2015年5月
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
STRUCTURAL DYNAMICS
- 巻
- 2
- 号
- 3
- 開始ページ
- 034901
- 終了ページ
- 記述言語
- 英語
- 掲載種別
- 研究論文(学術雑誌)
- DOI
- 10.1063/1.4918803
- 出版者・発行元
- AMER INST PHYSICS
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 center dot) Fe(II)(C2O4)(2)](3-) and subsequently [Fe(II)(C2O4)(2)](2-). (C) 2015 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution 3.0 Unported License.
- リンク情報
- ID情報
-
- DOI : 10.1063/1.4918803
- ISSN : 2329-7778
- Web of Science ID : WOS:000357690900001