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

Title: Carbon dioxide in an ionic liquid: Structural and rotational dynamics

Abstract

Ionic liquids (ILs), which have widely tunable structural motifs and intermolecular interactions with solutes, have been proposed as possible carbon capture media. In order to inform the choice of an optimal ionic liquid system, it can be useful to understand the details of dynamics and interactions on fundamental time scales (femtoseconds to picoseconds) of dissolved gases, particularly carbon dioxide (CO 2), within the complex solvation structures present in these uniquely organized materials. The rotational and local structural fluctuation dynamics of CO 2 in the room temperature ionic liquid 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (EmimNTf2) were investigated by using ultrafast infrared spectroscopy to interrogate the CO 2 asymmetric stretch. Polarization-selective pump probe measurements yielded the orientational correlation function of the CO 2 vibrational transition dipole. It was found that reorientation of the carbon dioxide occurs on 3 time scales: 0.91 ± 0.03, 8.3 ± 0.1, 54 ± 1 ps. The initial two are attributed to restricted wobbling motions originating from a gating of CO 2 motions by the IL cations and anions. The final (slowest) decay corresponds to complete orientational randomization. Two-dimensional infrared vibrational echo (2D IR) spectroscopy provided information on structural rearrangements, which cause spectral diffusion, through the time dependence of the 2Dmore » line shape. Analysis of the time-dependent 2D IR spectra yields the frequency-frequency correlation function (FFCF). Polarization-selective 2D IR experiments conducted on the CO 2 asymmetric stretch in the parallel- and perpendicular-pumped geometries yield significantly different FFCFs due to a phenomenon known as reorientation-induced spectral diffusion (RISD), revealing strong vector interactions with the liquid structures that evolve slowly on the (independently measured) rotation time scales. To separate the RISD contribution to the FFCF from the structural spectral diffusion contribution, the previously developed first order Stark effect RISD model is reformulated to describe the second order (quadratic) Stark effect—the first order Stark effect vanishes because CO 2 does not have a permanent dipole moment. Through this analysis, we characterize the structural fluctuations of CO 2 in the ionic liquid solvation environment, which separate into magnitude-only and combined magnitude and directional correlations of the liquid’s time dependent electric field. This new methodology will enable highly incisive comparisons between CO 2 dynamics in a variety of ionic liquid systems.« less

Authors:
ORCiD logo [1]; ORCiD logo [1];  [1];  [1]; ORCiD logo [1];  [1]
  1. Stanford Univ., CA (United States). Dept. of Chemistry
Publication Date:
Research Org.:
Stanford Univ., CA (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22). Chemical Sciences, Geosciences & Biosciences Division; US Air Force Office of Scientific Research (AFOSR)
OSTI Identifier:
1468530
Alternate Identifier(s):
OSTI ID: 1241420
Grant/Contract Number:  
FG03-84ER13251; FA9550-16-1-0104
Resource Type:
Accepted Manuscript
Journal Name:
Journal of Chemical Physics
Additional Journal Information:
Journal Volume: 144; Journal Issue: 10; Journal ID: ISSN 0021-9606
Publisher:
American Institute of Physics (AIP)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; ionic liquids; chemical compounds and components; infrared spectroscopy; chemical elements; rotational dynamics; intermolecular forces; energy storage; covariance and correlation; molecular dynamics; stark effect

