Origin of Dark-Channel X-ray Fluorescence from Transition-Metal Ions in Water
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- 作者：Robert Seidel ; Samira Ghadimi ; Kathrin M. Lange ; S茅bastien Bonhommeau ; Mikhail A. Soldatov ; Ronny Golnak ; Alexander Kothe ; Ren茅 K枚nnecke ; Alexander Soldatov ; Stephan Th眉rmer ; Bernd Winter ; Emad F. Aziz
- 刊名：The Journal of the American Chemical Society
- 出版年：2012
- 出版时间：January 25, 2012
- 年：2012
- 卷：134
- 期：3
- 页码：1600-1605
- 全文大小：373K
- 年卷期：v.134,no.3(January 25, 2012)
- ISSN：1520-5126
文摘
The nonradiative dark channels in the L-edge fluorescence spectra from transition-metal aqueous solution identify the ultrafast charge-transfer processes playing an important role in many biological and chemical systems. Yet, the exact origin of such spectral dips with respect to the X-ray transmission spectrum has remained unclear. In the present study we explore the nature of the underlying decay mechanism of 2p core-excited Co2+ in water by probing the nonradiative Auger-type electron emission channel using photoelectron spectroscopy from a liquid microjet. Our measurements demonstrate unequivocally that metal-to-water charge transfer quenches fluorescence and will inevitably lead to a dip in the total-fluorescence-yield X-ray absorption spectrum. This is directly revealed from the resonant enhancement of valence signal intensity arising from the interference of two identical final states created by a direct and Auger-electron emission, respectively.