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Sample records for chemical oxygen-iodine laser

  1. Scalable chemical oxygen - iodine laser

    SciTech Connect

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

    2011-12-31

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

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

    NASA Astrophysics Data System (ADS)

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

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

  3. Chemical oxygen-iodine laser with cryosorption vacuum pump

    NASA Astrophysics Data System (ADS)

    Vetrovec, John

    2000-05-01

    In a chemical oxygen-iodine laser (COIL), chemically prepared, gaseous gain medium at 3-10 Torr pressure is drawn through the laser cavity by vacuum suction. Multiple-stage vacuum pumps such as Roots blowers or steam ejectors are typically used to receive and compress the gas flowing from the laser and exhaust it to the atmosphere. The size and weight of such vacuum pumps present a significant challenge to engineering and packaging a transportable COIL system.

  4. Second harmonic generation of chemical oxygen-iodine laser

    NASA Astrophysics Data System (ADS)

    Miura, Noriaki; Mese, Norimichi; Yoshino, Satoru; Uchiyama, Taro

    1993-05-01

    Intracavity second harmonic generation of chemical oxygen iodine laser utilizing LiB3O5 crystal has been studied. A chemical oxygen iodine laser of which the fundamental maximum output power is 3 W in TEM00 mode with the Cl2 flow rate of 300 mmol/min is used. Obtained total second harmonic power is a maximum of about 6 W. Therefore, we could estimate that the effective extraction efficiency is 200%. It is thought that the latter is above 100% due to the condition that the output coupling for the fundamental beam is not optimum. And applying the result of a fundamental laser power measurement, the internal conversion efficiency is estimated at 0.29%.

  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; Jakubec, I

    2009-11-30

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

  6. Application of a telescopic resonator to high-power chemical oxygen-iodine lasers

    SciTech Connect

    Yoshida, Sanichiro; Shimizu, Kouki; Tahil, Hari; Tanaka, Ikuzo . Laser Lab.)

    1994-01-01

    The application of an intraresonator telescope to high-power chemical oxygen-iodine lasers to decrease the output beam divergence is analyzed and demonstrated. A theoretical formula based on the ABCD matrix theory is developed to analyze the characteristics of the telescopic resonator. Calculations are carried out using Galilean type telescopes with magnification factors in the range of two to four, and the high-power chemical oxygen-iodine laser as an analysis model. By locating the telescope at a proper position on the optical axis, the overall telescopic resonator can be conveniently tailored to the hardware of this model laser in a way that the beam divergence and the resonator stability can be improved simultaneously. Experiments are carried out for one of the conditions used in the calculations. Measured divergence angles are in excellent agreement with the theoretical values.

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

    NASA Astrophysics Data System (ADS)

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

    1997-04-01

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

  8. Advanced technologies in chemical oxygen-iodine lasers for industrial applications

    NASA Astrophysics Data System (ADS)

    Endo, Masamori; Nagatomo, Syoji; Takeda, Shuzaburo; Wani, Fumio; Nanri, Kenzo; Fujioka, Tomoo

    1998-05-01

    A new concept of energy network system, `optical power system', was proposed. In this system, optical power is generated at a laser facility and it is distributed to users through optical fiber such as electric power system. The authors have started a feasibility study of this concept based on the latest chemical oxygen-iodine laser technology. 23.4% of chemical efficiency was obtained using nitrogen as buffer gas. Buffer gas cooling remarkably increased chemical efficiency. Liquid-jet type singlet oxygen generator (SOG) and twisted aerosol SOG (TA-SOG) were compared with the same setup. TA-SOG showed good performance especially in the high gas flow velocity range.

  9. Efficient generation in a chemical oxygen - iodine laser with a low buffer-gas flow rate

    SciTech Connect

    Azyazov, V N; Safonov, V S; Ufimtsev, N I

    2002-09-30

    The efficient generation in a chemical oxygen - iodine laser (COIL) with a low buffer-gas flow rate for Mach numbers M {<=} 1 is demonstrated. The maximum output power of the COIL was 415 W for a molecular chlorine flow rate of 20 mmol s{sup -1}, which corresponds to a chemical efficiency {eta}{sub ch} =23%. It is shown that the substitution of the buffer gas CO{sub 2} for N{sub 2} does not cause any significant variation in the dependence of the output power on the degree of dilution of the active medium. (lasers)

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

    SciTech Connect

    Phipps, S.P.; Helms, C.A.; Copland, R.J.; Rudolph, W.; Truesdell, K.A.; Hager, G.D.

    1996-12-01

    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 TEM{sub 00} 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 been reached with a pulse width of 2.1 ns at a repetition rate of 43.68 MHz.

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

    SciTech Connect

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

    2004-11-30

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

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

    SciTech Connect

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

    2011-05-31

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

  13. Use of basic deuterium peroxide in the chemical oxygen-iodine laser

    NASA Astrophysics Data System (ADS)

    Vetrovec, John; Yang, Tientsai T.; Copeland, Drew A.

    2000-05-01

    The chemical oxygen-iodine laser (COIL) uses a reaction of gaseous chorine and aqueous solution of basic oxygen peroxide (BHP) to produce oxygen singlet delta molecules, O2(1(Delta) ). Quenching of O2(1(Delta) ) during its extraction from the BHP solution and quenching of excited atomic iodine I* by water vapor from the O2(1(Delta) ) production process are well-known parasitic effects in COIL. This paper shows that both of these effects can be significantly reduced by replacing the hydrogen 1H1 isotope atoms in BHP by the 1H2 isotope atoms. In addition to restoring laser power lost to parasitic quenching, use of basic deuterium peroxide (BDP) rather than BHP is expected to allow generation of O2(1(Delta) ) at elevated temperature. This approach promises to save refrigerant, reduce the risk of BDP freezing, and delay precipitation of salt form BDP solution. Methods for producing BDP are outlined.

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

    NASA Astrophysics Data System (ADS)

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

    2007-05-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-02-01

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

  16. Chemical oxygen-iodine laser (COIL) for the dismantlement of nuclear facilities

    NASA Astrophysics Data System (ADS)

    Hallada, Marc R.; Seiffert, Stephan L.; Walter, Robert F.; Vetrovec, John

    2000-05-01

    The dismantlement of obsolete nuclear facilities is a major challenge for both the US Department of Energy and nuclear power utilities. Recent demonstrations have shown that lasers can be highly effective for size reduction cutting, especially for the efficient storage and recycling of materials. However, the full benefits of lasers can only be realized with high average power beams that can be conveniently delivered, via fiber optics, to remote and/or confined areas. Industrial lasers that can meet these requirements are not available now or for the foreseeable future. However, a military weapon laser, a Chemical Oxygen Iodine Laser (COIL), which has been demonstrated at over a hundred kilo Watts, could be adapted to meet these needs and enable entirely new industrial applications. An 'industrialized' COIL would enable rapid sectioning of thick and complex structures, such as glove boxes, reactor vessels, and steam generators, accelerating dismantlement schedules and reducing worker hazards. The full advantages of lasers in dismantlement could finally be realized with a portable COIL which is integrated with sophisticated robotics. It could be built and deployed in less than two years, breaking the paradigm of labor-intensive dismantlement operations and cutting processing times and costs dramatically.

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

    NASA Astrophysics Data System (ADS)

    Kodymova, Jarmila

    2005-09-01

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

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

    NASA Astrophysics Data System (ADS)

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

    1998-05-01

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

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

    SciTech Connect

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

    1988-08-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2007-04-01

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

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

    SciTech Connect

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

    2008-08-01

    Singlet oxygen generators are multiphase flow chemical reactors used to generate energetic oxygen to be used as a fuel for chemical oxygen iodine lasers. In this paper, a theoretical model of the generator is presented along with its solutions over ranges of parameter space and oxygen maximizing optimizations. The singlet oxygen generator (SOG) is a low-pressure, multiphase flow chemical reactor that is used to produce molecular oxygen in an electronically excited state, i.e. singlet delta oxygen. The primary product of the reactor, the energetic oxygen, is used in a stage immediately succeeding the SOG to dissociate and energize iodine. The gas mixture including the iodine is accelerated to a supersonic speed and lased. Thus the SOG is the fuel generator for the chemical oxygen iodine laser (COIL). The COIL has important application for both military purposes--it was developed by the US Air Force in the 1970s--and, as the infrared beam is readily absorbed by metals, industrial cutting and drilling. The SOG appears in various configurations, but the one in focus here is a crossflow droplet generator SOG. A gas consisting of molecular chlorine and a diluent, usually helium, is pumped through a roughly rectangular channel. An aqueous solution of hydrogen peroxide and potassium hydroxide is pumped through small holes into the channel and perpendicular to the direction of the gas flow. So doing causes the solution to become aerosolized. Dissociation of the potassium hydroxide draws a proton from the hydrogen peroxide generating an HO{sub 2} radical in the liquid. Chlorine diffuses into the liquid and reacts with the HO{sub 2} ion producing the singlet delta oxygen; some of the oxygen diffuses back into the gas phase. The focus of this work is to generate a predictive multiphase flow model of the SOG in order to optimize its design. The equations solved are the so-called Eulerian-Eulerian form of the multiphase flow Navier-Stokes equations wherein one set of the

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

    NASA Astrophysics Data System (ADS)

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

    2015-02-01

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

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

    SciTech Connect

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

    2002-06-30

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

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

    NASA Astrophysics Data System (ADS)

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

    2007-07-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2007-06-01

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

  6. 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.

  7. Optically (solar) pumped oxygen-iodine lasers

    NASA Astrophysics Data System (ADS)

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

    2014-07-01

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

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

    SciTech Connect

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

    2009-09-15

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

  9. Development of the electric discharge oxygen-iodine laser

    NASA Astrophysics Data System (ADS)

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

    2007-05-01

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

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

    SciTech Connect

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

    2013-04-15

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

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

    SciTech Connect

    Azyazov, V N

    2009-11-30

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

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

    SciTech Connect

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

    2009-01-31

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

  13. 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

  14. Test bench for studying the outlook for industrial applications of an oxygen-iodine laser

    SciTech Connect

    Adamenkov, A A; Bakshin, V V; Bogachev, A V; Buryak, E V; Vdovkin, L A; Velikanov, S D; Vyskubenko, B A; Garanin, Sergey G; Gorbacheva, E V; Grigorovich, Sergei V; Il'in, S P; Il'kaev, R I; Ilyushin, Yurii N; Kalashnik, A M; Kolobyanin, Yu V; Leonov, M L; Svischev, V V; Troshkin, M V

    2007-07-31

    We report the development and tests of a chemical oxygen-iodine laser test bench based on a twisted-aerosol-flow singlet-oxygen generator and a supersonic laser model for studying the outlook for industrial applications of this laser. The maximal output power of the laser is {approx}65 kW (the average power is {approx}50 kW), corresponding to a specific output power of {approx}110 W cm{sup -2}. The maximal chemical efficiency is {approx}34%. (letters)

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

    SciTech Connect

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

    2009-08-31

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

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

    SciTech Connect

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

    2005-10-31

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

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

    NASA Astrophysics Data System (ADS)

    Zhou, Songqing; Qu, Pubo; Ren, Weiyan

    2013-05-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2012-04-01

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

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

    NASA Astrophysics Data System (ADS)

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

    1998-05-01

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

  20. 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.

  1. 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)

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

  3. 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.

  4. 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.

  5. Studies of oxygen-helium discharges for use in electric oxygen-iodine lasers

    NASA Astrophysics Data System (ADS)

    Zimmerman, Joseph William

    In recent work, the performance of the Electric Oxygen-Iodine Laser (ElectricOIL), developed in partnership by researchers at the University of Illinois and CU Aerospace, has been greatly improved through systematic study of various components of this new laser technology. One major contribution to the advancement of ElectricOIL technology has been the development of electric discharges capable of producing significant flow rates of the precursor electronically-excited molecular oxygen, O2(a1Delta). O2(a 1Delta) serves as an energy reservoir in the laser system, pumping atomic iodine by near-resonant energy transfer producing gain and laser on the I(2P1/2) → I(2P3/2 ) transition at 1315 nm. Initial experimental work with radio-frequency discharges showed the importance of controlling O-atom flow rates to reduce quenching losses of energy stored in O2(a1Delta), and determined proper selection of the helium diluent ratio and specific power deposition (power per O2 flow rate). Further experimental investigations with transverse capacitive radio-frequency discharges in O2/He/NO mixtures in the pressure range of 1-100 Torr and power range of 0.1-1.2 kW have indicated that O2(a1Delta) production is a strong function of geometry (transverse gap), excitation frequency, and pressure. These parameters along with gas flow mixture dictate the current density at which the discharge operates, and its modal characteristics (normal vs. abnormal, homogeneous vs. inhomogeneous). A key result is that to encourage efficient O2(a1Delta) production these parameters should be selected in order to promote a homogeneous (low current density) discharge. The discharge behavior is characterized using terminal current-voltage-characteristics, microwave interferometer measurements, and plasma emission intensity measurements. Numerous spectroscopic measurements of O2(a1Delta), oxygen atoms, and discharge excited states are made in order to describe the discharge performance dependent on

  6. 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

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

    SciTech Connect

    Pichugin, S Yu

    2012-09-30

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

  8. 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.

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

    SciTech Connect

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

    2010-08-03

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

  10. 2D gasdynamic simulation of the kinetics of an oxygen-iodine laser with electric-discharge generation of singlet oxygen

    SciTech Connect

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

    2011-03-15

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

  11. Generation of singlet oxygen for an oxygen-iodine laser in a radio-frequency discharge

    SciTech Connect

    Braginskii, O V; Vasil'eva, A N; Klopovskii, K S; Kovalev, A S; Lopaev, D V; Mankelevich, Yu A; Popov, N A; Rakhimov, Aleksandr T; Rakhimova, T V

    2005-01-31

    The generation of singlet oxygen (SO) in a radio-frequency discharge (13.56 MHz) in the gas flow was investigated experimentally and theoretically. The oxygen pressure was varied from 2 to 20 Torr and the energy deposition in gas from 10 to 2000 J mmol{sup -1}. The saturation of the SO concentration with increasing the energy deposition was shown to arise from the three-body process of SO quenching by atomic oxygen. Removing atomic oxygen allowed a 2.5-fold increase in the ultimate SO concentration at the discharge output. For an oxygen pressure of 15 Torr, the SO fraction amounts to 10%. (active media. lasers)

  12. Advances in chemical lasers

    SciTech Connect

    Miller, D.J.

    1987-09-25

    High-power chemical lasers thrive in an array of special environments and present many fascinating associated subjects ripe for developmental research. Included are processes to produce the source reactants; supersonic mixing and reacting flow fields; the production and dissipation of multiple vibrational-rotational molecular states; optical gain extraction in complex geometries; media inhomogeneity effects, and waste energy and reaction products removal. Some configurations require wavelength selectivity, special optical components, and coherent cavity or beam combining. In recent years, progress has been made in these areas on behalf of continuous-wave and repetitively pulsed hydrogen fluoride and deuterium fluoride lasers, subsonic and supersonic oxygen-iodine lasers, and potential shorter wavelength chemical lasers based on chemically excited higher electronic states. This paper presents a brief review of the technical approach of some of the technology areas, and the status in achieving practical, integrated high-power chemical lasers.

  13. 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%.

  14. Effect of vibrationally excited I{sub 2}(a{sup 1{Delta}}{sub g}) molecules on the parameters of the active medium of an oxygen - iodine laser

    SciTech Connect

    Azyazov, V N; Antonov, I O; Pichugin, S Yu; Ufimtsev, N I

    2004-12-31

    A comparison of the experimental and theoretical results shows that quenching of one singlet oxygen molecule leads to the formation of 4.5 vibrational quanta of the I{sub 2} molecule on the average in the active medium of an oxygen-iodine laser. The dependence of threshold yield of singlet oxygen and of the gain on the relative concentration of vibrationally excited I{sub 2}(a{sup 1{Delta}}{sub g}) molecules are studied. The threshold yield of singlet oxygen increases with the relative concentration of vibrationally excited I{sub 2} molecules and may be several percent higher than the value assumed earlier. The gain depends weakly on the relative concentration of vibrationally excited oxygen molecules. (active media)

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

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

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

  16. Chemical lasers

    NASA Astrophysics Data System (ADS)

    Khariton, Y.

    1984-08-01

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

  17. International Symposium on Gas Flow and Chemical Lasers, 8th, Madrid, Spain, Sept. 10-14, 1990, Proceedings

    SciTech Connect

    Orza, J.M.; Domingo, C.

    1991-01-01

    Papers are presented on current research developments and applications related to high-powered lasers. Recent advances in excimer laser technology, electron-beam-pumped excimer lasers, discharge technology for excimer lasers, and pulsed XeF lasers are examined. Consideration is given to short-wavelength lasers, chemical oxygen iodine lasers, and vibrational chemical lasers. Papers are presented on CO2, CO, N2O lasers, coupled CO2 lasers, laser induced perturbation in pulsed CO2 lasers, construction of sealed-off CO2 lasers, and computer modeling of discharge-excited CO gas flow. Topics discussed include gas-dynamic lasers, discharge and flow effects, matrix and laser optics and laser beam parameters. Laser-matter interactions, laser-induced surface plasma, plasma motion velocity along laser beams and thermocapillary effects are also discussed. Applications of laser technology are examined and high-speed laser welding, welding results, laser ablation, laser steel processing, and numerical modeling of laser-matter interaction in high-intensity laser applications are considered.

  18. 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.

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

    NASA Technical Reports Server (NTRS)

    Busch, G. E.

    1984-01-01

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

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

    NASA Astrophysics Data System (ADS)

    Takehisa, K.

    2015-05-01

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

  1. Optical pumping of the oxygen-iodine laser medium

    NASA Astrophysics Data System (ADS)

    Zagidullin, Marsel V.; Malyshev, Mikhail S.; Azyazov, Valeriy N.; Heaven, Michael C.

    2016-03-01

    The kinetics of the processes in an O2/I2/Ar/H2O gas flow that is irradiated simultaneously by light at wavelengths near 500 nm and 1315 nm, is considered. Radiation at 500 nm is used to photodissociate about 1% of the iodine molecules. The radiation at 1315 nm excites atomic iodine to the 2P1/2 state. Singlet oxygen molecules are produced via the energy exchange process I(2P1/2)+O2(X3Σ) → I(2P3/2) + O2(a1Δ), while I(2P1/2)+O2(a1Δ) energy pooling produces b1Σ oxygen. I(2P1/2) and O2(b1Σ) then accelerate the dissociation of I2. This active medium may reach ~40 W/cm-2 at an optical efficiency of 50%.

  2. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2015-08-01

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

  4. Laser Chemical Analysis.

    ERIC Educational Resources Information Center

    Zare, Richard N.

    1984-01-01

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

  5. High energy chemical laser system

    DOEpatents

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

    1975-12-23

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

  6. Chemically-Assisted Pulsed Laser-Ramjet

    SciTech Connect

    Horisawa, Hideyuki; Kaneko, Tomoki; Tamada, Kazunobu

    2010-10-13

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

  7. (Laser enhanced chemical reaction studies)

    SciTech Connect

    Not Available

    1992-01-01

    Experimental studies of dynamic molecular processes are described with particular emphasis on the use of a powerful infrared diode laser probe technique developed in our laboratory. This technique allows us to determine the final states of CO{sub 2} (and other molecules) produced by collisions, photofragmentation, or chemical reactions with a spectral resolution of 0.0003 cm{sup {minus}1} and a time resolution of 10{sup {minus}7} sec. Such high spectral resolution provides a detailed picture of the vibrational and rotational states of molecules produced by these dynamic events. We have used this experimental method to probe collisions between hot hydrogen/deuterium atoms and CO{sub 2}, between O({sup 1}D) atoms and CO{sub 2}, to study the final states of DC1 molecules produced as a result of the reactions of hot Cl atoms, and to investigate the dynamics of the reaction between OH and CO molecules. Advances in our techniques over the past two years have allowed us to identify and study more than 200 final rotational states in ten different vibrational levels of CO{sub 2} encompassing all 3 normal modes, many overtones, and combination states of the molecule. We have extended the technique to probe a variety of new molecules such as OCS, N{sub 2}O, DCl, and CS{sub 2}. All of this work is aimed at providing experimental tests for polyatomic molecule potential energy surfaces, chemical transition states in complex systems, and theories of reaction dynamic in molecules with more than 3 atoms.

  8. Laser Induced Chemical Liquid Phase Deposition (LCLD)

    SciTech Connect

    Nanai, Laszlo; Balint, Agneta M.

    2012-08-17

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

  9. Mixing enhancement in chemical lasers. II. Theory

    SciTech Connect

    Driscoll, R.J.

    1987-07-01

    A phenomenological model for reactant mixing in trip nozzle chemical lasers by means of a surface-stretching mechanism is used in conjunction with a two-level laser model to derive scaling laws for numerous features noted in the trip nozzle data. This mixing model is then employed with an aerokinetics code in order to obtain quantitative laser gain predictions. The results yielded by the code are in good agreement with small-signal data. It is determined that trip jet mixing will not increase laser efficiency at low cavity pressures, but will at high cavity pressures result in a doubling of laser power output. 12 references.

  10. Chemical stabilization of laser dyes

    NASA Astrophysics Data System (ADS)

    Koch, Tad H.

    1987-05-01

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

  11. Laser Induced Surface Chemical Epitaxy

    NASA Astrophysics Data System (ADS)

    Stinespring, Charter D.; Freedman, Andrew

    1990-02-01

    Studies of the thermal and photon-induced surface chemistry of dimethyl cadmium (DMCd) and dimethyl tellurium (DMTe) on GaAs(100) substrates under ultrahigh vacuum conditions have been performed for substrate temperatures in the range of 123 K to 473 K. Results indicate that extremely efficient conversion of admixtures of DMTe and DMCd to CdTe can be obtained using low power (5 - 10 mJ cm-2) 193 nm laser pulses at substrate temperatures of 123 K. Subsequent annealing at 473 K produces an epitaxial film.

  12. 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.

  13. Laser-based detection of chemical contraband

    NASA Astrophysics Data System (ADS)

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

    1997-02-01

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

  14. Remote Chemical Detection using Quantum Cascade Lasers

    SciTech Connect

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

    2006-02-01

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

  15. 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

  16. 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.

  17. Long pulse chemical laser. Final technical report

    SciTech Connect

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

    1989-02-01

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

  18. Remote Chemical Sensing Using Quantum Cascade Lasers

    SciTech Connect

    Harper, Warren W.; Schultz, John F.

    2003-01-30

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

  19. Mid-IR semiconductor lasers for chemical sensing

    NASA Technical Reports Server (NTRS)

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

    2003-01-01

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

  20. 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.

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

    NASA Astrophysics Data System (ADS)

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

    1982-10-01

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

  2. PHYSICAL EFFECTS OCCURRING DURING GENERATION AND AMPLIFICATION OF LASER RADIATION: Efficient solutions for low-temperature singlet-oxygen generators

    NASA Astrophysics Data System (ADS)

    Igoshin, Valerii I.; Karyshev, V. D.; Katulin, V. A.; Kirilin, A. V.; Kisletsov, A. V.; Konnov, S. A.; Kupriyanov, N. L.; Medvedev, A. M.; Nadezhina, T. N.

