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Title: Probing ultrafast ππ*/nπ* internal conversion in organic chromophores via K-edge resonant absorption

Abstract

Many photoinduced processes including photosynthesis and human vision happen in organic molecules and involve coupled femtosecond dynamics of nuclei and electrons. Organic molecules with heteroatoms often possess an important excited-state relaxation channel from an optically allowed ππ* to a dark nπ* state. The ππ*/nπ* internal conversion is difficult to investigate, as most spectroscopic methods are not exclusively sensitive to changes in the excited-state electronic structure. Here, we report achieving the required sensitivity by exploiting the element and site specificity of near-edge soft X-ray absorption spectroscopy. As a hole forms in the n orbital during ππ*/nπ* internal conversion, the absorption spectrum at the heteroatom K-edge exhibits an additional resonance. We demonstrate the concept using the nucleobase thymine at the oxygen K-edge, and unambiguously show that ππ*/nπ* internal conversion takes place within (60 ± 30) fs. Furthermore, high-level-coupled cluster calculations confirm the method’s impressive electronic structure sensitivity for excited-state investigations.

Authors:
ORCiD logo [1];  [2];  [1];  [3];  [4];  [1];  [5];  [6];  [7];  [1];  [4];  [1];  [8]; ORCiD logo [7];  [9];  [1];  [10]; ORCiD logo [1];  [5];  [1] more »;  [11];  [1];  [2];  [12] « less
  1. SLAC National Accelerator Lab., Menlo Park, CA (United States)
  2. SLAC National Accelerator Lab., Menlo Park, CA (United States); Norwegian Univ. of Science and Technology, Trondheim (Norway)
  3. Univ. degli Studi di Trieste, Trieste (Italy); Technical Univ. of Denmark, Lyngby (Denmark)
  4. Univ. of Gothenburg, Gothenburg (Sweden)
  5. Univ. of Connecticut, Storrs, CT (United States)
  6. SLAC National Accelerator Lab., Menlo Park, CA (United States); Argonne National Lab. (ANL), Lemont, IL (United States); Northwestern Univ., Evanston, IL (United States)
  7. SLAC National Accelerator Lab., Menlo Park, CA (United States); Stanford Univ., Stanford, CA (United States)
  8. Ecole Polytechnique Federal de Lausanne, Lausanne (Switzerland)
  9. SLAC National Accelerator Lab., Menlo Park, CA (United States); Stanford Univ., Stanford, CA (United States); RIKEN, Saitama (Japan)
  10. Uppsala Univ., Uppsala (Sweden)
  11. Elettra-Sincrotrone Trieste, Trieste (Italy)
  12. SLAC National Accelerator Lab., Menlo Park, CA (United States); Univ. Potsdam, Potsdam (Germany)
Publication Date:
Research Org.:
SLAC National Accelerator Lab., Menlo Park, CA (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1369334
Grant/Contract Number:  
AC02-76SF00515
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Nature Communications
Additional Journal Information:
Journal Volume: 8; Journal Issue: 1; Journal ID: ISSN 2041-1723
Publisher:
Nature Publishing Group
Country of Publication:
United States
Language:
English
Subject:
74 ATOMIC AND MOLECULAR PHYSICS; atomic and molecular interactions with photons; chemical physics

Citation Formats

Wolf, T. J. A., Myhre, R. H., Cryan, J. P., Coriani, S., Squibb, R. J., Battistoni, A., Berrah, N., Bostedt, C., Bucksbaum, P., Coslovich, G., Feifel, R., Gaffney, K. J., Grilj, J., Martinez, T. J., Miyabe, S., Moeller, S. P., Mucke, M., Natan, A., Obaid, R., Osipov, T., Plekan, O., Wang, S., Koch, Henrik, and Guhr, M.. Probing ultrafast ππ*/nπ* internal conversion in organic chromophores via K-edge resonant absorption. United States: N. p., 2017. Web. doi:10.1038/s41467-017-00069-7.
Wolf, T. J. A., Myhre, R. H., Cryan, J. P., Coriani, S., Squibb, R. J., Battistoni, A., Berrah, N., Bostedt, C., Bucksbaum, P., Coslovich, G., Feifel, R., Gaffney, K. J., Grilj, J., Martinez, T. J., Miyabe, S., Moeller, S. P., Mucke, M., Natan, A., Obaid, R., Osipov, T., Plekan, O., Wang, S., Koch, Henrik, & Guhr, M.. Probing ultrafast ππ*/nπ* internal conversion in organic chromophores via K-edge resonant absorption. United States. doi:10.1038/s41467-017-00069-7.
Wolf, T. J. A., Myhre, R. H., Cryan, J. P., Coriani, S., Squibb, R. J., Battistoni, A., Berrah, N., Bostedt, C., Bucksbaum, P., Coslovich, G., Feifel, R., Gaffney, K. J., Grilj, J., Martinez, T. J., Miyabe, S., Moeller, S. P., Mucke, M., Natan, A., Obaid, R., Osipov, T., Plekan, O., Wang, S., Koch, Henrik, and Guhr, M.. Thu . "Probing ultrafast ππ*/nπ* internal conversion in organic chromophores via K-edge resonant absorption". United States. doi:10.1038/s41467-017-00069-7. https://www.osti.gov/servlets/purl/1369334.
@article{osti_1369334,
title = {Probing ultrafast ππ*/nπ* internal conversion in organic chromophores via K-edge resonant absorption},
author = {Wolf, T. J. A. and Myhre, R. H. and Cryan, J. P. and Coriani, S. and Squibb, R. J. and Battistoni, A. and Berrah, N. and Bostedt, C. and Bucksbaum, P. and Coslovich, G. and Feifel, R. and Gaffney, K. J. and Grilj, J. and Martinez, T. J. and Miyabe, S. and Moeller, S. P. and Mucke, M. and Natan, A. and Obaid, R. and Osipov, T. and Plekan, O. and Wang, S. and Koch, Henrik and Guhr, M.},
abstractNote = {Many photoinduced processes including photosynthesis and human vision happen in organic molecules and involve coupled femtosecond dynamics of nuclei and electrons. Organic molecules with heteroatoms often possess an important excited-state relaxation channel from an optically allowed ππ* to a dark nπ* state. The ππ*/nπ* internal conversion is difficult to investigate, as most spectroscopic methods are not exclusively sensitive to changes in the excited-state electronic structure. Here, we report achieving the required sensitivity by exploiting the element and site specificity of near-edge soft X-ray absorption spectroscopy. As a hole forms in the n orbital during ππ*/nπ* internal conversion, the absorption spectrum at the heteroatom K-edge exhibits an additional resonance. We demonstrate the concept using the nucleobase thymine at the oxygen K-edge, and unambiguously show that ππ*/nπ* internal conversion takes place within (60 ± 30) fs. Furthermore, high-level-coupled cluster calculations confirm the method’s impressive electronic structure sensitivity for excited-state investigations.},
doi = {10.1038/s41467-017-00069-7},
journal = {Nature Communications},
number = 1,
volume = 8,
place = {United States},
year = {Thu Jun 22 00:00:00 EDT 2017},
month = {Thu Jun 22 00:00:00 EDT 2017}
}

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