Hofmann, TommyTommyHofmannWallacher, DirkDirkWallacherMayorova, MariaMariaMayorovaZorn, ReinerReinerZornFrick, BernhardBernhardFrickHuber, PatrickPatrickHuber2022-06-032022-06-032012-03-26Journal of Chemical Physics 136 (12): 124505 (2012-04-11)http://hdl.handle.net/11420/12801We present incoherent quasi-elastic neutron scattering measurements in a wavevector transfer range from 0.4 AA⁻¹ to 1.6AA⁻¹ on liquid n-hexane confined in cylindrical, parallel-aligned nanochannels of 6 nm mean diameter and 260 micrometer length in monolithic, mesoporous silicon. They are complemented with, and compared to, measurements on the bulk system in a temperature range from 50K to 250K. The time-of-flight spectra of the bulk liquid 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 1ps to 100ps 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 250K, gradually increases upon cooling and exhibits an abrupt increase at 160K (20K below bulk crystallization), which indicates pore freezingen1089-7690201212American Institute of PhysicsPhysics - Soft Condensed MatterPhysics - Soft Condensed MatterPhysics - Mesoscopic Systems and Quantum Hall EffectPhysics - Materials SciencePhysics - Chemical PhysicsPhysikJournal Article10.1063/1.36966841204.2362v1Journal Article