fracture surfaces and the dentinal tubules remained open. For higher fluences, the surface was more porous and the dentin structure was partially concealed by ablation debris and a few resolidified droplets. Independently on the laser processing parameters and laser processing method used no sub-superficial cracking was observed. The dentin constitution and chemical composition was not significantly modified by the laser treatment in the processing parameter range used. In particular, the organic matter is not preferentially removed from the surface and no traces of high temperature phosphates, such as the ?-tricalcium phosphate, were observed. The achieved results are compatible with an electrostatic ablation mechanism. In conclusion, the high beam quality and short pulse duration of the ultrafast laser used should allow the accurate preparation of cavities, with negligible damage of the underlying material.

  12. Effect of edge junction isolation on the performance of laser doped selective emitter solar cells

    Microsoft Academic Search

    Brett Hallam; Stuart Wenham; Haeseok Lee; Eunjoo Lee; Hyunwoo Lee; Jisun Kim; Jeoungeun Shin

    2011-01-01

    The effect of laser and chemical edge junction isolation on electrical performance of industrially manufactured laser doped selective emitter solar cells with light induced plated n-type contacts is investigated in this work. Directly after the formation of the aluminium back surface field, photoluminescence images indicates that laser edge junction isolation causes substantial damage around the perimeter of the cell, extending

  13. Optical detection system for multispectral UV fluorescence laser remote sensing measurements

    Microsoft Academic Search

    G. C. Tisone; B. Clark; C. Wakefield-Reyes; P. H. Jr. Hargis; B. Michie; T. L. Downey; R. A. Mills

    1994-01-01

    A mobile laser remote sensing system is being developed for multispectral UV fluorescence detection of vapor, liquid, and solid effluents. TM system uses laser wavelengths between 250 and 400 nm to excite UV fluorescence spectra that can be used to detect and identify species in multicomponent chemical mixtures. With a scanning mirror assembly, the system is designed to map chemical

  14. Solid state dye lasers with scattering feedback

    NASA Astrophysics Data System (ADS)

    Costela, A.; Cerdán, L.; García-Moreno, I.

    2013-11-01

    Over the last decade, significant advances have been made toward the development of practical, tunable solid state dye lasers, which resulted in improved lasing efficiency with reduced dye photodegradation. To achieve this goal, a “chemical” approach was followed, where attention was focused onto the particular dye/host interaction and compatibility, specifically choosing already existing hosts for a given dye, synthesizing new dyes and/or matrices, or chemically modifying existing ones. Nevertheless, this approach was limited by a single fact learnt from the experience: there is no universal matrix which optimizes the efficiency and photostability of all dyes. This limitation could be overcome by following a “physical” approach, where the emission properties of the active medium are tailored by means of physical and structural modifications of the dye host. Following this approach, in this paper recent theoretical and experimental work is reviewed where it is demonstrated that following a simultaneous “physical” and “chemical” approach to tailor the emission properties of the host materials for solid state dye lasers, may lead, under specific circumstances, to the improvement of both the laser efficiency and photostability. In particular, it is demonstrated that optical scattering is not always detrimental either to conventional bulk lasers (laser rods or colloidal suspensions) or to integrated devices, but may give place, on the contrary, to dramatic improvements in the laser operation of organic (hybrid) laser rods, and to alternative ways of obtaining laser light from integrated devices based on the phenomenon of coherent random lasing, where feedback is provided by light scattering in an appropriate medium, without the need to manufacture complex periodic structures in the substrate. The processing and pumping flexibility of these materials, together with their low cost and capability of efficient emission across the whole visible spectrum makes them very attractive for the fabrication and development of coherent light sources suitable for integration in optoelectronic and disposable spectroscopic and sensing devices.

  15. Femtosecond laser in laser in situ keratomileusis

    PubMed Central

    Salomão, Marcella Q.; Wilson, Steven E.

