Two-color resonant four-wave mixing spectroscopy of the X1A1(5 0 0) state of SO2 in a supersonic jet

We demonstrate an application of two-color resonant four-wave mixing (TC-RFWM) technique to produce and to detect vibrationally excited level (5 0 0) of the X1A1 state of SO2 in a supersonic jet. A stimulated-emission pumping (SEP) scheme of TC-RFWM was employed, with probe (pump) and grating (dump) wavelengths in resonance with transitions A1A2(E band)–X1A1(0 0 0) and A1A2–X1A1(5 0 0), respectively. The double-resonance nature of this technique facilitates unambiguous vibronic assignments. From 94 pairs of transitions we measured energies of 20 rotational levels in X1A1(5 0 0) and obtained rotational parameters and vibrational energy of this level.