Vibronic coupling in the superoxide anion: The vibrational dependence of the photoelectron angular distribution

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An approximate model for analytical prediction of photoelectron angular distributions in anion photodetachment from mixed s-p states is presented. Considering the dipole-allowed s, p, and d free-electron partial waves, the model describes photodetachment anisotropy in terms of the fractional p character of the initial orbital and the A and B coefficients describing the relative intensities of the p → d to p → s and s → p to p → s channels, respectively. The model represents an extension of the central-potential model to an intermediate regime encompassing varying degrees of s and p contributions to the initial bound orbital. This description is applicable to a broad class of hybrid molecular orbitals, particularly those localized predominantly on a single atom. Under the additional assumption of hydrogenic or Slater-type orbitals, the B/A ratio in photodetachment from a mixed 2s-2p state is shown to equal 8/3. Corresponding fractions are derived for other ns-np mixing cases. The predictions of the model are tested on several anion systems, including NH(2)(-) and CCl(2)(-). The quantitative discrepancies in the latter case are attributed to the breakdown of the central-atom approximation and a mechanism for corresponding corrections is indicated.

“…(2)) to a significant volume of O 2 − experimental data. 9,10,49,50 Once the self-consistency of the model is confirmed, it may be applied to other cases.…”

Section: The O 2 − Examplementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Photodetachment anisotropy for mixed s-p states: 8/3 and other fractions

Sanov

Grumbling

Goebbert

et al. 2013

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“…The circularisation method used in this study was designed by Lawrance and Gascooke 26 and has been used in previous VMI studies. 27,28 The process involves partitioning the image into wedges, each having a fixed angle and centred on the image centre. One wedge is taken as a reference wedge to which all other wedges can be compared.…”

Section: Experimental Methodsmentioning

confidence: 99%

Spectroscopic observation of gold-dicarbide: Photodetachment and velocity map imaging of the AuC2 anion

Visser

Addicoat

Gascooke

et al. 2013

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Photoelectron spectra following photodetachment of the gold dicarbide anion, ${\rm AuC}_2^ - $ AuC 2−, have been recorded using the velocity map imaging technique at several excitation wavelengths. The binding energy spectra show well-defined vibrational structure which, with the aid of computational calculations and Franck-Condon simulations, was assigned to a progression in the Au–C stretching mode, ν3. The experimental data indicate that the features in the spectrum correspond to a 2A′ ← 3A′ transition, involving states which we calculate to have bond angles ∼147° but with a low barrier to linearity.

“…[21][22][23][24] However, decades of successful and diverse applications of Hanstorp et al's approach 20 appear to suggest that, while the Wigner law predictions of partial wave cross sections are not accurate outside the threshold regime, its predictions of cross section ratios probably are. 10,18,[25][26][27][28][29][30][31][32][33][34][35][36][37][38][39] Assuming σ i +1 /σ i −1 ∝ ε 2 and, therefore,…”

Section: Introductionmentioning

confidence: 99%

“…[44][45][46] Similarly, the highest-occupied molecular orbital (HOMO) of O 2 − , a π g * (2p) molecular orbital, is well described as a d-like function (effective i = 2). 24,37 However, in other cases a single function with defined i value may not be sufficient, as for parent states that are best described as superpositions of two or more atomiclike orbitals. For example, describing the π * (2p) HOMO of the NO − anion as a d-like molecular orbital is useful, but not as good an approximation as in the O 2 − case, 31 while describing this HOMO as a sum of d and p functions would be more appropriate.…”

Section: Introductionmentioning

confidence: 99%

Photoelectron angular distributions in negative-ion photodetachment from mixed sp states

Grumbling

Sanov

2011

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We describe an approach for constructing analytical models for the energy-dependence of photoelectron angular distributions in the one-electron, non-relativistic approximation. We construct such a model for electron emission from an orbital described as a superposition of s- and p-type functions, using linearly polarized light. In the limits of pure s or pure p electron photodetachment or photoionization, the model correctly reproduces the familiar Cooper-Zare formula. The model predictions are compared to experimental results for strongly solvated H(-) and NH(2)(-), corresponding to predominantly s and predominantly p character parent states, respectively.