Abstract
We found that specific nuclear motion along low-frequency modes is effective in coupling electronic states and that this motion prevail in some small molecules. Thus, in direct contradiction to what is expected based on the standard models, the internal conversion process can proceed faster for smaller molecules. Specifically, we focus on the S2→S1 internal conversion in cyclobutanone, cyclopentanone, and cyclohexanone. By means of time-resolved mass spectrometry and photoelectron spectroscopy the relative rate of this transition is determined to be 13:2:1. Remarkably, we observe coherent nuclear motion on the S2 surface in a ring-puckering mode and motion along this mode in combination with symmetry considerations allow for a consistent explanation of the observed relative time-scales not afforded by only considering the density of vibrational states or other aspects of the standard models. Inherently non-ergodic: The nature of a fundamental process such as internal conversion is inherently more complex than simple models might suggest. By following the vibrational dynamics during a transition between two electronic states, the complex nature can be disentangled and it is revealed how specific low-frequency modes play a significant role revealing the non-ergodic behavior (see picture).
| Original language | English |
|---|---|
| Journal | ChemPhysChem |
| Volume | 13 |
| Issue number | 3 |
| Pages (from-to) | 820-827 |
| Number of pages | 8 |
| ISSN | 1439-4235 |
| DOIs | |
| Publication status | Published - Feb 2012 |