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1.
It is important to optimize the resonance ionization efficiency of the sputtered particle by evaluating the internal energy of it. And also the dependence of the change of the internal energy of it on primary ion species and accelerating voltages was investigated. For this study, we developed proto-type resonance laser ionization SNMS instrument, which is a quadrupole SIMS apparatus combined with a wavelength tunable laser. The internal energy of the sputtered aluminum atoms, which has lowly lying excited state (112 cm−1) on the ground state, was monitored. As the results, the internal energy of the sputtered aluminum atoms was not influenced by the change of the surface work function and primary ion beam energy at all. On the contrary, the density on lowly lying excited state drastically increased due to the existence of the oxygen on aluminum surface. 相似文献
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V. I. Mel'nikov 《Journal of statistical physics》1993,70(1-2):77-91
We consider the effect of a high-frequency pumping cost on the escape rate of a classical underdamped Brownian particle out of a deep potential well. The energy dependence of the oscillation frequency(E) is assumed to be weak on the scale of thermal energy,E(0)T(0)T/V0 (0)[E(0) is the derivative of(E) atE= 0,V
0 is the barrier height,V
0 T]. The quadratic-in- contribution to the decay rate is calculated in two different regimes: (1) for the case of resonance of the pumping frequency with the nth harmonic of the internal motion at an energye, when
= n(e); (2) for a rollout region of the basic resonance near the bottom of the potential well, when ¦-(0)¦ and is the damping coefficient. In the latter case the absorption spectrum and the enhancement of the decay rate are calculated as functions of two reduced parameters, the anharmonicity of the potential,v
E
(0)T/, and the resonance mismatch, [ —(0)]/. It is shown that the effect of the pumping increases with diminishing ¦v¦ and at small v is proportional tov
–1. In this regime, the dependence on is stepwise: the pumping contribution is large for v > 0 and small for v < 0. In the frame of our theory, the decay rate is invariant against the simultaneous alternation of the signs of andv. The spectrum of the energy absorption has the standard Lorentzian shape in the absence of anharmonicity,v=0, and with increasing of ¦v¦ shifts and widens retaining its bell-shape form. 相似文献
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We use tunable UV laser light in the region 200–320 nm, produced by frequency doubling the output of a dye laser, for the decomposition of organometallic compounds. This method has been applied to TMA, trimethylaluminum Al(CH3)3. Only the TMA monomer absorbs UV light for >220 nm. TMA decomposes by one-photon absorption mainly into two channels: aluminum atoms Al plus organic fragments, and aluminummonomethyl AlCH3 molecules plus organic fragments. The ratio [Al]/[AlCH3] is wavelength dependent. We present a mechanism to explain the photolysis of trimethyl compounds of group III elements (Al, Ga, In). 相似文献
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The GaCH3 radical has been directly detected by far UV laser mass spectrometry for the first time, as a UV laser photofragment from gaseous trimethylgallium Ga(CH3)3, but not from triethylgallium, Ga(C2H5)3. The relative yield Y() of GaCH3 was measured, at various UV photolysis laser wavelengths =193, 210 and 245 nm, and follows the absorption spectrum of the Ga(CH3)3 precursor molecules. 相似文献
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We have demonstrated a Cs vapor laser that utilizes fifteen laser diode arrays for transverse pumping of the gain medium. A maximum output power of 28 W was achieved with a total optical to optical efficiency of 14% and a slope efficiency of 15%. Transverse pumping allows scaling of such a laser system to a higher power level by simple increasing of the gain medium volume and the number of pump sources. 相似文献
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Mupparapu R Vynck K Malfanti I Vignolini S Burresi M Scudo P Fusco R Wiersma DS 《Optics letters》2012,37(3):368-370
Metallic nanoparticles are known to enhance nonlinear optical processes due to a local enhancement of the optical field. This strategy has been proposed to enhance downconversion in thin film solar cells, but has various disadvantages, among which is the fact that the enhancement occurs only in a tiny volume close to the particles. We report on a very different physical mechanism that can lead to significant downconversion enhancement, namely, that of resonant light scattering, and which is a large volume effect. We show that only a tiny amount of resonantly scattering metallic (aluminum) nanoparticles is enough to create a significant enhancement of the fluorescence of dye molecules in the visible wavelength range. The strategy can be applied in general to increase the emission of UV-absorbing constituents, and is of particular use for solar energy. 相似文献
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A new mechanism for pumping of an X-ray laser by an optical laser is suggested. The inverse population between the inner levels of atoms is attained by means of the use of fast laser plasma electrons. 相似文献
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《Infrared Physics & Technology》2008,51(2):95-101
Nitric oxide detection has been performed with a Helmholtz resonant photoacoustic sensor previously developed in Reims. The cell was coupled with a continuous wave distributed feedback quantum cascade laser working at cryogenic temperature in continuous wave mode in the 5.4 μm region. A detection limit of 20 ppb of nitric oxide in nitrogen with a laser power of 3 mW can be predicted. Possible applications and improvements are discussed. 相似文献
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A photoacoustic resonant cell with the inner volume is ∼0.5 cm3 is presented. The shape of the cell cavity is chosen such as to minimize a background signal arising due to the absorption
of laser beam in the cell windows. The experimental setup, the measurement procedure, and the design of the cell are described.
