Filament-Assisted Impulsive Raman Spectroscopy of Ozone and Nitrogen Oxides.

The filament-assisted impulsive Raman spectra of ozone, nitric oxide, and nitrogen dioxide are presented. The Raman response as a function of ozone concentration scales as N(2), where N is the number of oscillators in the interaction region. The system described has a detection limit of ∼300 ppm for gas-phase ozone. Ozone produced via the strong field chemistry occurring within the filament pump was also detected. The measurements reveal spectral interference in the Raman features. Simulations show the spectral fringing results from interference of the Raman signal with pump-induced cross-phase modulation. The fringes are used to classify the symmetric mode of the low concentration filament-generated ozone.