| Autor: |
Schmidt, S. C., Moore, D. S., Shaw, M. S., Johnson, J. D. |
| Předmět: |
|
| Zdroj: |
Journal of Chemical Physics; 12/1/1989, Vol. 91 Issue 11, p6765, 7p |
| Abstrakt: |
Vibrational spectra of liquid oxygen, 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 using a semiclassical model for the CARS intensities and best fit vibrational frequencies, peak Raman susceptibilities, and Raman linewidths. Up to the maximum shock pressure of 9.6 GPa, the vibrational frequencies were found to increase monotonically with pressure. An empirical fit, which could be used as a pressure/temperature/frequency calibration standard, showed that the Raman frequency shifts could be accurately described by linear pressure and temperature dependences. Above ≊9 GPa, the liquid oxygen opacity at 632.8 nm increased rapidly, presumably because of proximity (collision)-induced absorption. Calculations showed that the induced absorption did not resonantly enhance the CARS spectra, but did attenuate the laser beams and the CARS signals. The measured linewidths suggest that the vibrational dephasing time decreased to approximately 1 ps at the highest pressures. [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
| Externí odkaz: |
|
