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Titolo:
Absolute molecular orientational distribution of the polystyrene surface
Autore:
Briggman, KA; Stephenson, JC; Wallace, WE; Richter, LJ;
Indirizzi:
Natl Inst Stand & Technol, Gaithersburg, MD 20899 USA Natl Inst Stand & Technol Gaithersburg MD USA 20899 ersburg, MD 20899 USA
Titolo Testata:
JOURNAL OF PHYSICAL CHEMISTRY B
fascicolo: 14, volume: 105, anno: 2001,
pagine: 2785 - 2791
SICI:
1520-6106(20010412)105:14<2785:AMODOT>2.0.ZU;2-O
Fonte:
ISI
Lingua:
ENG
Soggetto:
FREQUENCY VIBRATIONAL SPECTROSCOPY; POTENTIAL SURFACE; POLYMER SURFACE; THIN-FILMS; BENZENE; GENERATION; INTERFACE; INTENSITIES; TEMPERATURE; SIMULATION;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Physical, Chemical & Earth Sciences
Citazioni:
44
Recensione:
Indirizzi per estratti:
Indirizzo: Richter, LJ Natl Inst Stand & Technol, 100 Bur Dr, Gaithersburg, MD 20899 USA Natl Inst Stand & Technol 100 Bur Dr Gaithersburg MD USA 20899
Citazione:
K.A. Briggman et al., "Absolute molecular orientational distribution of the polystyrene surface", J PHYS CH B, 105(14), 2001, pp. 2785-2791

Abstract

Vibrationally resonant sum frequency generation (VR-SFG) has been used to study the absolute molecular orientational distribution of the pendant phenyl groups at the foe surface of polystyrene (PS) thin films on oxidized Si substrates. Characterization of the dependence of the VR-SFG on film thickness allows unique identification of the origin of the signal, e.g., free surface, bulk, or buried interface. For films <400 nm thick, the dominant source of vibrationally resonant signal is the PS/air interface, while the dominant source of the nonresonant background is the Si/SiO2 interface. VR-SFGof a self-assembled phenylsiloxane layer is used to calibrate the relativephase between the vibrationally resonant phenyl ring hyperpolarizability and the Si/SiO2 interface nonresonant hyperpolarizability. It is found that the phenyl groups are ordered at the PS/air interface and are oriented awayfrom the polymer film. Quantitative analyses of the orientational distribution for both the PS free interface and the phenylsiloxane monolayer are reported. The phenyl groups at the PS free surface are tilted away from the surface normal in an angular range near 57<degrees>.

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Documento generato il 09/08/20 alle ore 23:21:17