1-乙基-3-甲基咪唑双（三氟甲基磺酰）胺室温离子液体表面的温度依赖性电子和振动结构：XPS、UPS、MIES和HREELS研究

Temperature-dependent electronic and vibrational structure of the 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)amide room-temperature ionic liquid surface: a study with XPS, UPS, MIES, and HREELS.

作者信息

Krischok S, Eremtchenko M, Himmerlich M, Lorenz P, Uhlig J, Neumann A, Ottking R, Beenken W J D, Höfft O, Bahr S, Kempter V, Schaefer J A

机构信息

Institut für Physik and Institut für Mikro- und Nanotechnologien, Technische Universität Ilmenau, P.O. Box 100565, D-98684 Ilmenau, Germany.

出版信息

J Phys Chem B. 2007 May 10;111(18):4801-6. doi: 10.1021/jp067136p.

DOI:10.1021/jp067136p

PMID:17474703

Abstract

The near-surface structure of the room-temperature ionic liquid 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)amide has been investigated as a function of temperature between 100 and 620 K. We used a combination of photoelectron spectroscopies (XPS and UPS), metastable induced electron spectroscopy (MIES), and high-resolution electron energy loss spectroscopy (HREELS). The valence band and HREELS spectra are interpreted on the basis of density functional theory (DFT) calculations. At room temperature, the most pronounced structures in the HREELS, UPS, and MIES spectra are related to the CF3 group in the anion. Spectral changes observed at 100 K are interpreted as a change of the molecular orientation at the outermost surface, when the temperature is lowered. At elevated temperatures, early volatilization, starting at 350 K, is observed under reduced pressure.

摘要

研究了室温离子液体1-乙基-3-甲基咪唑双（三氟甲基磺酰）胺在100至620 K温度范围内的近表面结构。我们结合使用了光电子能谱（XPS和UPS）、亚稳诱导电子能谱（MIES）和高分辨率电子能量损失谱（HREELS）。价带和HREELS光谱基于密度泛函理论（DFT）计算进行解释。在室温下，HREELS、UPS和MIES光谱中最明显的结构与阴离子中的CF3基团有关。当温度降低时，在100 K观察到的光谱变化被解释为最外表面分子取向的变化。在高温下，在减压条件下观察到从350 K开始的早期挥发。