High resolution continuous wave spectroscopy on the X²Π_3/2 to A²Σ⁺ transition in nitric oxide

Within the scope of the development of a new kind of gas sensor, we employ Doppler-free saturated absorption spectroscopy on the X²Π_3/2 to A²Σ⁺ transition in nitric oxide (NO) for different total angular momenta J on the P₁₂ branch. Spectroscopy is performed in continuous wave operation at 226 nm in a 50 cm long through-flow cell. Via phase sensitive detection by a lock-in amplifier the hyperfine structure of the X²Π_3/2 state of NO is partially resolved. The data is compared to previous measurements, showing good agreement. Investigation of the dependence of the spectroscopic feature on power and pressure, should yield hyperfine constants, natural transition linewidth and the collisional cross-section between NO molecules.