We report a photoelectron imaging study of (OCS)-2 and compare the results to OCS-.H2O. Two electron-emission mechanisms are observed for the dimer anion: direct photodetachment and autodetachment, while OCS-.H2O exhibits only the direct mechanism. The results provide evidence of covalent (OCS)-2 coexisting with the OCS-.OCS cluster anion. The autodetachment originating from the covalent species is modeled as thermionic emission transpiring in the regime of fragmentation. The bulk statistical model is found applicable to the small anion due to the availability of low-lying excited states.
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http://dx.doi.org/10.1103/PhysRevLett.90.093001 | DOI Listing |
J Phys Chem A
December 2024
Department of Chemistry, Durham University, Durham DH1 3LE, United Kingdom.
Photoelectron imaging of the doubly deprotonated ethylenediaminetetraacetic acid dianion (EDTA) at variable wavelengths indicates two electron loss pathways: direct detachment and thermionic emission from monoanions. The structure of EDTA is also investigated by electronic structure calculations, which indicate that EDTA has two intramolecular hydrogen bonds linking a carboxylate and carboxylic acid group at either end of the molecular backbone. The direct detachment feature in the photoelectron spectrum is very broad and provides evidence for a dissociative photodetachment, where decarboxylation occurs rapidly after electron loss.
View Article and Find Full Text PDFJ Chem Phys
December 2024
State Key Laboratory of Precision Spectroscopy, and School of Physics and Electronic Science, East China Normal University, Shanghai 200241, China.
The direct photodetachment and two-photon photodissociation-photodetachment processes of a series of PtIn- (n = 2-5) anions were systematically studied using cryogenic anion photoelectron spectroscopy and first-principles electronic structure calculations. The adiabatic/vertical detachment energies (ADEs/VDEs) of these anions were determined from their 193 nm photoelectron (PE) spectra, i.e.
View Article and Find Full Text PDFJ Phys Chem A
October 2024
Department of Chemistry and Biochemistry, University of Arizona, Tucson, Arizona 85721, United States.
The photoelectron spectra of cluster anions of superoxide (O) solvated by one molecule of benzoxazole (BzOx) reveal two competing photodetachment mechanisms: a direct photoemission from the solvated cluster core and an indirect pathway involving temporary anion states of benzoxazole accessed via the O·BzOx → O·BzOx charge-transfer transitions. Benzoxazole is a bicyclic unsaturated organic molecule that does not form permanent anions. However, its low-lying vacant π* orbitals permit a resonant capture of the electron emitted from the O cluster core.
View Article and Find Full Text PDFJ Chem Phys
September 2024
School of Chemistry, Norwich Research Park, University of East Anglia, Norwich NR4 7TJ, United Kingdom.
The recent discovery of cyano-substituted aromatic and two-ring polycyclic aromatic hydrocarbon molecules in Taurus Molecular Cloud-1 has prompted questions on how the electronic structure and excited-state dynamics of these molecules are linked with their existence and abundance. Here, we report a photodetachment and frequency- and angle-resolved photoelectron spectroscopy study of jet-cooled para-deprotonated benzonitrile (p-[Bzn-H]-). The adiabatic detachment energy was determined as 1.
View Article and Find Full Text PDFCommun Chem
August 2024
Physical Sciences Division, Pacific Northwest National Laboratory, Richland, WA, 99352, USA.
The oxidation of phenolic compounds is one of the most important reactions prevalent in various biological processes, often explicitly coupled with proton transfers (PTs). Quantitative descriptions and molecular-level understanding of these proton-coupled electron transfer (PCET) reactions have been challenging. This work reports a direct observation of PCET in photodetachment (PD) photoelectron spectroscopy (PES) of hydrogen-bonded phenolic (ArOH) nitrate (NO) complexes, in which a much slower rising edge provides a spectroscopic signature to evidence PCET.
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