Interpretation and Analysis of Perturbed Spectra of Axially Symmetric Molecules with Applications to Carbon 13 Labelled Trideutero Methyl Fluoride.
Abstract
The main thrust of this study is the development and testing of an algorithm to fit perturbed vibration rotation molecular spectra. The algorithm is first developed in a general form and then applied to the vibrationrotation spectra of axially symmetric molecules using simulated data. The 5 (mu)m absorption spectrum of ('13)CD(,3)F is very complex. There are 24 vibrational levels in the region from 1800 cm('1) to 2250 cm('1). There are many strong vibrational and rotational resonances linking these states. The states included in this analysis are (nu)(,4)(l(,4) = (+OR)1), 2(nu)(,2)(l = 0), (nu)(,2) + (nu)(,5)(l(,5) = (+OR)1), 2(nu)(,5)(l(,5) = 0,(+OR)2), (nu)(,2) + (nu)(,3)(l = 0), (nu)(,1)(l = 0) and (nu)(,3) + (nu)(,5)(l(,5) = (+OR )1), all of which lie above 2050 cm('1). The states omitted in this analysis are (nu)(,2) + (nu)(,6)(l(,6) = (+OR)1), (nu)(,5) + (nu)(,6)(l(,5) = (+OR)1,(nu)(,6) = (+OR)1), 2(nu)(,3)(l = 0), (nu)(,3) + (nu)(,6)(l(,6) = (+OR)1), and 2(nu)(,6)(l(,6) = 0,(+OR)2), all of which lie below 2025 cm('1). These two groups of vibrational states are weakly linked by a higher order vibrationrotation resonance between (nu)(,1) and (nu)(,2) + (nu)(,6)(l(,6) = 1) and a weak vibrational resonance between (nu)(,1) and 2(nu)(,3). The absorption spectrum of ('13)CD(,3)F was recorded at a resolution of 0.018 cm('1) and deconvolved to an effective resolution of 0.006 cm('1). The (nu)(,1), 2(nu)(,5)(l(,5) = 0), 2(nu)(,2) and (nu)(,4)(l(,4) = (+OR)1) bands were analyzed individually to obtain estimates of the molecular parameters of these states. The local and nonlocal resonances were characterized and interaction constants were estimated which gave a qualitative agreement with the observed spectrum. The parameters were then refined using a Hamiltonian model which included all possible interactions from the vibrationrotation Hamiltonian through third order with the restriction that (DELTA)K  (SUMM)(DELTA)l = 0.
 Publication:

Ph.D. Thesis
 Pub Date:
 1983
 Bibcode:
 1983PhDT........79H
 Keywords:

 Physics: Molecular