    1989-02-01

    Experimental investigations were made of the physicochemical characteristics of the active solutions for a chemical generator in an oxygen-iodine laser. A strong temperature dependence of the viscosity of the solution was observed. The influence of this factor on the operation of the singlet-oxygen generator and the laser is discussed. The cyclic operation of a laser with efficient neutralization of the reagents and the addition of an alkali is simulated. It is shown that hydrogen peroxide may be 50% utilized when the temperature of the solution is no higher than - 30 °C. A method of preparing a solution for an iodine laser with a low freezing point (between - 30 °C and - 40 °C) is developed. It is shown that an aqueous solution of hydrogen peroxide with a concentration of 25-40% is suitable.

  3. Remote chemical sensing with quantum cascade lasers

    SciTech Connect

    Harper, Warren W.; Strasburg, Jana D.

    2004-10-15

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

  4. 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.

  5. Laser-Beam-Absorption Chemical-Species Monitor

    NASA Technical Reports Server (NTRS)

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

    1996-01-01

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

  6. Chemically amplified laser direct-writing of aluminum

    NASA Astrophysics Data System (ADS)

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

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

  7. Chemical imaging sensor and laser beacon.

    PubMed

    Carrieri, Arthur H

    2003-05-20

    Design and functional aspects of PANSPEC, a panoramic-imaging chemical vapor sensor (PANSPEC is an abbreviation for infrared panoramic-viewing spectroradiometer), were advanced and its optical system reoptimized accordingly. The PANSPEC model unites camera and fused solid-state interferometer and photopolarimeter subsystems. The camera is an eye of the open atmosphere that collects, collimates, and images ambient infrared radiance from a panoramic field of view (FOV). The passive interferometer rapidly measures an infrared-absorbing (or infrared-emitting) chemical cloud traversing the FOV by means of molecular vibrational spectroscopy. The active photopolarimeter system provides a laser beam beacon. This beam carries identification (feature spectra measured by the interferometer) and heading (detector pixels disclosing these feature spectra) information on the hazardous cloud through a binary encryption of Mueller matrix elements. Interferometer and photopolarimeter share a common configuration of photoelastic modulation optics. PANSPEC was optimized for minimum aberrations and maximum resolution of image. The optimized design was evaluated for tolerances in the shaping and mounting of the optical system, stray light, and ghost images at the focal plane given a modulation transfer function metric. PMID:12777015

  8. Remote Chemical Sensing Using Quantum Cascade Lasers

    SciTech Connect

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

    2004-01-20

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

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

    SciTech Connect

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

    1982-01-01

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

  10. [Laser enhanced chemical reaction studies]. [Progress report

    SciTech Connect

    Not Available

    1992-04-01

    Experimental studies of dynamic molecular processes are described with particular emphasis on the use of a powerful infrared diode laser probe technique developed in our laboratory. This technique allows us to determine the final states of CO{sub 2} (and other molecules) produced by collisions, photofragmentation, or chemical reactions with a spectral resolution of 0.0003 cm{sup {minus}1} and a time resolution of 10{sup {minus}7} sec. Such high spectral resolution provides a detailed picture of the vibrational and rotational states of molecules produced by these dynamic events. We have used this experimental method to probe collisions between hot hydrogen/deuterium atoms and CO{sub 2}, between O({sup 1}D) atoms and CO{sub 2}, to study the final states of DC1 molecules produced as a result of the reactions of hot Cl atoms, and to investigate the dynamics of the reaction between OH and CO molecules. Advances in our techniques over the past two years have allowed us to identify and study more than 200 final rotational states in ten different vibrational levels of CO{sub 2} encompassing all 3 normal modes, many overtones, and combination states of the molecule. We have extended the technique to probe a variety of new molecules such as OCS, N{sub 2}O, DCl, and CS{sub 2}. All of this work is aimed at providing experimental tests for polyatomic molecule potential energy surfaces, chemical transition states in complex systems, and theories of reaction dynamic in molecules with more than 3 atoms.

  11. Laser cutting with chemical reaction assist

    DOEpatents

    Gettemy, Donald J.

    1992-01-01

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

  12. 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.

  13. Laser cutting with chemical reaction assist

    SciTech Connect

    Gettemy, D.J.

    1991-04-08

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

  14. Laser micromachining of chemically altered polymers

    SciTech Connect

    Lippert, T.

    1998-08-01

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

  15. Chemical and Laser Sciences Division annual report 1989

    SciTech Connect

    Haines, N.

    1990-06-01

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

  16. Chemical surface modification of fluorocarbon polymers by excimer laser processing

    NASA Astrophysics Data System (ADS)

    Niino, Hiroyuki; Yabe, Akira

    1996-04-01

    Surface of poly(tetrafluoroethylene) [PTFE] film was modified chemically by an ArF excimer laser-induced reaction in a hydrazine gas atmosphere. The polymer surface modified upon the irradiation of 1000 pulses at 27 mJ cm -2, which was a fairly lower fluence than the ablation threshold for usual polymer films, showed hydrophilicity (contact angle for water: 30°) enough to be metallized by chemical plating. The mechanism for chemical surface modification was investigated by FTIR, XPS, and SIMS analyses. The laser-treated PTFE film was metallized by a chemical plating process. These processes will be used to fabricate printed wiring boards for high frequency electronics.

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

    PubMed

    Sigrist, Markus W

    2015-05-01

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

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

    PubMed Central

    Sigrist, Markus W.

    2014-01-01

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

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

    SciTech Connect

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

    2003-01-31

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

  20. 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.

  1. 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.

  2. CW CO2 Laser Induced Chemical Reactions

    NASA Astrophysics Data System (ADS)

    Pola, Joseph

    1989-05-01

    CW CO2 laser driven reactions between sulfur hexafluoride and carbon oxide, carbon suboxide, carbonyl sulfide and carbon disulfide proceed at subatmospheric pressures and yield fluorinated carbon compounds and sulfur tetrafluoride. CW CO2 laser driven reactions of organic compounds in the presence of energy-conveying sulfur hexafluoride show reaction course different from that normally observed due to elimination of reactor hot surface effects. The examples concern the decomposition of polychlorohydrocarbons, 2-nitropropane, tert.-butylamine, allyl chloride, spirohexane, isobornyl acetate and the oxidation of haloolefins. CW CO2 laser induced fragmentation of 1-methyl-l-silacyclobutanes and 4-silaspiro(3.4)octane in the presence of sulfur hexafluoride is an effective way for preparation and deposition of stable organosilicon polymers.

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

    NASA Technical Reports Server (NTRS)

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

    1990-01-01

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

  4. Computationally efficient, rotational nonequilibrium CW chemical laser model

    SciTech Connect

    Sentman, L.H.; Rushmore, W.

    1981-10-01

    The essential fluid dynamic and kinetic phenomena required for a quantitative, computationally efficient, rotational nonequilibrium model of a CW HF chemical laser are identified. It is shown that, in addition to the pumping, collisional deactivation, and rotational relaxation reactions, F-atom wall recombination, the hot pumping reaction, and multiquantum deactivation reactions play a significant role in determining laser performance. Several problems with the HF kinetics package are identified. The effect of various parameters on run time is discussed.

  5. Comparison of Laser Chemical Processing and LaserMicroJet for structuring and cutting silicon substrates

    NASA Astrophysics Data System (ADS)

    Hopman, Sybille; Fell, Andreas; Mayer, Kuno; Mesec, Matthias; Rodofili, Andreas; Kray, Daniel

    2009-06-01

    This paper deals with the development of a new cutting method for thin silicon solar wafers with liquid-jet-guided lasers (LaserMicroJet®, LMJ, and Laser Chemical Processing, LCP). Several laser systems with different wavelengths were tested to find the optimum laser system and processing parameters in terms of efficient material removal and deep laser cutting. Water and potassium hydroxide were used as carrier liquids to enhance laser ablation. The ablation efficiency was defined as a target parameter and experimentally determined by performing single laser grooves. It is demonstrated that the ablation process of LMJ is mainly affected by silicon melting and then removing by the liquid-jet momentum for single laser grooves. Best result for deep laser grooves is achieved if evaporation dominates the ablation process. Better surface quality referred to laser-induced crystalline damage is presented for a cut wafer with LMJ in comparison to a standard multiwire slurry saw. This shows a great potential of wafering with liquid-jet-guided lasers although no optimal liquid media was used.

  6. Laser studies of chemical reaction and collision processes

    SciTech Connect

    Flynn, G.

    1993-12-01

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

  7. Investigation of performance and mechanism for chemical laser propulsion

    NASA Astrophysics Data System (ADS)

    Tang, Zhiping; Li, Long

    2013-05-01

    Chemical laser propulsion (CLP) is accompanied by the release of chemical energy in the process of laser propulsion, which can improve laser propulsion performance. In this article the propulsion performance of POM propellant under the constraint of a cylindrical tube-type thruster in atmospheric and nitrogen environments, respectively, has been conducted experimentally. The results indicate that the ablation masses of a single pulse under two gas environments are close, but the momentum coupling coefficient Cm and specific impulse Isp in atmospheric environment are higher than that in nitrogen environment, which demonstrates an exothermic reaction occurred between the ablation product and the environment oxygen. To learn the mechanism of CLP the molecular spectra for ablation products of POM propellant in atmospheric and vacuum environments are measured and analyzed, respectively, and it reveals that the final product in a vacuum is CH2O, while the final products are CO2 and H2O in the atmosphere. Then the chemical reaction, composition and chemical energy release have been confirmed in the atmospheric environment. By using Arrhenius finite rate chemical reaction model with the code Fluent the flow field evolution of ablation product was simulated numerically. The results show the intensity of chemical energy release is related to the contact and mixing degree of the ablation product and the oxygen in the atmosphere, mixing more fully, the chemical energy released more intensively.

  8. 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.

  9. 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.

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

    NASA Astrophysics Data System (ADS)

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

    1998-01-01

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

  11. 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

  12. Kinetic model of continuous-wave flow chemical lasers

    NASA Astrophysics Data System (ADS)

    Gao, Z.; X., E.

    1982-02-01

    A kinetic approach to modeling the gain in a chemical wave continuous laser when the lasing frequency is coincident with the center of the line shape is presented. Governing equations are defined for the relaxing behavior of an initially nonequilibrium distribution toward the local equilibrium Boltzmann-Maxwellian distribution. A new gain is introduced which is related to the thermal motion of the molecules and cold-reaction and premixed CW models are discussed. Coincidence of the lasing frequency with the line shape is demonstrated to result in a radiative intensity within the homogeneous broadening limit. The rate model predictions are compared with those of the kinetic model. It is found that when the broadening parameter is less than 0.2 the kinetic model more accurately describes the behavior of the CW chemical laser.

  13. Stabilized Quantum Cascade Lasers and Ultrasensitive Chemical Sensing

    NASA Astrophysics Data System (ADS)

    Taubman, Matthew S.

    2003-03-01

    Quantum Cascade Lasers (QCLs) are a relatively new type of semiconductor laser operating in the mid- to long-wave infrared. Being monopolar multilayered quantum well structures, they can be fabricated to operate anywhere in a 3 to 20 micron region. This makes them an ideal choice for infrared chemical sensing, a topic of great interest at present. The broad range of applications of this technology includes everything from environmental sensing to homeland security and the non-proliferation of weapons of mass destruction. In addition to a discussion of these new laser devices, we will show results of resent experiments, including frequency stabilization of QCLs down to a relative frequency of 5.6Hz. In this experiment we use two QCLs locked to two separate optical cavities, and we observe the heterodyne beat. A third control loop (in addition to the two for locking the lasers) is used to remove low frequency noise between the two cavity systems. We also present data from several different cavity-enhanced QCL chemical sensors demonstrating sensitivities down to the mid 10-11/cm/root(Hz).

  14. Laser-initiated chemical reactions in carbon suspensions.

    SciTech Connect

    McGrath, T. E.; Diebold, G. J.; Bartels, D. M.; Crowell, R. A.; Chemistry; Brown Univ.

    2002-10-31

    We report on laser-initiated chemical reactions in colloidal carbon suspensions. Irradiation of carbon particles ranging in size from 13 to 75 nm in diameter suspended in water, toluene, and benzene with high power nanosecond, picosecond, and femtosecond laser pulses leads to the formation of a number of gaseous hydrocarbons as well as a series of liquid-phase products. In the product gas above irradiated carbon suspensions in water, H{sub 2} and CO, the main reaction products of the carbon-steam reaction, and numerous hydrocarbons ranging from C{sub 1}-C{sub 4} were detected. Irradiation of particulate carbon in toluene and benzene gave H{sub 2} as the main gas product with small amounts of C{sub 1}-C{sub 3} hydrocarbons. Bibenzyl and biphenyl were found as the main liquid products produced in toluene and benzene suspensions, respectively, but with numerous polycyclic aromatic hydrocarbons in smaller concentrations. The amount of products generated by pulsed laser irradiation is shown to depend on particle size and concentration, as well as the laser fluence and pulse width. The chemical reactions reported take place under conditions characterized by extremely high temperatures and pressures of short duration.

  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 λ=60μm. A new laser micromachining system capable of producing mid-infrared devices will soon be operational. These proceedings review metallic hollow waveguide spatial filtering theory, feedhorn designs as well as laser chemical etching and the design of a new high-NA UV laser etcher capable of sub-micron resolution to fabricate spatial filters for use in the mid-infrared.

  16. Space-Based Chemical Lasers in strategic defense

    SciTech Connect

    Wildt, D. )

    1992-07-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2016-05-01

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

  18. Laser interrogation of surface agents (LISA) for chemical agent reconnaissance

    NASA Astrophysics Data System (ADS)

    Higdon, N. S.; Chyba, Thomas H.; Richter, Dale A.; Ponsardin, Patrick L.; Armstrong, Wayne T.; Lobb, C. T.; Kelly, Brian T.; Babnick, Robert D.; Sedlacek, Arthur J., III

    2002-06-01

    Laser Interrogation of Surface Agents (LISA) is a new technique which exploits Raman scattering to provide standoff detection and identification of surface-deposited chemical agents. ITT Industries, Advanced Engineering and Sciences Division is developing the LISA technology under a cost-sharing arrangement with the US Army Soldier and Biological Chemical Command for incorporation on the Army's future reconnaissance vehicles. A field-engineered prototype LISA-Recon system is being designed to demonstrate on-the- move measurements of chemical contaminants. In this article, we will describe the LISA technique, data form proof-of- concept measurements, the LISA-Recon design, and some of the future realizations envisioned for military sensing applications.

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

    SciTech Connect

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

    2011-05-25

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

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

    NASA Technical Reports Server (NTRS)

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

    1985-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    1997-01-01

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

  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. Space based chemical lasers for ballistic missile defense (BMD)

    NASA Astrophysics Data System (ADS)

    Griff, N.; Kline, D. C.

    The potential for space-based chemical lasers (SBCLs) for use in ballisitic missile defense is discussed. The requirements for such use are reviewed, and the concept of phasing SBCL modules together on-orbit to obtain very high brightness systems is examined. The application of SBCLs to interactive discrimination is considered, and the readiness of SBCLs with regard to beam control, optics, acquisition/pointing/tracking, rapid retargeting, and coherent beam combination is addressed. The survivability of SBCLs in the context of an entire SDI system is discussed, including possible adversarial responses and design features to increase survivability.

  4. Application of pulsed-uv laser Raman spectroscopy to chemical vapor deposition

    SciTech Connect

    Hargis, P.J. Jr.

    1981-01-01

    Raman detection limits obtained with a KrF laser excitation source were comparable to those obtained by laser-induced fluorescence and photofragment emission spectroscopy under chemical vapor deposition conditions.

  5. LASERS: Efficient chemical oxygen — iodine 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 oxygen — iodine 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(1Δ) 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.

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

    SciTech Connect

    Crosley, D.R.

    1992-09-01

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

  7. Modelling of Laser-Enhanced Chemical Vapor Deposition

    NASA Technical Reports Server (NTRS)

    Brown, R. A.

    1985-01-01

    Research is directed at development of a detailed model of mass and heat transfer and chemical reaction in the pyrolysis of silane for the growth of thin amorphous silicon substrates incorporating laser heating of the gas phase above the film. The model will be the basis for evaluation of the relative importances of the decomposition of SiH4 in the vapor phase, mass transfer of the intermediate species, e.g., SiH2, and the evolution of hydrogen gas. Plans are also underway for developing a model for homogeneous nucleation of Si in the vapor phase to model the rate limitations observed at high gas-phase temperatures and high partial pressures of silane. Work was concentrated on an almost one-dimensional model for the coupling of the CO2 laser beam for heat transfer of the vapor phase with simple kinetic models for SiH4 decomposition and subsequent absorption of Si vapor on the substrate. Mass transfer in the vapor phase is assumed to be solely by diffusion. The role of convection in the vapor phase caused by the large changes in density in and around the center of the laser beam will be analyzed to evaluate the potential of microgravity experiments for increasing the uniformity of the film and the deposition rate.

  8. 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.

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

    NASA Astrophysics Data System (ADS)

    Drouet D'Aubigny, Christian Yann Pierre

    2003-11-01

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

  10. 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.

  11. Application of a locally optimized control theory to pump dump laser-driven chemical reactions

    NASA Astrophysics Data System (ADS)

    Ohtsuki, Y.; Yahata, Y.; Kono, H.; Fujimura, Y.

    1998-05-01

    A locally optimized control theory is developed. This theory is applied to pump-dump laser-driven chemical reactions via an electronically excited state. The results show that the theory can design the pulse shapes for chemical reactions with high quantum yields in strong laser intensity regimes in which perturbative treatments break down.

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

    ERIC Educational Resources Information Center

    Kovalenko, Laurie J.; Leone, Stephen R.

    1988-01-01

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

  13. Modeling chemical reactions in laser-induced plasmas

    NASA Astrophysics Data System (ADS)

    Shabanov, S. V.; Gornushkin, I. B.

    2015-11-01

    Under the assumption of local thermal equilibrium, a numerical algorithm is proposed to find the equation of state for laser-induced plasmas (LIPs) in which chemical reactions are permitted in addition to ionization processes. The Coulomb interaction in plasma is accounted for by the Debye-Hückel method. The algorithm is used to calculate the equation of state for LIPs containing carbon, silicon, nitrogen, and argon. The equilibrium reaction constants are calculated using the latest experimental and ab initio data of spectroscopic constants for the molecules {N}_2, {C}_2, {Si}_2, {CN}, {SiN}, {SiC} and their ions. The algorithm is incorporated into a fluid dynamic numerical model based on the Navier-Stokes equations describing an expansion of LIP plumes into an ambient gas. The dynamics of LIP plumes obtained by the ablation of SiC, solid silicon, or solid carbon in an ambient gas containing {N}_2 and Ar is simulated to study formation of molecules and molecular ions.

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

    NASA Astrophysics Data System (ADS)

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

    1995-06-01

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

  15. EFFECT OF LASER LIGHT ON MATTER. LASER PLASMAS: Optical strength of mirrors on fluorite substrates subjected to cw radiation from a chemical CO laser

    NASA Astrophysics Data System (ADS)

    Dudkin, V. A.; Rukhin, V. B.

    1994-02-01

    Optimisation of the energy characteristics of a chemical CO laser revealed damage to the optical resonator mirrors. Estimates indicated that when the power density of the incident cw laser radiation was 2-2.5 kW cm-2 the induced thermoelastic stresses could reach the damage threshold of mirrors on fluorite substrates.

  16. Fast Infrared Chemical Imaging with a Quantum Cascade Laser

    PubMed Central

    2015-01-01

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

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

    SciTech Connect

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

    2010-03-01

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

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

    SciTech Connect

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

    2007-07-01

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

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

    SciTech Connect

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

    2012-08-31

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

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

    NASA Technical Reports Server (NTRS)

    Rosen, David L.; Gillespie, James B.

    1992-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2011-02-01

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

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

    SciTech Connect

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

    2008-10-31

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

  3. Localized planarization of optical damage using laser-based chemical vapor deposition

    NASA Astrophysics Data System (ADS)

    Matthews, Manyalibo J.; Elhadj, Selim; Guss, Gabe M.; Sridharan, Arun; Nielsen, Norman D.; Yoo, Jae-Hyuck; Lee, Daeho; Grigoropoulos, Costas

    2013-11-01

    We present a method to repair damaged optics using laser-based chemical vapor deposition (L-CVD). A CO2 laser is used to heat damaged silica regions and polymerize a gas precursor to form SiO2. Measured deposition rates and morphologies agree well with finite element modeling of a two-phase reaction. Along with optimizing deposition rates and morphology, we also show that the deposited silica is structurally identical to high-grade silica substrate and possesses high UV laser damage thresholds. Successful application of such a method could reduce processing costs, extend optic lifetime, and lead to more damage resistant laser optics used in high power applications.

  4. A Topics Course on Chemical Application of Lasers.

    ERIC Educational Resources Information Center

    Coleman, William F.

    1981-01-01

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

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

    SciTech Connect

    Edward A Whitaker

    2005-08-08

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

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

    NASA Astrophysics Data System (ADS)

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

    2004-09-01

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

  8. 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.

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

    NASA Astrophysics Data System (ADS)

    Gao, Ming; Ito, Akihiko; Goto, Takashi

    2015-06-01

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

  10. Zeeman laser interferometry for detection and chemical analysis

    SciTech Connect

    Johnston, R.G.

    1993-12-01

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

  11. Small molecule ambient mass spectrometry imaging by infrared laser ablation metastable-induced chemical ionization.

    PubMed

    Galhena, Asiri S; Harris, Glenn A; Nyadong, Leonard; Murray, Kermit K; Fernández, Facundo M

    2010-03-15

    Presented here is a novel ambient ion source termed infrared laser ablation metastable-induced chemical ionization (IR-LAMICI). IR-LAMICI integrates IR laser ablation and direct analysis in real time (DART)-type metastable-induced chemical ionization for open air mass spectrometry (MS) ionization. The ion generation in the IR-LAMICI source is a two step process. First, IR laser pulses impinge the sample surface ablating surface material. Second, a portion of ablated material reacts with the metastable reactive plume facilitating gas-phase chemical ionization of analyte molecules generating protonated or deprotonated species in positive and negative ion modes, respectively. The successful coupling of IR-laser ablation with metastable-induced chemical ionization resulted in an ambient plasma-based spatially resolved small molecule imaging platform for mass spectrometry (MS). The analytical capabilities of IR-LAMICI are explored by imaging pharmaceutical tablets, screening counterfeit drugs, and probing algal tissue surfaces for natural products. The resolution of a chemical image is determined by the crater size produced with each laser pulse but not by the size of the metastable gas jet. The detection limits for an active pharmaceutical ingredient (acetaminophen) using the IR-LAMICI source is calculated to be low picograms. Furthermore, three-dimensional computational fluid dynamic simulations showed improvements in the IR-LAMICI ion source are possible. PMID:20155978

  12. Chemical-ionization visible and ultraviolet gas lasers: A concept

    NASA Technical Reports Server (NTRS)

    Laudenslager, J. B.

    1975-01-01

    Charge-transfer reactions or Penning ionization reactions are used to produce population inversions between electronic states of molecular ions which should result in stimulated emission in ultraviolet and visible regions. Such lasers could be used in study of short-lived reaction intermediates, crystal structure and scattering, and photolysis.

