Translational diffusion of cumene and 3-methylpentane on free surfaces and pore walls studied by time-of-flight secondary ion mass spectrometry

Journal Article · Tue Dec 07 00:00:00 EST 2010 · Journal of Chemical Physics

DOI:https://doi.org/10.1063/1.3511709· OSTI ID:21559958

Souda, Ryutaro ^[1]

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1. International Center for Materials Nanoarchitectonics, National Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki 305-0044 (Japan)

Mobility of molecules in confined geometry has been studied extensively, but the origins of finite size effects on reduction of the glass transition temperature, T{sub g}, are controversial especially for supported thin films. We investigate uptake of probe molecules in vapor-deposited thin films of cumene, 3-methylpentane, and heavy water using secondary ion mass spectrometry and discuss roles of individual molecular motion during structural relaxation and glass-liquid transition. The surface mobility is found to be enhanced for low-density glasses in the sub-T{sub g} region because of the diffusion of molecules on pore walls, resulting in densification of a film via pore collapse. Even for high-density glasses without pores, self-diffusion commences prior to the film morphology change at T{sub g}, which is thought to be related to decoupling between translational diffusivity and viscosity. The diffusivity of deeply supercooled liquid tends to be enhanced when it is confined in pores of amorphous solid water. The diffusivity of molecules is further enhanced at temperatures higher than 1.2-1.3 T{sub g} irrespective of the confinement.

• OSTI ID: 21559958
• Journal Information: Journal of Chemical Physics, Vol. 133, Issue 21; Other Information: DOI: 10.1063/1.3511709; (c) 2010 American Institute of Physics; ISSN 0021-9606
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
36 MATERIALS SCIENCE
CUMENE
GLASS
HEAVY WATER
IONS
LIQUIDS
MASS SPECTRA
MASS SPECTROSCOPY
MOBILITY
MOLECULES
MORPHOLOGY
RELAXATION
SELF-DIFFUSION
SOLIDS
SUPERCOOLING
SURFACES
THIN FILMS
TIME-OF-FLIGHT METHOD
TRANSITION TEMPERATURE
VAPOR DEPOSITED COATINGS
VISCOSITY
AROMATICS
CHARGED PARTICLES
COATINGS
COOLING
DEUTERIUM COMPOUNDS
DIFFUSION
FILMS
FLUIDS
HYDROCARBONS
HYDROGEN COMPOUNDS
ORGANIC COMPOUNDS
OXYGEN COMPOUNDS
PHYSICAL PROPERTIES
SPECTRA
SPECTROSCOPY
THERMODYNAMIC PROPERTIES
WATER