Action-Absorption Spectroscopy at the Band Origin of the Deprotonated Green Fluorescent Protein Chromophore In Vacuo

The application of action spectroscopy in connection with determination of the S-0 to S-1 band origin in the GFP anion model chromophore (deprotonated HBDI) is discussed. We specifically address the consequences of the lowest vibrational levels in S-1 being located behind a potential-energy barrier that inhibits internal conversion to the S0 electronic ground state. Action spectroscopy based on consecutive absorption of two photons together with internal conversion will as a consequence reveal an apparent band origin that is significantly blue-shifted.

Automated summary

The study discusses the application of action spectroscopy in determining the S-0 to S-1 band origin in the GFP anion model chromophore. It points out the potential consequences of the lowest vibrational levels in S-1 leading to a significant blue-shift in the apparent band origin.