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Physical processes are investigated in active media of high-pressure gas lasers operating on electronic transitions of molecules. Lasing was obtained in the VUV ( = 172 nm) region of the spectrum by exciting compressed xenon and an Ar:Xe mixture. The effect of the temperature and pressure on the kinetics of the processes in the active laser media Ar:N2, Xe:02, and Ar:Kr:F2 are investigated. A new class of excimers, consisting of one halide and two inert atoms, is observed for the first time ever, and the temperature dependence of the spontaneous and laser emissions of XrF* is investigated; this dependence is due to the redistribution of the energy drawn from the electron beam among the excimers KrF* and Kr2F*.Translated from Trudy Ordena Lenina Fizicheskogo Instituta im. P. N. Lebedeva, Vol. 142, pp. 172–202, 1983. 相似文献
3.
S. Arai K. Sugita P. Ma Y. Ishikawa H. Kaetsu S. Isomura 《Applied physics. B, Lasers and optics》1989,48(5):427-435
We have been studying the practical CO2-laser-induced13C separation by a two-stage IRMPD process. The IRMPD of natural CHClF2 in the presence of Br2 mainly produced CBr2F2, which was found to be highly enriched with13C. The yield and13C-atom fraction of CBr2F2 were examined as functions of pulse number, laser line, laser fluence, total pressure, and Br2 pressure using a CO2 TEA laser with an output less than 1 J pulse–1 in order to optimize experimental conditions for13C separation. For example, we obtained CBr2F2 at a13C concentration of 55% in the irradiation of the mixture of 100-Torr CHClF2 and 10-Torr Br2 with the laser radiation at a wavenumber of 1045.02 cm–1 and at a fluence of 3.4 J cm–2. The mechanism for the IRMPD is discussed on the basis of observed results. Using 8-J pulses, we were able to obtain 1.9×10–4 g of13C-enriched CBr2F2 (13C-atom fraction, 47%) per pulse under selected conditions. It is possible to produce 90% or higher13C by the second-stage IRMPD of the CBr2F2 in the presence of oxygen. 相似文献
4.
D. C. Sun Z. Q. Yu F. M. Li Y. C. Du H. Wang 《Applied Physics A: Materials Science & Processing》1989,48(6):567-571
Rapid growth of ultra thin oxide films (40–180Å) of silicon using a low-energy large-area electron beam has been performed with a pressure ratio of 31 (O2/He) and a total pressure of 0.5–0.7 Torr. A higher oxidation rate of about 625Å2/s is found for shorter irradiation time of the e-beam in the e-beam dose range 0.75–3 Coulomb/cm2 and at lower substrate temperature 540–740°C. AES and XPS demonstrated a rapid electron-stimulated oxidation process of the Si surface. For the grown ultra thin oxide films, C-V characteristics, dielectric strength, uniformity of the film over the entire Si wafer and its thickness as a function of the processing time of the e-beam are also presented. 相似文献
5.
We describe the generation of excimer-laser pulses of <10 ps pulse width and up to 40 mJ pulse energy at 248.5 nm and their use in the measurement of ps gain dynamics in a KrF amplifier. Small-signal gain of >2×104, saturation energy density of 2.0 mJ/cm2, and gain recovery time of 4 ns were measured. In contrast to XeCl* no short-gain rcovery time was found in KrF* and the stored inversion could be fully depleted bya single ps pulse. 相似文献
6.
We report investigations of an NO laser employing specially profiled magnetic fields of up to 3.4T, and F2 pump laser intensities as great as 20 MW cm–2. We have observed laser oscillation at 226 nm on a rotational branch of the B'-X/it(3–11) band of NO for the first time, in addition to the previously reported oscillation at 218 nm on the B'-X/it(3–10) band. We have also observed visible laser emission on a rotational branch of the B
2-B
2
II(3–1) band of NO. Saturation of the NO laser pulse energy with pump intensity has been observed, the total NO laser pulse energy having been increased to 490 J. The possibility of increasing the NO laser pulse energy towards 1 mJ per transition is discussed. 相似文献
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G. Denifl D. Muigg I. Walker P. Cicman S. Matejcik J.D. Skalny A. Stamatovic T.D. Märk 《Czechoslovak Journal of Physics》1999,49(3):383-392
Using a recently constructed high resolution crossed electron/molecular beam apparatus consisting of a hemispherical electron monochromator and a quadrupole mass spectrometer we have measured the relative production cross sections for CI– and F– via electron attachment to CF2Cl2. The relative Cl– cross section is placed on an absolute scale by reference to an absolute rate coefficient using a calibration method involving integration of the measured anion signal. The most efficient Cl– production process is at about zero energy and its magnitude is resolution limited. The present high resolution value of 6 × 10–16 cm2 compares well with an earlier value reported by Chen and Chantry. A second peak is detected at around 0.8 eV in accordance with some of the earlier beam and swarm measurements. The observed production of F– has an appearance energy of 1.9 eV and the energy of maximum cross section is 3.36 eV, the latter value comparing well with several previous studies. 相似文献
8.
