Collision Broadening of Rotational Spectrum
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Date
1972Author
Gross, Eugene P
Otieno‐Malo, J
Type
ArticleLanguage
enMetadata
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The problem studied is the rotational absorption spectrum of linear molecules of moment inertia I in a simple nonpolar buffer gas. The focus is on the behavior of the spectrum as the buffer gas pressure and the associated collision frequency ν is increased. Four regions are distinguished. (1) ν≪ℏ/I, there are sharp lines with a van Vleck‐Weisskopf line shape; (2) ν ≃ ℏ/I, the contributions from overlapping lines are summed analytically. The ratio of minimum to maximum absorption in the weakly oscillatory spectrum is computed. (3) ℏ/I<ν<(2kT/I)1/2, This is the classical inertial region where there is a single maximum in the absorption per cycle. We compute its position as it moves from an angular frequency (2kT∕I)1∕2 to lower frequencies with increasing collision frequency. (4) ν>(2kT/I)1/2, this is the region where the Debye frequency profile is valid, with the peak of absorption at an angular frequency (1∕ν) (2kT∕I). The calculations are based on a kinetic equation for the density matrix with a single relaxation time, no position change, collision model. We also compute the time dependent correlation functions needed in the theory of the rotational Raman effect of linear molecules
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http://jcp.aip.org/resource/1/jcpsa6/v57/i6/p2229_s1?isAuthorized=nohttp://erepository.uonbi.ac.ke:8080/xmlui/handle/123456789/33719
Citation
J. Chem. Phys. 57, 2229 (1972);Publisher
School of Biological Sciences, University of Nairobi