Transient grating experiments on supercooled molecular liquids. II: Microscopic derivation of the phenomenological equations

• Published in: The European physical journal. B, Condensed matter physics Vol. 47; no. 3; pp. 341 - 361
• Main Authors: FRANOSCH, T, PICK, R. M
• Format: Journal Article
• Language: English
• Published: Les Ulis Springer 01-10-2005; Berlin EDP sciences; Springer-Verlag
• Subjects: Condensed matter: electronic structure, electrical, magnetic, and optical properties; Exact sciences and technology; Optical properties and condensed-matter spectroscopy and other interactions of matter with particles and radiation; Physics; Time-resolved optical spectroscopies and other ultrafast optical measurements in condensed matter; Wave absorption; Constitutive equation; Molecular liquid; Supercooled liquids; Phenomenological model; Fluctuations; Molecular orientation; Laser radiation; Density; Navier-Stokes equations; Transients; Onsager relations; WAVES; LONGITUDINAL ACOUSTIC MODES; COUPLING THEORY; SPECTROSCOPY; GLASS-FORMING LIQUID; LIGHT-SCATTERING; RELAXATION; METATOLUIDINE; SPECTRUM; WATER
• ISSN: 1434-6028; 1434-6036
• DOI: 10.1140/epjb/e2005-00341-x

The constitutive equations including the energy conservation aspect, for the long-wavelength dynamics of a liquid comprised of identical, axially symmetric, rigid molecules are microscopically derived. These equations are extended to the case where the dynamics is generated by the interactions of two coherent lasers (the pumps) with the liquid. This interaction corresponds to a weak energy absorption and also to the coupling of the pumps with fluctuations in the mass density, the molecular orientation density and the temperature of the liquid. The microscopic equations generalise those phenomenologically derived in Pick et al. [1] where the role of the temperature fluctuations was ignored. Constraints on the relaxation functions related to the temperature fluctuations and to their coupling with density are derived.