Introduction and Historical Development

Raman spectra of terephthalidine-bis-heptylaniline (TB7A) were recorded in the region 1125-1225 cm −1 from room temperature to 10 K at 18 different temperatures. The splitting of the ∼1165 cm −1 band, and the variation of the ratio of integrated intensities of the original band at ∼1165 cm −1 to the new component at 1170/1171 cm −1 reveals a solid modification. The analysis of the temperature dependence of the linewidth was made using Rakov's relation. A logarithmic plot as a function of 1/T gives two straight lines with an abrupt discontinuity, which clearly exhibits a phase transition at about 210 K. The temperature dependence of the linewidth of the ∼1165 cm −1 band was used to characterize this transition. A relatively large variation (∼3 cm −1 ) of the linewidth on going from 250 to 10 K in TB7A having an odd (n = 7) number of carbon atoms in the alkyl tail compared with those observed (∼1 cm −1 ) in other homologues having an even (n = 2 or 10) number of carbon atoms in the alkyl tail is a clear demonstration of the even-odd effect.

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The Paraboloidal Reflector Antenna in Radio Astronomy and Communication

Baars¹

2007

Astrophysics and Space Science Library

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Introduction and Historical Development

Cited by 3 publications

References 74 publications

Experimental Determination of Elastic and Viscous Parameters of Liquid Crystals

Experimental Determination of Elastic and Viscous Parameters of Liquid Crystals

Raman investigation of the low‐temperature phase transition in a liquid crystalline system: terephthalidine‐bis‐heptylaniline (TB7A)

The Paraboloidal Reflector Antenna in Radio Astronomy and Communication

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