Effectiveness of the formation of singlet oxygen in a non-self-maintaining discharge in mixtures of $\mathrm{O}_2$ with noble gases

The investigations were conducted in a discharge controlled by an electron beam in mixtures $\rm Ar:\rm O_2$ and $\rm He:\rm O_2$ in a wide range of values of the reduced electric field $E/N$, current density of the beam and discharge, and pulse durations. Dependences of the effective coefficient of excitation of the level $\text{a}^1\Delta_{\text{g}}\alpha_{\text{eff}}$ on $E/N$ were obtained. It is shown that $\rm Ar:\rm O_2$ mixtures with a low oxygen content $(\simeq1\%)$ at values of $E/N$ amounting to $(1$–$3)\cdot 10^{-17}$ V$\cdot$cm$^2$ are optimal for obtaining high values of $\rm O_2(a^1\Delta_{\text{g}})$.