Transition from Gas-like to Liquid-like Behavior in Supercritical N2

J E Proctor; C G Pruteanu; I Morrison; I F Crowe; J S Loveday

doi:10.1021/acs.jpclett.9b02358

Transition from Gas-like to Liquid-like Behavior in Supercritical N₂

J Phys Chem Lett. 2019 Nov 7;10(21):6584-6589. doi: 10.1021/acs.jpclett.9b02358. Epub 2019 Oct 15.

Authors

J E Proctor¹, C G Pruteanu², I Morrison¹, I F Crowe³, J S Loveday⁴

Affiliations

¹ Materials and Physics Research Group , University of Salford , Manchester M5 4WT , U.K.
² Department of Physics and Astronomy , University College London , Gower Street , London WC1E 6BT , U.K.
³ Photon Science Institute and School of Electrical and Electronic Engineering , University of Manchester , Oxford Road , Manchester M13 9PL , U.K.
⁴ SUPA, School of Physics and Astronomy and Centre for Science at Extreme Conditions , The University of Edinburgh , Edinburgh EH9 3JZ , U.K.

PMID: 31604009
DOI: 10.1021/acs.jpclett.9b02358

Abstract

We have studied in detail the transition from gas-like to rigid liquid-like behavior in supercritical N₂ at 300 K (2.4 T_C). Our study combines neutron diffraction and Raman spectroscopy with ab initio molecular dynamics simulations. We observe a narrow transition from gas-like to rigid liquid-like behavior at ca. 150 MPa, which we associate with the Frenkel line. Our findings allow us to reliably characterize the Frenkel line using both diffraction and spectroscopy methods, backed up by simulation, for the same substance. We clearly lay out what parameters change, and what parameters do not change, when the Frenkel line is crossed.