Correlation between Soft X-ray Absorption and Emission Spectra of the Nitrogen Atoms within Imidazolium-Based Ionic Liquids

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• 作者：Yuka Horikawa ; Takashi Tokushima ; Osamu Takahashi ; Hiroshi Hoke ; Toshiyuki Takamuku
• 刊名：Journal of Physical Chemistry B
• 出版年：2016
• 出版时间：August 4, 2016
• 年：2016
• 卷：120
• 期：30
• 页码：7480-7487
• 全文大小：441K
• 年卷期：0
• ISSN：1520-5207

文摘

Soft X-ray absorption spectroscopy (XAS) has been performed on the N K-edge of two imidazolium-based ionic liquids (ILs), 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)amide ([C₂mim][TFSA]) and 1-ethyl-3-methylimidazolium bromide ([C₂mim][Br]), to clarify the electronic structures of the ILs. Soft X-ray emission spectroscopy (XES) has also been applied to the ILs by excitation at various X-ray energies according to the XAS spectra. It was possible to fully associate the XAS peaks with the XES peaks. Additionally, both XAS and XES spectra of the ILs were well reproduced by the theoretical spectra for a single-molecule model on [C₂mim]⁺ and [TFSA]⁻ using density functional theory. The assignments for the XAS and XES peaks of the ILs were accomplished from both experimental and theoretical approaches. The theoretical XAS and XES spectra of [C₂mim]⁺ and [TFSA]⁻ did not significantly depend on the conformations of the ions. The reproducibility of the theoretical spectra for the single-molecule model suggested that the interactions between the cations and anions are very weak in the ILs, thus scarcely influencing the electronic structures of the nitrogen atoms.