Double-resonant photoionization efficiency spectroscopy: A precise determination of the adiabatic ionization potential of DCO

Foltynowicz, Robert J.; Robinson, Jason D.; Grant, Edward R.

doi:10.1063/1.1349080

Cited by 8 publications

(4 citation statements)

References 42 publications

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“…The spectra exhibit a slow rise from the adiabatic ionization energy (AIE) of HCO at 8.15022 ± 0.00006 eV and from the AIE of DCO at 8.1353 ± 0.0004 eV . The slow rise of the PI spectrum from threshold results from poor Franck–Condon overlap between the bent X̃ 2 A′ ground state of HCO (herein termed X̃) and the linear X 1 Σ + ground state of the cation (herein referred to as X + ).…”

Section: Results and Analysismentioning

confidence: 99%

“…The spectra exhibit a slow rise from the adiabatic ionization energy (AIE) of HCO at 8.15022 ± 0.00006 eV 29 and from the AIE of DCO at 8.1353 ± 0.0004 eV. 31 The slow rise of the PI spectrum from threshold results from poor Franck−Condon overlap between the bent X ̃2A′ ground state of HCO (herein termed X ̃) and the linear X 1 Σ + ground state of the cation (herein referred to as X + ). We estimate the end of the Franck− Condon envelope for the first photoelectron band is near 10.1 eV based on the He(Iα) photoelectron spectrum of HCO reported by Dyke et al 30 If direct ionization were the only ionization mechanism for HCO, we would expect the PI cross section to plateau at 10.1 eV and remain constant until the first excited electronic state of the cation became energetically available.…”

Section: Methodsmentioning

confidence: 99%

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Valence Photoionization and Autoionization of the Formyl Radical

et al. 2021

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We have used 308 nm photolysis of acetaldehyde to measure a photoionization spectrum of the formyl (HCO) radical between 8 and 11.5 eV using an 11 meV FWHM photoionization energy resolution. We have confirmed that the formyl radical is the carrier of the spectrum by generating an identical spectrum of the HCO product in the Cl + H 2 CO reaction. The spectrum of HCO and its deuterated isotopologue (DCO) have several resolved autoionizing resonances above the Franck−Condon envelope, which we assign to autoionization after initial excitation into neutral 3sσ and 3p Rydberg states converging to the first triplet excited state of HCO + (a3 A′). The quantum defects for these states are δ 3sσ = 1.06 ± 0.02 and δ 3p = 0.821 ± 0.019. We report absolute photoionization crosssection measurements of σ HCO PI (9.907 eV) = 4.5 ± 0.9 Mb, σ HCO PI (10.007 eV) = 4.8 ± 1.0 Mb, σ HCO PI (10.107 eV) = 6.0 ± 1.2 Mb, σ HCO PI (10.107 eV) = 5.7 ± 1.2 Mb, and σ HCO PI (10.304 eV) = 10.6 ± 2.2 Mb relative to the photoionization cross section of the methyl radical. The absolute cross-section measurements are a factor of ∼1.5 larger than those determined in past studies, although the presence of strong autoionizing features supports a dependence on photoionization energy resolution. We propose that the semiempirical model of Xu and Pratt for estimation of free radical photoionization cross sections is more accurate when applied with a reference species containing the same atoms as the free radical rather than isoelectronic species with different atoms.

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Section: Results and Analysismentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Valence Photoionization and Autoionization of the Formyl Radical

et al. 2021

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“…41 Introducing a new technique, which we term double-resonance photoionization efficiency (DR/PIE) spectroscopy, we made the first high-resolution measurement of the adiabatic ionization potential of DCO and determined the fundamental bending frequency of DCO + . 4 Fixing a first-laser frequency on selected ultraviolet transitions to individual rotational levels in the (000) band of the 3pπ …”

Section: Double-resonant Photoionization Efficiency (Dr/pie) Spectrosmentioning

confidence: 99%

“…Devising an approach that we call double-resonant photoionization efficiency (DR/PIE) spectroscopy, 4 we have established the ionization potential of DCO to within 3 cm -1 . This limit together with that for the formation of the lowest rotational level of the (010) state of DCO + , established by Rydberg extrapolation, provided the first precise determination of the fundamental bending frequency of the deuterated formyl cation.…”

Section: Introductionmentioning

confidence: 99%

Multiresonant Spectroscopy and the High-Resolution Threshold Photoionization of Combustion Free Radicals

Grant¹

2005

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This report describes the results of a program of research on the thermochemistry, spectroscopy and intramolecular relaxation dynamics of the combustion intermediate, HCO. We prepare this radical from acetaldehyde as a photo-precursor in a differentially pumped laser-ionization source quadrupole mass spectrometer. Using a multiresonant spectroscopic technique established in our laboratory, we select individual rotational states and overcome Franck-Condon barriers associated with neutral-to-cation geometry changes to promote transitions to individual autoionizing series and state-resolved ionization thresholds. Systematic analysis of rotational structure and associated lineshapes provide experimental insight on autoionization dynamics as input for theoretical modeling.Extrapolation of series, combined with direct thresholdphotoelectron detection, yield precise ionization potentials that constitute an important contribution to the thermochemical base of information on HCO.

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Mechanism of Photoinduced Reactions between 1‐Acetylisatin and Aldehydes

et al. 2004

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Hydrogen atom abstraction from aliphatic (2a, 2b) and aromatic (2c, 2d, 2e) aldehydes by the triplet nπ* state of 1-acetylisatin (1) yielded triplet (isatin ketyl-aldehyde acyl) radical pairs, which follow an out-of-cage pathway in subsequent reactions to give a series of radical coupling products 4−7. This out-of-cage mechanism is supported by examination of the primary products at various degrees of conversions during the course of the reaction, by the results of addition reactions of thermally generated isatin acyl radical with neutral 1, and by calculation of the charge density distribution in the acyl radicals and in ground state 1. Therefore, the oxygen-philic attack of the acyl radical, which had escaped out of cage from the triplet radical pair, at the C(3) carbonyl oxygen atom of a ground state 1 selectively afforded the thermodynamically more stable addition radical B. The recombination of two radicals B gave the 3-indolinone dimers 4 and 5 as diastereomers, while coupling of B with the isatin ketyl furnished the dihydroisoindigo derivative 6. Isatide 7

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Double-resonant photoionization efficiency spectroscopy: A precise determination of the adiabatic ionization potential of DCO

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Cited by 8 publications

References 42 publications

Valence Photoionization and Autoionization of the Formyl Radical

Valence Photoionization and Autoionization of the Formyl Radical

Multiresonant Spectroscopy and the High-Resolution Threshold Photoionization of Combustion Free Radicals

Mechanism of Photoinduced Reactions between 1‐Acetylisatin and Aldehydes

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