共查询到20条相似文献,搜索用时 15 毫秒
1.
2.
V. V. Komarov A. M. Popova I. O. Stureiko L. Schmidt H. Jungclas 《Moscow University Physics Bulletin》2007,62(6):339-342
We suggest a model that allows analysis of the photoprocesses in polyatomic organic molecules upon multiple IR photon capture. The dissociation and electron excitation of these molecules is shown to depend resonantly on the photon energy and intensity. The (CH2)n substructures of these molecules serve for IR photons as antennas that accumulate energy to values at which dissociation or electron excitation can be triggered. The model is applied to diphenylalkan molecules as an example. 相似文献
3.
N. Bloembergen 《Optics Communications》1975,15(3):416-418
The discussion of the physical processes involved in the dissociation of polyatomic molecules by intense infrared radiation at a vibrational absorption band leads to an estimate of the required electric field amplitude of (1–3) × 106 V/cm. 相似文献
4.
A novel form of phenomenological optical Bloch equations, with density matrix elements depending both on the number of laser quanta in the pumped molecular vibrational mode and on the number of quanta dumped into the thermal bath formed by the remaining vibrational modes, is used to derive rate equations for multiple photon excitation of polyatomic molecules. 相似文献
5.
An elementary procedure for calculating quantum mechanically the time-dependent rotation-vibration wave function for a collisionless model of a polyatomic molecule in a monochromatic radiation field is described and applied to some very simple cases. It is concluded that molecules can in principle be strongly and selectively excited at radiation intensities which are too low to produce appreciable excitation in classical calculations. The excitation process is a coherent multi-photon Rabi precession between two discrete levels followed by a transition to a quasi-continuum of vibration-rotation states. 相似文献
6.
7.
N. Aközbek A. Becker M. Scalora S.L. Chin C.M. Bowden 《Applied physics. B, Lasers and optics》2003,77(2-3):177-183
The continuum generation by intense femtosecond IR laser pulses focused in air including the effect of third-harmonic generation is investigated. We have used a theoretical model that includes the full spatio-temporal dynamics of both the fundamental and the third-harmonic pulses. Results of our numerical calculations show that a two-color filamentation effect occurs, in which the third-harmonic conversion efficiency remains almost constant over the whole filament length. It is found that this effect is rather independent of the wavelength of the input beam and the focal geometry. During the filamentation process the third-harmonic pulse itself generates a broad continuum, which can even overlap with the continuum of the fundamental pulse for the longer pump wavelengths. In consequence, the continuum generation generated by intense IR laser pulses is further extended into the UV. PACS 42.65.Jx; 42.65.Ky; 52.35.Mw 相似文献
8.
N. S. Malyshev V. V. Kuverova G. K. Ozerov G. V. Golubkov M. G. Golubkov S. O. Adamson 《Russian Journal of Physical Chemistry B, Focus on Physics》2017,11(1):77-82
A method taking into account valence (non-Rydberg) and dissociative configurations has been developed for calculation of potential energy surfaces of the NO molecule in an intense IR radiation field. The resonance rovibronic structure of the Rydberg molecule–laser field quantum system has been analyzed within the steady-state formalism of the radiation collision matrix using multi-channel quantum defect theory. Special conditions for field control of predissociation involving intermediate Rydberg and valence states have been formulated. 相似文献
9.
Simultaneous excitation of a considerable part of molecules from many rotational levels of the ground state to higher vibrational states by IR laser radiation can be explained by considering weak transitions in a rotational band structure as it is shown at the example of SF6 molecule. Very accurate compensation of anharmonicity in relatively wide spectral interval at comparatively low intensity of laser radiation can be explained on this basis. The considered scheme can be applied to the molecules of various symmetry with arbitrary anharmonicity. 相似文献
10.
11.
David M. Larsen 《Optics Communications》1976,19(3):404-408
A procedure is described for calculating the dependence of the collisionless dissociation probability of a polyatomic molecule on the frequency of the laser pulse impinging upon it. Sample calculations performed on a simple molecular model show how coherent multiphoton transitions in the vibrational excitation spectrum can be observed in the curve of dissociation probability versus laser frequency. 相似文献
12.
