Coherent anti-Stokes Raman spectroscopy of shock-compressed liquid nitrogen/argon mixtures

Journal Article · Thu Sep 01 04:00:00 EDT 1994 · Journal of Chemical Physics; (United States)

DOI:https://doi.org/10.1063/1.467533· OSTI ID:7070719

Moore, D S; Schmidt, S C; Shaw, M S ^[1]

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1. Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)

Single-pulse multiplex coherent anti-Stokes Raman scattering (CARS) was used to obtain vibrational spectra of 20%/80% liquid nitrogen/argon mixtures, shock compressed to several high-pressure/high-temperature states. A semiclassical model for CARS spectra was used to extract best fit vibrational frequencies, peak Raman susceptibilities, and Raman linewidths from the data. Up to a maximum single shock pressure of 17.1 GPa, the N[sub 2] vibrational frequency was found to increase monotonically with pressure. The vibrational frequencies measured in both the singly and doubly shocked N[sub 2]/Ar mixtures correspond within experimental error to those for pure nitrogen at equivalent pressures and temperatures, implying that the influence of the interaction potential on the N[sub 2] vibrational frequency for the N[sub 2]/Ar collision is not significantly different from that of a N[sub 2]/N[sub 2] collision at these conditions. The transition intensity and linewidth data suggest that thermal equilibrium of the vibrational levels is attained in less than 10 ns at these shock pressures. Vibrational temperatures obtained were used to improve the potential function of argon used to calculate equation-of-state pressures and temperatures. The measured linewidths suggest that the nitrogen vibrational dephasing time decreased to about 1 ps at the highest pressure shock state.

• OSTI ID: 7070719
• Journal Information: Journal of Chemical Physics; (United States), Journal Name: Journal of Chemical Physics; (United States) Vol. 101:5; ISSN JCPSA6; ISSN 0021-9606
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360606* -- Other Materials-- Physical Properties-- (1992-)
ARGON
BINARY MIXTURES
COMPRESSED GASES
DISPERSIONS
ELEMENTS
ENERGY LEVELS
EXCITED STATES
FLUIDS
GASES
LINE WIDTHS
MIXTURES
NITROGEN
NONLINEAR OPTICS
NONMETALS
OPTICS
RARE GASES
SEMICLASSICAL APPROXIMATION
SHOCK WAVES
VERY HIGH PRESSURE
VIBRATIONAL STATES