Fluorescence at 490 nm from the triatomic excimer Xe2Cl* has been investigated to determine the 308 nm absorption due to this species in an x-ray preionized, self-sustained gas discharge XeCl laser. The dependence of Xe2Cl* density on laser intensity (at 308 nm), buffer gas and Xe and HCl partial pressures has been determined for discharges with a peak electrical power deposition of 2.5 GWl–1. Xe2Cl* absorption is estimated to reach 0.6% cm–1 under non-lasing conditions but decreases to a non-saturable 0.2% cm–1 for intracavity laser intensity>1 MW cm–2. XeCl* and Xe2Cl* fluorescence intensities were found to be a similar for both helium and neon buffer gases but laser output was a factor of two greater with a neon buffer. 相似文献
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K. L. Hohla T. R. Loree C. A. Brau W. E. Stein 《Applied Physics A: Materials Science & Processing》1981,25(3):329-336
This work was an experimental investigation of a potential large-scale excimer laser system, in which a high-pressure KrF
gas mix was pumped by the 4-MeV electron beam from an available linear accelerator. As a function of the mix and the pressure,
fluorescence from KrF* and/or Kr2F* were produced with good efficiency. Comparing measured data with a kinetic model, it was found that the kinetics followed
the “normal” patterns seen in low-energy electron pumping. The data fitting process also resulted in a new value for the three-body
quenching rate constant for reactions involving Ar. A critical factor in the development of this laser will be an improvement
in beam control over that afforded by a simple solenoidal magnet. The conditions necessary for lasing are predicted; no inherent
limitations on scaling of the device were found. 相似文献
10.
The CO2-laser-induced infrared multiple photon decomposition of natural CBr2F2 in the presence of oxygen has been examined as a function of pulse number (30–1500), reactant pressures (CBr2F2, 10–150 Torr and O2, 5–90 Torr), laser line [9P(8)–9P(32)], and laser fluence (1–3 J cm–2) to optimize irradiation conditions for 13C-enrichment. CF2O was the main carbon containing product and afterwards was converted into CO2 via hydrolysis. A small amount of C2Br2F4 was detected only under extreme conditions, for example, at high laser fluences or wavenumbers close to an absorption band. The 13C-atom fraction of the final product CO2 was found to be 20–80%, depending on experimental conditions. The two-stage IRMPD process proposed previously has been examined in further detail in the present study. First, CBr2F2 containing about 30% of 13C was prepared in the 13C-selective IRMPD of natural CHClF2 in the presence of Br2. The second-stage IRMPD of the CBr2F2 in the presence of oxygen under selected conditions resulted in the high enrichment of 13C beyond 90%. 相似文献
11.
C.J. Zietkiewicz B.A. Knecht C.M. Herring N.P. Ostrom J.G. Eden 《Optical and Quantum Electronics》2002,34(10):1031-1044
The design, construction, and operating characteristics of a pulsed, transverse discharge-pumped HgBr laser, capable of operation at pulse repetition frequencies as high as 100 Hz, are presented. Having an active length of 53 cm, this laser system is preionized by two sets of spark arrays and average single pulse energies of 55 mJ are produced from Ne/N2/HgBr2 (natural abundance) vapor mixtures, with an output coupling of 50% and 17 J of energy stored in the pulse forming network. Based on measurements of the laser pulse energy for several values of cavity output coupling, the small signal gain coefficient and saturation intensity for the laser were determined to be 4.7% cm–1 and 260 kW cm–2, respectively. The single pass gain-to-loss ratio is 12.4. 相似文献
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In this paper, we report that mode-locked operation is realized in a flashlamp-pumped Nd:YAG laser with a nearly critical stable resonator, using LiF:F2− color center crystal as a modulation device. A single pulse train with the energy of 25 mJ and the pulse duration of 82 ps is obtained. Both the theoretical and experimental results have shown that the mode-locked operation has resulted from kerr-lens effect formed in combination with self-focusing within Nd:YAG and an aperture at a specific point, but not directly from the saturable absorption of LiF:F2− crystal. 相似文献
14.
