title: High resolution probe of spin-orbit coupling and the singlet-triplet gap in chlorocarbene.
abstract: Among the most important of chemical intermediates are the carbenes, characterized by a divalent carbon that generates low-lying biradical (triplet) and spin-paired (singlet) configurations with unique chemical reactivities. The "holy grail" of carbene chemistry has been determining the singlet-triplet gap and intersystem crossing rates. We report here the first high resolution spectra of singlet-triplet transitions in a prototypical singlet carbene, CHCl, which probe in detail the triplet state structure and spin-orbit coupling with the ground singlet state. Our spectra reveal a pronounced vibrational state dependence of the triplet state spin-spin splitting parameter, which we show is a sensitive probe of spin-orbit coupling with nearby singlet states. The parameters derived from our spectra, including a precise determination of the singlet-triplet energy gap, are in excellent agreement with recent ab initio calculations.
authors.affiliation: Department of Chemistry, Marquette University, Milwaukee, Wisconsin 53201-1881, USA.
authors.forename: Chong
authors.initials: C
authors.lastname: Tao
authors.forename: Calvin
authors.initials: C
authors.lastname: Mukarakate
authors.forename: Richard H
authors.initials: RH
authors.lastname: Judge
authors.forename: Scott A
authors.initials: SA
authors.lastname: Reid