5s←4dtransition of trigonalAg+in zeolite

The configurational (${4d}^{9}5s){}_{}{}^1{}_{}{}^{}D\leftarrow ({4d}^{10}){}_{}{}^1{}_{}{}^{}S$ excitation of trigonally coordinated ${\mathrm{Ag}}^{+}$ in zeolite $A$ is identified as a $\left(C_{3v}\right){}_{}{}^1{}_{}{}^{}A_1^{}{}_{}{}^{}\oplus {}_{}{}^1{}_{}{}^{}E\oplus {}_{}{}^1{}_{}{}^{}E\leftarrow {}_{}{}^1{}_{}{}^{}A_1^{}{}_{}{}^{}$ excitation multiplet centered at 5.55 eV. A single emission occurring in the 3.73-3.83-eV range is assigned to a $\left({4d}^{9}5s\right){}_{}{}^3{}_{}{}^{}E\to \left({4d}^{10}\right){}_{}{}^1{}_{}{}^{}A_1^{}{}_{}{}^{}$ transition. The total oscillator strength of the excitation multiplet is approximately 0.2 and is characteristic of a fully allowed transition. The doubly degenerate components exhibit $E\otimes \epsilon$ dynamic Jahn-Teller effects with $\epsilon$ modes of 458 ${\mathrm{cm}}^{-1\mathrm{}}$ in excitation and 196 ${\mathrm{cm}}^{-1\mathrm{}}$ in emission. Gaseous ethylene binds reversibly with the ${\mathrm{Ag}}^{+}$ ions at 338 K, and concomitant spectral changes provide the first electronic experimental confirmation of the $5s-\pi$ bonding scheme proposed by M. J. S. Dewar for complexation between ${\mathrm{Ag}}^{+}$ and olefins.