title: Structure and growth of vapor-deposited n-dotriacontane films studied by X-ray reflectivity.
abstract: We have used synchrotron X-ray reflectivity measurements to investigate the structure of n-dotriacontane (n-C(32)H(66) or C32) films deposited from the vapor phase onto a SiO(2)-coated Si(100) surface. Our primary motivation was to determine whether the structure and growth mode of these films differ from those deposited from solution on the same substrate. The vapor-deposited films had a thickness of approximately 50 A thick as monitored in situ by high-resolution ellipsometry and were stable in air. Similar to the case of solution-deposited C32 films, we find that film growth in vacuum begins with a nearly complete bilayer adjacent to the SiO(2) surface formed by C32 molecules aligned with their long axis parallel to the interface followed by one or more partial layers of perpendicular molecules. These molecular layers coexist with bulk particles at higher coverages. Furthermore, after thermally cycling our vapor-deposited samples at atmospheric pressure above the bulk C32 melting point, we find the structure of our films as a function of temperature to be consistent with a phase diagram inferred previously for similarly treated solution-deposited films. Our results resolve some of the discrepancies that Basu and Satija (Basu, S.; Satija, S. K. Langmuir 2007, 23, 8331) found between the structure of vapor-deposited and solution-deposited films of intermediate-length alkanes at room temperature.
authors: Facultad de Física, Pontificia Universidad Católica de Chile, Santiago 22, Chile.
authors: Valeria
authors: V
authors: del Campo
authors: Edgardo
authors: E
authors: Cisternas
authors: Haskell
authors: H
authors: Taub
authors: Ignacio
authors: I
authors: Vergara
authors: Tomás
authors: T
authors: Corrales
authors: Pamela
authors: P
authors: Soza
authors: Ulrich G
authors: UG
authors: Volkmann
authors: Mengjun
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authors: Bai
authors: Siao-Kwan
authors: SK
authors: Wang
authors: Flemming Y
authors: FY
authors: Hansen
authors: Haiding
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authors: Mo
authors: Steven N
authors: SN
authors: Ehrlich