Non-Markovian extension of the energy-corrected sudden approximation on binary collisions of linear molecules

Research output: Contribution to conferenceAbstract


Higher accuracy of spectroscopic data modeling of different gaseous media is urgently called by progress in
atmospheric physics and gas diagnostics. This task demands development of flexible theoretical models
applicable to different processes induced by collisional relaxation. Such flexibility is inherent to the energycorrected sudden approximation (ECSA) introduced almost 40 years ago [1] but still retaining its popularity for
fittings of congested spectral structures near the band centers. Its extended variants [2,3] are able to tackle the
non-Markovian collisional relaxation of arbitrary rank up to the far spectral wings but apply strictly to the
single case of linear rotators perturbed by structureless particles. Here, we report rigorous non-Markovian
ECSA relaxation matrix expressions obtained for collisions between pairs of linear molecules.
For that, the ECSA scattering operators and the intermolecular potential W are expanded in series of scalar
tripolar spherical harmonics [4] whose arguments are orientations of three axes, two of the linear colliders and
the third one of the intermolecular separation. All relaxation characteristics can be obtained when the Fouriertransforms of the ECSA time correlation functions are known. These transforms can be either calculated from
first principles or modeled using a priori information and accounting for the fundamental properties of the
relaxation matrix. Besides, the ECSA spectral functions can be mimicked in terms of the leading spectral
moments which are readily obtained from the tripolar expansions of W and of the binary distribution function.
The presented approach allows straightforward generalizations to collisions between any molecular tops whose
rotation is substantially slower than the relative translational motion.
[1] A.E. De Pristo, S.D. Augustin, R. Ramaswamy, and H. Rabitz, J. Chem. Phys. 71, 850 (1979) .
[2] A. Kouzov, Phys. Rev.A 60, 2931 (1999).
[3] J.V. Buldyreva and L. Bonamy, Phys. Rev.A 60, 370 (1999).
[4] D. A. Varshalovich, A. N. Moskalev, and V. K. Khersonskii, Quantum Theory of Angular Momentum (World
Scientific, Singapore, 1988)
Original languageEnglish
Number of pages1
StatePublished - 20 Aug 2017
EventThe 25th Colloquium on High-Resolution Molecular Spectroscopy - Helsinki, Finland
Duration: 20 Aug 201725 Aug 2017


ConferenceThe 25th Colloquium on High-Resolution Molecular Spectroscopy

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