Ultrafast XANES Monitors Femtosecond Sequential Structural Evolution in Photoexcited Coenzyme B12
| Autor: | Lindsay B Michocki, Pawel M. Kozlowski, Sanghoon Song, Aniruddha Deb, James E. Penner-Hahn, Roseanne J. Sension, James M. Glownia, Nicholas A. Miller, Kevin J. Kubarych, Roberto Alonso-Mori, Danielle L. Sofferman, Arkaprabha Konar |
|---|---|
| Rok vydání: | 2019 |
| Předmět: |
Materials science
010304 chemical physics 010402 general chemistry 01 natural sciences Molecular physics XANES 0104 chemical sciences Surfaces Coatings and Films Dipole Picosecond 0103 physical sciences Ultrafast laser spectroscopy Femtosecond Potential energy surface Materials Chemistry Stimulated emission Physical and Theoretical Chemistry Absorption (electromagnetic radiation) |
| Zdroj: | The Journal of Physical Chemistry B. 124:199-209 |
| ISSN: | 1520-5207 1520-6106 |
| DOI: | 10.1021/acs.jpcb.9b09286 |
| Popis: | Polarized X-ray absorption near-edge structure (XANES) at the Co K-edge and broadband UV–vis transient absorption are used to monitor the sequential evolution of the excited-state structure of coenzyme B12 (adenosylcobalamin) over the first picosecond following excitation. The initial state is characterized by sub-100 fs sequential changes around the central cobalt. These are polarized first in the y-direction orthogonal to the transition dipole and 50 fs later in the x-direction along the transition dipole. Expansion of the axial bonds follows on a ca. 200 fs time scale as the molecule moves out of the Franck–Condon active region of the potential energy surface. On the same 200 fs time scale there are electronic changes that result in the loss of stimulated emission and the appearance of a strong absorption at 340 nm. These measurements provide a cobalt-centered movie of the excited molecule as it evolves to the local excited-state minimum. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|