Anisotropy factor spectra for weakly allowed electronic transitions in chiral ketones

Abstract

Quantum chemical calculations of one-photon absorption, electronic circular dichroism and 
anisotropy factor spectra for the A-band transition of fenchone, camphor and 
3-methylcyclopentanone (3MCP) are reported. While the only weakly allowed nature of the 
transition leads to comparatively large anisotropies, a proper theoretical description of the 
absorption for such a transition requires to account for non-Condon effects. We present 
experimental data for the anisotropy of 3MCP in the liquid phase and show that corresponding 
Herzberg-Teller corrections are critical to reproduce the main experimental features. 
The results obtained with our comprehensive theoretical model highlight the importance of the 
vibrational degree of freedom, paving the way for a deeper understanding of the dynamics in 
electronic circular dichroism.