Direct observation of electronic relaxation dynamics in adenine via time-resolved photoelectron spectroscopy

J Am Chem Soc. 2004 Mar 3;126(8):2262-3. doi: 10.1021/ja030532q.

Abstract

We present femtosecond time-resolved photoelectron spectra of adenine in a molecular beam, recorded at pump wavelengths of 250, 267, and 277 nm. This leads to initial excitation of the bright S2(pipi*). Close to the band origin (277 nm), the lifetime is several picoseconds. Higher vibronic levels (267 and 250 nm excitation) show much shorter lifetimes of t < 50 fs, and we observe strong coupling between S2(pipi*) and S1(npi*). Rapid internal conversion (t < 50 fs) populates the lower lying S1(npi*) state which has a lifetime of 750 fs. At 267 nm, we found evidence for an additional channel which is consistent with the dissociative S3(pisigma*) state, previously proposed as an ultrafast relaxation pathway from S2(pipi*).

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adenine / chemistry*
  • Electrons
  • Spectrum Analysis / methods*

Substances

  • Adenine