    2014-01-01

    Flap creation is a critical step in laser in situ keratomileusis (LASIK). Efforts to improve the safety and predictability of the lamellar incision have fostered the development of femtosecond lasers. Several advantages of the femtosecond laser over mechanical microkeratomes have been reported in LASIK surgery. In this article, we review common considerations in management and complications of this step in femtosecond laser–LASIK and concentrate primarily on the IntraLase laser because most published studies relate to this instrument. PMID:20494777

  16. High efficiency laser-pumped emerald lasers

    Microsoft Academic Search

    S. T. Lai

    1987-01-01

    Highly efficient laser operation has been achieved in emerald. In a quasi-cw laser-pumped emerald laser, 64% output slope efficiency has been measured at 768 nm, corresponding to a laser quantum yield of 76%. An output power of 1.6 W was reached at 3.6 W of pump power at 647.1 nm from a krypton laser, and was pump power limited. The

  17. High efficiency laser-pumped emerald lasers

    Microsoft Academic Search

    S. T. Lai

    1987-01-01

    Highly efficient laser operation has been achieved in emerald. In a quasi-cw laser-pumped emerald laser, 64% output slope efficiency has been measured at 768 nm, corresponding to a laser quantum yield of 76%. An output power of 1.6 W was reached at 3.6 W of pump power at 647.1 nm from a krypton laser, and was pump power limited. The

  18. Laser resonators and coherent optics: Modeling, technology, and applications; Proceedings of the Meeting, Los Angeles, CA, Jan. 18-20, 1993

    Microsoft Academic Search

    Anup Bhowmik

    1993-01-01

    The topics discussed in these proceedings include free-electron laser resonators, excimer and CO2 lasers, resonator theory and modeling, solid state devices, resonator physics, and chemical and high-power laser resonators. Papers are presented on optical resonators for free-electron lasers (FELs), an experimental test of hole-coupled FEL resonator designs using a CW He-Ne laser, the dependence of laser properties on statistical distortions

  19. TOPICAL REVIEW: Physics and engineering of singlet delta oxygen production in low-temperature plasma

    NASA Astrophysics Data System (ADS)

    Ionin, A. A.; Kochetov, I. V.; Napartovich, A. P.; Yuryshev, N. N.

    2007-01-01

    An overview is presented of experimental and theoretical research in the field of physics and engineering of singlet delta oxygen (SDO) production in low-temperature plasma of various electric discharges. Attention is paid mainly to the SDO production with SDO yield adequate for the development of an electric discharge oxygen iodine laser (DOIL). The review comprises a historical sketch describing the main experimental results on SDO physics in low-temperature plasma obtained since the first detection of SDO in electric discharge in the 1950s and the first attempt to launch a DOIL in the 1970s up to the mid-1980s when several research groups started their activity aimed at DOIL development, stimulated by success in the development of a chemical oxygen iodine laser (COIL). A detailed analysis of theoretical and experimental research on SDO production in electric discharge from the mid-1980s to the present, when the first DOIL has been launched, is given. Different kinetic models of oxygen low-temperature plasma are compared with the model developed by the authors. The latter comprises electron kinetics based on the accompanying solution of the electron Boltzmann equation, plasma chemistry including reactions of excited molecules and numerous ion molecular reactions, thermal energy balance and electric circuit equation. The experimental part of the overview is focused on the experimental methods of SDO detection including experiments on the measurements of the Einstein coefficient for SDO transition a\\,^{1}\\,\\Delta_g\\--X\\,^3\\!\\Sigma _g^ - and experimental procedures of SDO production in self-sustained and non-self-sustained discharges and analysis of different plasma-chemical processes occurring in oxygen low-temperature plasma which brings limitation to the maximum SDO yield and to the lifetime of the SDO in an electric discharge and its afterglow. Quite recently obtained results on gain and output characteristics of DOIL and some projects aimed at the development of high-power DOIL are discussed.

