skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Fluorescence Correlation Spectroscopy Evidence for Structural Heterogeneity in Ionic Liquids

Abstract

Self-aggregation in room temperature ionic liquids (RTILs) has been a subject of intense interest in recent years. In this work, we provide new experimental evidence for chain length-dependent self-aggregation in RTILs using fluorescence correlation spectroscopy (FCS). In studying a homologous series of N-alkyl-N-methylpyrrolidinium bis(trifluoromethylsulfonyl) imide, [CnMPy][Tf2N] RTILs of varying alkyl chain length (n = 3, 4, 6, 8, and 10), biphasic rhodamine 6G solute diffusion dynamics were observed; both the fast and slow diffusion coefficients decrease with increasing alkyl chain length, with the relative contribution from slower diffusion increasing for longer-chained [CnMPy][Tf2N]. We propose that the biphasic diffusion dynamics originate from self-aggregation of the nonpolar alkyl chains in the cationic [CnMPy]+. The presence of this local liquid structuring provides important insight into the behavior of RTILs relevant to their application in photovoltaics, fuel cells, and batteries.

Authors:
 [1];  [1];  [1];  [1];  [1];  [1]
  1. ORNL
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org.:
USDOE Office of Science (SC)
OSTI Identifier:
1018611
DOE Contract Number:  
DE-AC05-00OR22725
Resource Type:
Journal Article
Journal Name:
Journal of the American Chemical Society
Additional Journal Information:
Journal Volume: 13; Journal Issue: 27; Journal ID: ISSN 0002-7863
Country of Publication:
United States
Language:
English
Subject:
30 DIRECT ENERGY CONVERSION; CHAINS; DIFFUSION; FLUORESCENCE; FUEL CELLS; MOLTEN SALTS; RHODAMINES; SOLUTES; SPECTROSCOPY

Citation Formats

Guo, Jianchang, Baker, Gary A, Hillesheim, Patrick C, Dai, Sheng, Shaw, Robert W, and Mahurin, Shannon Mark. Fluorescence Correlation Spectroscopy Evidence for Structural Heterogeneity in Ionic Liquids. United States: N. p., 2011. Web. doi:10.1039/c1cp20929a.
Guo, Jianchang, Baker, Gary A, Hillesheim, Patrick C, Dai, Sheng, Shaw, Robert W, & Mahurin, Shannon Mark. Fluorescence Correlation Spectroscopy Evidence for Structural Heterogeneity in Ionic Liquids. United States. https://doi.org/10.1039/c1cp20929a
Guo, Jianchang, Baker, Gary A, Hillesheim, Patrick C, Dai, Sheng, Shaw, Robert W, and Mahurin, Shannon Mark. 2011. "Fluorescence Correlation Spectroscopy Evidence for Structural Heterogeneity in Ionic Liquids". United States. https://doi.org/10.1039/c1cp20929a.
@article{osti_1018611,
title = {Fluorescence Correlation Spectroscopy Evidence for Structural Heterogeneity in Ionic Liquids},
author = {Guo, Jianchang and Baker, Gary A and Hillesheim, Patrick C and Dai, Sheng and Shaw, Robert W and Mahurin, Shannon Mark},
abstractNote = {Self-aggregation in room temperature ionic liquids (RTILs) has been a subject of intense interest in recent years. In this work, we provide new experimental evidence for chain length-dependent self-aggregation in RTILs using fluorescence correlation spectroscopy (FCS). In studying a homologous series of N-alkyl-N-methylpyrrolidinium bis(trifluoromethylsulfonyl) imide, [CnMPy][Tf2N] RTILs of varying alkyl chain length (n = 3, 4, 6, 8, and 10), biphasic rhodamine 6G solute diffusion dynamics were observed; both the fast and slow diffusion coefficients decrease with increasing alkyl chain length, with the relative contribution from slower diffusion increasing for longer-chained [CnMPy][Tf2N]. We propose that the biphasic diffusion dynamics originate from self-aggregation of the nonpolar alkyl chains in the cationic [CnMPy]+. The presence of this local liquid structuring provides important insight into the behavior of RTILs relevant to their application in photovoltaics, fuel cells, and batteries.},
doi = {10.1039/c1cp20929a},
url = {https://www.osti.gov/biblio/1018611}, journal = {Journal of the American Chemical Society},
issn = {0002-7863},
number = 27,
volume = 13,
place = {United States},
year = {Sat Jan 01 00:00:00 EST 2011},
month = {Sat Jan 01 00:00:00 EST 2011}
}