Journal Article

PUBDB-2026-01588

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Femtosecond Soft X-ray Absorption Spectroscopy Identifies Metal-Centered S$_1$ Excited State of Cyanocobalamin

Ghodrati, N. ; Adriano, L. ; Berry, S. M. ; Carinan, C. ; Carley, R. ; Chang, Y.-P. ; Danilevski, C. ; David, C. ; Engel, R. ; Gerasimova, N. ; Hammer, D. ; Harder, M. ; Lamb, R. M. ; Lomidze, D. ; Mamyrbayev, T. ; McClain, T. P. ; Mukherjee, A. ; Porro, M. ; Teichmann, M. ; Turcato, M. ; Valerio, J. ; Wang, R.-P. ; Yin, Z.Extern*XFEL.EU*DESY* ; Scherz, A. ; Huse, N. ; Penner-Hahn, J. E. ; Sension, R. J. ; Le Guyader, L. (Corresponding author)XFEL.EU* ; Kuiken, B. v. (Corresponding author)XFEL.EU*

2026
ACS Publications Washington, DC

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Please use a persistent id in citations: doi:10.1021/jacs.6c01860  doi:10.3204/PUBDB-2026-01588

Abstract: Time-resolved X-ray absorption spectroscopy(TRXAS) at the Co L3-edge was used to identify metal-centered(MC) character in the S1 excited state of cyanocobalamin (CNCbl).Cobalamins have UV/visible spectra that are dominated by intensecorrin-based excitations, but these ligand-centered states energeti-cally overlap with charge transfer and MC excited states that may bepopulated following photoexcitation. Ultrafast optical and hard X-ray spectroscopy have shown that CNCbl forms a structurallydistorted S1 state, but these probes lack a clear signature of the S1electronic identity, which theory has suggested is a ligand-to-metalcharge transfer (LMCT) state. Femtosecond soft X-ray TRXASoffers greater state-selectivity than many optical or hard X-rayprobes but has, so far, been limited to highly concentrated (≥100mM) samples. A new experimental setup at the European X-ray Free Electron Laser (EuXFEL) that enables studies of sub-10 mMsamples and provides ∼100 fs time-resolution is used to measure the TRXAS of CNCbl at the Co L3-edge. Comparison of the L3-edge XAS spectrum measured at 0.8 ps with ligand field multiplet simulations indicates that the S1 state is primarily an MC excitedstate. The sub-20 μOD detection sensitivity achieved in this study demonstrates the possibility of applying this method to a widerange of naturally occurring and synthetic transition metal complexes.

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Contributing Institute(s):

1. SCS (XFEL_E2_SCS)

Research Program(s):

1. 6G13 - Accelerator of European XFEL (POF4-6G13) (POF4-6G13)

Experiment(s):

1. Experiments at XFEL

Appears in the scientific report 2026

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Database coverage:
; ; ; BIOSIS Previews ; Biological Abstracts ; Chemical Reactions ; Clarivate Analytics Master Journal List ; Current Contents - Life Sciences ; Current Contents - Physical, Chemical and Earth Sciences ; Ebsco Academic Search ; Essential Science Indicators ; IF >= 15 ; Index Chemicus ; JCR ; Nationallizenz ; SCOPUS ; Science Citation Index Expanded ; Web of Science Core Collection

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