N. P. Vagin V. A. Zolotarev P. G. Kryukov V. S. Pazyuk Yu. P. Podmar'kov M. P. Frolov N. N. Yuryshev 《Journal of Russian Laser Research》1992,13(1):60-71
Conclusion It can be concluded from our experiments and calculations that the product CF3O2 of the interaction between the CF3 radical and the O2 molecule quenches the oxygen O2(1) more strongly. At low chlorine admixture density in the singlet-oxygen stream this output energy of the oxygen-iodine laser with CF3I as the atomic iodine donor is lower compared with CH3I. The rate constant of quenching singlet oxygen by CF3O2 molecules is (3–5)·10–11 cm3·sec–1. It would be possible to decrease the influence of CF3O2 by adding to the initial O2
*–O2–CF3I–Ar active mixture some other substance causing the CF3 radicals to enter in a chemical reaction with a shorter characteristic time than that for CF3O2 formation. Of course, neither the initial substance nor the reaction products should quench O2
* noticeably. This role can be possibly assumed by the NO molecule.The influence of the chlorine additive on the output energy of a laser with CH3I and CF3I differs greatly. The choice of the chlorine donor must therefore be determined by the amount of this additive. CH3I is preferable if the chlorine is fully utilized in the singlet-oxygen laser, and CF3I in the opposite case.Quantum Radiophysics Division, Lebdev Physics Institute. Translation of Preprint No. 21 of the Lebedev Physics Institute, Moscow, 1991. 相似文献
15.
R. R. Letfullin 《Journal of Russian Laser Research》2002,23(3):252-273
Huge energy gain is detected theoretically in a pulsed chemical laser-amplifier based on a photon-branched chain reaction initiating in a gaseous disperse medium composed of H2–F2–O2–He and Al particles by focused external infrared radiation. It is shown that this effect is observed due to the other optical effect of diffractive multifocal focusing of the input radiation on a certain type of bicomponent optical system coupled structurally with the input mirror of an unstable telescopic laser cavity. Such a relatively simple bicomponent diffraction system, consisting of two plane screens with circular apertures on a given optical axis, enables one to focus the input beam without using classical refraction elements such as lenses and prisms. The focusing of the input signal ensures the minimization of the initially excited volume of the laser active medium and the appropriate sharp lowering of the necessary energy of the input pulse up to 10-6 J. This enables the laser system to reach a high value of the energy gain of 109. The huge laser energy gain allows us to use a master oscillator in the form of a small microjoule laser powered by an accumulator, and consequently makes it possible to construct a completely self-contained compact pulsed chemical HF-laser. 相似文献
16.
P. T. Lang F. Sessler U. Werling K. F. Renk 《International Journal of Infrared and Millimeter Waves》1989,10(7):821-828
Summary We described a13CH3F Raman laser pumped by a grating tuned 20 atmospheres CO2 laser. The emission characteristics of the13CH3F laser extends from 14 cm–1–35 cm–1 and from 49 cm–1–72 cm–1; about 65% of these frequency ranges can be covered with tunable radiation. The characteristics shows a strong dependence on the rotaional quantum numbers of the states involved in the Raman laser transitions and, within each tuning interval, on the frequency offset with respect to the frequencies of resonant transitions. We obtained, at 51 cm–1, a maximum FIR laser pulse energy of about 800 J (at a pump energy of 200 mJ), corresponding to a photon conversion of about 8%. In some cases we have observed simultaneous emission at a Raman and a cascade frequency. In addition, FIR emission power dependence on13CH3F gas pressure and pump pulse power were investigated for different J quantum numbers. 相似文献
17.
