Abstract
We have investigated the ultrafast molecular dynamics of five pyrrolidinium cation room temperature ionic liquids using femtosecond optical heterodyne-detected Raman-induced Kerr effect spectroscopy. The ionic liquids studied are N -butyl- N -methylpyrrolidinium bis(trifluoromethylsulfonyl)imide P 14 + NTf2-), N -methoxyethyl- N -methylpyrrolidinium bis(trifluoromethylsulfonyl)imide P 1EOE + NTf2-), N -ethoxyethyl- N -methylpyrrolidinium bis(trifluoromethylsulfonyl)imide P 1EOE + NTf2-), N -ethoxyethyl- N -methylpyrrolidinium bromide P 1EOE +, and N -ethoxyethyl- N -methylpyrrolidinium dicyanoamide P 1EOE + DCA-). For comparing dynamics among the five ionic liquids, we categorize the ionic liquids into two groups. One group of liquids comprises the three pyrrolidinium cations P 14 +, P 1EOM +, and P 1EOE + paired with the NTf2- anion. The other group of liquids consists of the P 1EOE + cation paired with each of the three anions NTf2-, Br-, and DCA-. The overdamped relaxation for time scales longer than 2 ps has been fit by a triexponential function for each of the five pyrrolidinium ionic liquids. The fast (~2 ps) and intermediate (~20 ps) relaxation time constants vary little among these five ionic liquids. However, the slow relaxation time constant correlates with the viscosity. Thus, the Kerr spectra in the range from 0 to 750 cm-1 are quite similar for the group of three pyrrolidinium ionic liquids paired with the NTf2- anion. The intermolecular vibrational line shapes between 0 and 150 cm-1 are fit to a multimode Brownian oscillator model; adequate fits required at least three modes to be included in the line shape.
| Original language | English |
|---|---|
| Article number | 184512 |
| Journal | Journal of Chemical Physics |
| Volume | 122 |
| Issue number | 18 |
| DOIs | |
| Publication status | Published - May 8 2005 |
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ASJC Scopus subject areas
- Atomic and Molecular Physics, and Optics
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Ultrafast dynamics of pyrrolidinium cation ionic liquids. / Shirota, Hideaki; Funston, Alison M.; Wishart, James F.; Castner, Ed.
In: Journal of Chemical Physics, Vol. 122, No. 18, 184512, 08.05.2005.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Ultrafast dynamics of pyrrolidinium cation ionic liquids
AU - Shirota, Hideaki
AU - Funston, Alison M.
AU - Wishart, James F.
AU - Castner, Ed
PY - 2005/5/8
Y1 - 2005/5/8
N2 - We have investigated the ultrafast molecular dynamics of five pyrrolidinium cation room temperature ionic liquids using femtosecond optical heterodyne-detected Raman-induced Kerr effect spectroscopy. The ionic liquids studied are N -butyl- N -methylpyrrolidinium bis(trifluoromethylsulfonyl)imide P 14 + NTf2-), N -methoxyethyl- N -methylpyrrolidinium bis(trifluoromethylsulfonyl)imide P 1EOE + NTf2-), N -ethoxyethyl- N -methylpyrrolidinium bis(trifluoromethylsulfonyl)imide P 1EOE + NTf2-), N -ethoxyethyl- N -methylpyrrolidinium bromide P 1EOE +, and N -ethoxyethyl- N -methylpyrrolidinium dicyanoamide P 1EOE + DCA-). For comparing dynamics among the five ionic liquids, we categorize the ionic liquids into two groups. One group of liquids comprises the three pyrrolidinium cations P 14 +, P 1EOM +, and P 1EOE + paired with the NTf2- anion. The other group of liquids consists of the P 1EOE + cation paired with each of the three anions NTf2-, Br-, and DCA-. The overdamped relaxation for time scales longer than 2 ps has been fit by a triexponential function for each of the five pyrrolidinium ionic liquids. The fast (~2 ps) and intermediate (~20 ps) relaxation time constants vary little among these five ionic liquids. However, the slow relaxation time constant correlates with the viscosity. Thus, the Kerr spectra in the range from 0 to 750 cm-1 are quite similar for the group of three pyrrolidinium ionic liquids paired with the NTf2- anion. The intermolecular vibrational line shapes between 0 and 150 cm-1 are fit to a multimode Brownian oscillator model; adequate fits required at least three modes to be included in the line shape.
AB - We have investigated the ultrafast molecular dynamics of five pyrrolidinium cation room temperature ionic liquids using femtosecond optical heterodyne-detected Raman-induced Kerr effect spectroscopy. The ionic liquids studied are N -butyl- N -methylpyrrolidinium bis(trifluoromethylsulfonyl)imide P 14 + NTf2-), N -methoxyethyl- N -methylpyrrolidinium bis(trifluoromethylsulfonyl)imide P 1EOE + NTf2-), N -ethoxyethyl- N -methylpyrrolidinium bis(trifluoromethylsulfonyl)imide P 1EOE + NTf2-), N -ethoxyethyl- N -methylpyrrolidinium bromide P 1EOE +, and N -ethoxyethyl- N -methylpyrrolidinium dicyanoamide P 1EOE + DCA-). For comparing dynamics among the five ionic liquids, we categorize the ionic liquids into two groups. One group of liquids comprises the three pyrrolidinium cations P 14 +, P 1EOM +, and P 1EOE + paired with the NTf2- anion. The other group of liquids consists of the P 1EOE + cation paired with each of the three anions NTf2-, Br-, and DCA-. The overdamped relaxation for time scales longer than 2 ps has been fit by a triexponential function for each of the five pyrrolidinium ionic liquids. The fast (~2 ps) and intermediate (~20 ps) relaxation time constants vary little among these five ionic liquids. However, the slow relaxation time constant correlates with the viscosity. Thus, the Kerr spectra in the range from 0 to 750 cm-1 are quite similar for the group of three pyrrolidinium ionic liquids paired with the NTf2- anion. The intermolecular vibrational line shapes between 0 and 150 cm-1 are fit to a multimode Brownian oscillator model; adequate fits required at least three modes to be included in the line shape.
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U2 - 10.1063/1.1893797
DO - 10.1063/1.1893797
M3 - Article
VL - 122
JO - Journal of Chemical Physics
JF - Journal of Chemical Physics
SN - 0021-9606
IS - 18
M1 - 184512
ER -