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Dynamic light scattering in liquid and supercooled diphenylmethane
J E F Rubio1, V G Baonza, M Taravillo
1Departamento de Quimica Fisica I, Facultad de Quimicas, Universidad Complutense de Madrid, 28040 Madrid, Spain. jefrubio@quim.ucm.es
The Journal of Chemical Physics
|July 23, 2004
Summary
Dynamic light scattering reveals liquid diphenylmethane (DPM) dynamics. Structural relaxation and molecular reorientation follow Arrhenius behavior, indicating quasi-slipping conditions for DPM molecules.
Area of Science:
- Physical Chemistry
- Condensed Matter Physics
Background:
- Understanding molecular dynamics in liquids is crucial for predicting material properties.
- Diphenylmethane (DPM) is a key organic compound with applications in polymer science and pharmaceuticals.
Purpose of the Study:
- To investigate the structural relaxation, rotational motions, and reorientation phenomena in liquid diphenylmethane (DPM).
- To determine the temperature dependence of these dynamic processes.
Main Methods:
- Dynamic light scattering (DLS) measurements of polarized (VV) and depolarized (VH) spectra.
- Analysis using the microscopic theory of Wang and the Andersen-Pecora theory.
- Calculation of hydrodynamic volumes under slip and stick boundary conditions.
Main Results:
- Structural relaxation time in DPM exhibits Arrhenius behavior.
- Rayleigh dip observed in VH spectra, consistent with Andersen-Pecora theory.
- Rotation-translation coupling parameter is temperature-independent; collective reorientation time follows Arrhenius behavior.
Conclusions:
- DPM exhibits Arrhenius-type dynamics for structural relaxation and reorientation.
- Molecular reorientation in bulk liquid DPM occurs under quasi-slipping hydrodynamic conditions.