Rovibrational energy transfer in the 4vCH manifold of acetylene, viewed by IR-UV double resonance spectroscopy: kinetics of a collision-induced quasi-continuous background

Mark A. Payne, Angela P. Milce, Michael J. Frost, Brian J. Orr

Research output: Chapter in Book/Report/Conference proceedingConference proceeding contributionpeer-review

Abstract

The 4νCH rovibrational manifold at ~12 700 cm⁻¹ in the electronic ground state of acetylene (C₂H₂) has been studied by time-resolved IR-UV double resonance spectroscopy. An IR laser pulse prepares rotational J-states, associated with the "IR-bright" (ν₁ + 3ν₃) vibrational combination level, and subsequent collision-induced state-to-state energy transfer is probed by pulsed UV laser-induced fluorescence. Anharmonic, ℓ-resonance, and Coriolis couplings affect J-states of interest, resulting in a congested rovibrational manifold with complex intramolecular dynamics. These experiments reveal collision-induced rovibrational satellites, comprising regular even-ΔJ features and odd-ΔJ features that are unexpected in view of the ortho/para nuclear-spin symmetry of C₂H₂. An unusual collision-induced quasi-continuous background (CIQCB) effect is apparently ubiquitous, accompanying regular even-ΔJ rovibrational energy transfer and accounting for much of the observed collision-induced odd-ΔJ satellite structure. This CIQCB phenomenon is examined in terms of a congested IR-dark rovibrational manifold populated by collisional transfer from the nearby IR-bright (ν₁ + 3ν₃) submanifold. A kinetic master-equation model provides a satisfactory phenomenological fit to the processes of interest.
Original languageEnglish
Title of host publicationProceedings of the 17th Australian Institute of Physics national congress 2006
EditorsJohn Dobson, Robert Sang
PublisherAustralian Institute of Physics
Number of pages4
ISBN (Print)0959806474
Publication statusPublished - 2006
EventAustralian Institute of Physics National Congress (17th : 2006) - Brisbane
Duration: 3 Dec 20068 Dec 2006

Conference

ConferenceAustralian Institute of Physics National Congress (17th : 2006)
CityBrisbane
Period3/12/068/12/06

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