Fluorescence-dip infrared spectroscopy and predissociation dynamics of OH A(2)Sigma(+) (v=4) radicals - art. no. 244313

摘要

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 (2)Sigma(+) electronic state of the OH radical. Various lines of the 4 <- 2 overtone transition in the excited A (2)Sigma(+) state are observed, from which the rotational, centrifugal distortion, and spin-rotation constants for the A (2)Sigma(+) (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 (2)Sigma(+) (v=4) state undergo rapid predissociation with lifetimes of <= 23 ps. The experimental linewidths are in near quantitative agreement with first-principles theoretical predictions. (c) 2005 American Institute of Physics.