Spectroscopic studies of jet-cooled AgAu and Au2

Abstract

Resonant two-photon ionization spectroscopy has been applied to the jet-cooled Au, and AgAu molecules. Three new band systems of Au, and two new systems of the poorly characterized AgAu molecule have been observed. Excited state lifetime measurements have been made, and assignments of the excited states are suggested. For Au, the a 'Z;t +X '2: transition has been detected, and vibrational levels of the a "2;: state have been observed up to v' = 33, which lies only 120 cm-' below the convergence limit of the system. This allows a precise confirmation of previous high temperature Knudsen effusion measurements of the bond strength of Au, as D z (Au,) = 2.290 f 0.008 eV. In addition, the excited states of Au, of 0: symmetry are shown to have significantly shorter fluorescence lifetimes than the 1, states, and this is explained as resulting from an admixture of Au + Au-ion pair character in these a = 0: states. The ionization potential of Au, has been bracketed as IP(Au,) = 9.20 f 0.2 1 eV, which may be combined with the values of D g (Au,) and IP(Au) to provide the dissociation energy of the Au: ion as D g (Au,+) = 2.32 f 0.2 1 eV. Detailed comparisons with theoretical results are made for Au,, and assignments of the A and B states of AgAu to a = 0 + and a' = 1, respectively, are proposed.

Intense fluorescence of Au20

“…For bare Au clusters, experiments were limited to cluster sizes below the relevant one. Absorption spectra exist only up to a size of 9 atoms [23][24][25][26] and fluorescence measurements only up to a size of 3 atoms. 22,25 a) harald.brune@epfl.ch…”

UV–visible absorption of small gold clusters in neon: Aun (n = 1–5 and 7–9)

“…Fluorescence data 39 indicate that it is not due to a second site isomer. Comparison to gas phase measurements 47 suggests that it is related to the transition whose origin is situated at 2.98 eV. The measurements in argon 48 and krypton 49 matrices also find peaks situated around 5.0 and 5.9 eV.…”

“…Au 2 . The Au dimer has been studied in the gas phase, [45][46][47] in Ar (Refs 43 and 48) and in Kr (Ref. 49) matrices.…”

Application of a parallel genetic algorithm to the global optimization of medium-sized Au–Pd sub-nanometre clusters

“…In spite of the early investigations of neutral Au 2 [30] and Au 3 [31]. It is well known that experimental investigations of medium sized neutral Au clusters are limited for the reasons given above.…”