  20. Laser Angioplasty With Excimer Laser :Animal Experiment

    NASA Astrophysics Data System (ADS)

    Abe, Yuusuke; Chinzei, Tsuneo; Imanishi, Kaoru; Yonezawa, Takumi; Niwa, Shinichiro; Yotsuya, Koro; Sogawa, Ichiro; Uemiya, Takafumi; Kanazawa, Shinichi; Fujimasa, Iwao; Imachi, Kou; Suzukawa, Masayuki; Mabuchi, Kunihiko; Asano, Masahiro; Tago, Yutaro; Kouno, Akimasa; Ono, Toshiya; Atsumi, Kazuhiko

    1989-09-01

    Excimer laser is able to destruct tissue with less thermal effect. This characteristics was considered to prevent thermal perforation in laser angioplasty. In order to realize coronary laser angioplasty with excimer laser under the visual condition, the basic studies were performed to evaluate the tissue reactions of excimer laser on atheroma and to develop laser endoscopic system for the coronary arteries. The tissue reactions of excimer laser in atheroma were evaluated with rabbit's atherosclerotic aorta, which was made with 1.5% high cholesterol diet. The bigger tissue destruction was obtained in accordance with the increase of the oscillating frequency. Excimer laser indused rather selective destruction of atheroma with high oscillating frequency. The fiber transmission of excimer laser was tried and atheroma was destructed through 400 ?m core diameter fiber. Atheroma was observed as like as small lump under endoscopic obsevation, and excimer laser could be irradiated through the fiber under endoscopic view. In order to realize endoscopic application of excimer laser to the coronary arteries, the endoscope was designed from the point of percutaneous approach method to the coronary arteries, and 1.5 mm diameter of endoscope with the channel for laser fiber was developed experimentally. The endoscope could be inserted deeply into the coronary arteries of goat, and the laser irradiation could be performed under endoscopic observation. The possibility of visual coronary laser angioplasty with the combination of excimer laser and coronary endoscope was demonstrated with the endoscope.

  1. Chemical Mahjong

    ERIC Educational Resources Information Center

    Cossairt, Travis J.; Grubbs, W. Tandy

    2011-01-01

    An open-access, Web-based mnemonic game is described whereby introductory chemistry knowledge is tested using mahjong solitaire game play. Several tile sets and board layouts are included that are themed upon different chemical topics. Introductory tile sets can be selected that prompt the player to match element names to symbols and metric…

  2. Chemical Change

    NSDL National Science Digital Library

    2012-06-26

    In this chemistry activity, learners explore the amount of copper in a new penny. Learners use toilet bowl cleaner to hollow out the interior of a penny with zinc inside. This experiment will demonstrate how chemical changes can separate matter. Learners can also discuss how zinc is cheaper than copper, in a lesson about economics.

  3. Chemical Evolution

    E-print Network

    Francesca Matteucci

    2007-04-05

    In this series of lectures we first describe the basic ingredients of galactic chemical evolution and discuss both analytical and numerical models. Then we compare model results for the Milky Way, Dwarf Irregulars, Quasars and the Intra-Cluster- Medium with abundances derived from emission lines. These comparisons allow us to put strong constraints on the stellar nucleosynthesis and the mechanisms of galaxy formation.

  4. Chemical Ionization

    Microsoft Academic Search

    Jürgen H. Gross; Mass Spectrometry

    \\u000a Mass spectrometrists have ever been searching for ionization methods softer than EI, because molecular weight determination\\u000a is key for structure elucidation. Chemical ionization (CI) is the first of the so-called soft ionization methods we are going to discuss (cf. Fig. 1.2).

  5. Chemical Indicators.

    ERIC Educational Resources Information Center

    Prombain, Dorothy R.; And Others

    This science sourcebook was written for intermediate grade teachers to provide guidance in teaching a specially developed unit on chemical indicators. Directions and suggestions for guiding student science activities are given. Some of the activities concern soil testing, crystals, and household powders such as sugar and salt. A list of necessary…

  6. Characterization of semiconductor surface-emitting laser wafers

    SciTech Connect

    Gourley, P.L.; Vawter, G.A.; Brennan, T.M.; Hammons, B.E.

    1990-01-01

    The development of epitaxial semiconductor surface-emitting lasers has begun in recent years. These lasers are ultra-short (few {mu}m) Fabry-Perot resonators comprising epitaxial multilayer semiconductor mirrors and quantum well active regions. The resonators are single crystals grown along the lasing axis by molecular beam epitaxy (MBE) or chemical vapor deposition (CVD). They offer significant advances over conventional cleaved, edge-emitting lasers for creating lasers with single elements of 2 dimensional arrays, low beam divergence, engineered active regions, single longitudinal modes, and improved temperature characteristics. To realize the high potential of these new laser structures, techniques for characterizing the laser wafer after growth and between fabrication steps must be developed. In this paper we discuss several optical techniques that we have developed for this emerging surface-emitting laser technology.

