Optical measurements of impurities in room-temperature ionic liquids

Keywords

Absorption spectra, 1-methylimidazole, 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([EMIM][TFSI]), Mole fraction, Ultraviolet (UV) wavelengths, Infrared (IR) wavelengths, UV measurements, Time-dependent density functional theory (DFT) calculations

Abstract

The absorption spectra of 1-methylimidazole and 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, [EMIM][TFSI], mixtures from 0% to 20% mole fraction are reported at ultraviolet to infrared wavelengths. Quantitative measurement of 1-methylimidazole in [EMIM][TFSI] is reported using an isolated 1-methylimidazole absorption feature at 1520 cm−1. UV measurements reveal a 1-methylimidazole absorption feature at 270 nm and a 260 nm feature for [EMIM][TFSI]. Absorption at 280 nm is demonstrated to scale with 1-methylimidazole mole fraction in [EMIM][TFSI] and is used to measure 1-methylimidazole mole fractions. Absorption is shown to increase around 240 nm upon addition of 1-methylimidazole to [EMIM][TFSI], which preliminary time-dependent density functional theory (DFT) calculations identify as an intermolecular excitation between [EMIM][TFSI] and 1-methylimidazole. We report recommendations for UV and infrared detection schemes for the quantitative detection of 1-methylimidazole in [EMIM][TFSI].

Original Publication Citation

Jason M. Porter, Christopher B. Dreyer, David Bicknase, Shubham Vyas, C. Mark Maupin, Joe Poshusta, Jerry Martin, Optical measurements of impurities in room-temperature ionic liquids, Journal of Quantitative Spectroscopy and Radiative Transfer, vol. 133, (2014) pp. 300-310.

Document Type

Peer-Reviewed Article

Publication Date

2014

Publisher

Elsevier

Language

English

College

Ira A. Fulton College of Engineering and Technology

Department

Mechanical Engineering

University Standing at Time of Publication

Associate Professor

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