  13. Effects of pressure ratio on population inversion in a DF chemical laser with concurrent lasing

    NASA Astrophysics Data System (ADS)

    Park, Jun Sung; Baek, Seung Wook

    2005-04-01

    A numerical simulation is presented for investigating the effects of pressure ratio of D2 injector to supersonic nozzle on the population inversion in the DF chemical laser cavity, while a lasing concurrently takes place. The chemical laser is generally used for the industrial process and manufacturing as well as the military weapon system, which requires high power characteristic of laser system rather than the others. The population inversion is absolutely needed to generate the laser beam and is non-equilibrium process. The laser beam is generated between the mirrors in the cavity and it is important to obtain stronger population inversion and more uniform distribution of the excited molecules in the laser cavity in order to produce high-power laser beam with good quality. In this study, these phenomena are investigated by means of analyzing the distributions of the DF excited molecules and the F atom used as an oxidant, while simultaneously estimating the maximum small signal and saturated gains and power in the DF chemical laser cavity. For the numerical solution, a fully conservative implicit method and a second order total variation diminishing (TVD) scheme are used with the finite-volume method (FVM). An 11-species (including DF molecules in various excited states of energies), 32-step chemistry model is adopted for the chemical reaction of the DF chemical laser system. The results are discussed by comparison with two D2 injector pressure cases; 192 and 388.64 torr. Major results reveal that in the resonator, stronger population inversions occur in the all transitions except DF(1)-DF(0), when the D2 injection pressure is lower. But, the higher D2 injection pressure provides a favorable condition for DF(1)-DF(0) transition to generate the higher power laser beam. In other words, as the pressure of D2 injector increases, the maximum small signal gain in the v transition, which is in charge of generating most of laser power, becomes higher. Therefore, the

  14. 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.

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

    DOEpatents

    Taubman, Matthew S.; Phillips, Mark C.

    2016-01-12

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

  16. Numerical modeling of arc plasma generator for chemical laser applications

    NASA Astrophysics Data System (ADS)

    Sagar, Vidya; Ravikant, Chhaya; Singhal, Gaurav; Mittal, Alok P.

    2012-05-01

    The results of the numerical modeling of arc discharge phenomenon relevant to hydrogen fluoride/deuterium fluoride (HF/DF) laser applications are given. The overall mechanics of arc discharge phenomena on the basis of numerical modeling employing the commercial code COMSOL is discussed. The equations for a 2D axisymmetric, weakly compressible, laminar flow with heat transfer and the coupled hydrodynamic and electromagnetic equations are solved using the SIMPLE algorithm. The variations in the material properties, temperature, and velocity due to the generated arc are studied. A comparison of the results obtained with those from the studies available in the literature validates the computational data. Since each designed plasma arc tunnel is unique in itself and specific in application, this would enable one to alter arc discharge parameters to optimize a specific laser.

  17. Laser treatment of alumina surface with chemically distinct carbide particles

    NASA Astrophysics Data System (ADS)

    Yilbas, Bekir S.; Ali, Haider

    2014-12-01

    Laser treatment of pre-prepared alumina tile surface with a carbon film containing a mixture of 3 wt% TiC and 3 wt% B4C hard particles was conducted. Morphological and metallurgical changes at the laser treated surface were examined using optical and electron scanning microscopes, energy dispersive spectroscopy, and X-ray diffraction. Microhardness and fracture toughness of the treated surface were measured together with indentation tests. Residual stress generated at the surface region was determined from the X-ray diffraction data. It was found that TiC and B4C hard particles cause micro-crack formation in the vicinity of hard particles on the surface. This behavior is attributed to the differences between the thermal expansion coefficients of these particles. The laser treated surface is composed of a dense layer with fine sized grains and columnar structures formed below the dense layer. The presence of hard particles enhances the microhardness and lowers the fracture toughness of the surface. The formation of nitride compounds (AlN and AlON) contributes to volume shrinkage in the dense layer. Residual stress formed in the surface region is compressive.

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

    NASA Astrophysics Data System (ADS)

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

    2012-10-01

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

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

    SciTech Connect

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

    2011-07-31

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

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

    NASA Astrophysics Data System (ADS)

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

    2016-05-01

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

  1. 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.

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

    NASA Astrophysics Data System (ADS)

    Weber, Lothar W.; Meier, Thomas H.

    1996-01-01

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

  3. PPLN laser-based system for chemical imaging

    NASA Astrophysics Data System (ADS)

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

    1999-10-01

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

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

    SciTech Connect

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

    2010-02-02

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

  5. 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

  6. 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.

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

    NASA Astrophysics Data System (ADS)

    Leppaevuori, Seppo; Remes, Janne; Moilanen, Hannu

    1996-09-01

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

  8. Laser Ablation/Ionisation Mass Spectrometry: Sensitive and Quantitative Chemical Depth Profiling of Solid Materials.

    PubMed

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

    2016-01-01

    Direct quantitative and sensitive chemical analysis of solid materials with high spatial resolution, both in lateral and vertical direction is of high importance in various fields of analytical research, ranging from in situ space research to the semiconductor industry. Accurate knowledge of the chemical composition of solid materials allows a better understanding of physical and chemical processes that formed/altered the material and allows e.g. to further improve these processes. So far, state-of-the-art techniques such as SIMS, LA-ICP-MS or GD-MS have been applied for chemical analyses in these fields of research. In this report we review the current measurement capability and the applicability of our Laser Ablation/Ionisation Mass Spectrometer (instrument name LMS) for the chemical analysis of solids with high spatial resolution. The most recent chemical analyses conducted on various solid materials, including e.g. alloys, fossils and meteorites are discussed. PMID:27131112

  9. 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.

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

    NASA Astrophysics Data System (ADS)

    Rosenblum, Michael; Pikovsky, Arkady

    2003-05-01

    Many natural and human-made nonlinear oscillators exhibit the ability to adjust their rhythms due to weak interaction: two lasers, being coupled, start to generate with a common frequency; cardiac pacemaker cells fire simultaneously; violinists in an orchestra play in unison. Such coordination of rhythms is a manifestation of a fundamental nonlinear phenomenon--synchronization. Discovered in the 17th century by Christiaan Huygens, it was observed in physics, chemistry, biology and even social behaviour, and found practical applications in engineering and medicine. The notion of synchronization has been recently extended to cover the adjustment of rhythms in chaotic systems, large ensembles of oscillating units, rotating objects, continuous media, etc. In spite of essential progress in theoretical and experimental studies, synchronization remains a challenging problem of nonlinear sciences.

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

    NASA Technical Reports Server (NTRS)

    Hsu, George C.

    1989-01-01

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

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

    SciTech Connect

    Crosley, D.R.

    1991-01-22

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

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

    SciTech Connect

    Jung Park, Han; Diebold, Gerald J.

    2013-08-14

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

  14. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2015-02-01

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

  16. 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.

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

    SciTech Connect

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

    2013-01-01

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

  18. 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.

  19. Personnel protection equipment for use with laser chemicals

    SciTech Connect

    Smith, I.D.; Roepke, J.

    1984-08-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-08-01

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

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

    PubMed

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

    2015-01-01

    Control over the breakage of a certain chemical bond in a molecule by an ultrashort laser pulse has been considered for decades. With the availability of intense non-resonant laser fields it became possible to pre-determine femtosecond to picosecond molecular bond breakage dynamics by controlled distortions of the electronic molecular system on sub-femtosecond time scales using field-sensitive processes such as strong-field ionization or excitation. So far, all successful demonstrations in this area considered only fragmentation reactions, where only one bond is broken and the molecule is split into merely two moieties. Here, using ethylene (C2H4) as an example, we experimentally investigate whether complex fragmentation reactions that involve the breakage of more than one chemical bond can be influenced by parameters of an ultrashort intense laser pulse. We show that the dynamics of removing three electrons by strong-field ionization determines the ratio of fragmentation of the molecular trication into two respectively three moieties. We observe a relative increase of two-body fragmentations with the laser pulse duration by almost an order of magnitude. Supported by quantum chemical simulations we explain our experimental results by the interplay between the dynamics of electron removal and nuclear motion. PMID:26271602

  2. 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

  3. 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.

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

    PubMed

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

    2012-02-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-05-01

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

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

    PubMed

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

    2016-06-27

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

  7. ZnO-coated SMS structure interrogated by a fiber ring laser for chemical sensing

    NASA Astrophysics Data System (ADS)

    Wen, X. Y.; Huang, J.; Xiao, H.; Yang, M. H.

    2014-11-01

    A zinc oxide (ZnO)-coated single mode-multimode-single mode fiber (SMS) structure interrogated by a fiber ring laser has been developed as a chemical sensor. Response to relative humidity (RH) and ethanol volatilization was evaluated by tracking the wavelength shifts of the output laser line in different moisture environments and ethanol solutions, respectively. For humidity sensing a linear response with a measurement range of 4-96% RH, and a sensitivity of 0.06 nm per %RH were obtained. As for ethanol volatilization sensing obvious wavelength blue shift was observed for the sensor immersed in 50% and 62% ethanol solution, while no variation could be detected in pure ethanol solution (purity larger than 97%). With the advantages of low cost, ease of fabrication and sensitive response, ZnO-coated SMS interrogated with a fiber ring laser was demonstrated to be an effective sensor for humidity and ethanol volatilization sensing.

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

    NASA Astrophysics Data System (ADS)

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

    1992-11-01

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

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

    SciTech Connect

    Wise, Steven H.; Almirall, Jose R

    2008-11-01

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

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

    SciTech Connect

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

    2014-07-07

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

  11. Chemical analysis of human urinary and renal calculi by Raman laser fiber-optics method

    NASA Astrophysics Data System (ADS)

    Hong, Nguyen T. D.; Phat, Darith; Plaza, Pascal; Daudon, Michel; Dao, Nguyen Q.

    1991-11-01

    The Raman laser fiberoptics (RLFO) method using Raman spectroscopy for determination of chemical composition and optical fibers allowing multiplex, in situ, and remote possibilities, enabled chemical analysis of various human urinary and renal calculi. Raman spectra of about 40 constituents (synthetic or natural) in the authors''s possession and its 437 various binary and ternary mixtures are recorded using 1.06 micrometers radiation of a Nd:YAG laser and a FT Raman interferometer. These spectra--most of them are fluorescence free--constituted the calculi library. In the presence of urine, unknown stones can then be identified by RLFO method using an automatic computer procedure (at the present time, the Bruker IR search program is used). The results obtained for the identification of the stones are satisfactory. Major constituents of a complex calculus (

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

    NASA Astrophysics Data System (ADS)

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

    2003-06-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2007-12-01

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

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

    PubMed

    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 beta-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 CO(2) laser. It is shown that stoichiometric, nanocrystalline particles consisting of SrZrO(3) and SrTiO(3) can be formed from corresponding mixtures of beta-diketonates which are evaporated nonselectively and with high rates by laser flash evaporation. PMID:18163736

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

    NASA Astrophysics Data System (ADS)

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

    2015-12-01

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

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

    SciTech Connect

    Taniuchi, Toshiyuki Kotani, Yoshinori; Shin, Shik

    2015-02-15

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

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

    PubMed Central

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

    2014-01-01

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

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

    PubMed

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

    2014-01-01

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

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

    NASA Astrophysics Data System (ADS)

    MacLeod, Neil A.; Weidmann, Damien

    2012-10-01

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

  20. On the role of chemical reactions in initiating ultraviolet laser ablation in poly(methyl methacrylate)

    SciTech Connect

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

    2007-05-15

    The role of chemical reactions is investigated versus the thermal and mechanical processes occurring in a polymer substrate during irradiation by a laser pulse and subsequent ablation. Molecular dynamics simulations with an embedded Monte Carlo based reaction scheme were used to study ultraviolet ablation of poly(methyl methacrylate) at 157 nm. We discuss the onset of ablation, the mechanisms leading to ablation, and the role of stress relaxation of the polymer matrix during ablation. Laser induced heating and chemical decomposition of the polymer substrate are considered as ablation pathways. It is shown that heating the substrate can set off ablation via mechanical failure of the material only for very short laser pulses. For longer pulses, the mechanism of ejection is thermally driven limited by the critical number of bonds broken in the substrate. Alternatively, if the photon energy goes towards direct bond breaking, it initiates chemical reactions, polymer unzipping, and formation of gaseous products, leading to a nearly complete decomposition of the top layers of substrates. The ejection of small molecules has a hollowing out effect on the weakly connected substrates which can lead to lift-off of larger chunks. Excessive pressure buildup upon the creation of gaseous molecules does not lead to enhanced yield. The larger clusters are thermally ejected, and an entrainment of larger polymer fragments in gaseous molecules is not observed.

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

    NASA Astrophysics Data System (ADS)

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

    2010-04-01

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

  2. Chemical Laser Phase Conjugation Technology (CLPCT). Final report, 10 July 1985-9 November 1986

    SciTech Connect

    Schnurr, A.D.; Meisenholder, S.; Quon, S.; Betts, J.; Doyle, J.

    1986-11-30

    The final report for the Chemical Laser Phase Conjugation Technology (CLPCT) project presents the detailed design for an experimental facility for use in future phase-conjugation experiments, which will be conducted under a separate project. The objective of the CLPCT program was to design a facility that (1) is compatible with the use of an existing 50-liter repetitively HF pulsed chemical laser (RPCL) device and (2) would allow design flexibility/growth potential for other more-complex experiments. The detailed design of the facility for the HF Conjugation experiment is described. Phase conjugation is developed by the nonlinear optical process wherein the high energy HF chemical laser beam is focused within a stimulated Brillioun scattering (SBS) cell which is filled with xenon at 40 atmospheres. The experimental facility consists of the oscillator subsystem, RPCL subsystem, diagnostics subsystem and phase-conjugation subsystem. The detailed design of each subsystem is described. In addition, the conceptual is described. A flowing SBS cell was developed for this experiment.

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

    PubMed

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

    2013-03-19

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-05-01

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

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

    SciTech Connect

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

    2008-05-31

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

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

    PubMed

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

    2016-08-22

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

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

    PubMed

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

    2015-03-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-05-01

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

  10. 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)

  11. A Model for Incorporating Chemical Reactions in Mesoscale Modeling of Laser Ablation of Polymers

    NASA Astrophysics Data System (ADS)

    Garrison, Barbara J.; Yingling, Yaroslava G.

    2004-03-01

    We have developed a methodology for including effects of chemical reactions in coarse-grained computer simulations such as those that use the united atom or bead and spring approximations. The new coarse-grained chemical reaction model (CGCRM) adopts the philosophy of kinetic Monte Carlo approaches and includes a probabilistic element to predicting when reactions occur, thus obviating the need for a chemically correct interaction potential. The CGCRM uses known chemical reactions along with their probabilities and exothermicities for a specific material in order to assess the effect of chemical reactions on a physical process of interest. The reaction event in the simulation is implemented by removing the reactant molecules from the simulation and replacing them with product molecules. The position of the product molecules is carefully adjusted to make sure that the total energy change of the system corresponds to the reaction exothermicity. The CGCR model was initially implemented in simulations of laser irradiation at fluences such that there is ablation or massive removal of material. The initial reaction is photon cleavage of a chemical bond thus creating two radicals that can undergo subsequent abstraction and radical-radical recombination reactions. The talk will discuss application of the model to photoablation of PMMA. Y. G. Yingling, L. V. Zhigilei and B. J. Garrison, J. Photochemistry and Photobiology A: Chemistry, 145, 173-181 (2001); Y. G. Yingling and B. J. Garrison, Chem. Phys. Lett., 364, 237-243 (2002).

  12. 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.

  13. Laser studies of chemical dynamics at the gas-solid interface

    NASA Astrophysics Data System (ADS)

    Cavanagh, Richard R.; King, David S.

    The DOE funded research program Laser Studies of Chemical Dynamics at the Gas-Solid Interface has taken a detailed, microscopic view of molecules desorbed from surfaces in order to gain an understanding of energy flow and interaction potentials and how these control chemical reactivity at interfaces. Successful completion of these experiments required technical expertise both in surface science and laser-based molecular dynamics, a collaborative situation that exists in the NIST center for Atomic, Molecular and Optical Physics. During the three year period covered by this progress report, our goal was to use state-resolved techniques to examine a single chemisorption system in detail, and to observe how changes in the interaction potential or method of surface excitation are manifest in the desorption dynamics. The system chosen was NO/Pt(111). Studies were undertaken in which the effects on the NO-Pt interaction potential of coadsorbates--both weakly (CO) and strongly (NH(sub 3)) interacting-- could be examined. In addition, attempts were to be made to study non- equilibrium dynamics by using pulsed laser heating.

  14. 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.

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

    SciTech Connect

    Not Available

    1989-12-15

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

  16. Laser induced and controlled chemical reaction of carbon monoxide and hydrogen.

    PubMed

    du Plessis, Anton; Strydom, Christien A; Uys, Hermann; Botha, Lourens R

    2011-11-28

    Bimolecular chemical reaction control of gaseous CO and H(2) at room temperature and atmospheric pressure, without any catalyst, using shaped femtosecond laser pulses is presented. High intensity laser radiation applied to a reaction cell facilitates non-resonant bond breakage and the formation of a range of ions, which can then react to form new products. Stable reaction products are measured after irradiation of a reaction cell, using time of flight mass spectroscopy. Bond formation of C-O, C-C, and C-H bonds is demonstrated as CO(2)(+), C(2)H(2)(+), CH(+), and CH(3)(+) were observed in the time of flight mass spectrum of the product gas, analyzed after irradiation. The formation of CO(2) is shown to be dependent on laser intensity, irradiation time, and on the presence of H(2) in the reaction cell. Using negatively chirped laser pulses more C-O bond formation takes place as compared to more C-C bond formation for unchirped pulses. PMID:22128931

  17. Laser induced and controlled chemical reaction of carbon monoxide and hydrogen

    NASA Astrophysics Data System (ADS)

    du Plessis, Anton; Strydom, Christien A.; Uys, Hermann; Botha, Lourens R.

    2011-11-01

    Bimolecular chemical reaction control of gaseous CO and H2 at room temperature and atmospheric pressure, without any catalyst, using shaped femtosecond laser pulses is presented. High intensity laser radiation applied to a reaction cell facilitates non-resonant bond breakage and the formation of a range of ions, which can then react to form new products. Stable reaction products are measured after irradiation of a reaction cell, using time of flight mass spectroscopy. Bond formation of C-O, C-C, and C-H bonds is demonstrated as CO2+, C2H2+, CH+, and CH3+ were observed in the time of flight mass spectrum of the product gas, analyzed after irradiation. The formation of CO2 is shown to be dependent on laser intensity, irradiation time, and on the presence of H2 in the reaction cell. Using negatively chirped laser pulses more C-O bond formation takes place as compared to more C-C bond formation for unchirped pulses.

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

    NASA Astrophysics Data System (ADS)

    Hill, Alan E.

    2008-05-01

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

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

    NASA Astrophysics Data System (ADS)

    Hess, Peter

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

  20. Study on the surface chemical properties of UV excimer laser irradiated polyamide by XPS, ToF-SIMS and CFM

    NASA Astrophysics Data System (ADS)

    Yip, Joanne; Chan, Kwong; Sin, Kwan Moon; Lau, Kai Shui

    2003-01-01

    Polyamide (nylon 6) was irradiated by a pulsed ultraviolet (UV) excimer laser with a fluence below its ablation threshold. Chemical modifications on laser treated nylon were studied by X-ray photoelectron spectroscopy (XPS), time-of-flight secondary ion mass spectrometry (Tof-SIMS) and chemical force microscopy (CFM). XPS study provides information about changes in chemical composition and the chemical-state of atom types on the fiber surface. The high sensitivity of ToF-SIMS to the topmost layers was used to detect crosslinking after the laser treatment. Gold-coated AFM tips modified with COOH terminated self-assembled alkanethiol monolayers (SAMs) were used to measure adhesion forces on the untreated and laser treated samples. XPS results revealed that the irradiated samples have higher oxygen content than prior to laser irradiation. Tof-SIMS analysis illustrated that carbonyl groups in nylon 6 decrease significantly but hydroxyl groups increase after low-fluence laser irradiation. The adhesion force measurements by CFM showed spatial distribution of hydroxyl groups on nylon 6 after the laser treatment.

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

    NASA Astrophysics Data System (ADS)

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

    2014-03-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2016-03-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2016-05-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2002-12-01

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

  5. Supersonic jet/multiphoton ionization spectrometry of chemical species resulting from thermal decomposition and laser ablation of polymers

    NASA Astrophysics Data System (ADS)

    Hozumi, Masami; Murata, Yoshiaki; Cheng-Huang Lin, Imasaka, Totaro

    1995-04-01

    The chemical species resulting from thermal decomposition and laser ablation of polymers are measured by excitation/fluorescence and multiphoton ionization/mass spectrometries after supersonic jet expansion for rotational cooling to simply the optical spectrum. The signal of minor chemical species occurred is strongly enhanced by resonant excitation and multiphoton ionization, and even the isomer can be clearly differentiated. For example, p-cresol occurred by thermal decomposition of polycarbonate is detected selectively by mass-selected resonant multiphoton ionization spectrometry. Various chemical species occurred by laser ablation of even a polystyrene foam are also measured by this technique.

  6. Schottky diodes and ohmic contacts formed by thermally assisted photolytic laser chemical vapor deposition

    NASA Astrophysics Data System (ADS)

    Braichotte, D.; van den Bergh, H.

    Thermally assisted photolytic laser chemical vapor deposition (LCVD) of platinum on n-doped gallium arsenide, a two-phase hybrid scheme for the production of Schottky diodes, is discussed. The low temperature photolytic deposits of the initial slow phase contain a nonnegligible fraction of organic ligand material and tend to be amorphous. In the second phase, light absorption of the photolytically deposited metal causes a temperature rise which facilitates the removal of ligand material from the deposit, and which is sufficient for fast pyrolytic LCVD. Measurements of the influence of light intensity, in addition to metalorganic and inert gas pressure, on the deposition rates in both phases are obtained.

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

    NASA Astrophysics Data System (ADS)

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

    2016-05-01

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

  8. Diesel combustion: an integrated view combining laser diagnostics, chemical kinetics, and empirical validation

    SciTech Connect

    Akinyami, O C; Dec, J E; Durrett, R P; Flynn, P F; Hunter, G L; Loye, A O; Westbrook, C

    1999-02-01

    This paper proposes a structure for the diesel combustion process based on a combination of previously published and new results. Processes are analyzed with proven chemical kinetic models and validated with data from production-like direct injection diesel engines. The analysis provides new insight into the ignition and particulate formation processes, which combined with laser diagnostics, delineates the two-stage nature of combustion in diesel engines. Data are presented to quantify events occurring during the ignition and initial combustion processes that form soot precursors. A framework is also proposed for understanding the heat release and emission formation processes.

  9. 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.

