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Published July 1, 1989 | public
Journal Article

Determination of excited-state rotational constants and structures by Doppler-free picosecond spectroscopy

Abstract

Picosecond time-resolved fluorescence measurement of purely rotational coherence is developed as a Doppler-free technique for the determination of rotational constants of large molecules in their excited states. We present detailed analyses of purely rotational coherence measurements, supplying new information about the rotational constants and structures of the first excited electronic states of t-stilbene, four t-stilbene van der Waals complexes, and anthracene, including values for all three anthracene S_1 rotational constants. Evidence is considered in the case of stilbene for a transition dipole with a significant component perpendicular to the a inertial axis, and the consequences of such a dipole are explored by way of numerical simulations. Excited-state structures are proposed for stilbene and stilbene-rare-gas complexes and comparisons made with model calculations of the van der Waals potential. Application of the new spectroscopic technique to molecules of large asymmetry is demonstrated by the analysis of fluorene and fluorene-argon measurements, and the results are compared with data from previously published high-resolution frequency domain studies.

Additional Information

© 1989 American Chemical Society. Received: January 23, 1989. Publication Date: July 1989. This research was supported by a grant from the National Science Foundation (DMR-8521191).

Additional details

Created:
August 19, 2023
Modified:
October 20, 2023