Vibrational Phase Relaxation along the Critical Isochore of Nitrogen: The Role of Local Density Fluctuations in the Rate Enhancement

Roychowdhury, Swapan and Bagchi, Biman (2003) Vibrational Phase Relaxation along the Critical Isochore of Nitrogen: The Role of Local Density Fluctuations in the Rate Enhancement. In: Physical Review Letters, 90 (7). 075701.

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Abstract

Vibrational dephasing of the nitrogen molecule is known to show highly interesting anomalies near its gas-liquid critical point. Here we present theoretical and computational studies of the Raman linewidth of nitrogen along the critical isochore. The linewidth is found to have a lambda-shaped temperature dependence near the critical point. As observed in experimental studies, the calculated line shape becomes Gaussian as the critical temperature (Tc) is approached. Both the present simulation and a mode coupling theory analysis show that the slow decay of the enhanced density fluctuations near the critical point, probed at the subpicosecond time scales by vibrational frequency modulation, along with an enhanced vibration-rotation coupling, are the main causes of the observed anomalies.

Item Type:	Journal Article
Publication:	Physical Review Letters
Publisher:	American Physical Society (APS)
Additional Information:	Copyright for this article belongs to American Physical Society (APS)
Department/Centre:	Division of Chemical Sciences > Solid State & Structural Chemistry Unit
Date Deposited:	09 Jun 2004
Last Modified:	19 Sep 2010 04:12
URI:	http://eprints.iisc.ac.in/id/eprint/224

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