  10. Nonequilibrium population of the first vibrational level of O{sub 2}({sup 1{Sigma}}) molecules in O{sub 2} - O{sub 2}({sup 1{Delta}}) - H{sub 2}O gas flow at the output of chemical singlet-oxygen generator

    SciTech Connect

    Zagidullin, M V

    2010-11-13

    The concentrations of electron-excited particles have been determined by measuring the absolute spectral irradiance in the range of 600 - 800 nm of O{sub 2} - O{sub 2}({sup 1{Delta}}) - H{sub 2}O gas mixture at the output of a chemical singlet-oxygen generator (SOG). A nonequilibrium population of the first vibrational level of O{sub 2}({sup 1{Sigma}}) molecules has been clearly observed and found to depend on the water vapour content. In correspondence with the results of these measurements and according to the analysis of kinetics processes in the O{sub 2} - O{sub 2}({sup 1{Delta}}) - H{sub 2}O mixture, the maximum number of vibrational quanta generated in the O{sub 2}({sup 1{Delta}}) + O{sub 2}({sup 1{Delta}}) {yields} O{sub 2}({sup 1{Sigma}}) + O{sub 2}({sup 3{Sigma}}) reaction is 0.05 {+-} 0.03. It is concluded that the vibrational population of O{sub 2}({sup 1{Delta}}) at the output of the SOG used in a chemical oxygen-iodine laser is close to thermal equilibrium value. (active media)

  11. All-in-fiber optofluidic sensor fabricated by femtosecond laser assisted chemical etching.

    PubMed

    Yuan, Lei; Huang, Jie; Lan, Xinwei; Wang, Hanzheng; Jiang, Lan; Xiao, Hai

    2014-04-15

    An all-in-fiber prototype optofluidic device was fabricated by femtosecond laser irradiation and subsequent selective chemical wet etching. Horizontal and vertical microchannels can be flexibly created into an optical fiber to form a fluidic cavity with inlets/outlets. The fluidic cavity also functions as an optical Fabry-Perot cavity in which the filled liquid can be probed. The assembly-free microdevice exhibited a fringe visibility of 20 dB and was demonstrated for measurement of the refractive index of the filling liquids. The proposed all-in-fiber optofluidic micro device is attractive for chemical and biomedical sensing because it is flexible in design, simple to fabricate, mechanically robust, and miniaturized in size. PMID:24978992

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

    NASA Astrophysics Data System (ADS)

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

    2016-04-01

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

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

    NASA Technical Reports Server (NTRS)

    Scott, Carl D.

    2004-01-01

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

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

    PubMed

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

    2016-08-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2016-05-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2006-06-01

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

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

    PubMed

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

    2011-03-01

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

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

    NASA Astrophysics Data System (ADS)

    Haque, Moez

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

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

    SciTech Connect

    Vaughan, D.

    1992-04-01

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

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

    SciTech Connect

    Vaughan, D.

    1992-04-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2013-09-01

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

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

    NASA Astrophysics Data System (ADS)

    Paserin, Vlad

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

  3. Examination of the laser-induced variations in the chemical etch rate of a photosensitive glass ceramic

    NASA Astrophysics Data System (ADS)

    Voges, Melanie; Beversdorff, Manfred; Willert, Chris; Krain, Hartmut

    2007-10-01

    Previous studies in our laboratory have reported that the chemical etch rate of a commercial photosensitive glass ceramic (FoturanTM, Schott Corp., Germany) in dilute hydrofluoric acid is strongly dependent on the incident laser irradiance during patterning at λ=266 nm and λ=355 nm. To help elucidate the underlying chemical and physical processes associated with the laser-induced variations in the chemical etch rate, several complimentary techniques were employed at various stages of the UV laser exposure and thermal treatment. X-ray diffraction (XRD) was used to identify the crystalline phases that are formed in Foturan following laser irradiation and annealing, and monitor the crystalline content as a function of laser irradiance at λ=266 nm and λ=355 nm. The XRD results indicate the nucleation of lithium metasilicate (Li2SiO3) crystals as the exclusive phase following laser irradiation and thermal treatment at temperatures not exceeding 605 °C. The XRD studies also show that the Li2SiO3 density increases with increasing laser irradiance and saturates at high laser irradiance. For our thermal treatment protocol, the average Li2SiO3 crystal diameters are 117.0±10.0 nm and 91.2±5.8 nm for λ=266 nm and λ=355 nm, respectively. Transmission electron microscopy (TEM) was utilized to examine the microscopic structural features of the lithium metasilicate crystals. The TEM results reveal that the growth of lithium metasilicate crystals proceeds dendritically, and produces Li2SiO3 crystals that are ˜700 1000 nm in length for saturation exposures. Optical transmission spectroscopy (OTS) was used to study the growth of metallic silver clusters that act as nucleation sites for the Li2SiO3 crystalline phase. The OTS results show that the (Ag0)x cluster concentration has a dependence on incident laser irradiance that is similar to the etch rate ratios and Li2SiO3 concentration. A comparison between the XRD and optical transmission results and our prior etch rate

  4. Gas phase versus surface contributions to photolytic laser chemical vapor deposition rates

    NASA Astrophysics Data System (ADS)

    Braichotte, D.; van den Bergh, H.

    1988-04-01

    The rate of cw photolytic laser chemical vapor deposition (LCVD) of platinum is measured for λ≈350 nm as a function of the light intensity and the metalorganic vapor pressure. The growth of the metal films is studied in situ and in real time by monitoring their optical transmission. At low intensities the transmitted light decreases monotonically with time, and the LCVD process is photolytic with its rate limiting step in the surface adlayer. At higher intensities we observe two distinct time domains: Relatively slow initial photolytic deposition with its rate limiting step in the gas phase, which is followed by much faster pyrolytic LCVD. An improved method for distinguishing between adlayer and gas-phase limiting processes is demonstrated. These observations are confirmed by studying the photolytic deposition rates while varying the thickness of the adlayer.

  5. In situ chemical imaging of lithiated tungsten using laser-induced breakdown spectroscopy

    NASA Astrophysics Data System (ADS)

    Li, Cong; Wu, Xingwei; Zhang, Chenfei; Ding, Hongbin; Hu, Jiansheng; Luo, Guang-Nan

    2014-09-01

    Lithium conditioning can significantly improve the plasma confinement of EAST tokamak by reducing the amount of hydrogen and impurities recycled from the wall, but the details of this mechanism and approaches that reduce the concentrations of hydrogen and impurities recycle still remain unclear. In this paper, we studied lithiated tungsten via a cascaded-arc plasma simulator. An in situ laser-induced breakdown spectroscopy (LIBS) diagnostic system has been developed to chemically image the three-dimensional distribution of lithium and impurities on the surface of lithiated tungsten co-deposition layer for the first time. The results indicate that lithium has a strong ability to draw hydrogen and oxygen. The impurity components from the co-deposition processes present more intensity on the surface of co-deposition layer. This work improves the understanding of lithiated tungsten mechanism and is useful for using LIBS as a wall-diagnostic technique for EAST.

  6. 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.

  7. 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.

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

    SciTech Connect

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

    2007-07-15

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

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

    NASA Astrophysics Data System (ADS)

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

    2011-08-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2007-02-01

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

  11. 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.

  12. Luminescence properties of SiO{sub x}N{sub y} irradiated by IR laser 808 nm: The role of Si quantum dots and Si chemical environment

    SciTech Connect

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

    2012-01-23

    We investigated optical, structural, and chemical properties of SiO{sub x}N{sub y} layers irradiated by CW IR laser during a time lapse of few milliseconds. We observed tunable photoluminescence signal at room temperature in the range 750-950 nm, without Si/SiO{sub 2} phase separation, depending on the IR laser power irradiation. Furthermore, no photoluminescence signal was recorded when the IR laser power density was high enough to promote phase separation forming Si quantum dots. By chemical analysis the source of the luminescence signal has been identified in a change of silicon chemical environment induced by IR laser annealing inside the amorphous matrix.

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

    SciTech Connect

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

    2015-02-08

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

  14. Topographical and chemical microanalysis of surfaces with a scanning probe microscope and laser-induced breakdown spectroscopy

    PubMed

    Kossakovski; Beauchamp

    2000-10-01

    Spatially resolved chemical imaging is achieved by combining a fiber-optic scanning probe microscope with laser-induced breakdown spectroscopy in a single instrument, TOPOLIBS. Elemental composition of surfaces can be mapped and correlated with topographical data. The experiment is conducted in air with minimal sample preparation. In a typical experiment, surface topography is analyzed by scanning a sharp fiber-optic probe across the sample using shear force feedback. The probe is then positioned over a feature of interest and pulsed radiation is delivered to the surface using a nitrogen laser. The pulse vaporizes material from the surface and generates a localized plasma plume. Optical emission from the plume is analyzed with a compact UV/visible spectrometer. Ablation crater size is controlled by the amount of laser power coupled into the probe. Sampling areas with submicrometer dimensions are achieved by using reduced laser power. PMID:11028639

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

    SciTech Connect

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

    2012-04-01

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

  16. Emission of a pulsed purely rotational transition chemical H{sub 2}-F{sub 2} laser

    SciTech Connect

    Molevich, N E; Pichugin, S Yu

    2008-04-30

    The possibility of obtaining efficient emission at purely rotational transitions of HF molecules in a pulsed chemical hydrogen fluoride laser is studied theoretically. The operation of a H{sub 2}-F{sub 2} laser with a gas pressure of 1.1 atm emitting at the v, j {yields} v, j - 1 (v = 1 - 6, j = 10 - 14) transitions is simulated taking into account resonance VR processes. The total specific laser energy release calculated over all the vibrational levels is 5.5 J L{sup -1} on purely rotational transitions at {lambda}{approx}17 {mu}m (j = 14), 3.5 J L{sup -1} at {lambda}{approx}18.5 {mu}m (j = 13), and 2.5 J L{sup -1} at {lambda}{approx}20 {mu}m (j = 12). (lasers and amplifiers)

  17. SPECIAL ISSUE DEVOTED TO THE 80TH ANNIVERSARY OF ACADEMICIAN N G BASOV'S BIRTH: Problems in the development of autonomous mobile laser systems based on a cw chemical DF laser

    NASA Astrophysics Data System (ADS)

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

    2003-01-01

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

  18. Physico-chemical properties of Pd nanoparticles produced by Pulsed Laser Ablation in different organic solvents

    NASA Astrophysics Data System (ADS)

    Cristoforetti, Gabriele; Pitzalis, Emanuela; Spiniello, Roberto; Ishak, Randa; Giammanco, Francesco; Muniz-Miranda, Maurizio; Caporali, Stefano

    2012-01-01

    Palladium nanoparticles are arousing an increasing interest because of their strong activity in heterogeneous catalysis in a wide range of reactions. Driven by the interest of producing Pd nanoparticles to be deposited for catalysis over hydrophobic supports, we investigated their synthesis via Pulsed Laser Ablation in Liquid in several organic solvents, as acetone, ethanol, 2-propanol, toluene, n-hexane. The colloids were produced by using a Nd:YAG ns laser and without the addition of surfactant agents. The morphology, composition, stability and oxidation state of the obtained nanoparticles were investigated by TEM-EDS analysis, UV-vis spectroscopy, X-ray Photoelectron Spectroscopy and micro-Raman spectroscopy. The results evidence that the nature of the solvent influences both the yield and the physico-chemical properties of the produced nanoparticles. While in acetone and alcohols spheroidal, non aggregated and stable particles are obtained, in case of toluene and n-hexane few unstable particles surrounded by a gel-like material are produced. Raman/XPS measurements suggest the presence of amorphous or graphitic carbon onto crystalline Pd nanoparticles, which could have hindered their growth and determined the observed smaller sizes if compared to nanoparticles produced in water. The stability of Pd colloids obtained in acetone and alcohols was attributed to adsorbed anions like enolates or alcoholates; non polar solvents like toluene and n-hexane, unable to give rise to adsorbed anionic species, cannot provide any stabilization to the palladium nanoparticles. XPS analyses also evidenced a partial oxidation of particles surface, with a ratio Pd2+:Pd0 of 1:2.5 and 1:4 in acetone and ethanol, respectively.

  19. 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.

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

    PubMed

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

    2007-05-01

    In this work, the capability of laser-induced breakdown spectrometry for the in situ analytical assessment and chemical mapping of the façade of the cathedral of Malaga (Spain) has been demonstrated. The task required the use of a portable laser analyzer that allowed real-time spectral acquisitions in the field. A man-portable laser, based on a Q-switched Nd:YAG laser operating at its fundamental wavelength, has been utilized to generate a LIBS plasma of the sample surface. A chemical characterization of the different materials employed in the construction of this building has been performed. The purpose of this study was to use LIBS spectrochemical analysis to qualitatively discriminate between sandstone, limestone, marble, and cement mortar, which are the main components used in this class of historical monument. The field analysis was performed in two zones: the northern façade and the "girola"; the total areas of analysis of the two regions were 250 m(2) and 650 m(2), respectively. Chemical images of Si/Ca and Ca/Mg ratios from both parts of the building were generated. During the measurement campaign, a protocol of analysis was chosen so as to achieve an accurate description of the building materials with respectable spatial resolutions. PMID:17555626

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

    NASA Astrophysics Data System (ADS)

    Patel, C. K. N.

    2008-01-01

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

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

    NASA Astrophysics Data System (ADS)

    Johnson, Ryan William

    2005-07-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2016-04-01

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

  4. Atmospheric pressure laser-induced acoustic desorption chemical ionization mass spectrometry for analysis of saturated hydrocarbons.

    PubMed

    Nyadong, Leonard; Quinn, John P; Hsu, Chang S; Hendrickson, Christopher L; Rodgers, Ryan P; Marshall, Alan G

    2012-08-21

    We present atmospheric pressure laser-induced acoustic desorption chemical ionization (AP/LIAD-CI) with O(2) carrier/reagent gas as a powerful new approach for the analysis of saturated hydrocarbon mixtures. Nonthermal sample vaporization with subsequent chemical ionization generates abundant ion signals for straight-chain, branched, and cycloalkanes with minimal or no fragmentation. [M - H](+) is the dominant species for straight-chain and branched alkanes. For cycloalkanes, M(+•) species dominate the mass spectrum at lower capillary temperature (<100 °C) and [M - H](+) at higher temperature (>200 °C). The mass spectrum for a straight-chain alkane mixture (C(21)-C(40)) shows comparable ionization efficiency for all components. AP/LIAD-CI produces molecular weight distributions similar to those for gel permeation chromatography for polyethylene polymers, Polywax 500 and Polywax 655. Coupling of the technique to Fourier transform ion cyclotron resonance mass spectrometry (FTICR MS) for the analysis of complex hydrocarbon mixtures provides unparalleled mass resolution and accuracy to facilitate unambiguous elemental composition assignments, e.g., 1754 peaks (rms error = 175 ppb) corresponding to a paraffin series (C(12)-C(49), double-bond equivalents, DBE = 0) and higher DBE series corresponding to cycloparaffins containing one to eight rings. Isoabundance-contoured plots of DBE versus carbon number highlight steranes (DBE = 4) of carbon number C(27)-C(30) and hopanes of C(29)-C(35) (DBE = 5), with sterane-to-hopane ratio in good agreement with field ionization (FI) mass spectrometry analysis, but performed at atmospheric pressure. The overall speciation of nonpolar, aliphatic hydrocarbon base oil species offers a promising diagnostic probe to characterize crude oil and its products. PMID:22881221

  5. 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

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

    NASA Astrophysics Data System (ADS)

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

    2013-06-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2011-03-01

    Laser-induced acoustic desorption (LIAD) was successfully coupled to a conventional atmospheric pressure chemical ionization (APCI) source in a commercial 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. From the four APCI reagent systems tested, neat carbon disulfide provided the best results. 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 but minor amount of fragmentation was observed for these two 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 predominantly form stable molecular ions.

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

    SciTech Connect

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

    2013-01-01

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

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

    PubMed

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

    2011-06-10

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

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

    NASA Astrophysics Data System (ADS)

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

    2011-06-01

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

  11. Experimental investigation of a chemical-laser-cavity flowfield. Master's thesis

    SciTech Connect

    Stiglich, S.W.

    1989-12-01

    Chemical lasers require a cavity that establishes and maintains the proper gas dynamic properties during lasing. The design and performance of a flow system capable of supporting the hypersonic flow conditions in a lasing cavity are described. Using cold air as the working medium, the flow control system configuration and nozzle-cavity-supersonic diffuser assembly configuration were developed to establish acceptable flow conditions in the test section. Performance evaluation was based on pressure measurements in the nozzle-cavity-diffuser assembly and schlieren photographs of the flowfield in the cavity. Flow conditions in the test section were broken up into three different regions: flow in the hypersonic nozzles, flow in the base region and flow in the cavity region. Flow in the nozzles was analyzed using one-dimensional, steady, isentropic flow theory. Test results indicated that the hypersonic nozzles performed to design specifications. The Korst two-dimensional base-pressure flow model was used to describe the flow in the nozzle exit plane and base region. Experimentally calculated Mach numbers and static pressures corresponded very closely to theoretical values. Static pressure ports and schlieren photographs were used to describe the flow-field conditions in the cavity region. Pressure measurements indicated that supersonic conditions were reached in the cavity for specific supersonic diffuser throat areas settings, but conditions were short lived. Boundary layer, frictional, and three-dimensional effects were suspected as the main contributors to the flowfield degradation.

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

    SciTech Connect

    J. Thomas Dickinson; Michael L. Alexander

    2001-11-30

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

  13. 650-nm AlGaInP multiple-quantum-well lasers grown by metalorganic chemical vapor deposition using tertiarybutylphosphine

    NASA Astrophysics Data System (ADS)

    Dong, Jian-Rong; Teng, Jing-Hua; Chua, Soo-Jin; Foo, Boon-Chin; Wang, Yan-Jun; Yuan, Hai-Rong; Yuan, Shu

    2003-07-01

    Using tertiarybutylphosphine (TBP) as phosphorus precursor, high-quality AlGaInP epilayers and AlGaInP/GaInP multiple-quantum-well (MQW) structures have been grown by metalorganic chemical vapor deposition. The photoluminescence results indicate that the AlGaInP materials are as good as those grown using PH3 in terms of optical quality. Finally, AlGaInP MQW red laser structures have been grown, and the electrically pumped AlGaInP red lasers grown by TBP have been demonstrated with the emission wavelength of 647 nm, indicating that TBP can be used to grow high-quality AlGaInP epilayers and AlGaInP-based red lasers, which presently is dominated by the highly toxic gas source PH3.

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

    NASA Astrophysics Data System (ADS)

    MacLeod, Neil A.; Weidmann, Damien

    2016-05-01

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

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

    NASA Technical Reports Server (NTRS)

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

    1991-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2016-04-01

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

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

    PubMed

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

    2014-10-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2007-10-01

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

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

    PubMed

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

    2015-02-17

    High-resolution chemical depth profiling measurements of copper films are presented. The 10 μm thick copper test samples were electrodeposited on a Si-supported Cu seed under galvanostatic conditions in the presence of particular plating additives (SPS, Imep, PEI, and PAG) used in the semiconductor industry for the on-chip metallization of interconnects. To probe the trend of these plating additives toward inclusion into the deposit upon growth, quantitative elemental mass spectrometric measurements at trace level concentration were conducted by using a sensitive miniature laser ablation ionization mass spectrometer (LIMS), originally designed and developed for in situ space exploration. An ultrashort pulsed laser system (τ ∼ 190 fs, λ = 775 nm) was used for ablation and ionization of sample material. We show that with our LIMS system, quantitative chemical mass spectrometric analysis with an ablation rate at the subnanometer level per single laser shot can be conducted. The measurement capabilities of our instrument, including the high vertical depth resolution coupled with high detection sensitivity of ∼10 ppb, high dynamic range ≥10(8), measurement accuracy and precision, is of considerable interest in various fields of application, where investigations with high lateral and vertical resolution of the chemical composition of solid materials are required, these include, e.g., wafers from semiconductor industry or studies on space weathered samples in space research. PMID:25642789

  20. Effect of laser power on orientation and microstructure of Ba2TiO4 film prepared by laser chemical vapor deposition

    NASA Astrophysics Data System (ADS)

    Guo, Dongyun; Goto, Takashi; Wang, Chuanbin; Shen, Qiang; Zhang, Lianmeng

    2012-08-01

    Ba2TiO4 films were prepared on Pt/Ti/SiO2/Si substrates by laser chemical vapor deposition method. The effect of laser power (PL) on orientation and microstructure was investigated. With increasing PL from 52 to 93 W, the deposition temperature (Tdep) increased from 845 to 946 K. With increasing Tdep from 845 to 927 K, the preferred orientation of Ba2TiO4 films changed from (0 9 1) to (1 0 3), the surface morphologies changed from faceted to rectangular, and the columnar cross-section became thicker. The films prepared at high Tdep (931-946 K) had the porous cross-section consisted of powder-like grains. Ba2TiO4 film prepared at 881 K had high deposition rate (Rdep) of 51.4 μm h-1, which was advantageous to industrial production.

  1. A real time Monte Carlo simulation of thin film nucleation in localized-laser chemical vapor deposition

    NASA Astrophysics Data System (ADS)

    Kotecki, David E.; Herman, Irving P.

    1988-11-01

    A real time Monte Carlo simulation is used to model the nucleation and initial stages of thin film growth during localized-laser chemical vapor deposition (LLCVD). This model includes the effects of laser-substrate heating, heterogeneous pyrolytic decomposition of parent molecules on the laser-heated region of the surface, and adatom migration and desorption dynamics. The amount of material deposited as a function of time is obtained over a surface area of 150×150 Å for various values of the substrate temperature, parent gas pressure, and adsorbate-substrate binding energy. Additional information is obtained about the cluster density, and the role of surface defects and two-atom cluster dynamics on the initial growth rate. The deposition of silicon by heterogeneous pyrolytic decomposition of silane (SiH4) is used as a base case for the simulation. Predictions of the initial thin film morphology and its temporal evolution during static laser heating of micron-dimensional regions of the surface are presented. Simulation results indicate that for a given silane pressure and adsorbate-substrate binding energy, there is a critical temperature Tc such that for laser-induced peak temperatures Tplaser-heated region, while for Tp>Tc, nucleation occurs initially in an annulus region centered with respect to the incident laser irradiation. The inclusion of two-atom cluster dynamics in the simulation is shown to increase the value of Tc and alter the initial morphology for low adsorbate-substrate binding energies. The simulation results are extended to scanning LLCVD to predict the maximum scan speed at which nucleation will occur.

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

    SciTech Connect

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

    2008-07-31

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

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

    SciTech Connect

    Morse, T.M.

    1996-03-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2010-09-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2016-06-01

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

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

    SciTech Connect

    Van Berkel, Gary J; Kertesz, Vilmos

    2014-01-28

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

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

    NASA Astrophysics Data System (ADS)

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

    2007-04-01

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

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

    NASA Astrophysics Data System (ADS)

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

    1997-05-01

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

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

    SciTech Connect

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

    2004-12-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2011-03-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2016-02-01

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

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

    SciTech Connect

    Koch, T.H.

    1987-05-07

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

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

    NASA Technical Reports Server (NTRS)

    Shiner, C. S.

    1985-01-01

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

  14. 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...

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

    EPA Science Inventory

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

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

    NASA Astrophysics Data System (ADS)

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

    1993-03-01

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

  17. Laser induced chemical vapor deposition of Ni by decomposition of Ni(CO)4

    NASA Astrophysics Data System (ADS)

    Kräuter, W.; Bäuerle, D.; Fimberger, F.

    1983-05-01

    Polycrystalline Ni has been grown by decomposition of Ni(CO)4 using different wavelengths of the visible radiation of a Kr+ laser. The influence of laser irradiance, substrate material and scanning velocity on deposition rate and widths of patterns has been investigated. The deposition rates achieved are typically several μm/s, and the lateral dimensions of the deposits can be as small as 1 μm.

