Quenching of Cadmium Resonance Radiation by Foreign Gases

Measurements have been made on the quenching of the cadmium resonance line 3261 by ${\mathrm{H}}_2$, ${\mathrm{D}}_2$, CO, N${\mathrm{H}}_3$, ${\mathrm{N}}_2$ and C${\mathrm{H}}_4$. The experiment was carried out by comparing the intensity of 3261 emitted from a cell containing Cd vapor and foreign gas with that from a cell containing Cd vapor only. The cells were illuminated simultaneously and the results obtained by the method of photographic photometry. The experiments were performed under conditions (low vapor pressure, short light path through the vapor and small foreign gas pressure) which warrant the application of the Stern-Volmer formula. The quenching cross sections obtained therefrom are: ${\mathrm{H}}_2$, 0.67; ${\mathrm{D}}_2$, 0.19; CO, 0.14; N${\mathrm{H}}_3$, 0.041; ${\mathrm{N}}_2$, 0.021; C${\mathrm{H}}_4$, 0.012×${10}^{-16\mathrm{}}$ ${\mathrm{cm}}^2$.