Fluorescence-dip infrared spectroscopy, an UV-IR double-resonance technique, is employed to characterize the line positions, linewidths, and corresponding lifetimes of highly predissociative rovibrational levels of the excited A electronic state of the OH radical. Various lines of the 4←2 overtone transition in the excited A state are observed, from which the rotational, centrifugal distortion, and spin-rotation constants for the A (v = 4) state are determined, along with the vibrational frequency for the overtone transition. Homogeneous linewidths of 0.23–0.31 cm−1 full width at half maximum are extracted from the line profiles, demonstrating that the N = 0 to 7 rotational levels of the OH A (v = 4) state undergo rapid predissociation with lifetimes of ⩽ 23 ps. The experimental linewidths are in near quantitative agreement with first-principles theoretical predictions.
Journal of Chemical Physics
AMERICAN INSTITUTE OF PHYSICS
Digital Object Identifier (DOI)
E. L. Derro, I. B. Pollack, L. P. Dempsey, M. E. Greenslade, Y. Lei, D. Č. Radenović, M. I. Lester, “Fluorescence-Dip Infrared Spectroscopy and Predissociation Dynamics of OH A 2Σ+ (v=4) Radicals,” J. Chem. Phys. 122, 24431 (2005).
© 2005 American Institute of Physics. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of Physics. J. Chem. Phys. 122, 244313 (2005)