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71.
An ir multiphoton dissociation (MPD) process in multiple-frequency ir-laser fields has been experimentally realized. A selectivity ofS=104 was obtained in separating13C/12C isotopes upon multiple-frequency ir multiphoton dissociation (MFMPD) of the CF2HCl molecule, the dissociation yield13 for the13CF2HCl molecule amounting to around 1%. A yield of13 was reached at a selectivity ofS=102, and the total laser fluence required for the process was reduced. A new mechanism—sticking of molecules on the lower discrete vibrational levels—responsible for the low MPD yields observed for some molecules is discussed and a technique to eliminate it and thus maximize the dissociation yields is proposed. Ways to improve the selectivity by MFMPD are analyzed and a simple method for obtaining from a single TEA CO2 laser a multiple-frequency radiation suitable for experimental realization of MFMPD is suggested. 相似文献
72.
TheA
1
–X
1
+ system of SnO is studied by laser- induced fluorescence excitation spectroscopy using isotopically enriched tin Sn116. The rotational structure analysis has been carried out for 6-0, 5-0, 2-0 bands. All these spectra were well resolved only with few perturbed lines in 2-0 band. Rotational constantsB
2,B
5,B
6 and henceB
e
,
e
e
have been obtained for the Sn116O molecule. An extension of perturbation study on 4-0 band has been made showing the maximum perturbation occurs at different J values for different isotopes. 相似文献
73.
G. R. Sudhakaran J. C. Sarker R. L. Bhattacharjee L. H. Johnston 《International Journal of Infrared and Millimeter Waves》1987,8(12):1531-1540
Submillimeter laser-Stark spectra have been observed for the isotopic species of methyl fluoride,13CH3F, using the 337 m line of the HCN laser. We have identified the multiplet transitions as JK=18K17K in the ground vibrational state. Ten distinct families with K=8, 9, 10, 11, 12, 13, 14, 15, 16 and 17 have been observed. Zero-field frequencies for all the transitions are given and in most cases with better accuracy than predicted from the previous constants. 相似文献
74.
H. Pummer K. Hohla F. Rebentrost 《Applied Physics A: Materials Science & Processing》1979,20(2):129-134
Collisional coupling between theB, C, andD states of KrF is measured in a discharge pumped KrF laser. Detection of the time resolved populations in the three states
via measurement of the side fluorescence in theB→X, C→A, andD→X bands is used to record the collisional relaxation from theC andD state to theB state during laser emission. The experimentally determined limits for the collisional coupling times are τB-C≦1 ns and τB-D,τC-D<20 ns at total pressures of 2 bar. Investigation of theB→X fluorescence band shows that the vibrational manifold of theB state is not thermalized during laser emission. TheV-V,T coupling time is estimated to be τV-V,T=4±2 ns. The influence of collisional coupling on energy extraction in the KrF laser is discussed. 相似文献
75.
R. V. Ambartzumian I. N. Knyazev V. V. Lobko G. N. Makarov A. A. Puretzky 《Applied Physics A: Materials Science & Processing》1979,19(1):75-79
Multiple ir photon absorption spectra (MPAS) of OsO4 are obtained in the range of energy fluencies from 3·10−2 to 1.26 J/cm2. A possible interpretation of MPAS is given on the basis of weak forbidden rovibrational transitions. The stepwise character
of the absorption on the laser energy fluence is observed. 相似文献
76.
The optically induced polarization change was studied in the case of a standing elliptically polarized wave. Using a Zeeman-tuned
gas laser at 3.39 μm with an internal methane cell we have demonstrated the influence of the dichroism on the nonlinear absorption
signals. 相似文献
77.
In order to study the kinetic mechanism of the e-beam pumped Ar/Xe laser, the temporal profiles of individual laser lines during multiline oscillation have been measured as a function of power deposition (1–12MW/cm3) and gas laser pressure (2–14 bar) using a short pulse (30 ns) coaxial electron beam as excitation source. It was found that the optimum output energy at each pressure was obtained at the same specific power deposition.Strong line competition has been observed between the 2.65 and 1.73 m transitions. In order to explain our results we suggest that besides electron collision mixing (ECM) between the 5d and 6p levels of Xe, there is also a redistribution between all 6p levels which strongly favours the lower levels at higher pumping densities. 相似文献
78.
A continuum limit of the Toda lattice field theory, called the SDiff(2) Toda equation, is shown to have a Lax formalism and an infinite hierarchy of higher flows. The Lax formalism is very similar to the case of the self-dual vacuum Einstein equation and its hyper-Kähler version, however now based upon a symplectic structure on a cylinderS
1×R. An analogue of the Toda lattice tau function is introduced. The existence of hidden SDiff(2) symmetries are derived from a Riemann-Hilbert problem in the SDiff(2) group. Symmetries of the tau function turn out to have commutator anomalies, hence give a representation of a central extension of the SDiff(2) algebra. 相似文献
79.
Alexander V. Rozenblyum 《Acta Appl Math》1992,29(3):171-240
This work is devoted to the construction and investigation of two new classes of special functions, related to representations of groups of motions in the spaces of constant curvature as well as the unitary group of large ranks. These are special functions with matrix indices and some types of orthogonal polynomials in several continuous and discrete variables. The functions introduced generalize a number of classical scalar special functions in one variable. 相似文献
80.
G. Rousseau 《Aequationes Mathematicae》1992,43(2-3):145-155
Summary Gauss proved Seeber's Theorem, that the determinant of a reduced positive definite ternary quadratic form is at least half the product of its diagonal coefficients, by means of two determinantal identities whose origin has remained unclear. We examine Gauss's method from a general standpoint, as a method whereby, in certain circumstances, a polynomial in several variables may be shown to be non-negative on a convex polytope by representing it as a positive multilinear combination of the linear forms which determine the polytope. We show that Gauss's identities may be obtained in this manner and that the two identities can in fact be replaced by a simpler single identity which also gives Oppenheim's precise minimum for the determinant. 相似文献