Slow photoelectron velocity-map imaging spectroscopy of the C9H7 (indenyl) and C13H9 (fluorenyl) anions

Kim, Jongjin B.; Weichman, Marissa L.; Yacovitch, Tara I.; Shih, Corey; Neumark, Daniel M.

doi:10.1063/1.4820138

Cited by 34 publications

(124 citation statements)

References 109 publications

(127 reference statements)

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“…Therefore, there must be other vibronic coupling effects involved in addition to the JT effect, such as the Hertzberg-Teller (HT) coupling, which involves coupling between two electronic states via non-totally symmetric vibrational modes. [54][55][56][57] Extensive HT coupling has been observed recently in high-resolution PE imaging spectroscopy of the C 9 H 7 (indenyl) and C 13 H 9 (fluorenyl) anions by Neumark and co-workers. 55 HT coupling is a direct manifestation of the breakdown of the Born-Oppenheimer approximation, which assumes that the electronic motion is independent of the nuclear degrees of freedom.…”

Section: Observation Of Forbidden Vibrational Modes and Hertzberg-mentioning

confidence: 85%

High-resolution photoelectron imaging of cold ${\rm C}_{60}^ -$C60− anions and accurate determination of the electron affinity of C60

Huang

Dau

Liu

et al. 2014

The Journal of Chemical Physics

101

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High-resolution photoelectron imaging and spectroscopy of cold C₆₀⁻ anions are reported using a newly built photoelectron imaging apparatus coupled with an electrospray ionization source and a temperature-controlled cryogenic ion trap. Vibrationally resolved photoelectron spectra are obtained for the detachment transition from the ground state of C₆₀⁻ to that of C60 at various detachment wavelengths from 354.84 nm to 461.35 nm. The electron affinity of C60 is accurately measured to be 2.6835 ± 0.0006 eV. Numerous unexpected vibrational excitations are observed in the photoelectron spectra due to the Jahn-Teller effect in C₆₀⁻ and Hertzberg-Teller vibronic coupling in both C₆₀⁻ and C60. Both the relative intensities of vibrational peaks and their photoelectron angular distributions provide evidence for the vibronic couplings. The observed p-wave-like behavior in the angular distribution of the 0₀⁰ transition suggests that the electron is detached from an s-type orbital.

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Section: Observation Of Forbidden Vibrational Modes and Hertzberg-mentioning

confidence: 85%

High-resolution photoelectron imaging of cold ${\rm C}_{60}^ -$C60− anions and accurate determination of the electron affinity of C60

Huang

Dau

Liu

et al. 2014

The Journal of Chemical Physics

101

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“…32 Calculations of excited state geometries and harmonic frequencies were carried out with the maximum overlap method (MOM). 33 Dyson orbitals were calculated with EOM-IP-CCSD/6-311+G*.…”

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confidence: 99%

Vibrational and Electronic Structure of the α- and β-Naphthyl Radicals via Slow Photoelectron Velocity-Map Imaging

et al. 2015

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Slow photoelectron velocity-map imaging (SEVI) spectroscopy has been used to study the vibronic structure of gas-phase α-and β-naphthyl radicals (C 10 H 7 ). SEVI of cryogenically cooled anions yields spectra with <4 cm −1 resolution, allowing for the observation and interpretation of congested vibrational structure. Isomerspecific photoelectron spectra of detachment to the radical ground electronic states show detailed structure, allowing assignment of vibrational fundamental frequencies. Transitions to the first excited states of both radical isomers are also observed; vibronic coupling and photodetachment threshold effects are considered to explain the structure of the excited bands. P olycyclic aromatic hydrocarbons (PAHs) are of major importance in wide-ranging areas of chemistry. PAHs are involved in the combustion of organic matter 1 and subsequent soot formation, 2,3 while neutral, ionized, hydrogenated, and dehydrogenated PAHs are likely constituents of the interstellar medium (ISM). 4,5 PAHs are possible sources of mid-infrared emission features in the ISM 6−8 and have been considered tentative candidates for carriers of diffuse interstellar bands (DIBs) for many years. 9−11 No conclusive evidence of small PAHs as DIB carriers exists to date, despite much work searching for matches between laboratory spectra and astronomical data. 12,13 Decomposition of large interstellar PAHs may lead to the formation of carbon chains and hydrocarbon radicals in space. 14 In this Communication, we report high-resolution anion photoelectron spectra of α-and β-naphthyl, C 10 H 7 − , whose structures are shown in Figure 1. Naphthalene is the simplest PAH; its derivatives are therefore tractable models for the behavior of larger aromatic systems.There is a solid body of theoretical work on the electronic structure, geometries, and vibrations of the naphthyl radicals and anions 5,15−20 and some calculations of their reactivity in the context of combustion. 21,22 Experimental characterization is sparser. Reed and Kass 23 and Lardin et al. 24 measured the electron affinities (EAs) of the α-and β-naphthyl radicals through kinetic methods and calculated the α and β C−H bond dissociation energies of naphthalene. Both studies found the α anion to be lower in energy than the β anion by several kJ/mol, favoring α formation in deprotonation of naphthalene.Anion photoelectron spectroscopy (PES) is a powerful technique for probing the vibronic structure of neutral radicals through photodetachment of a closed-shell anion. 25,26 Ervin et al. 18 measured the photoelectron spectrum of C 10 H 7 − at 300 K and with a resolution of ∼100 cm −1 . The authors reported a congested, partially resolved spectrum of the radical ground state with an EA of 1.403(15) eV. By comparison to Franck− Condon (FC) simulations, the spectrum was assigned to an 11:1 α:β isomer ratio. Substantial enrichment in α-naphthyl is consistent with the authors' use of nonspecific deprotonation of naphthalene to generate anions.Slow photoelectron velocity-map ...

