Electric field-induced changes in the absorption spectrum (electrochromism) have been used to obtain the ground (S0) and second excited (S2) state dipole moments of two sulphur-containing heteroaromatics, pyranthione and xanthione, which have C2v symmetry. The magnitude of the change in the dipole moment (Δμ = |μ(S2) - μ(S0)|) was found to be nearly 2 D for both compounds, which is consistent with results reported previously based on microscopic solvent shifts. The transition dipole moment for the S0-S2 transition is parallel to the direction of the ground state dipole moment (μg), i.e. along the C2 axis which contains the CS bond. For comparison the ground state dipole moments of both compounds have also been calculated using the AM1 method will full geometry optimization.
ASJC Scopus subject areas
- Physical and Theoretical Chemistry
- Condensed Matter Physics
- Atomic and Molecular Physics, and Optics
- Surfaces and Interfaces