Vibrational and Electronic Energy Levels of Polyatomic Transient Molecules. Supplement A

Jacox, Marilyn E.

doi:10.1063/1.556017

Cited by 221 publications

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“…A comparison between the calculated vibrational frequency for the free CO molecule (2096 cm -1 ) and the experimental value (2143 cm -1 ) gave an indication of the accuracy of the method that was used. 23 A deviation of 3% was found for the DFT, molecular, and other periodic calculations. 18,24 This deviation of 3% in vibrational calculations was mainly caused by the VASP periodic method.…”

Section: Experiments and Methodologymentioning

confidence: 98%

Carbon Monoxide Adsorption on Molybdenum Phosphides: Fourier Transform Infrared Spectroscopic and Density Functional Theory Studies

Feng

Liang

et al. 2003

J. Phys. Chem. B

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Molybdenum phosphide (MoP) and supported molybdenum phosphide (MoP/γ-Al 2 O 3 ) have been prepared by the temperature-programmed reduction method. The surface sites of the MoP/γ-Al 2 O 3 catalyst were characterized by carbon monoxide (CO) adsorption with in situ Fourier transform infrared (FT-IR) spectroscopy. A characteristic IR band at 2037 cm -1 was observed on the MoP/γ-Al 2 O 3 that was reduced at 973 K. This band is attributed to linearly adsorbed CO on Mo atoms of the MoP surface and is similar to IR bands at 2040-2060 cm -1 , which correspond to CO that has been adsorbed on some noble metals, such as platinum, palladium, and rhodium. Density functional calculations of the structure of molybdenum phosphides, as well as CO chemisorption on the MoP(001) surface, have also been studied on periodic surface models, using the generalized gradient approximation (GGA) for the exchange-correlation functional. The results show that the chemisorption of CO on MoP occurred mainly on top of molybdenum, because the bonding of CO requires a localized mininum potential energy. The adsorption energy obtained is ∆H ads ≈ -2.18 eV, and the vibrational frequency of CO is 2047 cm -1 , which is in good agreement with the IR result of CO chemisorption on MoP/γ-Al 2 O 3 .

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Section: Experiments and Methodologymentioning

confidence: 98%

Carbon Monoxide Adsorption on Molybdenum Phosphides: Fourier Transform Infrared Spectroscopic and Density Functional Theory Studies

Feng

Liang

et al. 2003

J. Phys. Chem. B

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“…400 nm. It is likely that this is the CFCl 32,48 and it is clear that the relative intensity of the CFCl to CF 2 emission bands decreases as the photon energy increases above 11.37 eV. For excitation energies above 19 eV, the emission spectra are dramatically different (Fig.…”

Section: Ivb Cf 2 CLmentioning

confidence: 97%

“…The energies of the excited states of most of the emitting fragments were taken from standard sources. 31,32 The energies of the D' 3 Π g ion-pair state of Cl 2 and Br 2 were taken from Tellinghuisen et al 33 …”

Section: Energetics Of the Key Dissociation Channelsmentioning

confidence: 99%

Vacuum–ultraviolet absorption and fluorescence spectroscopy of CF2H2, CF2Cl2, and CF2Br2 in the range 8–22 eV

