Girijavallabhan, C P; Radhakrishnan, P; Nampoori, V P N; George, N A; Paul, T; Sebastian,M T(Journal of Materials Science Letters,Kluwer Academic Publishers, 2000)
Girijavallabhan, C P; Radhakrishnan, P; V P N Nampoori; Sajan, D George; George, A K(Smart Materials and Structures, July 5, 2007)
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Abstract:
Complete thermal characterization of liquid crystal mixtures in the smectic
phase consisting of various relative volume fractions of cholesterol and
1-hexadecanol have been carried out using the photoacoustic technique.
Thermal diffusivity values of these liquid crystal mixtures are evaluated using
the open cell photoacoustic technique whereas the thermal effusivity value is
measured using the conventional photoacoustic technique. From the
measured values of these transient thermophysical parameters, the thermal
conductivity and heat capacity of the sample under investigation are
calculated. Analyses of the results show that all the thermophysical
parameters depend strongly on the volume fraction of the constituents.
Results are interpreted in terms of enhanced hydrogen bonding and the
consequent enhancement in cohesive thermal energy transport with
increasing volume fraction of 1-hexadecanol
Girijavallabhan, C P; Radhakrishnan, P; Nibu, A George; Aneeshkumar, B(Journal of Physics D : Applied Physics, April 7, 1999)
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Abstract:
The photobleaching of the lasing dye Rhodamine 6G embedded in the solid
matrix poly(methyl methacrylate) was investigated using a photoacoustic technique.
Chopped laser radiation from an argon ion laser at four different wavelengths was used for
the study. Experimental results indicate that the photobleaching rate is directly proportional
to the incident laser power while it decreases with increase in concentration of the dye
molecules. In the present case we have not observed any dependence of photobleaching on
the chopping frequency. One-photon absorption is found to be responsible for the
photobleaching of the dye within the selected range of laser power
Bindhu, C V; Harilal, S S; Issac, Riju C; Geetha K, Varier; Nampoori, V P N; Vallabhan, C P G(Pramana, March , 1995)
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Abstract:
Pulsed photoacoustic measurements have been carried out in toluene at 532 nm
wavelength using a Q-switched frequency doubled Nd:YAG laser. The variation of photoacoustic
signal amplitude with incident laser power indicates that at lower laser powers one
photon absorption takes place at this wavelength while a clear two photon absorption occurs in
this liquid at higher laser powers. The studies made here demonstrate that pulsed photoacoustic
technique is simple and effective for the investigation of multiphoton processes in
liquids.