Large-scale silicon isotope separation based on the IRMPD of natural Si2F6 has been carried out using a commercially available high power CO2 TEA laser and a flow reaction system. The decomposition product SiF4 containing 19–33% of 30Si was obtained at a production rate of 1.5×10–2–2.6×10–2 mol·h–1, depending on experimental parameters such as laser wavelength, laser fluence, pressure, and flow rate. SiF4 containing 12% of 29Si was obtained under slightly different conditions, i.e., at a shorter wavelength than that for 30Si. When 39% of Si2F6 was decomposed at a slow flow rate, residual Si2F6 was found to have 99.7% of 28Si. The production rate was 4.2×10–2 mol·h–1. 相似文献
18.
Using two variants of the Laser Photoelectron Attachment (LPA) method
involving a differentially-pumped, seeded supersonic beam (0.05% and
12.5% of SF6 molecules in helium carrier gas, nozzle temperatures
T0= 300–600 K, stagnation pressures p0= 1–5 bar) and mass
spectrometric ion detection, we have investigated the energy dependence of
anion formation in low-energy electron collisions with SF6 molecules at
high energy resolution. Using the standard LPA method, the yield for
SF6- as well as SF5- and F- anions was studied
with an energy width around 1 meV over the electron energy range 0–200 meV. In addition, a variant of the LPA method with extended energy range
(denoted as EXLPA) was developed and applied to measure the yield for
SF6- and SF5- formation over the energy range 0–1.5 eV with an energy width of about 20 meV. The cross-section for formation of SF6- decreases by five orders of magnitude over the range 1–500 meV and is only weakly dependent on nozzle temperature. The yield
for SF5- formation shows — apart from a weak zero energy peak
which grows strongly with rising temperature — a broad maximum (located
around 0.6 eV for T0= 300 K and shifting to lower energies with rising
T0) and a monotonical decrease towards higher energies. SF5-
attachment spectra taken at elevated temperatures exhibit changes with
rising stagnation pressure which directly reflect rovibrational cooling of
the SF6 molecules with rising pressure. The SF5-/SF6- intensity ratio at near-zero energy and the low-energy shape of the broad peak in the SF5- spectra are used as
thermometers for the internal temperature of the SF6 molecules in the
seeded supersonic beam which (at p0= 1 bar) are found to be 50–100 K
lower than the nozzle temperature. The energy dependence of the yield for
F- formation is similar to that for SF6-, but the F-
signals are three to four orders of magnitude lower than those for
SF6-; in view of the rather high endothermicity of F-
formation the origin of the F- signals is discussed in some detail. 相似文献
19.
E. D'Anna S. Luby A. Luches E. Majkova M. Martino 《Applied Physics A: Materials Science & Processing》1993,56(5):429-436
Interdiffusion phenomena, thermal damage and ablation of W/Si and Si/W bilayers and multilayers under XeCl-excimer laser (=308 nm) irradiation at fluences of 0.15, 0.3 and 0.6 J/cm2 were studied. Samples were prepared by UHV e-beam evaporation onto oxidized Si. The thickness of W and Si layers and the total thickness of the structures were 1–20 nm and 40–100 nm, respectively. 1 to 300 laser pulses were directed to the same irradiation site. At 0.6 J/cm2 the samples were damaged even by a single laser pulse. At 0.3 J/cm2 WSi2 silicide formation, surface roughening and ablation were observed. The threshold for significant changes depends on the number of pulses: it was between 3–10 pulses and 10–30 pulses for bilayers with W and Si surfaces, respectively, and more than 100 pulses for multilayers with the same total thickness of tungsten. At 0.15 J/cm2 the periodicity of the multilayers was preserved. Temperature profiles in layered structures were obtained by numerical simulations. The observed differences of the resistance of various bilayers and multilayers against UV irradiation are discussed. 相似文献
20.
A short pulse (100 ns) high-energy x-ray source has been used to preionize a transversely excited carbon dioxide gas discharge laser of 600 cm3 active volume. The maximum output power of 60 MW in a 50 ns FWHM pulse was achieved from a CO2–N2–He–CO–Xe static gas mixture at 600 Torr pressure. The energy conversion efficiency was 6%. 相似文献