title: Fluorescence-dip infrared spectroscopy and predissociation dynamics of OH A 2Sigma+ (v = 4) radicals.
abstract: 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 < or =23 ps. The experimental linewidths are in near quantitative agreement with first-principles theoretical predictions.
authors.affiliation: Department of Chemistry, University of Pennsylvania, Philadelphia, 19104-6323, USA.
authors.forename: Erika L
authors.initials: EL
authors.lastname: Derro
authors.forename: Ilana B
authors.initials: IB
authors.lastname: Pollack
authors.forename: Logan P
authors.initials: LP
authors.lastname: Dempsey
authors.forename: Margaret E
authors.initials: ME
authors.lastname: Greenslade
authors.forename: Yuxiu
authors.initials: Y
authors.lastname: Lei
authors.forename: Dragana C
authors.initials: DC
authors.lastname: Radenović
authors.forename: Marsha I
authors.initials: MI
authors.lastname: Lester