Spectroscopic observation of gold-dicarbide: Photodetachment and velocity map imaging of the AuC2 anion

Abstract

Photoelectron spectra following photodetachment of the gold dicarbide anion, ${\rm AuC}_2^ - $ AuC 2−, have been recorded using the velocity map imaging technique at several excitation wavelengths. The binding energy spectra show well-defined vibrational structure which, with the aid of computational calculations and Franck-Condon simulations, was assigned to a progression in the Au–C stretching mode, ν3. The experimental data indicate that the features in the spectrum correspond to a 2A′ ← 3A′ transition, involving states which we calculate to have bond angles ∼147° but with a low barrier to linearity.

Probing the electronic structure and Au–C chemical bonding in AuC2− and AuC2 using high-resolution photoelectron spectroscopy

“…The relative intensities of these features are no more than ∼2% of the main spectral bands. The X band is consistent with the PE imaging data reported recently by Visser et al 13 and hence should be due to the putative electronically excited AuC 2 − anion. Figs.…”

“…These peaks are separated by about 195 cm −1 , which should be due to the bending mode. The peaks from a to f resemble a typical Franck-Condon envelope in the bending coordinate, suggesting that the neutral ground state is likely bent in agreement with the recent calculation by Visser et al 13 The band A in the 193 nm spectrum is resolved into a single sharp and intense peak at 3.4483 eV. The band B is resolved into four vibrational fine features between 3.57 and 3.67 eV, labeled as i, j, k, and l in Fig.…”

“…We have also obtained high-resolution PE imaging data from this very weakly populated excited anion. More interestingly, our high-resolution capability leads to a different spectral assignment from that proposed by Visser et al 13 The observed detachment transitions are assigned to be from the 3 2,1,0 (. .…”

“…Apart from mass spectrometric observations of the Au n C m + and Au n C m − species, 11,12 there is no experimental structural or spectroscopic information on any Au-C clusters, except a very recent PES and computational study on AuC 2 − . 13 In this work, Visser et al 13 reported interesting PE imaging on AuC 2 − in the photon energy range from 610 nm to 585 nm, showing a single vibrational progression starting at an electron binding energy of 1.442 eV with a vibrational frequency of 528 cm −1 due to the Au-C stretching in neutral AuC 2 . Surprisingly, the observed spectral features were assigned to derive from a highly excited state of AuC 2 − , whereas the electron binding energies of the ground state of AuC 2 − were suggested to be too high to be accessible with their available photon energies.…”

Stable Gold Carbide Nanostructures

“…To compare the closest contacts Au-C in various structures, the experimental data given in Ref. 9) for AuC nanoparticles and 11) for AuC 2 molecule showed 2.056 and 1.93 ¡, whereas our results for the periodic F-43m Au-C structure and Au 6 C 3 cluster showed 2.106 and 2.286 ¡, respectively. For the Au 6 C 3 cluster which is made of three packed pyramids with C atoms on the tops (Fig.…”