Quantitative evaluation of molecular orientation in thin Langmuir-Blodgett films by FT-IR transmission and reflection-absorption spectroscopy

Journal Article · Thu Jan 11 04:00:00 EST 1990 · Journal of Physical Chemistry; (USA)

DOI:https://doi.org/10.1021/j100364a009· OSTI ID:6667443

Umemura, Junzo; Kamata, Toshihide; Kawai, Takeshi; Takenaka, Tohru ^[1]

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1. Kyoto Univ. (Japan)

By a comparison of infrared reflection-absorption (RA) and transmission intensities, a method for the quantitative evaluation of molecular orientation in thin Langmuir-Blodgett (LB) films has been developed. The enhancement factors for the RA to transmission absorption intensities of hypothetical isotropic films were theoretically calculated by using Hansen's optical formulas for thin multilayer films. By combination of these values with the experimentally determined intensity ratios of the RA to transmission spectra for uniaxially oriented LB films, the orientation angles of the transition moments of major infrared bands were evaluated. Application of this method to the 7-monolayer LB film of cadmium stearate deposited on AG (for RA measurements) and on ZnSe (for transmission measurements) substrates gave reasonable tilt angles for the molecular chain as compared to those reported by other investigators and to the data from the X-ray analysis. This method will be discussed in detail and the various factors which influence the accuracy of the orientation analysis will also be covered.

• OSTI ID: 6667443
• Journal Information: Journal of Physical Chemistry; (USA), Journal Name: Journal of Physical Chemistry; (USA) Vol. 94:1; ISSN 0022-3654; ISSN JPCHA
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360602* -- Other Materials-- Structure & Phase Studies
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400200 -- Inorganic
Organic
& Physical Chemistry
ABSORPTION SPECTROSCOPY
CADMIUM COMPOUNDS
CHALCOGENIDES
DATA
DATA ANALYSIS
EXPERIMENTAL DATA
FILMS
INFORMATION
MEASURING INSTRUMENTS
MEASURING METHODS
MOLECULAR STRUCTURE
NUMERICAL DATA
SELENIDES
SELENIUM COMPOUNDS
SPECTROSCOPY
THEORETICAL DATA
THIN FILMS
ZINC COMPOUNDS
ZINC SELENIDES