Copper doping of small gold cluster cations: Influence on geometric and electronic structure

Abstract

Analytical approach for the excited-state Hessian in time-dependent density functional theory: Formalism, implementation, and performance J. Chem. Phys. 135, 184111 (2011) Stability analysis of multiple nonequilibrium fixed points in self-consistent electron transport calculations J. Chem. Phys. 135, 174111 (2011) Communication: Orbital instabilities and triplet states from time-dependent density functional theory and longrange corrected functionals J. Chem. Phys. 135, 151103 (2011) All-electron time-dependent density functional theory with finite elements: Time-propagation approach J. Chem. Phys. 135, 154104 (2011) Additional information on J. Chem. Phys. The effect of Cu doping on the properties of small gold cluster cations is investigated in a joint experimental and theoretical study. Temperature-dependent Ar tagging of the clusters serves as a structural probe and indicates no significant alteration of the geometry of Au n + (n = 1-16) upon Cu doping. Experimental cluster-argon bond dissociation energies are derived as a function of cluster size from equilibrium mass spectra and are in the 0.10-0.25 eV range. Near-UV and visible light photodissociation spectroscopy is employed in conjunction with time-dependent density functional theory calculations to study the electronic absorption spectra of Au 4-m Cu m + (m = 0, 1, 2) and their Ar complexes in the 2.00−3.30 eV range and to assign their fragmentation pathways. The tetramers Au 4 + , Au 4 + · Ar, Au 3 Cu + , and Au 3 Cu + · Ar exhibit distinct optical absorption features revealing a pronounced shift of electronic excitations to larger photon energies upon substitution of Au by Cu atoms. The calculated electronic excitation spectra and an analysis of the character of the optical transitions provide detailed insight into the composition-dependent evolution of the electronic structure of the clusters.

Optical Absorption of Small Palladium‐Doped Gold Clusters

“…Previous gas phase studies of Au 4 + were performed with photon energies below 3.5 eV and hence only reported band A at 2.58 eV, [19,20,22,32] and an onset of band B. [22] UV-visible absorption measurements of neutral mass selected gold clusters embedded in Ne matrices were carried out in the extended energy range of 1.5-6.0 eV, showing a strong absorption feature at 3.17 eV, close to band B.…”

“…Figure 2b shows that the computed spectrum, calculated with the rhombic minimum energy structure of Au 4 + shown as inset, is in good agreement with the experiment if a redshift of the computed bands B, C, and D of about 0.2 eV is taken into account. [19,22,32] Schafer et al [22] assigned the simulated peak at 3.3 eV to a low intensity band at 3.2 eV, and the existence of an experimental band at 3.5 eV was interpreted as the presence of additional isomers in the beam. In the current work, we suggest that the calculated peak B may be a redshifted representation of the experimental peak B.…”

“…[4] To enhance understanding, small unsupported atomic clusters, consisting of only a few atoms, represent ideal model systems for detailed investigations. [5] Moreover, many properties of small atomic clusters do not scale with size, are strongly composition and charge dependent, and can be very www.particle-journal.com www.MaterialsViews.com absorption measurements were carried out for Au 4-m Cu m + (m = 0-2) [32] and Ag n Au 4-n + (n = 1-3) [33] clusters in the gas phase.…”

“…This result is supported by the measurements presented in Figure 1a,b, in which Au 4 + depletion coincides with Au 3 + signal increase, as also seen in previous experiments. [19,22,32] PdAu 3 + preferentially dissociates Ar at 460 nm (indicated by an arrow) implies laser induced fragmentation of these clusters. In contrast, the increase in Au 3 + signal shows that this cluster is the fragmentation channel of Au 4 + (at 482 nm).…”

Nonlinear effects in infrared action spectroscopy of silicon and vanadium oxide clusters: experiment and kinetic modeling

“…In recent decades, advances in quantum chemistry methods and computer hardware have established density functional theory (DFT) as the framework of choice to compute IR and optical spectra. [10][11][12][13][14] This approach has well known limitations such as the poor description of long-range dispersion forces, strong correlation regimes or, in the case of time-dependent DFT for optical spectra, charge transfer excitations. Despite such restrictions, the DFT approach remains quite robust, relatively free of parameters, and computationally more efficient than most wavefunction-based methods.…”