Ravi Kumar, A V; Padmaja, G; Radhakrishnan, P; Nampoori, V P N; Vallabhan, C P G(Springer, October , 1991)
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Abstract:
The acoustic signals generated in solids due to interaction with pulsed laser beam is used to determine the ablation threshold of bulk polymer samples of teflon (polytetrafluoroethylene) and nylon under the irradiation from a Q-switched Nd:YAG laser at 1.06µm wavelength. A suitably designed piezoelectric transducer is employed for the detection of photoacoustic (PA) signals generated in this process. It has been observed that an abrupt increase in the amplitude of the PA signal occurs at the ablation threshold. Also there exist distinct values for the threshold corresponding to different mechanisms operative in producing damages like surface morphology, bond breaking and melting processes at different laser energy densities.
Joseph, Mathai C; Anantharaman, M R; Venkitachalam, S; Jayalekshmi,S(Elsevier, September , 2002)
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Abstract:
Polyfurfural thin films lying in the thickness range of 1300–2000 A˚ were prepared by ac plasma polymerization technique.
The current–voltage characteristics in symmetric and asymmetric electrode configuration were studied with a view to determining
the dominant conduction mechanism.It was found that the Schottky conduction mechanism is dominant in plasma polymerized
furfural thin films.The predominance of Schottky mechanism was further confirmed based on the thermally stimulated current
measurements.
Deepa, Jose; Shelly John, M; Radhakrishnan, P; Nampoori, V P N; Vallabhan, C P G(Elsevier, July 18, 1998)
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Abstract:
A novel fibre optic sensor for the in situ measurement of the rate of deposition of thin films has been developed. Evanescent wave in the uncladded portion of a multimode fibre is utilised for this sensor development. In the present paper we demonstrate how this sensor is useful for the monitoring of the deposition rate of polypyrrole thin films, deposited by an AC plasma polymerisation method. This technique is simple, accurate and highly sensitive compared with existing techniques.
Anantharaman, M R; Saravanan, S; Venkatachalam, S; Avasthi, D K(Elsevier, March 26, 2007)
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Abstract:
Polyaniline thin films prepared by RF plasma polymerisation were irradiated with 92MeV Si ions for various fluences of 1 1011,
1 1012 and 1 1013 ions/cm2. FTIR and UV–vis–NIR measurements were carried out on the pristine and Si ion irradiated polyaniline
thin films for structural evaluation and optical band gap determination. The effect of swift heavy ions on the structural and optical
properties of plasma-polymerised aniline thin film is investigated. Their properties are compared with that of the pristine sample. The
FTIR spectrum indicates that the structure of the irradiated sample is altered. The optical studies show that the band gap of irradiated
thin film has been considerably modified. This has been attributed to the rearrangement in the ring structure and the formation of CRC
terminals. This results in extended conjugated structure causing reduction in optical band gap