Photodetachment of the ion

2014

Annu. Rev. Phys. Chem.

119

129

This article provides an overview of some recent advances in the modeling of photoelectron angular distributions in negative-ion photodetachment. Building on the past developments in threshold photodetachment spectroscopy that first tackled the scaling of the partial cross sections with energy, depending on the angular momentum quantum number ℓ, it examines the corresponding formulation of the central potential model and extends it to the more general case of hybrid molecular orbitals. Several conceptual approaches to understanding photoelectron angular distributions are discussed. In one approach, the angular distributions are examined based on the contributions of the symmetry-allowed s and p partial waves of the photodetached electron. In another related approach, the parent molecular orbitals are described based on their dominant s and p characters, whereas the continuum electron is described in terms of interference of the corresponding Δℓ =±1 photodetachment channels.

Section: Hanstorp's Formulation Of the Cooper-zare Equationmentioning

confidence: 99%

Laboratory-Frame Photoelectron Angular Distributions in Anion Photodetachment: Insight into Electronic Structure and Intermolecular Interactions

2014

Annu. Rev. Phys. Chem.

119

129

“…Since only limited data are available for C − , 42,43 while N − does not exist, we first undertake further model development on the example of O − . Theoretical predictions for this anion can be compared to the known value of A = 0.55 ± 0.045 eV −1 , determined through empirical fitting of the WBCZ equation (Eq.…”

Section: A the A Coefficients For O − And C −mentioning

confidence: 99%

“…The electron affinity of atomic carbon is well known (1.262 eV), 47 but only limited data exist for C − PADs. The known data points are shown in Figure 5 and include measurements for the ground-state C − ( 4 S) (filled symbols) 42,43 and excited-state C − ( 2 D) (open symbols). 43,48 Although in all cases the electrons originate from 2p orbitals, the C − ( 4 S) results are most relevant to this discussion.…”

Section: − Photodetachmentmentioning

confidence: 99%

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

The Journal of Chemical Physics

Grumbling

Goebbert

et al. 2013

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.

“…[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%

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

Grumbling

The Journal of Chemical Physics

2011

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.