TY  - JOUR
AU  - Hofmann, T.
AU  - Wallacher, D.
AU  - Mayorova, M.
AU  - Zorn, R.
AU  - Frick, B.
AU  - Huber, P.
TI  - Molecular dynamics of n-hexane: A quasi-elastic neutron scattering study on the bulk and spatially nanochannel-confined liquid
JO  - Chemical physics
VL  - 136
SN  - 0301-0104
CY  - Amsterdam [u.a.]
PB  - Elsevier Science
M1  - PreJuSER-22230
SP  - 124505
PY  - 2012
N1  - This work was supported by the German Research Foundation (DFG) within the priority program 1144, Micro- and Nanofluidics, Grant No. Hu 850/2.
AB  - We present incoherent quasi-elastic neutron scattering measurements in a wave vector transfer range from 0.4 Å(-1) to 1.6Å (-1) on liquid n-hexane confined in cylindrical, parallel-aligned nanochannels of 6 nm mean diameter and 260 μm length in monolithic, mesoporous silicon. They are complemented with, and compared to, measurements on the bulk system in a temperature range from 50 K to 250 K. The time-of-flight spectra of the bulk liquid (BL) can be modeled by microscopic translational as well as fast localized rotational, thermally excited, stochastic motions of the molecules. In the nano-confined state of the liquid, which was prepared by vapor condensation, we find two molecular populations with distinct dynamics, a fraction which is immobile on the time scale of 1 ps to 100 ps probed in our experiments and a second component with a self-diffusion dynamics slightly slower than observed for the bulk liquid. No hints of an anisotropy of the translational diffusion with regard to the orientation of the channels' long axes have been found. The immobile fraction amounts to about 5% at 250 K, gradually increases upon cooling and exhibits an abrupt increase at 160 K (20 K below bulk crystallization), which indicates pore freezing.
KW  - J (WoSType)
LB  - PUB:(DE-HGF)16
C6  - pmid:22462872
UR  - <Go to ISI:>//WOS:000302216200048
DO  - DOI:10.1063/1.3696684
UR  - https://juser.fz-juelich.de/record/22230
ER  -