Seccombe

Chim

Tuckett

et al. 2001

The Journal of Chemical Physics

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The vacuum-UV absorption and fluorescence spectroscopy of CF 2 X 2 (X=H,Cl,Br) in the range nm is reported. Tunable vacuum-UV radiation in the range 8-22 eV from synchrotron sources at either Daresbury, UK or BESSY1, Germany is used to excite the titled molecules. Fluorescence excitation spectra, with undispersed detection of the fluorescence, were recorded at Daresbury with a resolution of 0.1 nm. VUV absorption spectra at a resolution of 0.08 nm, and dispersed emission spectra with an optical resolution of 8 nm were recorded at BESSY1. Action spectra, in which the VUV energy is scanned with detection of the fluorescence at a specific wavelength, were also recorded at BESSY1 with a resolution of 0.3 nm ; appearance energies for production of a particular emitting state of a fragment are then obtained. Using the single-bunch mode of BESSY1, lifetimes of all emitting states that fall in the range ca. 3-80 ns have been measured. The peaks in the VUV absorption spectra of CF 2 X 2 are assigned to Rydberg transitions. For CF 2 H 2 below 11 eV, there is good agreement between the absorption and the fluorescence excitation spectra, whereas above 11 eV and for the whole range 8-22 eV for CF 2 Cl 2 and CF 2 Br 2 there is little similarity. This suggests that photodissociation to emitting states of fragment species represent minor channels. In the range 8-15 eV, emission is due mainly to CF 2 Ã 1 B 1 − X 1 A 1 and weakly to CFX Ã 1 A" − X 1 A'. These products form by photodissociation of Rydberg states of CF 2 X 2 , and the thresholds for their production therefore relate to energies of the Rydberg states of the parent molecule. For CF 2 H 2 below 11.8 eV CF 2 Ã 1 B 1 can only form with H 2 , whereas for CF 2 Cl 2 and CF 2 Br 2 it is not possible to say whether the other products are 2X or X 2 . For energies above ca. 15 eV, emission is due to diatomic fragments ; CF B 2 ∆ and A 2 Σ + , CCl A 2 ∆, CH B 2 Σ -and A 2 ∆, Cl 2 and Br 2 D' 2 3 Π g , and possibly CBr A 2 ∆. From their appearance energies, there is evidence that, with the exception of CF B 2 ∆ / CF 2 H 2 where the ground state of HF must form , the excited state of CF, CCl or CH forms in association with three atoms. Our results yield no information whether the three bonds in CF 2 X 2 * break simultaneously or sequentially. We suggest that the anomalous behaviour of CF 2 H 2 , in forming H-H or H-F bonds in unimolecular photofragmentation processes, relates to the small size of the hydrogen atom, and hence the unimportance of steric effects in the tightlyconstrained transition state. In no cases is emission observed from excited states of either the CF 2 X free radical or the parent molecular ion, CF 2 X 2 + .4

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“…Since the outer electron in dipole-bound HOCO − occupies a region of space far from the neutral HOCO core, it is reasonable to assume the vibrational frequencies of dipolebound HOCO − and trans-HOCO to be very similar. The vibrational energy spacing between the OCO bend levels in trans-HOCO is 0.08 eV [43], which is also the spacing between the threshold photodetachment peaks observed by Lu and Continetti [8].…”

Section: A Photodetachment Cross Sectionsmentioning

confidence: 50%

“…As expected, the potential energy surfaces of the two species are essentially identical. The OCO bend vibrational energy levels, ν f are also shown in the figure and they are derived from the experimental IR frequency [43]. The binding energy of the anion and the dipole moment of the radical along the OCO bend are plotted in Fig 8b and 8c, respectively.…”

Section: A Photodetachment Cross Sectionsmentioning

confidence: 99%

Vibrational Feshbach resonances in near-threshold HOCO−photodetachment: A theoretical study

Miyabe

Haxton²,

Lawler³

et al. 2011

Phys. Rev. A

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The results of a theoretical study of HOCO − photodetachment are presented, with a view toward understanding the origin of two peaks observed by Lu and Continetti (Phys. Rev. Lett. 99, 113005 (2007)) in the photoelectron kinetic energy spectrum very close to threshold. It is shown that the peaks can be attributed to vibrational Feshbach resonances of dipole-bound trans-HOCO − , and not s-and p-wave shape resonances as previously assumed. Fixed-nuclei variational electron-HOCO scattering calculations are used to compute photodetachment cross sections and laboratory-frame photoelectron angular distributions. The calculations show a broad A ′′ (π*)-shape resonance several eV above threshold.

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Vibrational and Electronic Energy Levels of Polyatomic Transient Molecules. Supplement A

Cited by 221 publications

References 0 publications

Carbon Monoxide Adsorption on Molybdenum Phosphides: Fourier Transform Infrared Spectroscopic and Density Functional Theory Studies

Carbon Monoxide Adsorption on Molybdenum Phosphides: Fourier Transform Infrared Spectroscopic and Density Functional Theory Studies

Vacuum–ultraviolet absorption and fluorescence spectroscopy of CF2H2, CF2Cl2, and CF2Br2 in the range 8–22 eV

Vibrational Feshbach resonances in near-threshold HOCO−photodetachment: A theoretical study

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