Evidence of Electron Capture of an Outgoing Photoelectron Wave by a Nonvalence State in (C₆F₆)_n^–

Abstract

Frequency-resolved photoelectron spectra are presented for (CF) with n = 1-5 that show that CF is solvated by neutral CF molecules. Direct photodetachment channels of CF are observed for all n, leaving the neutral in the S ground state or triplet states, T and T. For n ≥ 2, an additional indirect electron loss channel is observed when the triplet-state channels open. This indirect emission appears to arise from the electron capture of the outgoing photoelectron s-wave by a neutral solvent molecule through an anion nonvalence state. The same process is not observed for the S detachment channel because the outgoing electron wave is predominantly a p-wave. Our results show that anion nonvalence states can act as electron-accepting states in cluster environments and can be viewed as precursor states for diffuse states of liquid CF.

On the Mechanism of Phenolate Photo-Oxidation in Aqueous Solution

“…Nevertheless, the rising edge at all wavelengths is very similar (see inset of Figure 3) between Ph − (aq) and I − (aq). This is surprising because Ph 0 has a large dipole-moment which one might anticipate would influence the ejection mechanism, [43][44][45][46] but apparently does not on the timescale of our experiment.…”

Photoelectron Spectroscopy of the Hexafluorobenzene Cluster Anions: (C6F6)n– (n = 1–5) and I–(C6F6)

“…Additionally, C6F6 is an exceedingly efficient scavenger of excess electrons in the non-attaching molecular liquid tetramethylsilane 2 , again suggesting an efficient electron accepting pathway. In a recent study, we have shown evidence for non-valence states in anionic clusters of C6F6, where a low energy outgoing electron produced by photodetachment from (C6F6)n − (where n = 2 -5) was observed to be recaptured, leading to an indirect electron loss channel 10 . Finally, twophoton photoemission and scanning tunnelling microscopy experiments of C6F6 on Cu(111) surfaces point to the formation of diffuse anion states during the electron-capture process 3,11 .…”

Electronic structure of the para-dinitrobenzene radical anion: a combined 2D photoelectron imaging and computational study

“…30,31 The excited states of pDNBwere calculated using an active space of 12 valence π-orbitals and 15 electrons. In order to include all states within our experimental range, we employed the XMCQDPT2 [11]/SA(9)-CASSCF (15,12) method with a reference space spanned by 11 CASCI wavefunctions, which were obtained through complete active space self-consistent field (CASSCF) calculations using a state averaging procedure (SA). A DFT/PBE0-based one-electron Fock-type matrix was used to obtain energies of all CASSCF semi-canonical orbitals used in perturbation theory.…”

“…For this type of calculations, vibrational analysis and geometry optimization for the closed-shell species, pDNB and NO2 -, were performed using MP2/(aug)-cc-pVTZ and MP2/aug-cc-pVTZ, respectively. Displacements between equilibrium geometries in the anion ground and detached states along each normal mode were estimated locally using the quadratic approximation, based on gradients calculated for the open-shell radical species, pDNBand NO2, at the Franck-Condon point at the MRMP2/CASSCF (15,12) and MRMP2/CASSCF(9,6) levels, respectively, using the same corresponding basis sets.…”

“…[6][7][8][9] We have recently developed an optical variant in which the photoelectron (PE) images are acquired as a function of photon energy (hv). [10][11][12] Here, we present such a 2D PE imaging study and employ highlevel electronic structure calculations to unravel the information-rich spectra of the para-dinitrobenzene radical anion (pDNB − ).…”