On the Role of the Electron-Dipole Interaction in Photodetachment Angular Distributions

The importance of including long-range electron-molecule interactions in treatments of photodetachment/photoionization is demonstrated. A combined experimental and computational study of CN− detachment is presented in which near threshold anisotropy parameters (β) are measured via photoelectron imaging. Calculated β values, based on an EOM-IP-CCSD/aug-cc-pVTZ Dyson orbital, are obtained using free particle and point dipole models. The results demonstrate the influence of the molecular dipole moment in the detachment process, and provide an explanation of the near threshold behavior of the overall photodetachment cross section in CN− detachment [J. Chem. Phys. 2020, 153, 184309]

Photodetachment of the H– ion in a forced harmonic potential

The photodetachment of a H– ion in a forced harmonic potential driven by a general time-dependent oscillating electric field has been investigated in the semi-classical closed orbit theory for the first time. It is found that the driven electric field frequency can affect the photodetachment cross-section of this system greatly. If the frequency of the driving electric field is equal to the harmonic frequency, a resonance phenomenon occurs in the classical motion of the detached electron. The interference effect between the returning electron wave travelling along the closed orbit with the initial outgoing wave gets stronger, causing the photodetachment cross-section to oscillate in a complicated manner. When the frequency of the driving electric field is unequal to the harmonic frequency, the driving electric field can weaken or strengthen the oscillatory structure in the photodetachment cross-section. In addition, the strength and initial phase in the driving electric field can also influence the photodetachment dynamics of the system. Our work provides a new method for controlling the photodetachment of negative ions in a harmonic potential and may guide future experimental research for cavity dynamics or in the ion trap.

Photodetachment spectrum of hydrogen negative ion near a spherical surface

The semi-classical closed orbit theory is applied to study photodetachment of H− near an elastic spherical surface for a z-polarized laser light. It is assumed that similar to the outgoing detached-electron waves from the source, waves propagate from an image of the source behind the surface. We then calculate the classical action for those trajectories that are perpendicular to the surface. The spherical effects in total photodetachment cross section are controlled by curvature κ of the surface. For zero curvature, our results match with the plane wall case while for a large curvature the results become the asymptotic value of the cross section recently published.

Photodetached electron spectrum of H- near a surface having spherical dent

The detached electron flux and photodetachment cross section are derived using the theoretical imaging method and quantum approach for system comprising of hydrogen negative ion ([Formula: see text]) placed near a surface having spherical dent. The dent is modeled like a spherical concave surface. It is observed that the spherical dent generates additional oscillatory and smooth structure in the detached electron flux and photodetachment cross section, respectively. The radius of curvature, inter-ion surface distance and the dent factor strongly manipulate the results. When the inter-ion surface distance is equal to the focal length of the concave surface, the detached electron flux and photodetachment cross section are not well behaved. The photodetachment cross section is also not well behaved for the inter-ion surface distance equal to the radius of curvature. The focus and center of curvature of the concave surface act as a spherical singularity. This study gives new understanding on the photodetachment of negative ions in the vicinity of concave surfaces.