The XΣ→XΣ anion to neutral ground state photodetachment of BeO has been studied by means of photoelectron velocity-map imaging spectroscopy in a newly constructed apparatus. Vibrational intervals, rotational constants, and the electron detachment threshold of BeO were determined for the first time. The small moment of inertia of beryllium oxide allowed for the observation of partially resolved rotational contours. Analyses of these contours provided evidence of several detachment channels resulting from changes in molecular rotational angular momenta of ΔN = 0, ±1, ±2, and ±3. The relative intensities of these detachment channels were found to be a function of the electron kinetic energy. Experimental results are compared to the predictions of high level ab initio calculations.
Beryllium can exhibit unusually strong attractive interactions under conditions where it is nominally a closed-shell atom. Two prominent examples are the Be dimer and the He-BeO complex. In the present study, we examine the bonding of the closed-shell Be-F anion. This molecule preserves the closed-shell character of the individual atoms as the electron affinity of F is high (328.16 kJ mol) while that of Be is negative. Photodetachment spectroscopy was used to determine the vibrational frequency for BeF and the electron affinity of BeF (104.2 kJ mol). The latter has been used to determine a lower bound of 343 kJ mol for the bond energy of BeF. Electronic structure calculations yielded predictions that were in good agreement with the observed data. A natural bond orbital analysis shows that BeF is primarily bound by a dative interaction.
Slow electron velocity map imaging (SEVI) spectroscopy was used to examine the BeS anion to neutral ground-state transition, X Σ → X Σ. Rotational constants, vibrational intervals, and the electron binding energy of BeS were determined. Partially resolved rotational contours were seen due to the relatively small moment of inertia of beryllium sulfide. Upon analysis of the rotational contours, it was found that changes in the molecular rotational angular momentum, ΔN = -1, -2, -3, and -4, facilitated photodetachment at near-threshold photon energies. The electron affinity of BeS was found to be 2.3346(2) eV. SEVI spectra recorded using photon energies near the threshold for Δv = -1 processes exhibited features that were associated with a dipole-bound state (DBS) of BeS. Autodetachment spectroscopy was used to probe this state, and rotationally resolved data were obtained for the DBS Σ, v' = 0 - X Σ, v″ = 0 transition. Analysis of this structure provided the rotational constants for BeS X, v″ = 0, and the electron binding energy of the DBS. Electronic structure calculations, performed at the RCCSD(T) and MRCI levels of theory, gave predictions that were in good agreement with the experimental observations.
Photoelectron Circular Dichroism (PECD) is a forward‐backward asymmetry in the photoemission from a non‐racemic sample induced by circularly polarized light. PECD spectroscopy has potential analytical advantages for chiral discrimination over other chiroptical methods due to its increased sensitivity to the chiral potential of the molecule. The use of anions for PECD spectroscopy allows for mass‐selectivity and provides a path to simple experimental schemes that employ table‐top light sources. Evidence of PECD for anions is limited, and insight into the forces that govern PECD electron dynamics in photodetachment is absent. Here, we demonstrate a PECD effect in the photodetachment of mass‐selected deprotonated 1‐indanol anions. By utilizing velocity map imaging photoelectron spectroscopy with a tunable light source, we determine the energy‐resolved PECD over a wide range of photon energies. The observed PECD reaches up to 11 %, similar to what has been measured for neutral species.
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