Rate constants of intersystem crossing, El Sayed rules

6 Rate Constants of Intersystem Crossing, El Sayed Rules 

Rates of ISC are around five orders of magnitude slower than those of IC in organic molecules not carrying heavy atoms and also obey the energy gap law (Equation 2.23). 

Caution is necessary when using Equation 2.23 to calculate singlet to triplet ISC rate constants, because the transition from Si may well occur to an upper triplet state Tx rather than to T1 as long as E(TX) E(Si). This will reduce the energy gap and may at the same 

JThe symmetry labels o and n are used to designate molecular orbitals (MOs) that are symmetric and antisymmetric, respectively, with respect to a plane of symmetry of the molecular structure (Section 4.4). Nonbonding o-orbitals (lone pairs) are designated with the label n. 

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