A phase-space approach to the T1⇝S radiationless decay in benzene: The effect of deuteration

Abstract

The influence of full deuteration on the T1 right arrow-wavy S0 intersystem crossing in benzene is studied by a phase space approach. A full treatment of all the vibrational modes in the molecule leads to a ratio of the rate between the two isotopomers which is very close to the experimental value. Several aspects of the results are compared to previous estimates, and the effects of anharmonicity on the rates and accepting modes are examined. This first successful application of the method to a real physical system encourages the possibility of establishing a routine procedure for simple calculations of transition rates even for relatively large molecules.

Geometry and bonding in the ground and lowest triplet state of D6h symmetric crenellated edged C6[3m(m−1)+1]H6(2m−1) (m=2,…,6) graphene hydrocarbon molecules

“…In our calculations for a planar benzene geometry we found two triplet state conformations with D 2h symmetry in agreement with the Gaussian calculations by Zamstein et al [37]. These are included in Table A1.…”

“…Zamstein et al [37] calculated features of the triplet state potential energy surface of benzene using Gaussian DFT 3BLYP as part of a study of radiationless transitions. In their paper, amongst the local minima, there were two very close in energy, called quinoidal and anti-quinoidal, with D 2h symmetry.…”

Isotopic effect and temperature dependent intramolecular excitation energy transfer in a model donor–acceptor dyad

“…Other theoretical work using saddle point methods to numerically evaluate the rate constant in the statistical limit give ratios of k (H) /k (D) = 24 36 to k (H) /k (D) = 1.1 × 10 4 and 2.2 × 10 2 depending upon the parameters for the e 2g mode 37 . Finally, recent work by Zamstein using an ab initio parameterization and a phase-space approach for the non-radiative 3 B 1u → 1 A 1g triplet to singlet conversion in benzene and benzene-d 6 gives a k (H) /k (D) = 3.7 − 7.8 38 .…”

Bonding and Magnetism in High Symmetry Nano-Sized Graphene Molecules: Linear Acenes C<SUB>4<I>m</I>+2</SUB>H<SUB>2<I>m</I>+4</SUB> (<I>m</I>=2,&hellip;25); Zigzag Hexangulenes C<SUB>6<I>m</I><SUP>**</SUP>2</SUB>H<SUB>6<I>m</I></SUB> (<I>m</I>=2,&hellip;10); Crenelated Hexangulenes C<SUB>6(3<I>m</I><SUP>**</SUP>2&minus;3<I>m</I

“…This provides a measure of reassurance that the plane wave based single determinant wavefunction methodology used here can get close to results of other ab initio methods. 31) by a different method. The S1a triplet has two short parallel CC bonds with the spin localized on the para-located carbon atoms C1 (as in CH ) and C4 (again like CH ).…”