Nb©Au: a molecular wheel with a short Nb[triple bond, length as m-dash]Nb triple bond coordinated by an Au ring and reinforced by σ aromaticity.

We report a photoelectron spectroscopy and high-resolution photoelectron imaging study of a bimetallic NbAu cluster. Theoretical calculations, in conjunction with the experimental data, reveal that NbAu possess high-symmetry structures featuring a Nb-Nb axis coordinated equatorially by an Au ring. Chemical bonding analyses show that there are two π bonds and one σ bond in the Nb moiety in Nb©Au, as well as five totally delocalized σ bonds.

Alignment of the hydrogen molecule under intense laser fields.

Alignment of the electronically excited E,F state of the H molecule is studied using the velocity mapping imaging technique. Photofragment images of H due to the dissociation mechanism that follows the 2-photon excitation into the (E,F; ν = 0, J = 0) electronic state show a strong dependence on laser intensity, which is attributed to the high polarizability anisotropy of the H (E,F) state. We observe a marked structure in the angular distribution, which we explain as the interference between the prepared J = 0 and Stark-mixed J = 2 rovibrational states of H, as the laser intensity increases.

Competition between drum and quasi-planar structures in RhB: motifs for metallo-boronanotubes and metallo-borophenes.

Metal-doped boron clusters provide new opportunities to design nanoclusters with interesting structures and bonding. A cobalt-doped boron cluster, CoB, has been observed recently to be planar and can be viewed as a motif for metallo-borophenes, whereas the drum isomer as a motif for metallo-boronanotubes is found to be much higher in energy. Hence, whether larger doped boron drums are possible is still an open question.

Manganese-centered tubular boron cluster - MnB16 (-): A new class of transition-metal molecules.

We report the observation of a manganese-centered tubular boron cluster (MnB16 (-)), which is characterized by photoelectron spectroscopy and ab initio calculations. The relatively simple pattern of the photoelectron spectrum indicates the cluster to be highly symmetric. Ab initio calculations show that MnB16 (-) has a Mn-centered tubular structure with C4v symmetry due to first-order Jahn-Teller effect, while neutral MnB16 reduces to C2v symmetry due to second-order Jahn-Teller effect.

Probing the structures of gold-aluminum alloy clusters AuxAly(-): a joint experimental and theoretical study.

Besides the size and structure, compositions can also dramatically affect the properties of alloy nanoclusters. Due to the added degrees of freedom, determination of the global minimum structures for multi-component nanoclusters poses even greater challenges, both experimentally and theoretically. Here we report a systematic and joint experimental/theoretical study of a series of gold-aluminum alloy clusters, AuxAly(-) (x + y = 7,8), with various compositions (x = 1-3; y = 4-7).

The Planar CoB18 (-) Cluster as a Motif for Metallo-Borophenes.

Monolayer-boron (borophene) has been predicted with various atomic arrangements consisting of a triangular boron lattice with hexagonal vacancies. Its viability was confirmed by the observation of a planar hexagonal B36 cluster with a central six-membered ring. Here we report a planar boron cluster doped with a transition-metal atom in the boron network (CoB18 (-) ), suggesting the prospect of forming stable hetero-borophenes.

A combined photoelectron spectroscopy and relativistic ab initio studies of the electronic structures of UFO and UFO(-).

The observation of the gaseous UFO(-) anion is reported, which is investigated using photoelectron spectroscopy and relativisitic ab initio calculations. Two strong photoelectron bands are observed at low binding energies due to electron detachment from the U-7sσ orbital. Numerous weak detachment bands are also observed due to the strongly correlated U-5f electrons.

Probing the Electronic Structure and Chemical Bonding of Mono-Uranium Oxides with Different Oxidation States: UOx(-) and UOx (x = 3-5).

Uranium oxide clusters UOx(-) (x = 3-5) were produced by laser vaporization and characterized by photoelectron spectroscopy and quantum theory. Photoelectron spectra were obtained for UOx(-) at various photon energies with well-resolved detachment transitions and vibrational resolution for x = 3 and 4. The electron affinities of UOx were measured as 1.

Bond-bending isomerism of AuI: competition between covalent bonding and aurophilicity.

We report a joint photoelectron spectroscopy and theoretical investigation of the gaseous AuI cluster, which is found to exhibit two types of isomers due to competition between Au-I covalent bonding and Au-Au aurophilic interactions. The covalent bonding favors a bent IAuIAuI structure with an obtuse Au-I-Au angle (100.7°), while aurophilic interactions pull the two Au atoms much closer, leading to an acutely bent structure (72.

