The determination of cross sections for quenching of resonance radiation of metal atoms III. Results for thallium

The intensity of fluorescence of thallium has been measured in hydrogen-oxygen flames diluted with each of the gases, argon, helium, nitrogen and carbon dioxide and the measurements used to obtain the following values for the quenching cross section (Å2) for the 7s2S½ state of thallium σ2H2 = 0.03, σ2O2 = 13.2 ± 1.5, σ2N2 = 6.4 ± 0.2, σ2H2O = 1.75 ± 0.2, σ2CO = 13.6 ± 0.8, σ2CO2 = 32.5 ± 1.5, σ2Ar ≤ 0.1, σ2He ≤ 0.12. These values for the cross sections have been used to re-calculate the rate constants of the reactions, Tl + H + X → HX + Tl*, where X = H, OH, Cl or Br, from the data obtained by Phillips & Sugden (1961). The re-calculated values are lower than the original ones by a factor of 2.2.