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

Abstract

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.

Aromatic Stabilization and Hybridization Trends in Photoelectron Imaging of Heterocyclic Radicals and Anions

“…These fits were performed with a caveat. As discussed previously, 9,10,30 the model is most reliable at low-to-moderate eKEs, where the Wigner-like scaling of the partial cross-section ratios holds up well. Hence, we emphasized the low-to-moderate eKE data (effectively limiting the fit range to eKE < 1.5 eV) and specifically aimed to reproduce the depths of the minima of the The Journal of Physical Chemistry A Article observed β(ε) curves.…”

High-resolution photoelectron spectroscopy of the pyridinide isomers

“…For detachment from an orbital localized on a particular atomic center, the choice of A 1 and B 1 is fairly straightforward; in the previously reported treatment of p-pyridinide and other deprotonated aromatic anions, 29 the basis set parameterization was set to that typical for detachment from a 2s-2p orbital centered on a carbon atom, A 1 = 0.75 eV −1 and B 1 = 8A 1 /3 (corresponding to Z 0 = Z 1 = 0.885). 62,63 Using these, Eq. (S5) gives a single-parameter expression for β(ε) that can be fit to experimental data to extract the fractional p-character of the detached orbital, giving a direct link between the experimental PAD and the orbital hybridization of the anion.…”

Communication: Photoelectron angular distributions of CH− reveal a temporary anion state

“…(4). 1,18 Equation (4) has a form that is superficially similar to Eq. (2), and it reduces to the same expression given by Eq.…”

“…[1][2][3][4][5][6][7][8][9][10] In addition to measuring traditional photoelectron spectra, the imaging experiment also provides an extra set of information, the photoelectron angular distributions (PADs). The PAD carries information about the parent ion orbital from which the electron is detached.…”

“…In an effort to retain the similar insight offered by the atomic treatment, a model has been developed for photodetachment from a mixed sp type molecular orbital. 1,18 This model applies to a system where electrons are detached from a molecular orbital that can be approximated as a linear combination of one s and one p type functions at the same atomic center:…”