Refractive index of a vibrationally excited gas

Осипов, А. И.; Panchenko, V. Ya.; Филиппов, А. А.

doi:10.1070/qe1984v014n09abeh006205

Cited by 15 publications

(11 citation statements)

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“…The influence of the mechanical anharmony also turns out to be small. According to estimates [5,8], they can be neglected if the following conditions are satisfied ~<<o, vs~<<v a.…”

Section: (2)mentioning

confidence: 99%

“…Taking account of the higher derivatives, i.e., the next terms of the electrooptical anharmony, as well as corrections to the mechanical anharmony associated with replacement of a harmonic by an anharmonic oscillator, is executed in [5,8]. It is shown in [8] that the contribution of terms due to the electrooptical anharmony to the polarizability ~v' and hypolarizability ~v' is small, as a rule, and is of the magnitude of 3-5% of =v and ~v for the CO molecule, say.…”

Section: (2)mentioning

confidence: 99%

“…The influence of vibrational excitation on the self-focusing effect was first discussed in [3]. A detailed theoretical examination of the influence of vibrational excitation on the refractive index and also specific computations of the refractive index of a nonequilibrium gas and the effect of selffocusing induced by vibrational excitation are executed in [4][5][6][7][8].…”

Section: (2)mentioning

confidence: 99%

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Optical properties of a nonequilibrium vibrationally excited gas

Осипов

Филиппов

1989

Journal of Engineering Physics

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“…The influence of the mechanical anharmony also turns out to be small. According to estimates [5,8], they can be neglected if the following conditions are satisfied ~<<o, vs~<<v a.…”

Section: (2)mentioning

confidence: 99%

Section: (2)mentioning

confidence: 99%

Section: (2)mentioning

confidence: 99%

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Optical properties of a nonequilibrium vibrationally excited gas

Осипов

Филиппов

1989

Journal of Engineering Physics

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“…It is known that the excitation of vibrational and rotational degrees of freedom of molecules can influence their dipole moment and polarizability [2][3][4][5]. This can result in the change of some important properties of molecular gases, such as refractive index, intermolecular potential, transport coefficients and rate constants of chemical reactions.…”

Section: Introductionmentioning

confidence: 99%

Influence of vibrations and rotations of diatomic molecules on their physical properties: II. Refractive index, reactivity and diffusion coefficients

Sharipov¹,

Loukhovitski²,

Starik³

2016

J. Phys. B: At. Mol. Opt. Phys.

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The influence of the excitation of vibrational and rotational states of diatomic molecules (H 2 , N 2 , O 2 , NO, OH, CO, CH, HF and HCl) on refractive index, reactivity and transport coefficients was analyzed by using ab initio calculated data on the effective state-specific dipole moment and static polarizability obtained in the preceding paper of the present series. It has been revealed that, for non-polar molecules, the excitation both of vibrational and rotational degrees of freedom increases the averaged polarizability and, as a consequence, the refractive index. Meanwhile, for polar molecules, the effect of molecule excitation is more complex: it can either increase or decrease the refractive index. It was also shown that the excitation of molecules slightly influences the rate constants of barrierless chemical reactions between neutral particles; whereas, for ion-molecule reactions, this effect can be more pronounced. Analysis of the variation of diffusion coefficients, taking into account the effect of molecule excitation both on the collision diameter and on the well depth of intermolecular potential, exhibited that, for non-polar molecules, the effect associated with the change of collision diameter prevails. However, for polar molecules, the effect of the excitation of vibrational states on the well depth of intermolecular potential can compensate or even exceed the decrease of diffusion coefficient due to the averaged collision diameter rise.

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“…Special attention is devoted to the analysis of the mechanism of the change in n during propagation of an IR pulse (radiation in this region of the spectrum is usually absorbed on vibrational-rotational transitions) [2][3][4][5][6][7]. The dielectric permittivity of the medium has both imaginary and real parts.…”

mentioning

confidence: 99%

Modeling of the dynamics of the change in the index of refraction during resonance interaction of radiation with vibrational-rotational transitions

Grabovskii¹,

Starik²

1994

J Appl Mech Tech Phys

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It is well known that resonance absorption of radiation by a gas can lead to excitation of molecular internal degrees of freedom, and this determines, to a significant degree, the nonlinear response of the medium. The dielectric permittivity of the medium has both imaginary and real parts. The imaginary part is associated with the absorption coefficient tq, and the real part is associated with the index of refraction n. A change of n in the beam channel causes the light rays to be deflected from the initial direction and determines, to a significant degree, the character of laser propagation in a nonlinear medium [1]. This is why there are so many works on the mechanisms responsible for the change in the index of refraction under the action of resonance radiation. Special attention is devoted to the analysis of the mechanism of the change in n during propagation of an IR pulse (radiation in this region of the spectrum is usually absorbed on vibrational-rotational transitions) [2][3][4][5][6][7]. This is because it is with IR lasers that the high intensities at which nonlinear effects become very significant are achieved.It has been shown that the main mechanisms responsible for the change in n are the change in molecular polarizability of the medium due to excitation of molecular vibrations and the change in the density of the medium due to hydrodynamic effects produced by the nonuniform heat transfer from vibrational into translational degrees of freedom. Hydrodynamic effects have been analyzed primarily within the model of a nonviscous thermally nonconducting gas, neglecting the influence of diffusion and heat conduction, which in a vibrationally nonequilibrium gas depends significantly on the degree of excitation and can significantly influence the behavior of the concentrations of the mixture components even over times shorter than the characteristic times of these processes [8]. It is thus of interest to make a comprehensive analysis of the mechanisms of the change in the index of refraction of a mixture of gases, taking into account all processes associated with the excitation of molecular vibrations by resonance radiation. This paper is devoted to such an analysis.The analysis is performed for a two-component mixture of gases, consisting of molecules of different types, for example A (1) and B (2). The molecules of type A have at least two different types of vibrations k and q with frequencies u k < Uq, while type-B molecules have vibrations of one type s with frequencies u s _< Uq or u s _> Uq. Let the vibrationaltranslational relaxational time for the mode q be much longer than the vibrational-vibrational exchange times Uq ---u k and Uq --, u s, and let the frequency u I of the acting radiation be in resonance with the frequency at the line center of the vibrationalrotational transition m --, n, whose upper n and lower m states are vibrations of the types k and q, respectively: ~, = (~v. -Ev, + ~. -~,)/hwhere E v. and E v, are the vibrational energies of the excited states n and m of a type-A molecule, E...

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Refractive index of a vibrationally excited gas

Cited by 15 publications

References 0 publications

Optical properties of a nonequilibrium vibrationally excited gas

Optical properties of a nonequilibrium vibrationally excited gas

Influence of vibrations and rotations of diatomic molecules on their physical properties: II. Refractive index, reactivity and diffusion coefficients

Modeling of the dynamics of the change in the index of refraction during resonance interaction of radiation with vibrational-rotational transitions

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