Cobalt-centred boron molecular drums with the highest coordination number in the CoB16- cluster.

The electron deficiency and strong bonding capacity of boron have led to a vast variety of molecular structures in chemistry and materials science. Here we report the observation of highly symmetric cobalt-centered boron drum-like structures of CoB16(-), characterized by photoelectron spectroscopy and ab initio calculations. The photoelectron spectra display a relatively simple spectral pattern, suggesting a high symmetry structure.

Photoelectron Spectroscopy of BiAu(-) and BiBO(-): Further Evidence of the Analogy between Au and Boronyl.

Boronyl (BO) is a monovalent σ radical with a B≡O triple bond. Its chemistry has remained relatively unknown, though analogy has been established for BO with monovalent atoms, such as H or Au. Here we report a photoelectron spectroscopic study of BiAu(-) and BiBO(-), showing further evidence of the analogy between Au and BO.

High resolution photoelectron imaging of UO(-) and UO2(-) and the low-lying electronic states and vibrational frequencies of UO and UO2.

We report a study of the electronic and vibrational structures of the gaseous uranium monoxide and dioxide molecules using high-resolution photoelectron imaging. Vibrationally resolved photoelectron spectra are obtained for both UO(-) and UO2(-). The spectra for UO2(-) are consistent with, but much better resolved than a recent study using a magnetic-bottle photoelectron analyzer [W.

Probing the electronic and vibrational structure of Au2Al2(-) and Au2Al2 using photoelectron spectroscopy and high resolution photoelectron imaging.

The electronic and vibrational structures of Au2Al2(-) and Au2Al2 have been investigated using photoelectron spectroscopy (PES), high-resolution photoelectron imaging, and theoretical calculations. Photoelectron spectra taken at high photon energies with a magnetic-bottle apparatus reveal numerous detachment transitions and a large energy gap for the neutral Au2Al2. Vibrationally resolved PE spectra are obtained using high-resolution photoelectron imaging for the ground state detachment transition of Au2Al2(-) at various photon energies (670.

Electronic structure and chemical bonding of a highly stable and aromatic auro-aluminum oxide cluster.

We have produced an auro-aluminum oxide cluster, Au2(AlO)2(-), as a possible model for an Au-alumina interface and investigated its electronic and structural properties using photoelectron spectroscopy and density functional theory. An extremely large energy gap (3.44 eV) is observed between the lowest unoccupied and the highest occupied molecular orbitals of Au2(AlO)2, suggesting its high electronic stability.

Strong electron correlation in UO2(-): a photoelectron spectroscopy and relativistic quantum chemistry study.

The electronic structures of actinide systems are extremely complicated and pose considerable challenges both experimentally and theoretically because of significant electron correlation and relativistic effects. Here we report an investigation of the electronic structure and chemical bonding of uranium dioxides, UO2(-) and UO2, using photoelectron spectroscopy and relativistic quantum chemistry. The electron affinity of UO2 is measured to be 1.

Probing the electronic structures of low oxidation-state uranium fluoride molecules UF(x)- (x = 2-4).

We report the experimental observation of gaseous UF(x)(-) (x = 2-4) anions, which are investigated using photoelectron spectroscopy and relativistic quantum chemistry. Vibrationally resolved photoelectron spectra are obtained for all three species and the electron affinities of UF(x) (x = 2-4) are measured to be 1.16(3), 1.

Temperature-dependent, nitrogen-perturbed line shape measurements in the ν1 + ν3 band of acetylene using a diode laser referenced to a frequency comb.

The P(11) line of the ν1 + ν3 combination band of C2H2 was studied using an extended cavity diode laser locked to a frequency comb. Line shapes were measured for acetylene and nitrogen gas mixtures at a series of temperatures between 125 and 296 K and total pressures up to 1 atm. The data were fit to two speed-dependent line shape models and the results were compared.

What is the best DFT functional for vibronic calculations? A comparison of the calculated vibronic structure of the S1-S0 transition of phenylacetylene with cavity ringdown band intensities.

The sensitivity of vibronic calculations to electronic structure methods and basis sets is explored and compared to accurate relative intensities of the vibrational bands of phenylacetylene in the S(1)(A(1)B(2)) ← S(0)(X(1)A(1)) transition. To provide a better measure of vibrational band intensities, the spectrum was recorded by cavity ringdown absorption spectroscopy up to energies of 2000 cm(-1) above the band origin in a slit jet sample. The sample rotational temperature was estimated to be about 30 K, but the vibrational temperature was higher, permitting the assignment of many vibrational hot bands.