  7. Characterization of laser-tissue interaction processes by low-boiling emitted substances

    Microsoft Academic Search

    Hans-Juergen Weigmann; Juergen Lademann; Ulrike Serfling; W. Lehnert; Wolfram Sterry; H. Meffert

    1996-01-01

    Main point in this study was the investigation of the gaseous and low-boiling substances produced in the laser plume during cw CO2 laser and XeCl laser irradiation of tissue by gas chromatography (GC)\\/mass spectrometry. The characteristic emitted amounts of chemicals were determined quantitatively using porcine muscular tissue. The produced components were used to determine the character of the chemical reaction

  8. Making a Laser Level

    ERIC Educational Resources Information Center

    Hawkins, Harry

    2004-01-01

    This article describes how to construct a laser level. This laser level can be made using a typical 4' (or shorter) bubble level and a small laser point. The laser unit is detachable, so the bubble level can also be used in the conventional way. However, the laser level works better than a simple bubble level. Making this inexpensive device is an…

  9. Heterodyne laser diagnostic system

    DOEpatents

    Globig, Michael A. (Antioch, CA); Johnson, Michael A. (Pleasanton, CA); Wyeth, Richard W. (Livermore, CA)

    1990-01-01

    The heterodyne laser diagnostic system includes, in one embodiment, an average power pulsed laser optical spectrum analyzer for determining the average power of the pulsed laser. In another embodiment, the system includes a pulsed laser instantaneous optical frequency measurement for determining the instantaneous optical frequency of the pulsed laser.

  10. Surface-enhanced Raman mapping of chemical hot spots

    NASA Astrophysics Data System (ADS)

    Voronine, Dmitri

    2015-03-01

    Surface-enhanced Raman spectroscopy (SERS) and atomic force microscopy (AFM) are used for simultaneous chemical-topographic mapping of Raman hot spots on dielectric, semiconductor and metal surfaces. Raman signals enhanced by electromagnetic and chemical mechanisms are separated. Several approaches of nanoscale surface analysis are compared. Future experimental advances for spatiotemporal imaging of surface dynamics using ultrafast lasers and multiple tips are discussed.

  11. Diode Laser

    NSDL National Science Digital Library

    Zollman, Dean

    This resource, part of the Spectroscopy Lab Suite, illustrates the physics of a semiconductor Diode Laser. Students can create conduction and valence band energy levels and build in a bias due to impurity doping. The basic processes for light emission, including external voltage bias and level transitions are shown. The band energy levels and internal and external bias can all be adjusted to achieve an output spectrum similar to the measured physical spectrum.

  12. Project LASER

    NASA Technical Reports Server (NTRS)

    1990-01-01

    NASA formally launched Project LASER (Learning About Science, Engineering and Research) in March 1990, a program designed to help teachers improve science and mathematics education and to provide 'hands on' experiences. It featured the first LASER Mobile Teacher Resource Center (MTRC), is designed to reach educators all over the nation. NASA hopes to operate several MTRCs with funds provided by private industry. The mobile unit is a 22-ton tractor-trailer stocked with NASA educational publications and outfitted with six work stations. Each work station, which can accommodate two teachers at a time, has a computer providing access to NASA Spacelink. Each also has video recorders and photocopy/photographic equipment for the teacher's use. MTRC is only one of the five major elements within LASER. The others are: a Space Technology Course, to promote integration of space science studies with traditional courses; the Volunteer Databank, in which NASA employees are encouraged to volunteer as tutors, instructors, etc; Mobile Discovery Laboratories that will carry simple laboratory equipment and computers to provide hands-on activities for students and demonstrations of classroom activities for teachers; and the Public Library Science Program which will present library based science and math programs.

  13. Laser stimulated thermoluminescence

    NASA Astrophysics Data System (ADS)

    Abtahi, A.; Bräunlich, P.; Kelly, P.; Gasiot, J.

