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The photodissociation dynamics of Au-Xe leading to Xe+ formation via the Ξ1/2-X2Σ+ (v′, 0) band system (41 500-41 800 cm-1) have been investigated by velocity map imaging. Five product channels have been indentified, which can be assigned to photoinduced charge transfer followed by photodissociation in either the neutral or the [Au-Xe]+ species. For the neutral species, charge transfer occurs via a superexcited Rydberg state prior to dissociative ionization, while single-photon excitation of the gold atom in Au+-Xe accesses an (Au+)*-Xe excited state that couples to a dissociative continuum in Au-Xe+. Mechanisms by which charge transfer occurs are proposed, and branching ratios for Xe+ formation via the superexcited Rydberg state are reported. The bond dissociation energy for the first excited state of Au+-Xe is determined to be ∼9720 ± 110 cm-1. [ABSTRACT FROM AUTHOR]

The ultraviolet photodissociation dynamics of the gold-rare gas atom van der Waals complexes (Au–RG, RG=Ar, Kr, and Xe) have been studied by velocity map imaging. Photofragmentation of Au–Ar and Au–Kr at several wavelengths permits extrapolation to zero of the total kinetic energy release (TKER) spectra as monitored in the Au(2P3/2°[5d106p]) fragment channel, facilitating the determination of ground state dissociation energies of D0″(Au–Ar)=149±13 cm-1 and D0″(Au–Kr)=240±19 cm-1, respectively. In the same spectral region, transitions to vibrational levels of an Ω′=1/2 state of the Au–Xe complex result in predissociation to the lower Au(2P1/2°[5d106p])+Xe(1S0[5p6]) fragment channel for which TKER extrapolation yields a value of D0″(Au–Xe)=636±27 cm-1. Asymmetric line shapes for transitions to the v′=14 level of this state indicate coupling to the Au(2P3/2°[5d106p])+Xe(1S0[5p6]) continuum, which allows us to refine this value to D0″(Au–Xe)=607±5 cm-1. The dissociation dynamics of this vibrational level have been studied at the level of individual isotopologues by fitting the observed excitation spectra to Fano profiles. These fits reveal a remarkable variation in the predissociation dynamics for different Au–Xe isotopologues. For Au–Ar and Au–Xe, the determined ground state dissociation energies are in good agreement with recent theoretical calculations; the agreement of the Au–Kr value with theory is less satisfactory. [ABSTRACT FROM AUTHOR]

Gold nanoparticles are known to be highly versatile oxidation catalysts utilizing molecular oxygen as a feedstock, but the mechanism and species responsible for activating oxygen remain unclear. The reaction between unsupported cationic gold clusters and molecular oxygen has been investigated. The resulting complexes were characterized in the gas phase using IR spectroscopy. A strong red-shift in the observed ν(O-O) stretching frequency indicates the formation of superoxo (O2(-)) moieties. These moieties are seen to form spontaneously in systems, which upon electron transfer attain a closed shell within the spherical jellium model (Au10(+) and Au22(+)), whereas an oxygen induced self-promotion in the activation is observed for other systems (Au4(+), Au12(+), Au21(+))., (© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)