Absolute CO number densities measured using TALIF in a non-thermal plasma environment

We report first measurements of time-resolved absolute CO number densities and rotational temperatures in a non-thermal CO₂ plasma environment using TALIF with a nanosecond pulsed laser. Two-photon excitation spectra from the $B^1{\Sigma }^{+}$(v′ = 0) ← $X^1{\Sigma }^{+}$(v″ = 0) Q-branch are recorded and fitted to extract rotational temperatures. Absolute number densities are determined from the frequency-integrated excitation spectrum. The plasma under investigation is a pulsed glow discharge operated at a frequency of 60 Hz with an plasma-on time of 5 ms per plasma cycle, 50 mA plasma current and a pressure of 6.67 mbar. CO number densities range from $(2.6\pm 0.6)\times {10}^{22}$ m⁻³ to $(1.2\pm 0.3)\times {10}^{22}$ m⁻³, while rotational temperatures range from 370 ± 40 K to 700 ± 70 K at the beginning and end of the plasma-on phase, respectively. Our results show fair agreement with literature data. (paper)