Nanosecond Pulse Radiolysis of Ammoniacal Solutions of Silver Salts

In pulse radiolysis of silver salts in liquid ammonia at 23°C, the reaction of <tex-math>$e_{{\rm am}}{}^{-}$</tex-math> with Ag⁺ produces Ag, and subsequently the reaction of Ag with Ag⁺ produces <tex-math>${\rm Ag}_{2}{}^{+}$</tex-math> which probably disproportionates to <tex-math>${\rm Ag}_{2}$</tex-math>. The maxima in absorption spectra at 435, 390, and 300 nm are ascribed to Ag, <tex-math>${\rm Ag}_{2}{}^{+}$</tex-math>, and <tex-math>${\rm Ag}_{2}$</tex-math>, respectively. The measured specific rate of the reaction of <tex-math>$e_{{\rm am}}{}^{-}$</tex-math> with Ag⁺ is <tex-math>$1.5\ \times 10^{12}\ M^{-1}\ {\rm sec}^{-1}$</tex-math> at 23°C. The calculated specific rate with the Smoluchowski-Debye equation for a diffusion-controlled reaction of <tex-math>$e_{{\rm am}}{}^{-}$</tex-math> with Ag⁺ is <tex-math>$1.4\ \times 10^{12}\ M^{-1}\ {\rm sec}^{-1}$</tex-math> at 25°C. The specific rate for the reaction of Ag with Ag⁺ is <tex-math>$1.3\times 10^{10}\ M^{-1}\ {\rm sec}^{-1}$</tex-math> at 23°C. At the same temperature, the ratio of the specific rate for the disporportionation of <tex-math>${\rm Ag}_{2}{}^{+}$</tex-math> and extinction coefficient of <tex-math>${\rm Ag}_{2}{}^{+}$</tex-math> at the 390 nm is <tex-math>$10^{6}\ {\rm cm}\ {\rm sec}^{-1}$</tex-math>. A comparison of the spectra of various silver species dissolved in water with the spectra for same species dissolved in liquid ammonia shows that spectra in liquid ammonia are shifted toward longer wavelengths.