    1985-08-01

    Experimental and computational methods are presented for the complete characterization of the thermoluminescence response obtained from thermoluminescent phosphors upon exposure to localized Gaussian laser heating beams. A number of different phosphor configurations are described as examples. These include LiF:Mg,Ti (TLD-100, Harshaw Chemical Corporation) in form of chips, which are widely used in the dosimetry of ionizing radiation, and thin-layer dosimeters prepared either as self-supporting films or powder in a polyimide matrix, or on substrates of LiF single crystals or borosilicate glass. It is demonstrated that all relevant optical and thermal properties of the dosimeters can be determined by these methods and that, based on this knowledge, the expected thermoluminescence response of a given configuration can be simulated as a function of a number of experimental parameters.

  14. Characterization of hard coatings produced by laser cladding using laser-induced breakdown spectroscopy technique

    NASA Astrophysics Data System (ADS)

    Varela, J. A.; Amado, J. M.; Tobar, M. J.; Mateo, M. P.; Yañez, A.; Nicolas, G.

    2015-05-01

    Protective coatings with a high abrasive wear resistance can be obtained from powders by laser cladding technique, in order to extend the service life of some industrial components. In this work, laser clad layers of self-fluxing NiCrBSi alloy powder mixed with WC powder have been produced on stainless steel substrates of austenitic type (AISI 304) in a first step and then chemically characterized by laser-induced breakdown spectroscopy (LIBS) technique. With the suitable laser processing parameters (mainly output power, beam scan speed and flow rate) and powders mixture proportions between WC ceramics and NiCrBSi alloys, dense pore free layers have been obtained on single tracks and on large areas with overlapped tracks. The results achieved by LIBS technique and applied for the first time to the analysis of laser clads provided the chemical composition of the tungsten carbides in metal alloy matrix. Different measurement modes (multiple point analyses, depth profiles and chemical maps) have been employed, demonstrating the usefulness of LIBS technique for the characterization of laser clads based on hardfacing alloys. The behavior of hardness can be explained by LIBS maps which evidenced the partial dilution of some WC spheres in the coating.

  15. Enhanced relativistic laser–plasma coupling utilizing laser-induced micromodified target

    NASA Astrophysics Data System (ADS)

    Ivanov, K. A.; Brantov, A. V.; Kudryashov, S. I.; Makarov, S. V.; Gozhev, D. A.; Volkov, R. V.; Ionin, A. A.; Bychenkov, V. Yu; Savel’ev, A. B.

    2015-04-01

    The interaction of slighly relativistic femtosecond laser radiation with microstructured Si targets was studied. The microstructuring was performed by nanosecond pulse laser ablation with additional chemical etching of the target material. An analysis was made of the optical damage under the action of femtosecond radiation near the ablation threshold. It was experimentally demonstrated that the hot electron temperature increases appreciably in the laser-driven plasma (from ~370 to almost 500?keV) as well as radiation yield in the MeV range at the interaction of a high power femtosecond laser pulse with a microstructured surface in comparison with a flat surface. Numerical simulations using 3D3V PIC code Mandor revealed that the charged particle energy growth is caused by the stochastic motion of electrons in the complex field formed by the laser field and the quasistatic field at the sharp tips of micromodifications.

  16. Advanced laser remote sensing

    SciTech Connect

    Schultz, J.; Czuchlewski, S.; Karl, R. [and others

    1996-11-01

    This is the final report of a three-year, Laboratory-Directed Research and Development (LDRD) project at the Los Alamos National Laboratory. Remote measurement of wind velocities is critical to a wide variety of applications such as environmental studies, weather prediction, aircraft safety, the accuracy of projectiles, bombs, parachute drops, prediction of the dispersal of chemical and biological warfare agents, and the debris from nuclear explosions. Major programs to develop remote sensors for these applications currently exist in the DoD and NASA. At present, however, there are no real-time, three-dimensional wind measurement techniques that are practical for many of these applications and we report on two new promising techniques. The first new technique uses an elastic backscatter lidar to track aerosol patterns in the atmosphere and to calculate three dimensional wind velocities from changes in the positions of the aerosol patterns. This was first done by Professor Ed Eloranta of the University of Wisconsin using post processing techniques and we are adapting Professor Eloranta`s algorithms to a real-time data processor and installing it in an existing elastic backscatter lidar system at Los Alamos (the XM94 helicopter lidar), which has a compatible data processing and control system. The second novel wind sensing technique is based on radio-frequency (RF) modulation and spatial filtering of elastic backscatter lidars. Because of their compactness and reliability, solid state lasers are the lasers of choice for many remote sensing applications, including wind sensing.

