Abstract

Binary liquid mixtures near their consolute critical points are shown to possess desirable thermophysical properties for thermal lens absorption measurements. By use of a 2,6-dimethylpyridine/water mixture near critical composition and temperature, sensitivity was found to be enhanced relative to pure liquids by the Soret effect in which a concentration gradient is created between the two solvent components by thermally induced mass diffusion within the laser-excited temperature gradient. A 35-fold increase in sensitivity relative to a thermal expansion lens effect in pure water was obtained. A mechanism of phase separation unique to the critical point region known as spinodol decomposition was observed, as the sample temperature was driven above the critical point by laser excitation. This phenomenon was also found to be a potentially useful spectrophotometric technique for the thermooptical detection of small absorbances.

Kerr effect in binary liquid mixtures

Roberto Piazza, Vittorio Degiorgio, and Tommaso Bellini
J. Opt. Soc. Am. B 3(12) 1642-1646 (1986)

Capillary-to-bulk crossover of nonequilibrium fluctuations in the free diffusion of a near-critical binary liquid mixture

Pietro Cicuta, Alberto Vailati, and Marzio Giglio
Appl. Opt. 40(24) 4140-4145 (2001)

Thermal-lensing measurement of particle thermophoresis in aqueous dispersions

Roberto Rusconi, Lucio Isa, and Roberto Piazza
J. Opt. Soc. Am. B 21(3) 605-616 (2004)

Soret effect and photochemical reaction in liquids with laser-induced local heating

L. C. Malacarne, N. G. C. Astrath, A. N. Medina, L. S. Herculano, M. L. Baesso, P. R. B. Pedreira, J. Shen, Q. Wen, K. H. Michaelian, and C. Fairbridge
Opt. Express 19(5) 4047-4058 (2011)

Induction and detection of pressure waves by pulsed thermal lens technique in water–ethanol mixtures

Otávio A. Capeloto, Vitor S. Zanuto, Vinicius G. Camargo, Gabriel A. S. Flizikowski, Flávia A. P. Morais, Gustavo V. B. Lukasievicz, Leandro S. Herculano, Marcos P. Belançon, Nelson G. C. Astrath, and Luis C. Malacarne
Appl. Opt. 60(13) 4029-4033 (2021)