  18. 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

    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)

  19. High-power supersonic chemical lasers: gas-dynamic problems of operation of mobile systems with PRS

    NASA Astrophysics Data System (ADS)

    Boreysho, A. S.; Malkov, V. M.; Savin, A. V.

    2008-10-01

    Supersonic chemical lasers, such as HF /DF and COIL, have always been in the focus of special interest as the most powerful sources of continuous wave generation. Presently, autonomous mobile laser complexes (both air- and landbased) are being developed on the basis of SCL [1-3]. It is commonly accepted that SCL appeared, conditionally speaking, at the crossroads of a number of sciences: of physics - quantum electronics and physical kinetics; chemistry - combustion theory and chemical kinetics; classic optics - theory of resonators, aero-optics, and gas dynamics (there is a supersonic flow in the SCL channel). Due to this fact, all tasks and problems which could be resolved in the course of SCL development have complex character and could be considered as the next stage of complexity in comparison with the well known similar tasks which had been considered earlier. This is why they should be resolved anew with consideration of the specific aspects of the SCL processes. This is true for the gas-dynamic problems: new parameter areas, non-traditional channel geometry, consideration of new phenomena, etc.Supersonic chemical lasers, such as HF /DF and COIL, have always been in the focus of special interest as the most powerful sources of continuous wave generation. Presently, autonomous mobile laser complexes (both air- and landbased) are being developed on the basis of SCL [1-3]. It is commonly accepted that SCL appeared, conditionally speaking, at the crossroads of a number of sciences: of physics - quantum electronics and physical kinetics; chemistry - combustion theory and chemical kinetics; classic optics - theory of resonators, aero-optics, and gas dynamics (there is a supersonic flow in the SCL channel). Due to this fact, all tasks and problems which could be resolved in the course of SCL development have complex character and could be considered as the next stage of complexity in comparison with the well known similar tasks which had been considered earlier

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

    NASA Astrophysics Data System (ADS)

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

    2016-03-01

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

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

    SciTech Connect

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

    2010-05-01

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

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

    NASA Astrophysics Data System (ADS)

    Knochenmuss, Richard

    2015-08-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2016-12-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-05-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-12-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-07-01

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

  7. 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

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

    NASA Astrophysics Data System (ADS)

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

    2015-01-01

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

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

    SciTech Connect

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

    1982-07-01

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

  10. 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.

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

    SciTech Connect

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

    2015-09-29

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

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

    SciTech Connect

    Falco, B.

    1992-04-09

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

  13. Identification and quantification of selected chemicals in laser pyrolysis products of mammalian tissues

    NASA Astrophysics Data System (ADS)

    Spleiss, Martin; Weber, Lothar W.; Meier, Thomas H.; Treffler, Bernd

    1995-01-01

    Liver and muscle tissue have been irradiated with a surgical CO2-laser. The prefiltered fumes were adsorbed on different sorbents (activated charcoal type NIOSH and Carbotrap) and desorbed with different solvents (carbondisulphide and acetone). Analysis was done by gas chromatography/mass spectrometry. An updated list of identified substances is shown. Typical Maillard reaction products as found in warmed over flavour as aldehydes, aromatics, heterocyclic and sulphur compounds were detected. Quantification of some toxicological relevant substances is presented. The amounts of these substances are given in relation to the laser parameters and different tissues for further toxicological assessment.

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

    DOEpatents

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

    2013-08-27

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

  15. 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.

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

    PubMed

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

    2015-08-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2009-12-01

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

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

    PubMed

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

    2004-12-01

    Quantum cascade lasers (QCLs) are a relatively new type of semiconductor laser operating in the mid- to long-wave infrared. These monopolar multilayered quantum well structures can be fabricated to operate anywhere between 3.5 and 20 microm, which includes the molecular fingerprint region of the infrared. This makes them an ideal choice for infrared chemical sensing, a topic of great interest at present. Frequency stabilization and injection locking increase the utility of QCLs. We present results of locking QCLs to optical cavities, achieving relative linewidths down to 5.6 Hz. We report injection locking of one distributed feedback grating QCL with light from a similar QCL, demonstrating capture ranges of up to +/-500 MHz, and suppression of amplitude modulation by up to 49 dB. We also present various cavity-enhanced chemical sensors employing the frequency stabilization techniques developed, including the resonant sideband technique known as NICE-OHMS. Sensitivities of 9.7 x 10(-11) cm(-1) Hz(-1/2) have been achieved in pure nitrous oxide. PMID:15561632

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

    NASA Astrophysics Data System (ADS)

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

    2015-08-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2016-07-01

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

  1. Influence of laser power on the orientation and microstructure of CeO 2 films deposited on Hastelloy C276 tapes by laser chemical vapor deposition

    NASA Astrophysics Data System (ADS)

    Zhao, Pei; Ito, Akihiko; Tu, Rong; Goto, Takashi

    2010-08-01

    CeO 2 films were prepared on LaMnO 3/MgO/Gd 2Zr 2O 7 multi-coated Hastelloy C276 tapes by laser chemical vapor deposition at different laser power ( PL) from 46 to 101 W. Epitaxial (1 0 0) CeO 2 films were prepared at PL = 46-93 W (deposition temperature, Tdep = 705-792 K). Epitaxial CeO 2 films had rectangular-shaped grains at PL = 46-77 W ( Tdep = 705-754 K), while square-shaped grains were obtained at PL = 85-93 W ( Tdep = 769-792 K). CeO 2 films showed a columnar microstructure. Epitaxial (1 0 0) CeO 2 films with rectangular grains exhibited full width at half maximum of ω-scan on (2 0 0) reflection and ϕ-scan on (2 2 0) reflection of 3.4-3.2° and 6.0-7.2°, respectively. The deposition rate of the epitaxial (1 0 0) CeO 2 films had a maximum of 4.6 μm h -1 at PL = 77 W ( Tdep = 754 K).

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

    SciTech Connect

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

    1996-01-01

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

  3. 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...

  4. 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 ...

  5. Chemical transformations of the polyimide Kapton brought about by ultraviolet laser radiation

    NASA Astrophysics Data System (ADS)

    Srinivasan, R.; Hall, R. R.; Loehle, W. D.; Wilson, W. D.; Allbee, D. C.

    1995-10-01

    By the use of ultraviolet laser pulses of microsecond and millisecond duration it is shown that the chemistry of the transformations of Kapton by UV laser radiation is strongly dependent on the intensity (power/unit area) of the laser beam. With these long pulses, the polymer was not ablated. The decomposition resulted in 51% of the polymer weight being converted to gaseous products consisting mostly of CO (67%), HCN (15%), C2H2 (12%), and some (<5%) CO2. The major solid product that remained was ``glassy'' carbon which was identified from its Raman spectrum. This material can be viewed as the product of the secondary addition reactions of the residue that is left after the loss of the gaseous products listed above. With 20 ms pulses, the evolution of the gaseous products increased linearly with intensity and the product composition was constant within the experimental uncertainty over a 12-fold range of intensity up to 50 kW/cm2 (≡1 kJ/cm2). These results show that pulses of duration much greater than ns do not lead to ablation even at fluences that are 104 greater than the threshold for ablation using nanosecond pulses. It is therefore more appropriate to view the ablation of this polymer by UV laser pulses of nanosecond duration as being due to the scaling of an intensity threshold rather than a fluence threshold as has become the practice.

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

    SciTech Connect

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

    1987-01-01

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

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

    PubMed Central

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

    2011-01-01

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

  8. 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

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

    SciTech Connect

    Not Available

    1990-01-19

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

  10. Acoustic monitoring of carbon film formation by laser-induced chemical vapor deposition

    SciTech Connect

    Iida, Y.; Yeung, E.S. )

    1993-04-01

    Acoustic signals generated by the deposition of carbon thin films were monitored in situ by a microphone. Photolysis of benzene or adamantane vapor in the presence of helium buffer gas of 5 to 100 Torr by an ArF excimer laser formed several kinds of carbon films (e.g., polymeric, amorphous, and graphitic films), depending on the optical configuration, the ambient pressure, the laser fluence, and the reagent pressure. Analysis of the acoustic signal offers some insight into the mechanism of the deposition processes, which include the graphitization of the deposited films and the role of energetic particles, such as vibrationally excited benzene, in the deposition of amorphous hydrogenated carbon film. Also, the acoustic signal clearly showed the presence of surface-related processes in the course of film deposition. 26 refs., 6 figs., 1 tab.

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

    NASA Technical Reports Server (NTRS)

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

    2002-01-01

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

  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

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

    NASA Astrophysics Data System (ADS)

    Chu, Shirley S.; Chu, Ting L.

    1991-05-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2016-07-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-04-01

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

  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

  18. Solution-based synthesis of crystalline silicon from liquid silane through laser and chemical annealing.

    PubMed

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

    2012-05-01

    We report a solution process for the synthesis of crystalline silicon from the liquid silane precursor cyclohexasilane (Si(6)H(12)). Polysilane films were crystallized through thermal and laser annealing, with plasma hydrogenation at atmospheric pressure generating further structural changes in the films. The evolution from amorphous to microcrystalline is characterized using scanning electron microscopy (SEM), atomic force microscopy (AFM), Raman spectroscopy and impedance spectroscopy. A four-decade enhancement in the electrical conductivity is attributed to a disorder-order transition in a bonded Si network. Our results demonstrate a potentially attractive approach that employs a solution process coupled with ambient postprocessing to produce crystalline silicon thin films. PMID:22545711

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

    SciTech Connect

    Livingston, P.M.; Bullock, D.L.

    1980-07-01

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

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

    PubMed

    Livingston, P M; Bullock, D L

    1980-07-01

    The new hypersonic wedge nozzle (HYWN) supersonic wedge nozzle design produces a significant component of directed gas flow along the optical axis of a laser cavity comparable to thermal speeds. The gain-line-shape function is broadened and the refractive-index line shape is also spread as a function of wedge-flow half-angle. An analytical treatment as well as a numerical study is presented that evaluates the Doppler-directed-flow impact on the number of longitudinal modes and their frequencies as well as on gain and refractive-index saturation of those that lase in a Fabry-Perot cavity. PMID:19693204

  1. Laser-induced etching of few-layer graphene synthesized by Rapid-Chemical Vapour Deposition on Cu thin films.

    PubMed

    Piazzi, Marco; Croin, Luca; Vittone, Ettore; Amato, Giampiero

    2012-12-01

    The outstanding electrical and mechanical properties of graphene make it very attractive for several applications, Nanoelectronics above all. However a reproducible and non destructive way to produce high quality, large-scale area, single layer graphene sheets is still lacking. Chemical Vapour Deposition of graphene on Cu catalytic thin films represents a promising method to reach this goal, because of the low temperatures (T < 950°C-1000°C) involved during the process and of the theoretically expected monolayer self-limiting growth. On the contrary such self-limiting growth is not commonly observed in experiments, thus making the development of techniques allowing for a better control of graphene growth highly desirable. Here we report about the local ablation effect, arising in Raman analysis, due to the heat transfer induced by the laser incident beam onto the graphene sample. PMID:23503582

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

    SciTech Connect

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

    2013-09-16

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

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

    NASA Technical Reports Server (NTRS)

    Steinberg, M.; Schofield, K.

    1983-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2016-02-01

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

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

    SciTech Connect

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

    2011-01-01

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

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

    DOE PAGESBeta

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

    2012-05-23

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

  7. Laser-induced chemical vapor deposition of SiO2

    NASA Astrophysics Data System (ADS)

    Boyer, P. K.; Roche, G. A.; Ritchie, W. H.; Collins, G. J.

    1982-04-01

    We have demonstrated rapid (3000 Å/min) photochemical deposition of silicon dioxide from gas phase donor molecules. An ArF (193 nm) laser was used to excite and dissociate gas phase SiH4 and N2O molecules in contrast to earlier work with incoherent mercury lamps. We have achieved 20 times the deposition rate, limited the dissociation volume to a localized region, and minimized the direct impingement of UV photons on the substrate. Although the SiO2 deposition rate was insensitive to substrate temperature from 20 to 600 °C, film quality noticeably improved above 200 °C. Metal-oxide-semiconductor capacitors were fabricated and characterized in order to measure SiO2 electrical properties. Film composition was investigated using Auger and infrared spectroscopy techniques and showed that the SiO2 is stoichiometric and contains less than 5% nitrogen.

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

    SciTech Connect

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

    2012-05-23

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

  9. 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.

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

    SciTech Connect

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

    2009-01-01

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

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

    PubMed

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

    2014-12-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2010-01-01

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

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

    SciTech Connect

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

    2010-01-23

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

  14. Continuous-wave operation of AlGaInP/GaInP quantum-well lasers grown by metalorganic chemical vapor deposition using tertiarybutylphosphine

    NASA Astrophysics Data System (ADS)

    Dong, Jian-Rong; Teng, Jing-Hua; Chua, Soo-Jin; Foo, Boon-Chin; Wang, Yan-Jun; Zhang, Lian-Wen; Yuan, Hai-Rong; Yuan, Shu

    2004-05-01

    Strained AlGaInP/GaInP multiple-quantum-well laser structures have been grown by metalorganic chemical vapor deposition using teriarybutylphosphine as the phosphorus precursor and ridge waveguide lasers of 4 μm wide have been fabricated. Room temperature continuous-wave lasing has been obtained with an emission wavelength of about 670 nm. A single-facet output power of more than 18 mW has been achieved for an as-cleaved laser chip. It can be concluded that it is feasible to fabricate AlGaInP red lasers using less toxic metalorganic source tertiarybutylphosphine in parallel with conventionally used highly toxic PH3.

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

    SciTech Connect

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

    2011-08-31

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-06-01

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

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

    NASA Technical Reports Server (NTRS)

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

    1993-01-01

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

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

    SciTech Connect

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

    2015-06-07

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

  19. Laser enhanced chemical reaction studies. Technical report, January 1, 1994--February 28, 1995

    SciTech Connect

    1995-07-01

    The relaxation of vibrationally excited pyrazine (E=40,640 cm{sup -1}) by collisions which populate the high J tail (J=58-82) of the vibrationless ground state (00{sup 0}0) of CO{sub 2} has been studied using tunable infrared diode lasers to probe the scattered CO{sub 2} molecules. The nascent rotational populations and translational recoil velocities for a series of rotational states in the high J tail of the 00{sup 0}0 level of CO{sub 2} were measured at five collision cell temperatures: 243, 263, 298, 339, and 364 K. Both the rate constants describing these V-R/T processes and the translational temperatures describing the recoiling CO{sub 2} molecules exhibit a very weak positive temperature dependence indicating that the high energy CO{sub 2} molecules must originate from near the center of the pre-collision energy distribution. Quantitative estimates of the actual amount of energy transferred in collisions between CO{sub 2} and vibrationally excited pyrazine, based on an angular momentum and translational energy exponential gap model of the cross section, indicate that {triangle}E{sub total} can be as large as 7090 cm{sup -1} ({approximately}20 kcal/mol). These experiments offer compelling evidence that these energy transfer events can indeed be classified as supercollisions since they involve unusually large, single collision energy transfer magnitudes; and despite their relative infrequency, they play a most important role in the collisional deactivation of vibrationally excited pyrazine by a CO{sub 2} bath.

  20. 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.

  1. Comparison of silver nanoparticles confined in nanoporous silica prepared by chemical synthesis and by ultra-short pulsed laser ablation in liquid

    NASA Astrophysics Data System (ADS)

    Szegedi, Á.; Popova, M.; Valyon, J.; Guarnaccio, A.; De Stefanis, A.; De Bonis, A.; Orlando, S.; Sansone, M.; Teghil, R.; Santagata, A.

    2014-10-01

    Hexagonally ordered mesoporous silica materials, MCM-41 and SBA-15, have been synthesized and loaded with Ag nanoparticles, utilizing both chemical synthesis and ultra-short pulsed laser ablation in liquid. In laser ablation, a silver target, immersed in aqueous suspension of ordered mesoporous silica SBA-15, was irradiated by ultra-short laser pulses to generate silver nanoparticles. For comparison, samples of similar silver contents were prepared either by incorporating silver into the SBA-15 during a hydrothermal synthesis or by introducing silver in MCM-41 by template ion-exchange. Samples were characterized by XRD, N2 physisorption, TEM and UV-vis spectroscopy. All preparations contained significant amount of 5-50 nm size silver agglomerates on the outer surface of the silica particles. The laser ablation process did not cause significant destruction of the SBA-15 structure and metallic silver (Ag0) nanoparticles were mainly generated. It is demonstrated that by laser ablation in aqueous silica suspension smaller and more uniform metallic silver particles can be produced and loaded on the surface of the silica support than by synthesis procedures. Catalytic properties of the samples have been tested in the total oxidation of toluene. Because of its favorable Ag dispersity, the Ag/SBA-15 catalyst, generated by the laser ablation method, had better catalytic stability and, relative to its Ag load, higher activity than the conventional Ag/SBA-15 preparations.

  2. 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.

  3. 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).

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

    PubMed Central

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

    2013-01-01

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

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

    SciTech Connect

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

    1994-10-06

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

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

    SciTech Connect

    Miyamoto, Yoshiyuki; Zhang Hong; Rubio, Angel

    2010-12-10

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

  7. Optically pumped laser oscillation at about 2.9 microns of a HgCdTe layer grown by metalorganic chemical vapor deposition

    NASA Astrophysics Data System (ADS)

    Ravid, A.; Zussman, A.; Cinader, G.; Oron, A.

    1989-12-01

    Photopumped pulsed stimulated emission at 2.9 microns in an HgCdTe layer grown by metalorganic chemical vapor deposition on a CdTe substrate was studied as a function of temperature. The threshold power of the HgCdTe laser (photoexcited by a GaAs diode laser) increased from 0.04 W at 12 K to 1.58 W at 150 K. Above 50 K, the temperature dependence of the threshold is exponential, yielding a T0 of 31 K. From the observed laser emission wavelength a Cd mole fraction of x = 0.422 was determined. The far-field angular full width at e exp -2 of peak intensity was 5.5 and 9.5 deg perpendicular and parallel to the film plane, respectively.

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

    SciTech Connect

    Orel, A.E.

    1980-12-01

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

  9. 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.; Sapetskiĭ, 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.

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

    NASA Astrophysics Data System (ADS)

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

    2016-07-01

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

  11. 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.

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

    NASA Astrophysics Data System (ADS)

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

    1993-02-01

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

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

    NASA Astrophysics Data System (ADS)

    Kusiński, Jan

    1995-02-01

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

  14. Interpretation of Absolute Laser Reflectance During Optical Monitoring of Polycrystalline GaAs Deposition on Quartz Using Metalorganic Chemical Vapor Deposition

    NASA Astrophysics Data System (ADS)

    Clayton, Andrew J.; Irvine, Stuart J. C.

    2011-06-01

    Gallium arsenide (GaAs) was deposited by metalorganic chemical vapor deposition in a horizontal quartz reactor tube using trimethylgallium and arsine at 400°C to 500°C. Nucleation time and deposition rate were monitored using in situ laser reflectometry. This allowed differentiation between film and parasitic growth, which was not possible with other optical techniques. An absolute reflectance model was developed using measurements prior to GaAs deposition, and then employed to calculate values for GaAs on quartz. Detected reflectance intensities during experimental GaAs deposition were low compared with the model due to three-dimensional island growth, causing scattering of the incident laser radiation.

  15. 1. 5-. mu. m GaInAsP planar buried heterostructure lasers grown using chemical-beam-epitaxial base structures

    SciTech Connect

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

    1988-02-15

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

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

    NASA Astrophysics Data System (ADS)

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

    2016-03-01

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

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

    SciTech Connect

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

    1996-12-31

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

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

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

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

  19. 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

  20. Mechanical and Electro-Chemical Properties of Laser Surface Alloyed AISI 304 Stainless Steel with WC+Ni+NiCr

    NASA Astrophysics Data System (ADS)

    Majumdar, J. D.

    In the present study, a detailed evaluation of wear and corrosion resistance properties of laser surface alloyed of AISI 304 stainless steel with WC+Ni+NiCr (in the ratio of 70:15:15) has been undertaken. Laser processing has been carried out using a 5 kW continuous wave (CW) Nd:YAG laser (at a beam diameter of 3 mm) by surface melting and simultaneous deposition of precursor powder mixture in the melt zone (at a flow rate of 10 mg/s) and using Ar shroud at a gas flow rate of 5 l/min. Followed by laser processing, a detailed evaluation of fretting wear behavior has been conducted against WC surface. Finally, the corrosion property is measured using a potentiodynamic polarization testing unit in a 3.56 wt.% NaCl solution. The wear resistance property is significantly improved due to laser surface alloying which is attributed to the improvement in surface microhardness to 1350 VHN as compared to 220 VHN of as-received γ-stainless steel substrate. The mechanism of wear is established. The pitting corrosion resistance property is also improved due to the presence of Ni and Cr in solution and homogenization of microstructure due to laser processing.

  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

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

    NASA Astrophysics Data System (ADS)

    Gerber, Gustav

    2009-05-01

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

  3. High-Jc YBa2Cu3O7-δ superconducting film grown by laser-assisted chemical vapor deposition using a single liquid source and its microstructure

    NASA Astrophysics Data System (ADS)

    Zhao, Pei; Ito, Akihiko; Kato, Takeharu; Yokoe, Daisaku; Hirayama, Tsukasa; Goto, Takashi

    2013-09-01

    A YBa2Cu3O7-δ (YBCO) film was prepared on a multilayer-coated Hastelloy C276 substrate by laser-assisted metalorganic chemical vapor deposition using a single liquid source precursor. A c-axis-oriented YBCO film was grown epitaxially on a (100) CeO2 layer at a deposition rate of 11 μm h-1. A screw dislocation and stacking faults were observed in the cross-section of the YBCO film. The critical current density of the YBCO film reached 2.7 MA cm-2.

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

    NASA Astrophysics Data System (ADS)

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

    2013-02-01

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

  5. Atmospheric propagation for tactical directed-energy applications

    NASA Astrophysics Data System (ADS)

    MacGovern, Alan J.; Nahrstedt, David A.; Johnson, Michael M.

    2000-07-01

    As a corollary to the USAF strategic Airborne Laser program, Boeing has been analyzing the use of the Chemical Oxygen Iodine Laser for tactical scenarios. These include its use in an airborne platform operating against low flying cruise missiles and miscellaneous ground targets, as well as on a mobile ground platform providing support defense against shorter-range rocket attack. Practical design concepts yielding high target lethality at significant ranges have been developed.

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

    NASA Astrophysics Data System (ADS)

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

    2016-02-01

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

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

    PubMed

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

    2005-03-15

    The rate coefficient of the gas-phase reaction C(2)H + H(2)O-->products has been experimentally determined over the temperature range 500-825 K using a pulsed laser photolysis-chemiluminescence (PLP-CL) technique. Ethynyl radicals (C(2)H) were generated by pulsed 193 nm photolysis of C(2)H(2) in the presence of H(2)O vapor and buffer gas N(2) at 15 Torr. The relative concentration of C(2)H radicals was monitored as a function of time using a CH* chemiluminescence method. The rate constant determinations for C(2)H + H(2)O were k(1)(550 K) = (2.3 +/- 1.3) x 10(-13) cm(3) s(-1), k(1)(770 K) =(7.2 +/- 1.4) x 10(-13) cm(3) s(-1), and k(1)(825 K) = (7.7 +/- 1.5) x 10(-13) cm(3) s(-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 C(2)H(3)O in its doublet electronic ground state has been investigated using density functional theory B3LYP6-311 + + 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 C(2)H(2)+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. Almlof and P. R. Taylor, J. Chem. Phys.86, 4070 (1987)] were performed, yielding zero

  8. 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.

