Photoelectron velocity-map imaging spectroscopic and theoretical study on the reactivity of the gold atom toward CH3SH, CH3OH, and H2O

Structural and photoelectron spectroscopic study on the heterotrinuclear nickel-titanium dioxide carbonyl complexes Ni2TiO2(CO) n - (n = 2-4)

Herein, the configurations and intrinsic electronic properties of heteronuclear transition metal dioxide carbonyl anions Ni₂TiO₂(CO) _n ^- (n = 2-4) in the gas phase were investigated using mass spectrometry coupled anionic photoelectron spectroscopy, ab initio calculations, and simulated density-of-state (DOS) spectra. The results clearly show that the binding of electrons is enhanced by the addition of CO. The ground state structures of Ni₂TiO₂(CO) _n ^- (n = 2-4) are characterized to show that three transition metal atoms (one Ti atom and two Ni atoms) forming a quasi-line is favored. The interaction between Ni and C becomes weaker as the cluster size increases. The natural electron configuration shows that the extra electron is enriched on O atoms attached to Ti, and there is strong interaction between Ti and O atoms. This work gives significant insight into the configuration and electronic structures of nickel-titanium dioxide carbonyl anions, which has potential application in adsorption of carbon monoxide on the surfaces/interfaces of alloys.

Comparison of Conventional and Nonconventional Hydrogen Bond Donors in Au- Complexes

Although gold has become a well-known nonconventional hydrogen bond acceptor, interactions with nonconventional hydrogen bond donors have been largely overlooked. In order to provide a better understanding of these interactions, two conventional hydrogen bonding molecules (3-hydroxytetrahydrofuran and alaninol) and two nonconventional hydrogen bonding molecules (fenchone and menthone) were selected to form gas-phase complexes with Au^-. The Au^-[M] complexes were investigated using anion photoelectron spectroscopy and density functional theory. Au^-[fenchone], Au^-[menthone], Au^-[3-hydroxyTHF], and Au^-[alaninol] were found to have vertical detachment energies of 2.71 ± 0.05, 2.76 ± 0.05, 3.01 ± 0.03, and 3.02 ± 0.03 eV, respectively, which agree well with theory. The photoelectron spectra of the complexes resemble the spectrum of Au^- but are blueshifted due to the electron transfer from Au^- to M. With density functional theory, natural bond orbital analysis, and atoms-in-molecules analysis, we were able to extend our comparison of conventional and nonconventional hydrogen bonding to include geometric and electronic similarities. In Au^-[3-hydroxyTHF] and Au^-[alaninol], the hydrogen bonding comprised of Au^-···HO as a strong, primary hydrogen bond, with secondary stabilization by weaker Au^-···HN or Au^-···HC hydrogen bonds. Interestingly, the Au^-···HC bonds in Au^-[fenchone] and Au^-[menthone] can be characterized as hydrogen bonds, despite their classification as nonconventional hydrogen bond donors.

Note: A simple method to suppress the artificial noise for velocity map imaging spectroscopy

A simple method has been proposed to suppress artificial noise from the counts with respect to the central line (or point) for the reconstructed 3D images with cylindrical symmetry in the velocity-map imaging spectroscopy. A raw 2D projection around the z-axis (usually referred to as central line) for photodetachment, photoionization, or photodissociation experiments is pre-processed via angular tailored method to avoid the signal counts distributed near the central line (or point). Two types of photoelectron velocity-map imaging (O(-) and Au(-)⋅NH3) are demonstrated to give rise to the 3D images with significantly reduced central line noise after pre-processing operation. The major advantages of the pre-operation are the ability of suppression of central-line noise to resolve weak structures or vibrational excitation in atoms or molecules near photon threshold.

Photoelectron imaging and theoretical study on nascent hydrogen bond network in microsolvated clusters of Au- (CH3OH)n (n = 1-5)

We first demonstrate the photoelectron spectroscopic evidence of the transition of two competitive solvation patterns in the Au(-)(CH3OH)n (n = 1-5) clusters. Quantum chemical calculations have been carried out to characterize the geometric structures, energy properties and hydrogen-bonded patterns, and to aid the spectral assignment. It has been found that the nonconventional hydrogen bonds dominate the small clusters (n = 1 and 2), whereas the conventional hydrogen bonds play more and more important role from n = 2 to n = 5. This finding provides concrete hydrogen bond network evolution of Au(-) surrounded by methanol molecules.