X-ray transient absorption reveals the 1Au (nπ*) state of pyrazine in electronic relaxation

Valeriu Scutelnic; Shota Tsuru; Mátyás Pápai; Zheyue Yang; Michael Epshtein; Tian Xue; Eric Haugen; Yuki Kobayashi; Anna I Krylov; Klaus B Møller; Sonia Coriani; Stephen R Leone

doi:10.1038/s41467-021-25045-0

X-ray transient absorption reveals the ¹A_u (nπ*) state of pyrazine in electronic relaxation

Nat Commun. 2021 Aug 18;12(1):5003. doi: 10.1038/s41467-021-25045-0.

Authors

Valeriu Scutelnic¹, Shota Tsuru^{2

3}, Mátyás Pápai^{2

4}, Zheyue Yang^{1

5}, Michael Epshtein^{1

6

7}, Tian Xue¹, Eric Haugen^{1

6}, Yuki Kobayashi^{1

8}, Anna I Krylov⁹, Klaus B Møller², Sonia Coriani², Stephen R Leone^{10

11

12}

Affiliations

¹ Department of Chemistry, University of California, Berkeley, CA, USA.
² DTU Chemistry, Technical University of Denmark, Kongens Lyngby, Denmark.
³ Ruhr-Universität, Bochum, Germany.
⁴ Wigner Research Centre for Physics, Budapest, Hungary.
⁵ , Shanghai, China.
⁶ Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA.
⁷ , Beer-Sheva, Israel.
⁸ Stanford PULSE Institute, SLAC National Accelerator Laboratory, Menlo Park, CA, USA.
⁹ Department of Chemistry, University of Southern California, Los Angeles, CA, USA.
¹⁰ Department of Chemistry, University of California, Berkeley, CA, USA. srl@berkeley.edu.
¹¹ Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA. srl@berkeley.edu.
¹² Department of Physics, University of California, Berkeley, CA, USA. srl@berkeley.edu.

Abstract

Electronic relaxation in organic chromophores often proceeds via states not directly accessible by photoexcitation. We report on the photoinduced dynamics of pyrazine that involves such states, excited by a 267 nm laser and probed with X-ray transient absorption spectroscopy in a table-top setup. In addition to the previously characterized ¹B_2u (ππ*) (S₂) and ¹B_3u (nπ*) (S₁) states, the participation of the optically dark ¹A_u (nπ*) state is assigned by a combination of experimental X-ray core-to-valence spectroscopy, electronic structure calculations, nonadiabatic dynamics simulations, and X-ray spectral computations. Despite ¹A_u (nπ*) and ¹B_3u (nπ*) states having similar energies at relaxed geometry, their X-ray absorption spectra differ largely in transition energy and oscillator strength. The ¹A_u (nπ*) state is populated in 200 ± 50 femtoseconds after electronic excitation and plays a key role in the relaxation of pyrazine to the ground state.

Publication types

Research Support, U.S. Gov't, Non-P.H.S.
Research Support, Non-U.S. Gov't