  9. 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.

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

    EPA Science Inventory

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

  11. Treatment of Acne Vulgaris With Salicylic Acid Chemical Peel and Pulsed Dye Laser: A Split Face, Rater-Blinded, Randomized Controlled Trial

    PubMed Central

    Lekakh, Olga; Mahoney, Anne Marie; Novice, Karlee; Kamalpour, Julia; Sadeghian, Azeen; Mondo, Dana; Kalnicky, Cathy; Guo, Rong; Peterson, Anthony; Tung, Rebecca

    2015-01-01

    Introduction: Pulsed dye laser (PDL) has been used to treat acne lesions and scar erythema by interrupting superficial vasculature. Salicylic acid chemical peels are employed chiefly due to their lipophilic, comedolytic, and anti-inflammatory properties. Although studies have looked at peels and laser therapy independently in acne management, we examined these treatments in combination. Our primary objective was to evaluate the safety and efficacy of concurrent use of salicylic acid peels with PDL versus salicylic acid peels alone in the treatment of moderate to severe acne vulgaris. Methods: Adult patients with moderate to severe acne were included. Subjects received a total of 3 treatments at 3-week intervals. Per randomized split-face treatment, at week 0, one half of the subject’s face was treated with PDL (595 nm) followed by whole face application of a 30% salicylic acid peel. At weeks 3 and 6, the treatments were repeated. At 0 and 9 weeks, patients were assessed with the Global Evaluation Acne (GEA) scale and Dermatology Life Quality Index (DLQI) questionnaire. Results: Nineteen subjects were enrolled, and 18 completed the study. Significant improvement in acne was seen in both the combined (laser and peel) and chemical peel alone treatment arms (P < .0005 and P = .001). Using the GEA scale score, compared to week 0, the mean difference in acne improvement at week 9 was -1.61 in the combination therapy group versus -1.11 in the peel only group. Based on the GEA scale scoring, a statistically significant greater difference in acne improvement was seen, from week 0 to week 9, in the combination treatment group compared with the peel only group (P = .003). Conclusion: While acne subjects had significant benefit from the salicylic acid peel alone, they experienced greater significant benefit from PDL treatment used in conjunction with salicylic acid peels. The adjunctive utilization of PDL to salicylic acid peel therapy can lead to better outcomes in acne

  12. Development of routines for simultaneous in situ chemical composition and stable Si isotope ratio analysis by femtosecond laser ablation inductively coupled plasma mass spectrometry.

    PubMed

    Frick, Daniel A; Schuessler, Jan A; von Blanckenburg, Friedhelm

    2016-09-28

    Stable metal (e.g. Li, Mg, Ca, Fe, Cu, Zn, and Mo) and metalloid (B, Si, Ge) isotope ratio systems have emerged as geochemical tracers to fingerprint distinct physicochemical reactions. These systems are relevant to many Earth Science questions. The benefit of in situ microscale analysis using laser ablation (LA) over bulk sample analysis is to use the spatial context of different phases in the solid sample to disclose the processes that govern their chemical and isotopic compositions. However, there is a lack of in situ analytical routines to obtain a samples' stable isotope ratio together with its chemical composition. Here, we evaluate two novel analytical routines for the simultaneous determination of the chemical and Si stable isotope composition (δ(30)Si) on the micrometre scale in geological samples. In both routines, multicollector inductively coupled plasma mass spectrometry (MC-ICP-MS) is combined with femtosecond-LA, where stable isotope ratios are corrected for mass bias using standard-sample-bracketing with matrix-independent calibration. The first method is based on laser ablation split stream (LASS), where the laser aerosol is split and introduced simultaneously into both the MC-ICP-MS and a quadrupole ICP-MS. The second method is based on optical emission spectroscopy using direct observation of the MC-ICP-MS plasma (LA-MC-ICP-MS|OES). Both methods are evaluated using international geological reference materials. Accurate and precise Si isotope ratios were obtained with an uncertainty typically better than 0.23‰, 2SD, δ(30)Si. With both methods major element concentrations (e.g., Na, Al, Si, Mg, Ca) can be simultaneously determined. However, LASS-ICP-MS is superior over LA-MC-ICP-MS|OES, which is limited by its lower sensitivity. Moreover, LASS-ICP-MS offers trace element analysis down to the μg g(-1)-range for more than 28 elements due to lower limits of detection, and with typical uncertainties better than 15%. For in situ simultaneous

  13. Production of Singlet Oxygen within a Flow Discharge

    NASA Astrophysics Data System (ADS)

    Lange, Matthew; Pitz, Greg; Perram, Glen

    2008-10-01

    The Airborne laser program is an Air Force sponsored program to place a laser on the battle field for use as a tactical weapon. The chemical oxygen iodine laser offers the powers necessary for this weapons application, but it requires significant logistical support. The goal of this current research program is to demonstrate an oxygen-iodine laser with electrical discharge production of singlet oxygen. Optical diagnostics have been applied to microwave and radio frequency discharges within a pure oxygen flow. The O2(a) emissions within a discharge are complicated by atomic oxygen emission requiring care in determining gas concentrations from optically measured emissions. Thermal effects also complicate optical emissions. The inclusion of vibrationally excited oxygen as a quencher of the O2(a) state appears to be the limiting rate for production of O2(a) within the electric discharge conditions studied in this research.

  14. Characteristics of a pulsed chemical laser utilizing an H2-F2 mixture and initiated by radiation from an XeCl excimer laser

    NASA Astrophysics Data System (ADS)

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

    1982-11-01

    Using He, Kr, Xe, N2 and SF6 as diluents, a study was undertaken of the influence of active mixture composition on the energy and temporal characteristics of an HF laser. A 1500 percent efficiency was obtained by an F2:O2:H2:SF6 = 7.5:0.75:2.5:3.5 mixture at a pressure of 110 Torr. Specific output energy was found to increase in proportion to both the initiation energy and the fuel mixture concentration for a given initiation energy. In the case of an F2:O2:H2:SF6 = 25:2.5:2.5:20 mixture at a pressure of 0.5 atm, an output energy of 38 J/liter was reached, with a concentration of atoms created by the UV radiation of F(zero) of approximately 2 x 10 to the 16th/cu cm.

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

    NASA Astrophysics Data System (ADS)

    Wang, Haohao; Odawara, Osamu; Wada, Hiroyuki

    2016-02-01

    A YVO4:Eu3+ colloid with an interesting nanostructure was formed by pulsed laser ablation in deionized water without any additives or surfactants. Analyses of particle morphology, composition and optical properties were accomplished by SEM, TEM, EDS PL and UV-vis. Ovoid-like particles formed by the agglomeration of numerous nanocrystals were observed by SEM and TEM, while EDS with area-mode analysis revealed that the content of dopant ion was well retained within the nanoparticles. In addition, the formation mechanism is deduced and discussed for the first time in this research. The findings of this study could provide new insights into the understanding of laser-induced oxide materials and offer an opportunity for other research groups to pursue red emitting nanophosphors with outstandingly purity.

  16. T-v energy transfer and chemical reactions of laser-produced hot H and D atoms

    SciTech Connect

    Cousins, L.M.; Leone, S.R.

    1988-01-01

    Laser photolysis of various molecular precursors provides a means to generate translationally fast H and D atoms with laboratory energies in the range of 1 - 3 eV. Because of the large disparity in the mass of the H atom compared to the mass of the other photolysis fragment, almost all of the excess energy of the photon is deposited into the kinetic energy of the light H atom. From conservation of energy and momentum, the energy of the H atom may be calculated almost exactly. With typical precursors such as HI, HBr, HC1, and H/sub 2/S, and excimer laser wavelengths at 193 and 248 nm, the widths of the H atom kinetic energy distributions are small compared to the total energies, providing a rather precise collision energy.

  17. Growth Kinetics of Microscopic Silicon Rods Grown on Silicon Substrates by the Pyrolytic Laser-Induced Chemical Vapor Deposition Process

    NASA Astrophysics Data System (ADS)

    Park, Se Il; Lee, Sang Soo

    1990-01-01

    By using a cw Ar+ ion laser beam, microscopic crystalline silicon rods ≈ 102 μm in diameter and ≈ 103 μm in height have been grown on a silicon substrate by pyrolytic dissociation of SiH4. The kinetics of lateral growth of the silicon rods is derived from the time integration of the Arrhenius equation using a reasonable assumption that the temperature on the edge of the deposit saturates inversely to the substrate temperature with illumination time. For the axial growth, excluding the initial transient growth, the same result as Bäuerle and his collaborators is derived. The influences of laser power and illumination time on the deposited diameter and height are found experimentally, and it is found that the derived theory agrees well with the experimental results.

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

    PubMed Central

    Wang, Haohao; Odawara, Osamu; Wada, Hiroyuki

    2016-01-01

    A YVO4:Eu3+ colloid with an interesting nanostructure was formed by pulsed laser ablation in deionized water without any additives or surfactants. Analyses of particle morphology, composition and optical properties were accomplished by SEM, TEM, EDS PL and UV-vis. Ovoid-like particles formed by the agglomeration of numerous nanocrystals were observed by SEM and TEM, while EDS with area-mode analysis revealed that the content of dopant ion was well retained within the nanoparticles. In addition, the formation mechanism is deduced and discussed for the first time in this research. The findings of this study could provide new insights into the understanding of laser-induced oxide materials and offer an opportunity for other research groups to pursue red emitting nanophosphors with outstandingly purity. PMID:26842419

  19. Photoexcitation of lasers and chemical reactions for NASA missions: A theoretical study. [optical pumping in high pressure gas

    NASA Technical Reports Server (NTRS)

    Javan, A.; Guerra, M.

    1981-01-01

    The possibility of obtaining CW laser oscillation by optical pumping in the infrared at an elevated gas pressure is reviewed. A specific example utilizing a mixture of CO and NO gases is included. The gas pressures considered are in excess of several atmospheres. Laser frequency tuning over a broad region becomes possible at such elevated gas pressures due to collisional broadening of the amplifying transitions. The prior-rate and surprisal analysis are applied to obtain detailed VV and VT rates for CO and NO molecules and the transfer rates in a CO-NO gas mixture. The analysis is capable of giving temperature dependence of the rate constants. Computer estimates of the rates are presented for vibrational levels up to v = 50. The results show that in the high-lying vibrational states the VV transfer rates with Delta nu = 2 become appreciable.

  20. 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.

  1. Chemical characterization of single micro- and nano-particles by optical catapulting-optical trapping-laser-induced breakdown spectroscopy

    NASA Astrophysics Data System (ADS)

    Fortes, Francisco J.; Fernández-Bravo, Angel; Javier Laserna, J.

    2014-10-01

    Spectral identification of individual micro- and nano-sized particles by the sequential intervention of optical catapulting, optical trapping and laser-induced breakdown spectroscopy is presented. The three techniques are used for different purposes. Optical catapulting (OC) serves to put the particulate material under inspection in aerosol form. Optical trapping (OT) permits the isolation and manipulation of individual particles from the aerosol, which are subsequently analyzed by laser-induced breakdown spectroscopy (LIBS). Once catapulted, the dynamics of particle trapping depends both on the laser beam characteristics (power and intensity gradient) and on the particle properties (size, mass and shape). Particles are stably trapped in air at atmospheric pressure and can be conveniently manipulated for a precise positioning for LIBS analysis. The spectra acquired from the individually trapped particles permit a straightforward identification of the material inspected. Variability of LIBS signal for the inspection of Ni microspheres was 30% relative standard deviation. OC-OT-LIBS permits the separation of particles in a heterogeneous mixture and the subsequent analysis of the isolated particle of interest. In order to evaluate the sensitivity of the approach, the number of absolute photons emitted by a single trapped particle was calculated. The limit of detection (LOD) for Al2O3 particles was calculated to be 200 attograms aluminium.

  2. The chemical digestion of Ti6Al7Nb scaffolds produced by Selective Laser Melting reduces significantly ability of Pseudomonas aeruginosa to form biofilm.

    PubMed

    Junka, Adam F; Szymczyk, Patrycja; Secewicz, Anna; Pawlak, Andrzej; Smutnicka, Danuta; Ziółkowski, Grzegorz; Bartoszewicz, Marzenna; Chlebus, Edward

    2016-01-01

    In our previous work we reported the impact of hydrofluoric and nitric acid used for chemical polishing of Ti-6Al-7Nb scaffolds on decrease of the number of Staphylococcus aureus biofilm forming cells. Herein, we tested impact of the aforementioned substances on biofilm of Gram-negative microorganism, Pseudomonas aeruginosa, dangerous pathogen responsible for plethora of implant-related infections. The Ti-6Al-7Nb scaffolds were manufactured using Selective Laser Melting method. Scaffolds were subjected to chemical polishing using a mixture of nitric acid and fluoride or left intact (control group). Pseudomonal biofilm was allowed to form on scaffolds for 24 hours and was removed by mechanical vortex shaking. The number of pseudomonal cells was estimated by means of quantitative culture and Scanning Electron Microscopy. The presence of nitric acid and fluoride on scaffold surfaces was assessed by means of IR and rentgen spetorscopy. Quantitative data were analysed using the Mann-Whitney test (P ≤ 0.05). Our results indicate that application of chemical polishing correlates with significant drop of biofilm-forming pseudomonal cells on the manufactured Ti-6Al-7Nb scaffolds ( p = 0.0133, Mann-Whitney test) compared to the number of biofilm-forming cells on non-polished scaffolds. As X-ray photoelectron spectroscopy revealed the presence of fluoride and nitrogen on the surface of scaffold, we speculate that drop of biofilm forming cells may be caused by biofilm-supressing activity of these two elements. PMID:27150429

  3. Sensitive determinations of Cu, Pb, Cd, and Cr elements in aqueous solutions using chemical replacement combined with surface-enhanced laser-induced breakdown spectroscopy.

    PubMed

    Yang, X Y; Hao, Z Q; Li, C M; Li, J M; Yi, R X; Shen, M; Li, K H; Guo, L B; Li, X Y; Lu, Y F; Zeng, X Y

    2016-06-13

    In this study, chemical replacement combined with surface-enhanced laser-induced breakdown spectroscopy (CR-SENLIBS) was for the first time applied to improve the detection sensitivities of trace heavy metal elements in aqueous solutions. Utilizing chemical replacement effect, heavy metal ions in aqueous solution were enriched on the magnesium alloy surface as a solid replacement layer through reacting with the high chemical activity metallic magnesium (Mg) within 1 minute. Unitary and mixed solutions with Cu, Pb, Cd, and Cr elements were prepared to construct calibration curves, respectively. The CR-SENLIBS showed a much better detection sensitivity and accuracy for both unitary and mixed solutions. The coefficients of determination R2 of the calibration curves were above 0.96, and the LoDs were of the same order of magnitude, i.e., in the range of 0.016-0.386 μg/mL for the unitary solution, and in the range of 0.025-0.420 μg/mL for the mixed solution. These results show that CR-SENLIBS is a feasible method for improving the detection sensitivity of trace element in liquid sample, which definitely provides a way for wider application of LIBS in water quality monitoring. PMID:27410358

  4. Rapid High Spatial Resolution Chemical Characterization of Soil Structure to Illuminate Nutrient Distribution Mechanisms Related to Carbon Cycling Using Laser Ablation Aerosol Mass Spectrometry

    NASA Astrophysics Data System (ADS)

    Hicks, R. K.; Alexander, M. L. L.; Newburn, M. K.

    2015-12-01

    Soils contain approximately half of Earth's terrestrial carbon. As such, it is important to understand the factors that control the cycling of this soil organic carbon between the land and the atmosphere. Models that attribute the persistence of soil organic carbon to the intrinsic properties of the molecules themselves are inconsistent with recent observations— for example, materials that are more thermodynamically stable have been found to have a shorter lifetime in soils than ones that are less stable, and vice versa. A new explanation has therefore been posited that invokes ecosystem properties as a whole, and not just intrinsic molecular properties, as the kinetic factor controlling soil carbon dynamics. Because soil dynamics occur on a small scale, techniques with high spatial resolution are required for their study. Existing techniques such as TOF-SIMS require preparation of the sample and introduction into a high vacuum system, and do not address the need to examine large numbers of sample systems without perturbation of chemical and physical properties. To address this analytical challenge, we have coupled a laser ablation (LA) module to an Aerodyne aerosol mass spectrometer (AMS), thereby enabling sample introduction and subsequent measurement of small amounts of soil organic matter by the laser ablation aerosol mass spectrometer (LA-AMS). Due to the adjustable laser beam width, the LA-AMS can probe spot sizes ranging from 1-150 μm in diameter, liberating from 10-100 ng/pulse. With a detection limit of 1 pM, the AMS allows for chemical characterization of the ablated material in terms of elemental ratios, compound classes, and TOC/TOM ratios. Furthermore, the LA-AMS is capable of rapid, in-situ sampling under ambient conditions, thereby eliminating the need for sample processing or transport before analysis. Here, we will present the first results from systematic studies aimed at validating the LA-AMS method as well as results from initial measurements

  5. Time-Resolved O3 Chemical Chain Reaction Kinetics Via High-Resolution IR Laser Absorption Methods

    NASA Technical Reports Server (NTRS)

    Kulcke, Axel; Blackmon, Brad; Chapman, William B.; Kim, In Koo; Nesbitt, David J.

    1998-01-01

    Excimer laser photolysis in combination with time-resolved IR laser absorption detection of OH radicals has been used to study O3/OH(v = 0)/HO2 chain reaction kinetics at 298 K, (i.e.,(k(sub 1) is OH + 03 yields H02 + 02 and (k(sub 2) is H02 + 03 yields OH + 202). From time-resolved detection of OH radicals with high-resolution near IR laser absorption methods, the chain induction kinetics have been measured at up to an order of magnitude higher ozone concentrations ([03] less than or equal to 10(exp 17) molecules/cu cm) than accessible in previous studies. This greater dynamic range permits the full evolution of the chain induction, propagation, and termination process to be temporally isolated and measured in real time. An exact solution for time-dependent OH evolution under pseudo- first-order chain reaction conditions is presented, which correctly predicts new kinetic signatures not included in previous OH + 03 kinetic analyses. Specifically, the solutions predict an initial exponential loss (chain "induction") of the OH radical to a steady-state level ([OH](sub ss)), with this fast initial decay determined by the sum of both chain rate constants, k(sub ind) = k(sub 1) + k(sub 2). By monitoring the chain induction feature, this sum of the rate constants is determined to be k(sub ind) = 8.4(8) x 10(exp -14) cu cm/molecule/s for room temperature reagents. This is significantly higher than the values currently recommended for use in atmospheric models, but in excellent agreement with previous results from Ravishankara et al.

  6. 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

  7. Performance of chemical vapor deposition fabricated graphene absorber mirror in Yb3+ : Sc2SiO5 mode-locked laser

    NASA Astrophysics Data System (ADS)

    Cai, Wei; Li, Yaqi; Zhu, Hongtong; Jiang, Shouzhen; Xu, Shicai; Liu, Jie; Zheng, Lihe; Su, Liangbi; Xu, Jun

    2014-12-01

    A reflective graphene saturable absorber mirror (SAM) was successfully fabricated by chemical vapor deposition technology. A stable diode-pumped passively mode-locked Yb3+:Sc2SiO5 laser using a graphene SAM as a saturable absorber was accomplished for the first time. The measured average output power amounts to 351 mW under the absorbed pump power of 12.5 W. Without prisms compensating for dispersion, the minimum pulse duration of 7 ps with a repetition rate of 97 MHz has been obtained at the central wavelength of 1063 nm. The corresponding peak power and the maximum pulse energy were 516 W and 3.6 nJ, respectively.

  8. Laser Research

    NASA Technical Reports Server (NTRS)

    1979-01-01

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

  9. The influence of multivariate analysis methods and target grain size on the accuracy of remote quantitative chemical analysis of rocks using laser induced breakdown spectroscopy

    NASA Astrophysics Data System (ADS)

    Anderson, Ryan B.; Morris, Richard V.; Clegg, Samuel M.; Bell, James F.; Wiens, Roger C.; Humphries, Seth D.; Mertzman, Stanley A.; Graff, Trevor G.; McInroy, Rhonda

    2011-10-01

    Laser-induced breakdown spectroscopy (LIBS) was used to quantitatively analyze 195 rock slab samples with known bulk chemical compositions, 90 pressed-powder samples derived from a subset of those rocks, and 31 pressed-powder geostandards under conditions that simulate the ChemCam instrument on the Mars Science Laboratory Rover (MSL), Curiosity. The low-volatile (<2 wt.%) silicate samples (90 rock slabs, corresponding powders, and 22 geostandards) were split into training, validation, and test sets. The LIBS spectra and chemical compositions of the training set were used with three multivariate methods to predict the chemical compositions of the test set. The methods were partial least squares (PLS), multilayer perceptron artificial neural networks (MLP ANNs) and cascade correlation (CC) ANNs. Both the full LIBS spectrum and the intensity at five pre-selected spectral channels per major element (feature selection) were used as input data for the multivariate calculations. The training spectra were supplied to the algorithms without averaging ( i.e. five spectra per target) and with averaging ( i.e. all spectra from the same target averaged and treated as one spectrum). In most cases neural networks did not perform better than PLS for our samples. PLS2 without spectral averaging outperformed all other procedures on the basis of lowest quadrature root mean squared error (RMSE) for both the full test set and the igneous rocks test set. The RMSE for PLS2 using the igneous rock slab test set is: 3.07 wt.% SiO 2, 0.87 wt.% TiO 2, 2.36 wt.% Al 2O 3, 2.20 wt.% Fe 2O 3, 0.08 wt.% MnO, 1.74 wt.% MgO, 1.14 wt.% CaO, 0.85 wt.% Na 2O, 0.81 wt.% K 2O. PLS1 with feature selection and averaging had a higher quadrature RMSE than PLS2, but merits further investigation as a method of reducing data volume and computation time and potentially improving prediction accuracy, particularly for samples that differ significantly from the training set. Precision and accuracy were influenced

  10. 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

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

    NASA Astrophysics Data System (ADS)

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

    2005-07-01

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

  12. Lasers '90; Proceedings of the 13th International Conference on Lasers and Applications, San Diego, CA, Dec. 10-14, 1990

    NASA Astrophysics Data System (ADS)

    Harris, Dennis G.; Herbelin, John

    Various papers on lasers are presented. The general topics considered are: X-ray lasers; FELs, solid state lasers; techniques and phenomena of ultrafast lasers; optical filters and free space laser communications, discharge lasers; tunable lasers; application of lasers in medicine and surgery; lasers in materials processing; high power lasers; dynamic gratings, wave mixing, and holography; up-conversion lasers; lidar and laser radar; laser resonators; excimer lasers; laser propagation; nonlinear and quantum optics; blue-green technology; imaging; laser spectroscopy; chemical lasers; dye lasers; lasers in chemistry.

  13. Laser propulsion

    NASA Technical Reports Server (NTRS)

    Rom, F. E.; Putre, H. A.