Citation Formats

Giammanco, Chiara H., Kramer, Patrick L., Yamada, Steven A., Nishida, Jun, Tamimi, Amr, and Fayer, Michael D. Carbon dioxide in an ionic liquid: Structural and rotational dynamics. United States: N. p., 2016. Web. doi:10.1063/1.4943390.
Giammanco, Chiara H., Kramer, Patrick L., Yamada, Steven A., Nishida, Jun, Tamimi, Amr, & Fayer, Michael D. Carbon dioxide in an ionic liquid: Structural and rotational dynamics. United States. doi:10.1063/1.4943390.
Giammanco, Chiara H., Kramer, Patrick L., Yamada, Steven A., Nishida, Jun, Tamimi, Amr, and Fayer, Michael D. Fri . "Carbon dioxide in an ionic liquid: Structural and rotational dynamics". United States. doi:10.1063/1.4943390. https://www.osti.gov/servlets/purl/1468530.
@article{osti_1468530,
title = {Carbon dioxide in an ionic liquid: Structural and rotational dynamics},
author = {Giammanco, Chiara H. and Kramer, Patrick L. and Yamada, Steven A. and Nishida, Jun and Tamimi, Amr and Fayer, Michael D.},
abstractNote = {Ionic liquids (ILs), which have widely tunable structural motifs and intermolecular interactions with solutes, have been proposed as possible carbon capture media. In order to inform the choice of an optimal ionic liquid system, it can be useful to understand the details of dynamics and interactions on fundamental time scales (femtoseconds to picoseconds) of dissolved gases, particularly carbon dioxide (CO2), within the complex solvation structures present in these uniquely organized materials. The rotational and local structural fluctuation dynamics of CO2 in the room temperature ionic liquid 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (EmimNTf2) were investigated by using ultrafast infrared spectroscopy to interrogate the CO2 asymmetric stretch. Polarization-selective pump probe measurements yielded the orientational correlation function of the CO2 vibrational transition dipole. It was found that reorientation of the carbon dioxide occurs on 3 time scales: 0.91 ± 0.03, 8.3 ± 0.1, 54 ± 1 ps. The initial two are attributed to restricted wobbling motions originating from a gating of CO2 motions by the IL cations and anions. The final (slowest) decay corresponds to complete orientational randomization. Two-dimensional infrared vibrational echo (2D IR) spectroscopy provided information on structural rearrangements, which cause spectral diffusion, through the time dependence of the 2D line shape. Analysis of the time-dependent 2D IR spectra yields the frequency-frequency correlation function (FFCF). Polarization-selective 2D IR experiments conducted on the CO2 asymmetric stretch in the parallel- and perpendicular-pumped geometries yield significantly different FFCFs due to a phenomenon known as reorientation-induced spectral diffusion (RISD), revealing strong vector interactions with the liquid structures that evolve slowly on the (independently measured) rotation time scales. To separate the RISD contribution to the FFCF from the structural spectral diffusion contribution, the previously developed first order Stark effect RISD model is reformulated to describe the second order (quadratic) Stark effect—the first order Stark effect vanishes because CO2 does not have a permanent dipole moment. Through this analysis, we characterize the structural fluctuations of CO2 in the ionic liquid solvation environment, which separate into magnitude-only and combined magnitude and directional correlations of the liquid’s time dependent electric field. This new methodology will enable highly incisive comparisons between CO2 dynamics in a variety of ionic liquid systems.},
doi = {10.1063/1.4943390},
journal = {Journal of Chemical Physics},
number = 10,
volume = 144,
place = {United States},
year = {2016},
month = {3}
}

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record

Citation Metrics:
Cited by: 13 works
Citation information provided by
Web of Science

Save / Share:

Works referenced in this record:

Ionic-liquid materials for the electrochemical challenges of the future
journal, July 2009

  • Armand, Michel; Endres, Frank; MacFarlane, Douglas R.
  • Nature Materials, Vol. 8, Issue 8, p. 621-629
  • DOI: 10.1038/nmat2448

Advances in CO2 capture technology—The U.S. Department of Energy's Carbon Sequestration Program
journal, January 2008

  • Figueroa, José D.; Fout, Timothy; Plasynski, Sean
  • International Journal of Greenhouse Gas Control, Vol. 2, Issue 1, p. 9-20
  • DOI: 10.1016/S1750-5836(07)00094-1

Room-Temperature Ionic Liquids. Solvents for Synthesis and Catalysis
journal, August 1999

  • Welton, Thomas
  • Chemical Reviews, Vol. 99, Issue 8, p. 2071-2084
  • DOI: 10.1021/cr980032t

Power plant post-combustion carbon dioxide capture: An opportunity for membranes
journal, September 2010

  • Merkel, Tim C.; Lin, Haiqing; Wei, Xiaotong
  • Journal of Membrane Science, Vol. 359, Issue 1-2, p. 126-139
  • DOI: 10.1016/j.memsci.2009.10.041

Vapor–liquid equilibria of mixtures containing alkanes, carbon dioxide, and nitrogen
journal, July 2001

  • Potoff, Jeffrey J.; Siepmann, J. Ilja
  • AIChE Journal, Vol. 47, Issue 7, p. 1676-1682
  • DOI: 10.1002/aic.690470719

CO2 Capture by a Task-Specific Ionic Liquid
journal, February 2002

  • Bates, Eleanor D.; Mayton, Rebecca D.; Ntai, Ioanna
  • Journal of the American Chemical Society, Vol. 124, Issue 6, p. 926-927
  • DOI: 10.1021/ja017593d