Mass spectrometric determination of the dissociation energy of the AuMg diatomic molecule

Dopant induced modulation in the structure and electronic properties of Au10 cluster

DFT calculations at PBE0/SDD ∪ 6-31++G(d,p) level suggest that doped Au₁₀ clusters (with alkali and alkaline earth metals as dopants) are better potential candidates for use in heterogeneous catalysis.

The uncertain bond energy of the NaAu molecule: experimental redetermination and coupled cluster calculations

The dissociation energy of the intermetallic molecule NaAu, for which two largely at variance experimental values are available in the literature, has been redetermined by the Knudsen effusion mass spectrometry method. The molecule has been produced in the vapor phase by a specially designed experimental setting inspired by the double oven technique. The equilibrium of dissociation to atoms as well as the exchange equilibrium with the gold dimer were monitored mass-spectrometrically over about a 600 K temperature range. The third-law analysis of the equilibrium data provides the dissociation energy D0° (NaAu, g) = 245.3 ± 6.8 kJ/mol, corresponding to a formation enthalpy at 298 K of 228.3 ± 7.5 kJ/mol. The NaAu species was also studied computationally at the CCSD(T) level with basis sets of increasing zeta quality thus allowing to evaluate the molecular parameters and the dissociation energy at the complete basis set limit.

A mass spectrometric and density functional study of the intermetallic molecules AuBe, AuMg, and AuCa

The intermetallic molecules AuBe and AuCa were identified by means of the Knudsen-Effusion Mass Spectrometry technique in the high-temperature vapors produced by vaporizing Au-Be-Ca alloys of proper composition. The gaseous equilibria AuBe(g)+Au(g)=Au(2)(g)+Be(g) and AuCa(g)+Au(g)=Au(2)(g)+Ca(g) were studied in the temperature ranges 1720-1841 K and 1669-1841 K, respectively, by monitoring the partial pressures of all the species involved. The equilibrium data were analyzed by the third-law method, obtaining for the first time the dissociation energy D(0) ( composite function) of the two intermetallic species: D(0) ( composite function)(AuBe)=234.0+/-4.0 kJ/mol; D(0) ( composite function)(AuCa)=246.7+/-4.0 kJ/mol. These values are significantly higher than the recently published D(0) ( composite function) of the species AuMg (175.4+/-2.7 kJ/mol). Furthermore, the ionization energies (IE) of AuBe, AuMg, and AuCa were obtained by measuring the electron impact ionization efficiency curves, IE(AuBe)=7.5+/-0.3 eV, IE(AuMg)=6.7+/-0.3 eV, and IE(AuCa)=5.5+/-0.3 eV. Theoretical calculations were also carried out for these species by density functional theory methods (PW91 and BP86) used in conjunction with Stuttgart relativistic effective core potentials. Both functionals were found to perform very well in reproducing experimental D(0) ( composite function), IE, and molecular parameters.