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

Journal Article · Tue Jun 15 00:00:00 EDT 1993 · Journal of Chemical Physics; (United States)

DOI:https://doi.org/10.1063/1.464418· OSTI ID:6608514

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

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

Vibrational spectra of liquid nitrogen/carbon monoxide mixtures, shock compressed to several high-pressure/high-temperature states, were obtained using single-pulse multiplex coherent anti-Stokes Raman scattering (CARS). The experimental spectra were compared to synthetic spectra calculated with a semiclassical model for CARS intensities and using best fit vibrational frequencies, peak Raman susceptibilities, and Raman linewidths. Up to a maximum shock pressure of 9.3 GPa, both the N[sub 2] and CO vibrational frequencies were found to increase monotonically with pressure but depended strongly on the nitrogen/carbon monoxide mixture ratio. An empirical fit of the Raman frequency shifts incorporating previously published neat nitrogen and carbon monoxide data, using a functional form dependent on pressure, temperature, and mixture ratio, accurately describes both the N[sub 2] and CO shifts. 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 and the vibrational temperatures obtained were used to improve the potential function used to calculate equation-of-state pressures and temperatures. The measured linewidths were different for N[sub 2] and CO and suggest that the vibrational dephasing time decreased to a few ps at the highest pressure shock state.

• OSTI ID: 6608514
• Journal Information: Journal of Chemical Physics; (United States), Vol. 98:12; ISSN 0021-9606
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
BINARY MIXTURES
VIBRATIONAL STATES
CARBON MONOXIDE
NITROGEN
COMPRESSION
LINE WIDTHS
LIQUIDS
RAMAN SPECTROSCOPY
SHOCK WAVES
CARBON COMPOUNDS
CARBON OXIDES
CHALCOGENIDES
DISPERSIONS
ELEMENTS
ENERGY LEVELS
EXCITED STATES
FLUIDS
LASER SPECTROSCOPY
MIXTURES
NONMETALS
OXIDES
OXYGEN COMPOUNDS
SPECTROSCOPY
360606* - Other Materials- Physical Properties- (1992-)