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Title:
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Laser Induced Photoacoustic Technique for the Detection of Phase Transitions in Liquid Crystals |
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Author:
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Nibu, A George; Vallabhan, C P G; Nampoori, V P N; George, A K; Radhakrishnan, P
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Abstract:
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In this paper we report the use of a laser induced phoroacoustic technique for the detection of multiple phase transitions in heptyl-oxy-cyanobiphenyl (70CB) and octyl-oxy-cyanobiphenyl (80CB) liquid crystals. The observed photoacoustic signal amplitude profile carries clear signatures of two tirst order transitions in 70CB and two tirst order and a second order transitions in 80CB. Analysis of the experimental data using Rosencwaig-Gersho theory shows that the sudden decrease in the photoacoustic (PA) signal amplitude during phase transitions is due to a sharp increase in the heat capacity of the samples near the transition temperatures. |
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URI:
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http://dyuthi.cusat.ac.in/purl/2496
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Date:
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2001 |