title: Spectral signatures of inter-system crossing mediated by energetically distant doorway levels: examples from the acetylene S1 state.
abstract: We review recent research on the acetylene S(1) state that illustrates how mechanistic rather than phenomenological information about intersystem crossing (ISC) may be obtained directly from frequency-domain spectra. The focus is on the dynamically rich "doorway-mediated" ISC domain that lies between isolated spectroscopic spin-orbit perturbations and statistical-limit interactions between one singlet "bright state" and a quasi-continuum of triplet "dark states". New and improved experimental and data processing techniques permit the statistical-model curtain to be drawn back to reveal mechanistically explicit pathways via one or more identifiable, hence, manipulatable, doorway states, between a user-selected bright state and the undifferentiated bath of dark states.
authors.affiliation: Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.
authors.forename: Kyle L
authors.initials: KL
authors.lastname: Bittinger
authors.forename: Wilton L
authors.initials: WL
authors.lastname: Virgo
authors.forename: Robert W
authors.initials: RW
authors.lastname: Field