《Journal of Molecular Spectroscopy》1986,119(1):144-152
Irreducible tensorial sets are used for constructing the reduced rotational Hamiltonian of the molecule, i.e., for obtaining the Hamiltonian with independent rotational, centrifugal distortion, and resonance parameters. General formulas are obtained which allow one to do this, and are valid for molecules of any symmetry. As an illustration of the general results, molecules of Td symmetry are considered. 相似文献
13.
M.V. Fedorov 《Physics letters. A》1977,61(4):224-226
The vibrational-rotational quasienergy spectra and the excitation probabilities of a diatomic molecule are found, arising under the action of a strong resonance infrared radiation field. 相似文献
14.
15.
I. N. Knyazev Yu. A. Kudriavtzev N. P. Kuzmina V. S. Letokhov A. A. Sarkisian 《Applied Physics A: Materials Science & Processing》1978,17(4):427-429
A new approach to laser isotope separation is considered. It is based on collisionless multiple photon ir laser excitation
and subsequent uv laser dissociation of vibrationally excited molecules. TEA CO2 and excimer XeF, XeCl lasers are used for ir excitation and uv dissociation, respectively. The products of photolysis (C2F6) are enriched with12C. 相似文献
16.
A first infrared pulse at frequency ν1 generates transitions to intermediate states in S0 and a simultaneous visible pulse at ν2 raises the excited molecules to a state in S1. Tuning the frequencies ν1 and ν2 over several hundred wave numbers and holding the sum ν1 + ν2 constant allows the observation of various combination vibrations. The technique is demonstrated on polyatomic molecules consisting of 42 atoms. 相似文献
17.
N. V. Chekalin V. S. Dolzhikov Yu. R. Kolomisky V. S. Letokhov V. N. Lokhman E. A. Ryabov 《Applied Physics A: Materials Science & Processing》1977,13(4):311-316
Consideration is given to selectivity estimation methods during polyatomic molecules dissociation by multiple photon absorption.
Taking the CH3NO2 molecule as an example, the possibilities of selectivity estimations made on the electron-excited dissociation products (luminescence)
are shown, as well as on the measurements of the energy absorbed in a strong IR field being transformed into heat. Some advantages
of the last method of the selectivity estimation are discussed. The experiments on nitrogen-isotopes separation in the mixture
of CH3
14NO2 and CH3
15NO2 molecules are carried out when exciting thev
7 vibration with the isotope shift of about 7 cm−1 and thev
13 vibration with no isotope shift in the linear absorption spectrum. The contribution of secondary chemical reactions to the
separation process is discussed. 相似文献
18.
An analytic approach to calculations of the density of vibrational states in a system consisting of independent anharmonic
oscillators was developed. The method worked at all energies from zero point energies to the complete dissociation energies
of the selected oscillators. 相似文献
19.
V. V. Gruzinskii S. M. Kazakov M. N. Kaputerko I. I. Kulak V. A. Suchkov 《Journal of Applied Spectroscopy》1998,65(2):224-231
Information on paths in absorption and deactivation of energy gained by molecules in their excitation by electron impact to
low-lying singlet states has been obtained from an analysis of changes in the fluorescence spectra of these molecules. It
is shown that there is a significant difference in the formation of fluorescence spectra when free molecules are excited by
optical radiation and by electrons. It contrast to optical excitation, the interaction of an electron with a molecule is nonselective
in character. All electronic states have a chance to be excited, which results in ensembles of emitting molecules with a different
store of vibrational energy, and these ensembles each contribute to the fluorescence spectrum.
Deceased.
Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 65, No. 2, pp. 216–223, March–April, 1998. 相似文献
20.
Measurement of filament length generated by an intense femtosecond laser pulse using electromagnetic radiation detection 总被引:4,自引:0,他引:4
We present a new method to measure the length of a filament induced by the propagation of intense femtosecond laser pulses
in air. We used an antenna to detect electromagnetic pulses radiated from multipole moments inside the filament oscillating
at the plasma frequency. The results are compared with the values detected from the backscattered fluorescence induced by
multiphoton ionization of nitrogen molecules excited inside the filament. The values are found to be in good agreement.
Received: 6 November 2002 / Revised version: 27 January 2003 / Published online: 24 April 2003
RID="*"
ID="*"Corresponding author. Fax: +1-418/656-2623, E-mail: shosseini@phy.ulaval.ca 相似文献