Adiabatic and isothermal sound waves: the case of supercritical nitrogen

TL;DR

This study investigates how sound waves behave in supercritical nitrogen, revealing a transition from adiabatic to isothermal regimes as conditions approach supercritical states, using inelastic X-ray scattering data.

Contribution

It provides experimental evidence of the crossover between adiabatic and isothermal sound propagation in supercritical nitrogen through dynamic structure factor analysis.

Findings

Disappearance of positive sound dispersion near supercritical conditions

Evidence of a crossover between adiabatic and isothermal regimes

Dynamic structure factor analysis supports the transition

Abstract

The acoustic sound dispersion of nitrogen in its liquid and supercritical phases has been studied by Inelastic X-Ray Scattering. Approaching supercritical conditions, the gradual disappearance of the positive sound dispersion, characteristic of the low temperature liquid, is observed. In the supercritical state, evidence for a crossover between adiabatic and isothermal sound propagation regimes is inferred by an analysis of the dynamic structure factor based on generalized hydrodynamics.