Ultraviolet photochemical reaction of [Fe(III)(C2O4)3]3- in aqueous solutions studied by femtosecond time-resolved X-ray absorption spectroscopy using an X-ray free electron laser
| Autor: | S. Owada, Kazuhiko Misawa, Yuichi Inubushi, N. C.-M. Bartlett, Makina Yabashi, Yoshi-Ichi Suzuki, Naoya Kurahashi, Yuki Obara, Shutaro Karashima, Tadashi Togashi, Tetsuo Katayama, S. Y. Liu, Yoshihiro Ogi, Petr Slavíček, Martina Rubešová, Toshinori Suzuki, Kanade Ogawa |
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| Jazyk: | angličtina |
| Rok vydání: | 2015 |
| Předmět: |
X-ray absorption spectroscopy
Radiation Absorption spectroscopy Chemistry X-ray Analytical chemistry Condensed Matter Physics Photochemistry medicine.disease_cause Dissociation (chemistry) Photoexcitation ARTICLES Liquids and Solutions Femtosecond lcsh:QD901-999 medicine Density functional theory lcsh:Crystallography Instrumentation Spectroscopy Ultraviolet |
| Zdroj: | Structural Dynamics Structural Dynamics, Vol 2, Iss 3, Pp 034901-034901-19 (2015) |
| ISSN: | 2329-7778 |
| Popis: | Time-resolved X-ray absorption spectroscopy was performed for aqueous ammonium iron(III) oxalate trihydrate solutions using an X-ray free electron laser and a synchronized ultraviolet laser. The spectral and time resolutions of the experiment were 1.3 eV and 200 fs, respectively. A femtosecond 268 nm pulse was employed to excite [Fe(III)(C2O4)3](3-) in solution from the high-spin ground electronic state to ligand-to-metal charge transfer state(s), and the subsequent dynamics were studied by observing the time-evolution of the X-ray absorption spectrum near the Fe K-edge. Upon 268 nm photoexcitation, the Fe K-edge underwent a red-shift by more than 4 eV within 140 fs; however, the magnitude of the redshift subsequently diminished within 3 ps. The Fe K-edge of the photoproduct remained lower in energy than that of [Fe(III)(C2O4)3](3-). The observed red-shift of the Fe K-edge and the spectral feature of the product indicate that Fe(III) is upon excitation immediately photoreduced to Fe(II), followed by ligand dissociation from Fe(II). Based on a comparison of the X-ray absorption spectra with density functional theory calculations, we propose that the dissociation proceeds in two steps, forming first [(CO2 (•))Fe(II)(C2O4)2](3-) and subsequently [Fe(II)(C2O4)2](2-). |
| Databáze: | OpenAIRE |
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