Collision-induced state-to-state energy transfer in perturbed rovibrational manifolds of small polyatomic molecules

mechanistic insights and observations

Brian J. Orr*

*Corresponding author for this work

Research output: Contribution to journalArticle

35 Citations (Scopus)


This paper considers collision-induced rovibrational energy transfer in small polyatomic molecules, measured on a state-to-state basis by rotationally selective, time-resolved optical double-resonance (DR) spectroscopy. Particular attention is given to the extent to which the rovibrational manifold of interest is energetically congested and/or affected by intramolecular perturbations. A semiclassical dynamical description is used to visualise how such perturbations, manifested in spectroscopic energies and transition probabilities, affect the efficiencies of collision-induced bovibrational energy transfer. Perturbation-induced enhancement (and, in some cases, inhibition) of V-V transfer efficiencies is examined, with regard to several DR measurements of perturbed manifolds of CO2, D2CO, C2H2, and C2D2 at various levels of vibrational excitation. Specific questions considered include: the feasibility of separating rotationally specific channels of collision-induced V-V transfer from the scrambling effects of rotational relaxation; how to characterise dynamical processes in which intermolecular perturbations exceed (and effectively override) those of intramolecular origin; the role of vibrational angular momentum in propensities and efficiencies of collision-induced V-V transfer; physically realistic molecular bases to minimise perturbation-induced contributions to rovibrational energy transfer; reconciliation of apparently contrasting dynamics of small and large polyatomic molecules, over a range of vibrational energies, spectral congestion, and molecular complexity.

Original languageEnglish
Pages (from-to)261-278
Number of pages18
JournalChemical Physics
Issue number2-3
Publication statusPublished - 15 Jan 1995

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