Valence-bound anions with a dipolar core can support dipole-bound states (DBSs) below the electron detachment threshold. The highly diffuse DBS observed is usually of σ symmetry with an s-like orbital. Recently, a π-type DBS was observed experimentally in the 9-anthrolate anion (9AT) and it was shown to be stabilized due to the large anisotropic polarizability of the 9AT core. To confirm the general existence of π-DBS and its structural dependence, here we report an investigation of the 9-phenanthrolate anion (9PT), which has a different structure and lower symmetry than 9AT. Photodetachment spectroscopy revealed a DBS 257 cm below the detachment threshold of 9PT at 19 627 cm (2.4334 eV). Resonant two-photon photoelectron imaging indeed showed a π symmetry for the DBS. Similar to that observed in 9AT, the π-DBS in 9PT is also stabilized by the anisotropic polarizability of the 9PT core and accessed via nonadiabatic population transfer from the initially populated σ-DBS. Photodetachment spectroscopy unveiled nine above-threshold vibrational resonances of the DBS, resulting in nine highly non-Franck-Condon resonant photoelectron spectra by tuning the detachment laser to the vibrational resonances. The combination of photodetachment spectroscopy and resonant photoelectron spectroscopy allowed frequencies for nine vibrational modes of the 9-phenathroxy radical to be measured, including the six lowest frequency bending modes.
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http://dx.doi.org/10.1021/acs.jpca.1c01563 | DOI Listing |
J Phys Chem A
December 2024
Department of Chemistry, KAIST, Daejeon 34141, Republic of Korea.
A photodetachment and photoelectron spectroscopic study by employing a cryogenically cooled ion trap combined with a velocity-map imaging setup has been carried out to unravel the vibrational structures and autodetachment dynamics of the dipole-bound states (DBSs) of -, -, and -methylphenolate anions (-, -, and -CHPhO). The electron binding energy of the DBS increases monotonically with the increase of the neutral dipole moment to give respective values of 66 ± 15, 123 ± 18, or 154 ± 14 cm for the -, -, or -isomer. The different electron-donating effects of the methyl moieties in the three geometrically different isomers seem to be reflected in the experiment.
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 Lett
December 2024
Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218, United States.
J 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 PDFJ Chem Phys
August 2024
INFIQC: Instituto de Investigaciones en Fisicoquímica de Córdoba (CONICET - UNC) - Haya de la Torre y Medina Allende, Ciudad Universitaria, X5000HUA Córdoba, Argentina.
Dipole-bound states in anions exist when a polar neutral core binds an electron in a diffuse orbital through charge-dipole interaction. Electronically excited polar neutral cores can also bind an electron in a diffuse orbital to form Core-Excited Dipole-Bound States (CE-DBSs), which are difficult to observe because they usually lie above the electron detachment threshold, leading to very short lifetimes and, thus, unstructured transitions. We report here the photodetachment spectroscopy of cryogenically cooled acetylacetonate anion (C5H7O2-) recorded by detecting the neutral radical produced upon photodetachment and the infrared spectroscopy in He-nanodroplets.
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