The results of detecting ammonia in a nitrogen flow using the R(30) oscillating line of a CO2 laser are represented. The minimal detectable absorption achieved in experiment is ∼3.2 × 10−8 cm−1 W Hz−1/2. 相似文献
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V. I. Balykin V. S. Letokhov V. G. Minogin T. V. Zueva 《Applied physics. B, Lasers and optics》1984,35(3):149-153
The application of the resonant light pressure created by an axially symmetrical light field for collimating atomic beams has been considered. As an example, consideration is given to the possibility of collimating an atomic beam by the light field produced by the reflection of a plane wave from the internal surface of a metal cone. It has been shown that the radiation pressure can reduce the atomic-beam transverse velocities to the value of the order of 100 cm/s which corresponds to effective temperature of about 10–3 K. A method for producing collimated beams of cold atoms based on simultaneous deceleration and collimation of atomic beams by resonant laser radiation pressure is proposed. 相似文献
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N.L. Dygert A.P. Gies K.E. Schriver R.F. Haglund Jr. 《Applied Physics A: Materials Science & Processing》2007,89(2):481-487
We report the successful deposition of a polyimide precursor using resonant infrared laser ablation (RIR-LA). A solution of
poly(amic acid) (PAA) dissolved in N-methyl-2-pyrrolidinone (NMP), the melt processable precursor to polyimide, was frozen
in liquid nitrogen for use as an ablation target in a high-vacuum chamber. Fourier transform infrared spectroscopy was used
to determine that the local chemical structure remained unaltered. Gel permeation chromatography demonstrated that the transferred
PAA retained its molecular weight, showing that RIR-LA is able to transfer the polymer intact, with no detectable chain fragmentation.
These results are in stark contrast to UV-processing which degrades the polymer. After deposition the PAA may be removed with
a suitable solvent; however, once the material has undergone cyclodehydration it forms an impenetrable three-dimensional network
associated with thermosetting polymers. The transfer of uncured PAA precursor supports the hypothesis that RIR-LA is intrinsically
a low temperature process, because the PAA is transferred without reaching the curing temperature. The RIR-LA also effectively
removes the solvent NMP from the PAA, during both the ablation and deposition phases; this is a necessary step in generating
PI films.
PACS 41.60.Cr; 78.30.Jw; 81.15.Fg 相似文献
17.
Pulsed oscillation from XeCl at λ = 3080 Å has been obtained by exciting a mixture of He:Xe:BCl3 at pressures of 1 to 7 atm with a transverse discharge. The laser efficiency relative to the discharge absorbed energy exceeds 1%. The role of dissociation recombination in the processes of excitation of XeCl1 is discussed. 相似文献
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A. G. Leonov D. I. Chekhov A. N. Starostin 《Journal of Experimental and Theoretical Physics》1997,84(4):703-715
An experimental investigation and numerical simulation of resonant laser breakdown are performed. As a result, quantitative
agreement between the experimental data on the parameters of a dense resonant plasma (the electron density and the electron
temperature) and the results of calculations in the range of detunings of the laser radiation from resonance Δλ>2–2.5 nm, in which the spatial instability of the intense resonant laser beam and the absorption of radiation are minimal,
is obtained for the first time. It is shown that the previously proposed mechanism of resonant breakdown associated with laser-induced
associative ionization introduces only a small correction to the final extent of ionization of the resonant plasma and scarcely
alters its temperature. The influence of quantum stimulated inverse bremsstrahlung processes, which are usually described
as collisions of the second kind in the resonance case, on the energy gain by electrons is analyzed for the first time in
reference to specific experimental findings. The numerical calculations show that at detunings of the order of the Rabi frequency,
the mechanism by which electrons gain energy through the resonant system does not reduce to collisions of the second kind
and can significantly increase the density of the resonant plasma. However, in this range of detunings the laser beam is still
strongly perturbed by instability processes, precluding a proper comparison of the theory with experiment. At large Δλ the classical and quantum cases differ from one another only slightly, and the values of N
e calculated for both mechanisms lie within the measurement error.
Zh. éksp. Teor. Fiz. 111, 1274–1296 (April 1997) 相似文献
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V. I. Balykin V. S. Letokhov V. G. Minogin 《Applied physics. B, Lasers and optics》1984,33(4):247-251
The application of laser deceleration and monochromatization of atoms in the schemes of single atom fluorescent detection is examined. The analysis performed shows that the use of resonant-light pressure in experiments with atomic beams enables one to obtain an ultimate value of detection selectivity that ranges from 1013 to 1016. 相似文献