    1972-01-01

    The use of an earth-based high-power laser beam to provide energy for earth-launched rocket vehicle is investigated. The laser beam energy is absorbed in an opaque propellant gas and is converted to high-specific-impulse thrust by expanding the heated propellant to space by means of a nozzle. This laser propulsion scheme can produce specific impulses of several thousand seconds. Payload to gross-weight fractions about an order of magnitude higher than those for conventional chemical earth-launched vehicles appear possible. There is a potential for a significant reduction in cost per payload mass in earth orbit.

  14. Coupled simulation of chemical lasers based on intracavity partially coherent light model and 3D CFD model.

    PubMed

    Wu, Kenan; Huai, Ying; Jia, Shuqin; Jin, Yuqi

    2011-12-19

    Coupled simulation based on intracavity partially coherent light model and 3D CFD model is firstly achieved in this paper. The dynamic equation of partially coherent intracavity field is derived based on partially coherent light theory. A numerical scheme for the coupled simulation as well as a method for computing the intracavity partially coherent field is given. The presented model explains the formation of the sugar scooping phenomenon, and enables studies on the dependence of the spatial mode spectrum on physical parameters of laser cavity and gain medium. Computational results show that as the flow rate of iodine increases, higher order mode components dominate in the partially coherent field. Results obtained by the proposed model are in good agreement with experimental results. PMID:22274214

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

    SciTech Connect

    Crosley, D.R.

    1991-01-22

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

  16. Infrared Scattering Scanning Near-Field Optical Microscopy Using An External Cavity Quantum Cascade Laser For Nanoscale Chemical Imaging And Spectroscopy of Explosive Residues

    SciTech Connect

    Craig, Ian M.; Phillips, Mark C.; Taubman, Matthew S.; Josberger, Erik E.; Raschke, Markus Bernd

    2013-02-04

    Infrared scattering scanning near-field optical microscopy (s-SNOM) is an apertureless superfocusing technique that uses the antenna properties of a conducting atomic force microscope (AFM) tip to achieve infrared spatial resolution below the diffraction limit. The instrument can be used either in imaging mode, where a fixed wavelength light source is tuned to a molecular resonance and the AFM raster scans an image, or in spectroscopy mode where the AFM is held stationary over a feature of interest and the light frequency is varied to obtain a spectrum. In either case, a strong, stable, coherent infrared source is required. Here we demonstrate the integration of a broadly tunable external cavity quantum cascade laser (ECQCL) into an s-SNOM and use it to obtain infrared spectra of microcrystals of chemicals adsorbed onto gold substrates. Residues of the explosive compound tetryl was deposited onto gold substrates. s-SNOM experiments were performed in the 1260-1400 cm-1 tuning range of the ECQCL, corresponding to the NO2 symmetric stretch vibrational fingerprint region. Vibrational infrared spectra were collected on individual chemical domains with a collection area of *500nm2 and compared to ensemble averaged far-field reflection-absorption infrared spectroscopy (RAIRS) results.

  17. Infrared scattering scanning near-field optical microscopy using an external cavity quantum cascade laser for nanoscale chemical imaging and spectroscopy of explosive residues

    NASA Astrophysics Data System (ADS)

    Craig, Ian M.; Phillips, Mark C.; Taubman, Matthew S.; Josberger, Erik E.; Raschke, Markus B.

    2013-01-01

    Infrared scattering scanning near-field optical microscopy (s-SNOM) is an apertureless superfocusing technique that uses the antenna properties of a conducting atomic force microscope (AFM) tip to achieve infrared spatial resolution below the diffraction limit. The instrument can be used either in imaging mode, where a fixed wavelength light source is tuned to a molecular resonance and the AFM raster scans an image, or in spectroscopy mode where the AFM is held stationary over a feature of interest and the light frequency is varied to obtain a spectrum. In either case, a strong, stable, coherent infrared source is required. Here we demonstrate the integration of a broadly tunable external cavity quantum cascade laser (ECQCL) into an s-SNOM and use it to obtain infrared spectra of microcrystals of chemicals adsorbed onto gold substrates. Residues of the explosive compound tetryl was deposited onto gold substrates. s-SNOM experiments were performed in the 1260-1400cm-1 tuning range of the ECQCL, corresponding to the N02 symmetric stretch vibrational fingerprint region. Vibrational infrared spectra were collected on individual chemical domains with a collection area of ~500 nm2 and compared to ensemble averaged far-field reflection-absorption infrared spectroscopy (RAIRS) results.

  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. Tunable lasers- an overview

    SciTech Connect

    Guenther, B.D.; Buser, R.G.

    1982-08-01

    This overview of tunable lasers describes their applicability to spectroscopy in the ultraviolet and middle infrared ranges; to rapid on-line diagnostics by ultrashort cavity lasers; to exploration, by the free electron laser, for its wide tuning in the far infrared to submillimeter region; to remote detection, in areas such as portable pollution monitors, on-line chemical analyzers, auto exhaust analyzers, and production line controls; to photochemistry; and to other potential areas in diagnostics, communications, and medical and biological sciences. The following lasers are characterized by their tunability: solid state lasers, primarily alexandrite, with a tuning range of ca 1000 Angstroms; color center lasers; semiconductor lasers; dye lasers; gas lasers, where high-pressure CO/sub 2/ discharges are the best known example for a wide tunability range, and research is continuing in systems such as the alkali dimers; and, at wavelengths beyond 10 micrometers, the possibilities beyond Cerenkov and free electron lasers.

  20. 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

  1. Novel two-step laser ablation and ionization mass spectrometry (2S-LAIMS) of actor-spectator ice layers: Probing chemical composition of D2O ice beneath a H2O ice layer

    NASA Astrophysics Data System (ADS)

    Yang, Rui; Gudipati, Murthy S.

    2014-03-01

    In this work, we report for the first time successful analysis of organic aromatic analytes imbedded in D2O ices by novel infrared (IR) laser ablation of a layered non-absorbing D2O ice (spectator) containing the analytes and an ablation-active IR-absorbing H2O ice layer (actor) without the analyte. With these studies we have opened up a new method for the in situ analysis of solids containing analytes when covered with an IR laser-absorbing layer that can be resonantly ablated. This soft ejection method takes advantage of the tenability of two-step infrared laser ablation and ultraviolet laser ionization mass spectrometry, previously demonstrated in this lab to study chemical reactions of polycyclic aromatic hydrocarbons (PAHs) in cryogenic ices. The IR laser pulse tuned to resonantly excite only the upper H2O ice layer (actor) generates a shockwave upon impact. This shockwave penetrates the lower analyte-containing D2O ice layer (spectator, a non-absorbing ice that cannot be ablated directly with the wavelength of the IR laser employed) and is reflected back, ejecting the contents of the D2O layer into the vacuum where they are intersected by a UV laser for ionization and detection by a time-of-flight mass spectrometer. Thus, energy is transmitted from the laser-absorbing actor layer into the non-absorbing spectator layer resulting its ablation. We found that isotope cross-contamination between layers was negligible. We also did not see any evidence for thermal or collisional chemistry of PAH molecules with H2O molecules in the shockwave. We call this "shockwave mediated surface resonance enhanced subsurface ablation" technique as "two-step laser ablation and ionization mass spectrometry of actor-spectator ice layers." This method has its roots in the well-established MALDI (matrix assisted laser desorption and ionization) method. Our method offers more flexibility to optimize both the processes—ablation and ionization. This new technique can thus be

  2. Novel two-step laser ablation and ionization mass spectrometry (2S-LAIMS) of actor-spectator ice layers: probing chemical composition of D2O ice beneath a H2O ice layer.

    PubMed

    Yang, Rui; Gudipati, Murthy S

    2014-03-14

    In this work, we report for the first time successful analysis of organic aromatic analytes imbedded in D2O ices by novel infrared (IR) laser ablation of a layered non-absorbing D2O ice (spectator) containing the analytes and an ablation-active IR-absorbing H2O ice layer (actor) without the analyte. With these studies we have opened up a new method for the in situ analysis of solids containing analytes when covered with an IR laser-absorbing layer that can be resonantly ablated. This soft ejection method takes advantage of the tenability of two-step infrared laser ablation and ultraviolet laser ionization mass spectrometry, previously demonstrated in this lab to study chemical reactions of polycyclic aromatic hydrocarbons (PAHs) in cryogenic ices. The IR laser pulse tuned to resonantly excite only the upper H2O ice layer (actor) generates a shockwave upon impact. This shockwave penetrates the lower analyte-containing D2O ice layer (spectator, a non-absorbing ice that cannot be ablated directly with the wavelength of the IR laser employed) and is reflected back, ejecting the contents of the D2O layer into the vacuum where they are intersected by a UV laser for ionization and detection by a time-of-flight mass spectrometer. Thus, energy is transmitted from the laser-absorbing actor layer into the non-absorbing spectator layer resulting its ablation. We found that isotope cross-contamination between layers was negligible. We also did not see any evidence for thermal or collisional chemistry of PAH molecules with H2O molecules in the shockwave. We call this "shockwave mediated surface resonance enhanced subsurface ablation" technique as "two-step laser ablation and ionization mass spectrometry of actor-spectator ice layers." This method has its roots in the well-established MALDI (matrix assisted laser desorption and ionization) method. Our method offers more flexibility to optimize both the processes--ablation and ionization. This new technique can thus be potentially

  3. Novel two-step laser ablation and ionization mass spectrometry (2S-LAIMS) of actor-spectator ice layers: Probing chemical composition of D{sub 2}O ice beneath a H{sub 2}O ice layer

    SciTech Connect

    Yang, Rui Gudipati, Murthy S.

    2014-03-14

    In this work, we report for the first time successful analysis of organic aromatic analytes imbedded in D{sub 2}O ices by novel infrared (IR) laser ablation of a layered non-absorbing D{sub 2}O ice (spectator) containing the analytes and an ablation-active IR-absorbing H{sub 2}O ice layer (actor) without the analyte. With these studies we have opened up a new method for the in situ analysis of solids containing analytes when covered with an IR laser-absorbing layer that can be resonantly ablated. This soft ejection method takes advantage of the tenability of two-step infrared laser ablation and ultraviolet laser ionization mass spectrometry, previously demonstrated in this lab to study chemical reactions of polycyclic aromatic hydrocarbons (PAHs) in cryogenic ices. The IR laser pulse tuned to resonantly excite only the upper H{sub 2}O ice layer (actor) generates a shockwave upon impact. This shockwave penetrates the lower analyte-containing D{sub 2}O ice layer (spectator, a non-absorbing ice that cannot be ablated directly with the wavelength of the IR laser employed) and is reflected back, ejecting the contents of the D{sub 2}O layer into the vacuum where they are intersected by a UV laser for ionization and detection by a time-of-flight mass spectrometer. Thus, energy is transmitted from the laser-absorbing actor layer into the non-absorbing spectator layer resulting its ablation. We found that isotope cross-contamination between layers was negligible. We also did not see any evidence for thermal or collisional chemistry of PAH molecules with H{sub 2}O molecules in the shockwave. We call this “shockwave mediated surface resonance enhanced subsurface ablation” technique as “two-step laser ablation and ionization mass spectrometry of actor-spectator ice layers.” This method has its roots in the well-established MALDI (matrix assisted laser desorption and ionization) method. Our method offers more flexibility to optimize both the processes—ablation and

  4. Optical-chemical-microphysical relationships and closure studies for mixed carbonaceous aerosols observed at Jeju Island; 3-laser photoacoustic spectrometer, particle sizing, and filter analysis

    NASA Astrophysics Data System (ADS)

    Flowers, B. A.; Dubey, M. K.; Mazzoleni, C.; Stone, E. A.; Schauer, J. J.; Kim, S.-W.; Yoon, S. C.

    2010-11-01

    Transport of aerosols in pollution plumes from the mainland Asian continent was observed in situ at Jeju, South Korea during the Cheju Asian Brown Cloud Plume-Asian Monsoon Experiment (CAPMEX) field campaign throughout August and September 2008 using a 3-laser photoacoustic spectrometer (PASS-3), chemical filter analysis, and size distributions. The PASS-3 directly measures the effects of morphology (e.g. coatings) on light absorption that traditional filter-based instruments are unable to address. Transport of mixed sulfate, carbonaceous, and nitrate aerosols from various Asian pollution plumes to Jeju accounted for 74% of the deployment days, showing large variations in their measured chemical and optical properties. Analysis of eight distinct episodes, spanning wide ranges of chemical composition, optical properties, and source regions, reveals that episodes with higher organic carbon (OC)/sulfate (SO42-) and nitrate (NO3-)/SO42- composition ratios exhibit lower single scatter albedo at shorter wavelengths (ω405). We infer complex refractive indices (n-ik) as a function of wavelength for the high, intermediate, and low OC/SO42- pollution episodes by using the observed particle size distributions and the measured optical properties. The smallest mean particle diameter corresponds to the high OC/SO42- aerosol episode. The imaginary part of the refractive index (k) is greater for the high OC/SO42- episode at all wavelengths. A distinct, sharp increase in k at short wavelength implies enhanced light absorption by OC, which accounts for 50% of the light absorption at 405 nm, in the high OC/SO42- episode. Idealized analysis indicates increased absorption at 781 nm by factors greater than 3 relative to denuded black carbon in the laboratory. We hypothesize that coatings of black carbon cores are the mechanism of this enhancement. This implies that climate warming and atmospheric heating rates from black carbon particles can be significantly larger than have been

  5. Laser Safety Device

    NASA Technical Reports Server (NTRS)

    1992-01-01

    A major focus of work done at Air Products and Chemicals' Laser Application Laboratory is on use of ultraviolet radiation using high energy excimer lasers. Because light within the wavelength of excimer lasers is invisible, it can cause serious damage to eyes and tissue. To contain the laser beam, Air Products Incorporated a Jet Propulsion Laboratory invention described in a technical support package into its beam stops. The technology interrupts the laser pathway and allows workers to remain in the target area without shutting off the laser.

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

    NASA Astrophysics Data System (ADS)

    1988-03-01

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

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

    NASA Astrophysics Data System (ADS)

    1984-03-01

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

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

    NASA Astrophysics Data System (ADS)

    1984-05-01

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

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

    NASA Astrophysics Data System (ADS)

    1989-02-01

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

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

    NASA Astrophysics Data System (ADS)

    1988-10-01

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

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

    NASA Astrophysics Data System (ADS)

    1987-09-01

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

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

    NASA Astrophysics Data System (ADS)

    1987-12-01

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

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

    NASA Astrophysics Data System (ADS)

    1983-10-01

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

  14. High-throughput trace analysis of explosives in water by laser diode thermal desorption/atmospheric pressure chemical ionization-tandem mass spectrometry.

    PubMed

    Badjagbo, Koffi; Sauvé, Sébastien

    2012-07-01

    Harmful explosives can accumulate in natural waters in the long term during their testing, usage, storage, and dumping and can pose a health risk to humans and the environment. For the first time, attachment of small anions to neutral molecules in laser diode thermal desorption/atmospheric pressure chemical ionization was systematically investigated for the direct determination of trace nitroaromatics, nitrate esters, and nitramine explosives in water. Using ammonium chloride as an additive improved the instrument response for all the explosives tested and promoted the formation of several characteristic adduct ions. The method performs well achieving good linearity over at least 2 orders of magnitude, with coefficients of determination greater than 0.995. The resulting limits of detection are in the range of 0.009-0.092 μg/L. River water samples were successfully analyzed by the proposed method with accuracy in the range of 96-98% and a response time of 15 s, without any further pretreatment or chromatographic separation. PMID:22746321

  15. Relation between crystallinity and chemical nature of surface on wettability: A study on pulsed laser deposited TiO{sub 2} thin films

    SciTech Connect

    Shirolkar, Mandar M.; Phase, Deodatta; Sathe, Vasant; Choudhary, Ram Janay; Rodriguez-Carvajal, J.

    2011-06-15

    Pure titania (TiO{sub 2}) polycrystalline thin films in rutile, anatase and mixed phase have been grown on amorphous glass substrates by pulsed laser deposition method at various oxygen gas pressure. Wettability investigations have been carried out on these films. Consistent with our previous report [J. Phys. D: Appl. Phys. 41, 155308 (2008)] it has been observed that for nearly same surface roughness large contact angle or superhydrophobicity is present when sample has a pure single phase and lower contact angle or hydrophobicity when mixed phases were present. Structural characterizations suggest that in addition to roughness, pure phase film surface associated with hydrophobic sites and mixed phase film surface show association of both hydrophobic and hydrophilic sites, which might be inducing specific wetting character. UV treatment induces superhydrophilicity in the films. It was observed that UV irradiation causes nonequilibrium state on the TiO{sub 2} surface, leading to changes in the electron density, which in turn produces decrement in the crystallinity and lattice expansion. Reversible changes in the wetting state on the pure phase surfaces were observed to be faster than those on the mixed phase surfaces. We tried to establish the possible relation between crystalline phases, chemical nature of surface on reversible wettability besides the main governing parameter viz. surface roughness.

  16. 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

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

    PubMed

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

    2012-09-15

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

  18. Influence of plasma density on the chemical composition and structural properties of pulsed laser deposited TiAlN thin films

    SciTech Connect

    Quiñones-Galván, J. G.; Camps, Enrique; Muhl, S.; Flores, M.; Campos-González, E.

    2014-05-15

    Incorporation of substitutional Al into the TiN lattice of the ternary alloy TiAlN results in a material with improved properties compared to TiN. In this work, TiAlN thin films were grown by the simultaneous ablation of Ti and Al targets in a nitrogen containing reactive atmosphere. The deposit was formed on silicon substrates at low deposition temperature (200 °C). The dependence of the Al content of the films was studied as a function of the ion density of the plasma produced by the laser ablation of the Al target. The plasma parameters were measured by means of a planar Langmuir probe and optical emission spectroscopy. The chemical composition of the films was measured by energy dispersive X-ray spectroscopy. The results showed a strong dependence of the amount of aluminum incorporated in the films with the plasma density. The structural characterization of the deposits was carried out by Raman spectroscopy, X-ray diffraction, and transmission electron microscopy, where the substitutional incorporation of the Al into the TiN was demonstrated.

  19. Determination of Os by isotope dilution-inductively coupled plasma-mass spectrometry with the combination of laser ablation to introduce chemically separated geological samples

    NASA Astrophysics Data System (ADS)

    Sun, Yali; Ren, Minghao; Xia, Xiaoping; Li, Congying; Sun, Weidong

    2015-11-01

    A method was developed for the determination of trace Os in geological samples by laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) with the combination of chemical separation and preconcentration. Samples are digested using aqua regia in Carius tubes, and the Os analyte is converted into volatile OsO4, which is distilled and absorbed with HBr. The HBr solution is concentrated for further Os purification using the microdistillation technique. The purified Os is dissolved in 10 μl of 0.02% sucrose-0.005% H3PO4 solution and then evaporated on pieces of perfluoroalkoxy (PFA) film, resulting in the formation of a tiny object (< 3 × 104 μm2 superficial area). Using LA-ICP-MS measurements, the object can give Os signals at least 100 times higher than those provided by routine solution-ICP-MS while successfully avoiding the memory effect. The procedural blank and detection limit in the developed technique are 3.0 pg and 1.8 pg for Os, respectively when 1 g of samples is taken. Reference materials (RM) are analyzed, and their Os concentrations obtained by isotope dilution are comparable to reference or literature values. Based on the individual RM results, the precision is estimated within the range of 0.6 to 9.4% relative standard deviation (RSD), revealing that this method is applicable to the determination of trace Os in geological samples.

  20. The influence of laser-induced nanosecond rise-time stress waves on the microstructure and surface chemical activity of single crystal Cu nanopillars

    SciTech Connect

    Youssef, G.; Crum, R.; Seif, D.; Po, G.; Prikhodko, S. V.; Kodambaka, S.; Ghoniem, N.; Gupta, V.

    2013-02-28

    An apparatus and test procedure for fabrication and loading of single crystal metal nanopillars under extremely high pressures (>1 GPa) and strain rates (>10{sup 7} s{sup -1}), using laser-generated stress waves, are presented. Single-crystalline Cu pillars ({approx}1.20 {mu}m in tall and {approx}0.45 {mu}m in diameter) prepared via focused ion beam milling of Cu(001) substrates are shock-loaded using this approach with the dilatational stress waves propagating along the [001] axis of the pillars. Transmission electron microscopy observations of shock-loaded pillars show that dislocation density decreases and that their orientation changes with increasing stress wave amplitude, indicative of dislocation motion. The shock-loaded pillars exhibit enhanced chemical reactivity when submerged in oil and isopropyl alcohol solutions, due likely to the exposure of clean surfaces via surface spallation and formation of surface steps and nanoscale facets through dislocation motion to the surface of the pillars, resulting in growth of thin oxide films on the surfaces of the pillars.

  1. The influence of laser-induced nanosecond rise-time stress waves on the microstructure and surface chemical activity of single crystal Cu nanopillars

    PubMed Central

    Youssef, G.; Crum, R.; Prikhodko, S. V.; Seif, D.; Po, G.; Ghoniem, N.; Kodambaka, S.; Gupta, V.

    2013-01-01

    An apparatus and test procedure for fabrication and loading of single crystal metal nanopillars under extremely high pressures (>1 GPa) and strain rates (>107 s−1), using laser-generated stress waves, are presented. Single-crystalline Cu pillars (∼1.20 μm in tall and ∼0.45 μm in diameter) prepared via focused ion beam milling of Cu(001) substrates are shock-loaded using this approach with the dilatational stress waves propagating along the [001] axis of the pillars. Transmission electron microscopy observations of shock-loaded pillars show that dislocation density decreases and that their orientation changes with increasing stress wave amplitude, indicative of dislocation motion. The shock-loaded pillars exhibit enhanced chemical reactivity when submerged in oil and isopropyl alcohol solutions, due likely to the exposure of clean surfaces via surface spallation and formation of surface steps and nanoscale facets through dislocation motion to the surface of the pillars, resulting in growth of thin oxide films on the surfaces of the pillars. PMID:23526837

  2. Total Analysis of Microcystins in Fish Tissue Using Laser Thermal Desorption-Atmospheric Pressure Chemical Ionization-High-Resolution Mass Spectrometry (LDTD-APCI-HRMS).

    PubMed

    Roy-Lachapelle, Audrey; Solliec, Morgan; Sinotte, Marc; Deblois, Christian; Sauvé, Sébastien

    2015-08-26

    Microcystins (MCs) are cyanobacterial toxins encountered in aquatic environments worldwide. Over 100 MC variants have been identified and have the capacity to covalently bind to animal tissue. This study presents a new approach for cell-bound and free microcystin analysis in fish tissue using sodium hydroxide as a digestion agent and Lemieux oxidation to obtain the 2-methyl-3-methoxy-4-phenylbutyric acid (MMPB) moiety, common to all microcystin congeners. The use of laser diode thermal desorption-atmospheric pressure chemical ionization coupled with Q-Exactive mass spectrometry (LDTD-APCI-HRMS) led to an analysis time of approximately 10 s per sample and high-resolution detection. Digestion/oxidation and solid phase extraction recoveries ranged from 70 to 75% and from 86 to 103%, respectively. Method detection and quantification limits values were 2.7 and 8.2 μg kg(-1), respectively. Fish samples from cyanobacteria-contaminated lakes were analyzed, and concentrations ranging from 2.9 to 13.2 μg kg(-1) were reported. PMID:26211936

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

    NASA Astrophysics Data System (ADS)

    Zhao, Pei; Ito, Akihiko; Tu, Rong; Goto, Takashi

    2011-02-01

    a-axis- and c-axis-oriented YBa2Cu3O7-δ (YBCO) films were epitaxially grown on (1 0 0) LaAlO3 substrates by laser chemical vapor deposition. The preferred orientation in the YBCO film changed from the a-axis to the c-axis with increasing laser powers from 77 to 158 W (the deposition temperatures from 951 to 1087 K). The a-axis-oriented YBCO film showed in-plane epitaxial growth of YBCO [0 0 1]//LAO [0 0 1], and the c-axis-oriented YBCO film showed that of YBCO [0 1 0]//LAO [0 0 1]. A c-axis-oriented YBCO film with a high critical temperature of 90 K was prepared at a deposition rate of 90 μm h-1, about 2-1000 times higher than that of metalorganic chemical vapor deposition.