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“…Communications vibrational frequencies of FL9 + derived from the spectrum are close to the ones observed for the ground state of FL9 in the photoelectron spectrum of the anion. [9] Excitation energy calculations (Table 1) show that both BeI + and BfI + are candidates for the 538 nm absorption system. As BeI + is approximately 50 kJ mol À1 less stable than BfI + ,t he 538 nm system was assigned to the 1 1 A 1 !…”

Section: Angewandte Chemiementioning

confidence: 99%

“…[7] TheFL9 À anion was the focus of gas-phase photoelectron studies that provided vibrational frequencies for the ground state and the first excited state of neutral FL9. [8,9] This radical, which was produced by electron bombardment and UV photolysis of fluorene and trapped in solid argon, has also been studied by infrared, Raman, and UV/Vis spectroscopy. [10,11] Theb ands observed in the vibrational spectra were attributed to specific modes of FL9 on the basis of calculated ground-state frequencies.E lectronic absorptions apparent in an argon matrix starting at 494.6 nm were assigned to the 1 2 A 2 !…”

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confidence: 99%

Electronic Characterization of Reaction Intermediates: The Fluorenylium, Phenalenylium, and Benz[f]indenylium Cations and Their Radicals

2016

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Three vibrationally resolved absorption systems commencing at 538, 518, and 392 nm were detected in a6K neon matrix after mass-selected deposition of C 13 H 9 + ions (m/z = 165) produced from fluorene in ah ot-cathode discharge ion source.T he benz[f]indenylium (BfI + :5 38 nm), fluorenylium (FL9 + :5 18 nm), and phenalenylium (PHL + : 392 nm) cations are the absorbing molecules.T wo electronic systems corresponding to neutral species are apparent at 490 and 546 nm after irradiation of the matrix with l < 260 nm photons and were assigned to the FL9 and BfI radicals, respectively.T he strongest peak at 518 nm is the origin of the 2 1 B 2 ! X 1 A 1 absorption of FL9 + ,a nd the 490 nm band is the 2 2 A 2 ! X 2 B 1 origin of FL9. The electronic systems commencing at 538 nm and 546 nm were assigned to the 1 1 A 1 ! X 1 A 1 and 1 2 A 2 ! X 2 A 2 transitions of BfI + and BfI. The 392 nm band is the 1 1 E' ! X 1 A 1 ' transition of PHL + .T he electronic spectra of C 13 H 9 + /C 13 H 9 were assigned on the basis of the vertical excitation energies calculated with SAC-CI and MS-CASPT2 methods.The challenge in probing reaction intermediates is that they are short-lived and thus difficult to characterize.I nt he last decades,pulse radiolysis and flash photolysis techniques have been employed for the in situ synthesis and characterization of transient organic species. [1][2][3] Themain impuissance of these techniques is that they are not species-selective.W ith this concern, the approach involving isolation of mass-selected ions and their neutralization in solid neon serves apivotal role in the spectroscopic characterization of transient organic intermediates. [4] Thespectroscopic investigation of the fluorenylium cation (FL9 + ), at extbook example of an antiaromatic carbenium ion, has been as tanding goal in physical organic chemistry. Some information has been obtained by the photolysis of 9-hydroxyfluorene (9-OH-FL) in H 2 O/CH 3 OH solution. A broad transient absorption identified around 515 nm was assigned to FL9 + , [5,6] in agreement with previous studies,such as the photolysis of 9-OH-FL within metal zeolites [2] and 9-diazafluorene (9-DAFL) in CH 3 OH. [3] Recently,a ni nvestigation of the photochemical products of 9-DAFL in amorphous water ice in the infrared and optical domain confirmed that the broad absorption at 515 nm originates from FL9 + . [7] TheFL9 À anion was the focus of gas-phase photoelectron studies that provided vibrational frequencies for the ground state and the first excited state of neutral FL9. [8,9] This radical, which was produced by electron bombardment and UV photolysis of fluorene and trapped in solid argon, has also been studied by infrared, Raman, and UV/Vis spectroscopy. [10,11] Theb ands observed in the vibrational spectra were attributed to specific modes of FL9 on the basis of calculated ground-state frequencies.E lectronic absorptions apparent in an argon matrix starting at 494.6 nm were assigned to the 1 2 A 2 ! X 2 B 2 system of FL9. [11] Thes pectroscopic properties of another r...

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Slow photoelectron velocity-map imaging spectroscopy of the C9H7 (indenyl) and C13H9 (fluorenyl) anions

Cited by 34 publications

References 109 publications

High-resolution photoelectron imaging of cold ${\rm C}_{60}^ -$C60− anions and accurate determination of the electron affinity of C60

High-resolution photoelectron imaging of cold ${\rm C}_{60}^ -$C60− anions and accurate determination of the electron affinity of C60

Vibrational and Electronic Structure of the α- and β-Naphthyl Radicals via Slow Photoelectron Velocity-Map Imaging

Electronic Characterization of Reaction Intermediates: The Fluorenylium, Phenalenylium, and Benz[f]indenylium Cations and Their Radicals

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