Observation of the two-photon resonant parametric four-wave mixing in the NO C 2Π ( ν = 0) state

Abstract

When the laser frequency was tuned through the C 2Π (ν = 0) « X 2Π (ν″ = 0) two-photon transition of NO, near-IR as well as UV radiations were ejected along the laser propagation with a narrow solid angle. It was shown that the UV wave corresponds to the A 2 Σ + ( ν′ = 0) → X 2 Π ( ν″ = 0) transition. Temporal profiles and polarization properties of output waves indicate that the parametric four wave mixing (PFWM) process is mainly responsible for the simultaneous generation of near-IR and UV radiations. Excitation spectra corresponding to the C 2Π (ν = 0) « X 2Π (ν″ = 0) band exhibited an excellent S/N ratio, implying that the PFWM technique might be utilized as a novel spectroscopic method which can interrogate the two-photon resonant levels.