  17. Chemical distinction by nuclear spin optical rotation.

    PubMed

    Ikäläinen, Suvi; Romalis, Michael V; Lantto, Perttu; Vaara, Juha

    2010-10-01

    Nuclear spin optical rotation (NSOR) arising from the Faraday effect constitutes a novel, advantageous method for detection of nuclear magnetic resonance, provided that a distinction is seen between different chemical surroundings of magnetic nuclei. Efficient first-principles calculations for isolated water, ethanol, nitromethane, and urea molecules at standard laser wavelengths reveal a range of NSOR for different molecules and inequivalent nuclei, indicating the existence of an optical chemical shift. 1H results for H2O(l) are in excellent agreement with recent pioneering experiments. We also evaluate, for the same systems, the Verdet constants of Faraday rotation due to an external magnetic field. Calculations of NSOR in ethanol and a 11-cis-retinal protonated Schiff base imply an enhanced chemical distinction between chromophores at laser wavelengths approaching optical resonance. PMID:21230897

  18. Chemical Distinction by Nuclear Spin Optical Rotation

    NASA Astrophysics Data System (ADS)

    Ikäläinen, Suvi; Romalis, Michael V.; Lantto, Perttu; Vaara, Juha

    2010-10-01

    Nuclear spin optical rotation (NSOR) arising from the Faraday effect constitutes a novel, advantageous method for detection of nuclear magnetic resonance, provided that a distinction is seen between different chemical surroundings of magnetic nuclei. Efficient first-principles calculations for isolated water, ethanol, nitromethane, and urea molecules at standard laser wavelengths reveal a range of NSOR for different molecules and inequivalent nuclei, indicating the existence of an optical chemical shift. H1 results for H2O(l) are in excellent agreement with recent pioneering experiments. We also evaluate, for the same systems, the Verdet constants of Faraday rotation due to an external magnetic field. Calculations of NSOR in ethanol and a 11-cis-retinal protonated Schiff base imply an enhanced chemical distinction between chromophores at laser wavelengths approaching optical resonance.

  19. Impulsive rotational Raman scattering of N2 by a remote "air laser" in femtosecond laser filament.

    PubMed

    Ni, Jielei; Chu, Wei; Zhang, Haisu; Zeng, Bin; Yao, Jinping; Qiao, Lingling; Li, Guihua; Jing, Chenrui; Xie, Hongqiang; Xu, Huailiang; Cheng, Ya; Xu, Zhizhan

    2014-04-15

    We report on experimental realization of impulsive rotational Raman scattering from neutral nitrogen molecules in a femtosecond laser filament using an intense self-induced white-light seeding "air laser" generated during the filamentation of an 800 nm Ti:sapphire laser in nitrogen gas. The impulsive rotational Raman fingerprint signals are observed with a maximum conversion efficiency of ?0.8%. Our observation provides a promising way of remote identification and location of chemical species in the atmosphere by a rotational Raman scattering of molecules. PMID:24978965

  20. Chemical Reactions

    NSDL National Science Digital Library

    Mrs. Hicken

    2009-05-04

    We are going go over a general view of reactions to prepare us for our unit on Chemical Reactions! Have fun learning! WARNING: If you are caught looking at ANY other site, without permission, you will be sent to the ALC, and you will not participate in any other computer activities for the rest of the year. Get your worksheet and begin! Overview Take this quiz and have me come over and sign off on your worksheet when you have completed the quiz! Overview Quiz Next let's take a look at what effect the rate of a chemical reaction. Rates of Reactions Another quiz, another check off by me! Rates of Reactions Quiz Now how do we measure how fast a ...