  4. Metastable alloy nanoparticles, metal-oxide nanocrescents and nanoshells generated by laser ablation in liquid solution: influence of the chemical environment on structure and composition.

    PubMed

    Scaramuzza, Stefano; Agnoli, Stefano; Amendola, Vincenzo

    2015-11-14

    Alloy nanoparticles are characterized by the combination of multiple interesting properties, which are attractive for technological and scientific purposes. A frontier topic of this field is nanoalloys with compositions not thermodynamically allowed at ordinary temperature and pressure (i.e. metastable), because they require out-of-equilibrium synthetic approaches. Recently, laser ablation synthesis in solution (LASiS) was successfully applied for the realization of metastable nanoalloys because of the fast kinetics of nanoparticle formation. However, the role played by the chemical environment on the final composition and structure of laser generated nanoalloys still has to be fully elucidated. Here, we investigated the influence of different synthetic conditions on the LASiS of metastable nanoalloys composed of Au and Fe, such as the use of water instead of ethanol, the bubbling of inert gases and the addition of a few vol% of H2O2 and H2O. The two elements showed different reactivity when LASiS was performed in water instead of ethanol, while minor effects were observed from bubbling pure gases such as N2, Ar and CO2 in the liquid solution. Moreover, the plasmonic response and the structure of the nanoalloys were sensibly modified by adding H2O2 to water. We also found that nanoparticle production is dramatically influenced just by adding 0.2% of H2O in ethanol. These results suggest that the formation of a cavitation bubble with long lifetime and large size during LASiS is useful for the preservation of the metastable alloy composition, whereas an oxidative environment hampers the formation of metastable alloy nanoparticles. Overall, by acting on the type of solvent and solutes, we were able to switch from a traditional synthetic approach for the composition of Au-Fe nanoalloys to one using a reactive environment, which gives unconventional structures such as metal@iron-oxide nanoshells and nanocrescents of oxide supported on metal nanospheres. These results

  5. Combustion diagnostics by laser spectrometry

    NASA Astrophysics Data System (ADS)

    Kitagawa, Kuniyuki; Morita, Shigeaki; Kodama, Kenji; Matsumoto, Kozo

    2009-03-01

    We have developed three different types of visualization methods for energy conversion systems by means of laser spectrometry. (1) Laser-induced fluorescence (LIF) spectroscopy and (2) laser ionization mass spectrometry (LIMS) have been applied to visualization of chemical species in combustion fields of flames. (3) Near-infrared laser absorption spectroscopy has been used for visualization of water in a polymer electrolyte fuel cell (PEFC). Complex physicochemical processes in the energy conversion systems have been revealed by laser spectrometry.

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

    NASA Astrophysics Data System (ADS)

    1990-03-01

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

  7. Laser nanoablation of graphite

    NASA Astrophysics Data System (ADS)

    Frolov, V. D.; Pivovarov, P. A.; Zavedeeev, E. V.; Komlenok, M. S.; Kononenko, V. V.; Konov, V. I.

    2014-01-01

    Experimental data on laser ablation of highly oriented pyrolitic graphite by nanosecond pulsed UV ( nm) and green ( nm) lasers are presented. It was found that below graphite vaporization threshold 1 J/cm, the nanoablation regime can be realized with material removal rates as low as 10 nm/pulse. The difference between physical (vaporization) and physical-chemical (heating + oxidation) ablation regimes is discussed. Special attention is paid to the influence of laser fluence and pulse number on ablation kinetics. Possibility of laser-induced graphite surface nanostructuring has been demonstrated. Combination of tightly focused laser beam and sharp tip of scanning probe microscope was applied to improve material nanoablation.

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

    EPA Science Inventory

    We investigate particles produced by laser irradiation and their analysis by Laser Ablation Inductively Coupled Plasma Mass Spectroscopy (LA/ICP-MS), with a view towards optimizing particle production for analysis of high level waste materials and waste glass. LA/ICP-MS has consi...

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

    PubMed Central

    Zhao, Mengjiao; Hu, Jie; Jiang, Lan; Zhang, Kaihu; Liu, Pengjun; Lu, Yongfeng

    2015-01-01

    We developed an efficient fabrication method of high-quality concave microarrays on fused silica substrates based on temporal shaping of femtosecond (fs) laser pulses. This method involves exposures of fs laser pulse trains followed by a wet etching process. Compared with conventional single pulses with the same processing parameters, the temporally shaped fs pulses can enhance the etch rate by a factor of 37 times with better controllability and higher quality. Moreover, we demonstrated the flexibility of the proposed method in tuning the profile of the concave microarray structures by changing the laser pulse delay, laser fluence, and pulse energy distribution ratio. Micro-Raman spectroscopy was conducted to elucidate the stronger modification induced by the fs laser pulse trains in comparison with the single pulses. Our calculations show that the controllability is due to the effective control of localized transient free electron densities by temporally shaping the fs pulses. PMID:26307148

  10. Direct chemical-analysis of uv laser-ablation products of organic polymers by using selective ion monitoring mode in gas-chromatography mass-spectrometry

    USGS Publications Warehouse

    Cho, Yirang; Lee, H.W.; Fountain, S.T.; Lubman, D.M.

    1994-01-01

    Trace quantities of laser ablated organic polymers were analyzed by using commercial capillary column gas chromatography/mass spectrometry; the instrument was modified so that the laser ablation products could be introduced into the capillary column directly and the constituents of each peak in the chromatogram were identified by using a mass spectrometer. The present study takes advantage of the selective ion monitoring mode for significantly improving the sensitivity of the mass spectrometer as a detector, which is critical in analyzing the trace quantities and confirming the presence or absence of the species of interest in laser ablated polymers. The initial composition of the laser ablated polymers was obtained by using an electron impact reflectron time-of-flight mass spectrometer and the possible structure of the fragments observed in the spectra was proposed based on the structure of the polymers.

  11. Instabilities and structure formation in laser processing

    SciTech Connect

    Baeuerle, D.; Arenholz, E.; Arnold, N.; Heitz, J.; Kargl, P.B.

    1996-12-31

    This paper gives an overview on different types of instabilities and structure formation in various fields of laser processing. Among the examples discussed in detail are non-coherent structures observed in laser-induced chemical vapor deposition (LCVD), in laser-induced surface modifications, and in laser ablation of polymers.

  12. Lasers '85; Proceedings of the Eighth International Conference, Las Vegas, NV, Dec. 2-6, 1985

    SciTech Connect

    Wang, C.P.

    1986-01-01

    The present conference on laser technology development encompasses issues in such areas as VUV and X-ray lasers; optical phase conjugation and nonlinear optics; laser applications in medicine; methods for optical processing; laser and nonlinear spectroscopy; ultrashort-pulse lasers and their applications; frequency selection in pulsed lasers; and interactions between laser beams, material surfaces, and material volumes. Also treated are laser applications in the Strategic Defense Initiative program, chemical laser design and performance, the lasing of biophysical materials, laser diagnostics in fluids and plasma, semiconductor laser diodes and arrays, solid state lasers, radiation- and solar-pumped lasers, laser cavities and propagation, remote sensing with lasers and fiber-optics, coupled resonators and diode lasers, industrial applications of lasers, excimer lasers, optoelectronics, CO/sub 2/ lasers, fiber-optic sensors, alexandrite lasers, free electron lasers, and IR and visible wavelength lasers.

  13. [Study of flow properties of wet solids using laser induced photo chemical anemometry]. Quarterly technical progress report, July--September 1991

    SciTech Connect

    Falco, B.

    1992-04-09

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

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

    NASA Astrophysics Data System (ADS)

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

    2016-02-01

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

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

    SciTech Connect

    Not Available

    1987-10-01

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

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

    SciTech Connect

    Not Available

    1986-09-01

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

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

    SciTech Connect

    Not Available

    1987-09-01

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

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

    SciTech Connect

    Not Available

    1987-12-01

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

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

    SciTech Connect

    Not Available

    1986-05-01

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

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

    SciTech Connect

    Not Available

    1986-06-01

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

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

    SciTech Connect

    Not Available

    1987-11-01

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

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

    SciTech Connect

    Not Available

    1987-08-01

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

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

    SciTech Connect

    Not Available

    1986-12-01

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

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

    SciTech Connect

    Not Available

    1987-01-01

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

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

    SciTech Connect

    Not Available

    1986-09-01

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

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

    SciTech Connect

    Not Available

    1987-03-01

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

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

    NASA Astrophysics Data System (ADS)

    1984-02-01

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

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

    NASA Astrophysics Data System (ADS)

    1984-12-01

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

  9. Lasers '86; Proceedings of the Ninth International Conference on Lasers and Applications, Orlando, FL, Nov. 3-7, 1986

    SciTech Connect

    Mcmillan, R.W.

    1987-01-01

    Laser physics, technology, and applications are examined in reviews and reports. Topics addressed include VUV and X-ray lasers, vibrational energy transfer and kinetics, medical applications, ultrashort lasers and spectroscopy, surface and material interactions, lasers in atmospheric physics, and fiber-optic systems. Consideration is given to alexandrite lasers, four-wave mixing and nonlinear optics, chemical lasers, semiconductor lasers, photothermal and photoacoustic spectroscopy, dye lasers, optical phase conjugation and SBS, excimer lasers, SDI laser applications, remote-sensing with lasers, FELs, and applications in chemistry. Diagrams, drawings, graphs, and photographs are provided.

  10. Laser Technology.

    ERIC Educational Resources Information Center

    Gauger, Robert

    1993-01-01

    Describes lasers and indicates that learning about laser technology and creating laser technology activities are among the teacher enhancement processes needed to strengthen technology education. (JOW)

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

    DOEpatents

    Krumhansl, James L; Nenoff, Tina M

    2013-02-26

    Materials and methods of synthesizing mixed-layered bismuth oxy-iodine materials, which can be synthesized in the presence of aqueous radioactive iodine species found in caustic solutions (e.g. NaOH or KOH). This technology provides a one-step process for both iodine sequestration and storage from nuclear fuel cycles. It results in materials that will be durable for repository conditions much like those found in Waste Isolation Pilot Plant (WIPP) and estimated for Yucca Mountain (YMP). By controlled reactant concentrations, optimized compositions of these mixed-layered bismuth oxy-iodine inorganic materials are produced that have both a high iodine weight percentage and a low solubility in groundwater environments.

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

    DOEpatents

    Krumhansl, James L; Nenoff, Tina M

    2015-01-06

    Materials and methods of synthesizing mixed-layered bismuth oxy-iodine materials, which can be synthesized in the presence of aqueous radioactive iodine species found in caustic solutions (e.g. NaOH or KOH). This technology provides a one-step process for both iodine sequestration and storage from nuclear fuel cycles. It results in materials that will be durable for repository conditions much like those found in Waste Isolation Pilot Plant (WIPP) and estimated for Yucca Mountain (YMP). By controlled reactant concentrations, optimized compositions of these mixed-layered bismuth oxy-iodine inorganic materials are produced that have both a high iodine weight percentage and a low solubility in groundwater environments.

  13. 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.

  14. Understanding lasers

    SciTech Connect

    Gibilisco, S.

    1989-01-01

    Covering all different types of laser applications-Gibilisco offers an overview of this fascinating phenomenon of light. Here he describes what lasers are and how they work and examines in detail the different kinds of lasers in use today. Topics of particular interest include: the way lasers work; the different kinds of lasers; infrared, ultraviolet and x-ray lasers; use of lasers in industry and manufacturing; use of lasers for long-distance communications; fiberoptic communications; the way laser shows work; the reality of Star Wars; lasers in surgical and medical applications; and holography and the future of laser technology.

  15. 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...

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

    SciTech Connect

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

    2011-06-15

    We present the extension of time-resolved optical pump/x-ray absorption spectroscopy (XAS) probe experiments towards data collection at MHz repetition rates. The use of a high-power picosecond laser operating at an integer fraction of the repetition rate of the storage ring allows exploitation of up to two orders of magnitude more x-ray photons than in previous schemes based on the use of kHz lasers. Consequently, we demonstrate an order of magnitude increase in the signal-to-noise of time-resolved XAS of molecular systems in solution. This makes it possible to investigate highly dilute samples at concentrations approaching physiological conditions for biological systems. The simplicity and compactness of the scheme allows for straightforward implementation at any synchrotron beamline and for a wide range of x-ray probe techniques, such as time-resolved diffraction or x-ray emission studies.

  17. 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

  18. 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.

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

    NASA Astrophysics Data System (ADS)

    1984-09-01

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

  20. Qualitative and quantitative spectro-chemical analysis of dates using UV-pulsed laser induced breakdown spectroscopy and inductively coupled plasma mass spectrometry.

    PubMed

    Mehder, A O; Habibullah, Y B; Gondal, M A; Baig, Umair

    2016-08-01

    Laser Induced Breakdown Spectroscopy (LIBS) is demonstrated for the spectral analysis of nutritional and toxic elements present in several varieties of date fruit samples available in the Saudi Arabia market. The method analyzes the optical emission of a test sample when subjected to pulsed laser ablation. In this demonstration, our primary focus is on calcium (Ca) and magnesium (Mg), as nutritional elements, and on chromium (Cr), as a toxic element. The local thermodynamic equilibrium (LTE) condition was confirmed prior to the elemental characterization of date samples to ensure accuracy of the LIBS analysis. This was achieved by measuring parameters associated with the plasma, such as the electron temperature and the electron number density. These plasma parameters aid interpretation of processes such as ionization, dissociation, and excitation occurring in the plasma plume formed by ablating the date palm sample. The minimum detection limit was established from calibration curves that involved plotting the LIBS signal intensity as a function of standard date samples with known concentrations. The concentration of Ca and Mg detected in different varieties of date samples was between 187 and 515 and 35-196mgL(-1) respectively, while Cr concentration measured between 1.72 and 7.76mgL(-1). In order to optimize our LIBS system, we have studied how the LIBS signal intensity depends on the incident laser energy and the delay time. In order to validate our LIBS analysis results, standard techniques such as inductively coupled plasma mass spectrometry (ICP-MS) were also applied on an identical (duplicate) date samples as those used for the LIBS analysis. The LIBS results exhibit remarkable agreement with those obtained from the ICP-MS analysis. In addition, the finger print wavelengths of other elements present in date samples were also identified and are reported here, which has not been previously reported, to the best of our knowledge. PMID:27216665

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

    NASA Astrophysics Data System (ADS)

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

    2005-08-01

    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) on the statistical models have also been studied. Results indicate the use of spectral averaging and weighting schemes may be used to significantly improve sample differentiation.

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

    NASA Astrophysics Data System (ADS)

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

    2011-10-01

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

  3. 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...

  4. Excimer laser photoresist stripping

    NASA Astrophysics Data System (ADS)

    Genut, Menachem; Tehar-Zahav, Ofer; Iskevitch, Eli; Livshits, Boris

    1996-06-01

    A new method for stripping the most challenging photoresists on deep sub-micron technology semiconductor wafers has been developed. The method uses a combination of UV excimer laser ablation and reactive chemistry to strip the photoresist in a single dry process, eliminating the wet acids or solvents often used following ashing of high dose implantation (HDI) and reactive ion etching (RIE). The stripping process combines new removal mechanisms: chemical assisted UV excimer laser ablation/etching, laser induced chemical etching of side walls and residues, and enhanced combustion. During the laser pulses photolysis of the process gas occurs, UV laser radiation breaks the photoresist polymer chain bonds, and the photoresist (including foreign materials imbedded in it) is ablated. The combustion is ignited by the ablative impact of laser radiation and enhanced by the radicals formed during photo-thermal decomposition of the process gases. Following this process, the volatilized products and gases are evacuated. The optimum laser stripping conditions were developed to provide a wide process window for the most challenging stripping conditions, such as after HDI and RIE (metal, polysilicon), without causing damage to the wafer devices. A photoresist stripping system based on the described technology was designed and built. The system has been designated as the L-StripperTM and provides stripping time of 0.15 s/(micrometer cm2).

  5. Development of a flow injection analysis (FIA) system for the measurement of heavy metals using a fiber optic chemical sensor based on laser-induced fluorescence

    NASA Astrophysics Data System (ADS)

    Zhang, Jingdong; Prestel, Harald; Gahr, Achim; Niessner, Reinhard

    2000-05-01

    The development of a fiber optic sensor system is described, for the on-line detection of heavy metal ions in water. This is based on laser-induced fluorescence spectroscopy of suitable metal-ligand complexes. The sensor system is designed to measure heavy metal ions in the field. Flow injection analysis (FIA) is coupled with the sensor system, to overcome problems of a slow diffusion rate of heavy metals through the membrane of an in situ sensor head. Preliminary experiments show the new FIA system has good reproducibility, a high sample analysis rate and it can measure heavy metal ions (Cu(II), Ni(II), Cd(II) and Zn(II)) at the ppb level, when using the appropriate ligands.

  6. Engineering Light: Quantum Cascade Lasers

    ScienceCinema

    Claire Gmachl

    2010-09-01

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

  7. Chemical recognition software

    SciTech Connect

    Wagner, J.S.; Trahan, M.W.; Nelson, W.E.; Hargis, P.J. Jr.; Tisone, G.C.

    1994-12-01

    We have developed a capability to make real time concentration measurements of individual chemicals in a complex mixture using a multispectral laser remote sensing system. Our chemical recognition and analysis software consists of three parts: (1) a rigorous multivariate analysis package for quantitative concentration and uncertainty estimates, (2) a genetic optimizer which customizes and tailors the multivariate algorithm for a particular application, and (3) an intelligent neural net chemical filter which pre-selects from the chemical database to find the appropriate candidate chemicals for quantitative analyses by the multivariate algorithms, as well as providing a quick-look concentration estimate and consistency check. Detailed simulations using both laboratory fluorescence data and computer synthesized spectra indicate that our software can make accurate concentration estimates from complex multicomponent mixtures. even when the mixture is noisy and contaminated with unknowns.

  8. 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.

  9. Chemical Emergencies

    MedlinePlus

    When a hazardous chemical has been released, it may harm people's health. Chemical releases can be unintentional, as in the case of an ... the case of a terrorist attack with a chemical weapon. Some hazardous chemicals have been developed by ...

  10. Method for laser induced isotope enrichment

    DOEpatents

    Pronko, Peter P.; Vanrompay, Paul A.; Zhang, Zhiyu

    2004-09-07

    Methods for separating isotopes or chemical species of an element and causing enrichment of a desired isotope or chemical species of an element utilizing laser ablation plasmas to modify or fabricate a material containing such isotopes or chemical species are provided. This invention may be used for a wide variety of materials which contain elements having different isotopes or chemical species.

  11. 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.

  12. COIL power extraction enhanced by reducing/eliminating iodine clusters in a high Mach number nitrogen mixing nozzle

    NASA Astrophysics Data System (ADS)

    Marshall, J.; Healey, K.; Croker, B.; Kendrick, K.; Yang, T. T.; Hsia, Y. C.; Dickerson, R. A.; Forman, L.

    2006-02-01

    Heterogeneous iodine cluster formation has been identified as the responsible factor resulting in large iodine titration requirements for Boeing's first high Mach number nitrogen ejector nozzle. A solution employing geometrically produced aerodynamic heating in the flow was envisioned to break up these clusters. Horizontal and vertical wire arrays (cluster busters) placed downstream of the nozzle exit plane (NEP) have been shown to significantly reduce the optimal iodine titration and to greatly improve the power extraction efficiency of the Chemical Oxygen-Iodine Laser utilizing this first generation ejector nozzle.

  13. 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 γrec <= 10-5.

  14. Spray generator of singlet oxygen with a centrifugal separation of liquid

    NASA Astrophysics Data System (ADS)

    Špalek, Otomar; Jirásek, Vít; Censký, Miroslav; Kodymová, Jarmila; Picková, Irena

    2008-10-01

    A new spray-type generator of singlet oxygen, O2(1Δ), with a following centrifugal separation of depleted liquid was studied. This generator was developed to fulfill following requirements suitable for an advanced Chemical Oxygen- Iodine Laser (COIL): (i) a high-pressure operation, (ii) a single pass of reaction liquid, (iii) an efficient disengagement of gas/liquid mixture, and (iv) a scalability for airborne and mobile application. The generator design takes advantage of very high g/l interfacial surface area of a fine spray produced by a two-phase nozzle and a very fast liquid separation by applying a high centrifugal force.

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

    NASA Astrophysics Data System (ADS)

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

    2014-06-01

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

  16. Remote sensing of chemical warfare agent by CO2 -lidar

    NASA Astrophysics Data System (ADS)

    Geiko, Pavel P.; Smirnov, Sergey S.

    2014-11-01

    The possibilities of remote sensing of chemical warfare agent by differential absorption method were analyzed. The CO2 - laser emission lines suitable for sounding of chemical warfare agent with provision for disturbing absorptions by water vapor were choose. The detection range of chemical warfare agents was estimated for a lidar based on CO2 - laser The other factors influencing upon echolocation range were analyzed.

  17. 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.

  18. Laser energy conversion

    NASA Technical Reports Server (NTRS)

    Billman, K. W.

    1975-01-01

    Laser radiation could possibly provide a feasible approach for the transmission of energy between stations and vehicles in space and on earth. The transmitted energy could be used for the operational requirements of the receiving space station, lunar base, or spacecraft. In addition, laser energy could also be employed to provide power for the propulsion of vehicles in space. The present status of development regarding the various technological areas involved in an implementation of these objectives is examined, taking into account the possibility of further advances needed to satisfy the technical requirements. Attention is given to laser-induced chemistry for converting the radiation energy into chemical energy. Other subjects considered are related to photovoltaics, optical diodes, thermo-electronics, laser rockets, and photon engines.

  19. Analysis of Laser Breakdown Data

    NASA Astrophysics Data System (ADS)

    Becker, Roger

    2009-03-01

    Experiments on laser breakdown for ns pulses of 532 nm or 1064 nm light in water and dozens of simple hydrocarbon liquids are analyzed and compared to widely-used models and other laser breakdown experiments reported in the literature. Particular attention is given to the curve for the probability of breakdown as a function of the laser fluence at the beam focus. Criticism is made of the na"ive forms of both ``avalanche'' breakdown and multi-photon breakdown. It appears that the process is complex and is intimately tied to the chemical group of the material. Difficulties with developing an accurate model of laser breakdown in liquids are outlined.

  20. Laser removal of sludge from steam generators

    DOEpatents

    Nachbar, Henry D.

    1990-01-01

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