Rotational selection rules for nonradiative processes

Abstract

Recent experiments indicate that nonradiative transitions not only differ for various single vibronic levels but are also strongly dependent on the rotational states involved. Thus the rotational selection rules should be considered for these rotational transitions. Rotational matrix elements and selection rules are presented for internal conversion between two triplet or two singlet states and for intersystem crossing between a singlet and a triplet for polyatomic molecules in Hund's case b. The selection rules are, in general, different for each process and depend on the nature of the angular momentum coupling as well as the interaction operator.

Hyperfine quantum beats in the 209 nm fluorescence excitation spectrum of cyanogen

“…The nuclear quadrupole interaction for Iϭ1 results in only a small difference in energy between the FϭNϮ1 hyperfine levels for large N. 15 This difference is partially resolved for Fϭ7 and 9 levels shown in the Fourier-transformed fluorescence decay of Fig. 9, while the FϭNϮ1 beats were completely overlapped for the R(7) and P(23) [R (21)] transitions of the 219 nm band. 9 A check on the F assignments of Fig.…”

“…The coupling rates between the S 1 manifold and the T 1 and S 0 manifolds depend on the existence of numerous nearresonant intermanifold interactions between vibronic states, subject to the selection rules ⌬Nϭ0 for S 1 -S 0 and ⌬N ϭ0,Ϯ1 for S 1 -T 1 couplings. 21 The observed variation of lifetimes may therefore reflect a sparse distribution of vibronic states of appropriate symmetries and rotational quantum numbers.…”

“…2͒ is consistent with an unresolvably small splitting between the Iϭ0 and Iϭ2 states with Fϭ1. If we adopt the labeling F Ј ,F ϭ 31 , 21 , and 32 for these three principal beats, the quantum beats with the observed frequencies 21 /2ϭ2.22 MHz and 31 /2ϭ0. 16 MHz are actually unresolved doublets, while the beat at 32 /2ϭ2.06 MHz is a singlet; the sixth quantum beat, corresponding to the Iϭ0 and Iϭ2 splitting for Fϭ1, is unresolvable from the zero frequency fluorescence component.…”

Magnetic Field Influence on Dynamics of Singlet‐Triplet Conversion

“…Using the theory developed by Howard and Schlag [108], the operator of the spin-orbit interaction for the case studied may be written as…”

S–T conversion induced by external magnetic field in gaseous oxalylfluoride excited to the 7151-level of the à 1Au state

“…The T (0) ratio is defined as 21 that the S -T coupling in the oxalylfluoride molecule is mainly determined by the second order vibronicspin-orbit ͑VSO͒ interaction. The oxalylfluoride molecule may be treated using the Hund's case ͑b͒ and prolate symmetric top approximations, for which the selection rules for the VSO interaction may be represented as 26,27 ⌬Nϭ0,Ϯ1; ⌬K a ϭϮ1 ͑2͒…”