2-PHOTON POLARIZATION SPECTROSCOPY AND (2-PHOTON LASER-INDUCED FLUORESCENCE OF N-2(3))

Two-photon induced polarization spectroscopy (TIPS) for the detection of molecular nitrogen is demonstrated. Laser induced fluorescence (LIF ) from N-2(+), which was created via a (2 + 3)-photon resonance from N -2, was monitored simultaneously to allow a quantitative comparison be tween the two techniques in different operating regimes. Power depende nce checks for both techniques were performed and the effects of colli sional partners were investigated in different gas flow mixtures. Thes e preliminary results suggest that TIPS is not as severely affected by molecular quenching collisions as LIF. The high signal levels obtaine d prove that the technique is sensitive and may have potential as diag nostic tool for combustive and non combustive flows.