Infrared absorption spectra of liquid crystals—I. Determination of the preorientation potential barriers of the molecules in crystal, nematic crystal, and isotropie phases

1973 ◽  
Vol 29 (1) ◽  
pp. 55-62 ◽  
Author(s):  
N. Kirov ◽  
P. Simova
Keyword(s):  
Liquid Crystals ◽  
Absorption Spectra ◽  
Infrared Absorption ◽  
Potential Barriers ◽  
Infrared Absorption Spectra

ANALYSIS OF THE COMPOSITION OF WATER-ALCOHOL MIXTURES USING THE INFRARED ABSORPTION SPECTRA OF THEIR VAPORS

2021 ◽  
Vol 88 (6) ◽  
pp. 933-941
Author(s):  
V. L. Vesnin
Keyword(s):  
Linear Regression ◽  
Multiple Linear Regression ◽  
Absorption Spectra ◽  
Infrared Absorption ◽  
Liquid Mixture ◽  
The Mean ◽  
Alcohol Mixtures ◽  
Infrared Absorption Spectra ◽  
Water Alcohol

The article presents the results of studies of infrared absorption spectra of saturated vapors of alcohols and alcohol-containing mixtures in the range of 1.3—1.5 μm. A method was developed for the quantitative determination of the composition of water-alcohol mixtures based on the use of multiple linear regression, and a range of methanol concentrations was determined, in which the nonlinearity of the dependence of the concentration of alcohols in saturated vapors over a liquid mixture on the concentration of alcohols in this liquid mixture does not significantly affect the results of analysis of the mixture composition. A method for optimizing a set of wavelengths for multiple linear regression, based on minimizing the mean-square error in determining the concentration is proposed and implemented. The developed methods make it possible to determine the presence of small (<1%) amounts of methanol against the background of large amounts of ethanol and water using relatively inexpensive and accessible spectroscopic equipment.

Determination of the crystallinity of polytetrafluoroethylene from infrared absorption spectra

1976 ◽  
Vol 24 (6) ◽  
pp. 732-734 ◽  
Author(s):  
I. S. Perelygin ◽  
M. Z. Peskova ◽  
Z. Z. Zakirov ◽  
I. M. Glinkin
Keyword(s):  
Absorption Spectra ◽  
Infrared Absorption ◽  
Infrared Absorption Spectra
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