Relaxation processes in room temperature ionic liquids: The case of 1-methyl-3-butyl imidazolium hexafluorophosphate

Triolo, A.; Nieuwenhuyzen, M.; Russina, O.; Grimm, H.; Gonzalez, M. A.; Hardacre, C.

doi:10.1021/jp053355j

Journal Article

Relaxation processes in room temperature ionic liquids: The case of 1-methyl-3-butyl imidazolium hexafluorophosphate

Triolo, A. ; Russina, O. ; Hardacre, C. ; Nieuwenhuyzen, M. ; Gonzalez, M. A. ; Grimm, H.FZJ*

2005
Soc. Washington, DC

The journal of physical chemistry <Washington, DC> / B 109, 22061 - 22066 (2005) [10.1021/jp053355j]

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Please use a persistent id in citations: http://hdl.handle.net/2128/1144 doi:10.1021/jp053355j

Abstract: A detailed investigation on the nature of the relaxation processes occurring in a typical room temperature ionic liquid (RTIL), namely, 1-butyl-3-methyl imidazolium hexafluorophosphate ([bmim][PF(6)]), is reported. The study was conducted using both elastic and inelastic neutron scattering over a wide temperature range from 10 to 400 K, accessing the dynamic features of both the liquid and glassy amorphous states. In this study, the inelastic fixed energy scan technique has been applied for the first time to this class of materials. Using this technique, the existence of two relaxation processes below the glass transition and a further diffusive process occurring above the glass-liquid transition are observed. The low temperature processes are associated with methyl group rotation and butyl chain relaxation in the glassy state and have been modeled in terms of two Debye-like, Arrhenius activated processes. The high temperature process has been modeled in terms of a Kohlraush-Williams-Watts relaxation, with a distinct Vogel-Fulcher-Tamman temperature dependence. These results provide novel information that will be useful in rationalizing the observed structural and dynamical behavior of RTILs in the amorphous state.

Keyword(s): Imidazoles: chemistry (MeSH) ; Ionic Liquids: chemistry (MeSH) ; Models, Chemical (MeSH) ; Neutron Diffraction (MeSH) ; Phase Transition (MeSH) ; Temperature (MeSH) ; 1-butyl-3-methylimidazolium hexafluorophosphate ; Imidazoles ; Ionic Liquids ; J