Chemical evolution in nitrogen shocked beyond the molecular stability limit

Rebecca K Lindsey; Sorin Bastea; Yanjun Lyu; Sebastien Hamel; Nir Goldman; Laurence E Fried

doi:10.1063/5.0157238

Chemical evolution in nitrogen shocked beyond the molecular stability limit

J Chem Phys. 2023 Aug 28;159(8):084502. doi: 10.1063/5.0157238.

Authors

Rebecca K Lindsey^{1

2}, Sorin Bastea³, Yanjun Lyu², Sebastien Hamel³, Nir Goldman^{3

4}, Laurence E Fried³

Affiliations

¹ Department of Chemical Engineering, University of Michigan, Ann Arbor, Michigan 48109, USA.
² Department of Materials Science and Engineering, University of Michigan, Ann Arbor, Michigan 48109, USA.
³ Physical and Life Sciences Directorate, Lawrence Livermore National Laboratory, Livermore, California 94550, USA.
⁴ Department of Chemical Engineering, University of California, Davis, California 95616, USA.

PMID: 37622598
DOI: 10.1063/5.0157238

Abstract

Evolution of nitrogen under shock compression up to 100 GPa is revisited via molecular dynamics simulations using a machine-learned interatomic potential. The model is shown to be capable of recovering the structure, dynamics, speciation, and kinetics in hot compressed liquid nitrogen predicted by first-principles molecular dynamics, as well as the measured principal shock Hugoniot and double shock experimental data, albeit without shock cooling. Our results indicate that a purely molecular dissociation description of nitrogen chemistry under shock compression provides an incomplete picture and that short oligomers form in non-negligible quantities. This suggests that classical models representing the shock dissociation of nitrogen as a transition to an atomic fluid need to be revised to include reversible polymerization effects.