The excited electronic state of the silver–ammonia complex

Abstract

The first excited electronic state of the silver–ammonia 1:1 complex AgNH3 was studied by resonantly enhanced two-photon ionization. The complex was formed using laser ablation and cooled in a free jet expansion. The origin of the à 2E1/2–X̃ 2A1 band system located at 467 nm is redshifted by 8142 cm−1 from the corresponding 5p 2P1/2–5s 2S transition of Ag, indicating a significant stabilization upon electronic excitation. The splitting of the origins of the spin–orbit substates, E1/22 and E3/22, was determined to be 805 cm−1. The intermolecular stretching (ν3) overtones and their combination bands with the intermolecular bending (ν6) mode are observed for the E1/22 state, whereas only the ν3 mode appears in the E3/22–A12 bands. The vibronic assignment was supported by the spectrum of its deuterated isotopomer, AgND3. The vibrational frequencies of the ν3 and ν6 mode in the à 2E1/2 state of AgNH3 were determined to be 371 and 185 cm−1, respectively. The anomalously small frequency of the ν6 mode is explained as a result of Jahn–Teller interaction and spin–orbit interaction in the à 2E state.