Suneela Arif

Photodetachment of Di-atomic Negative Ion H 2 − near a Surface

We describe the effects of plane surface on the photo-detached electron spectra from H−2. A z-polarized laser is used for the detachment of electrons. The detached electron flux and photodetachment cross section are derived. There exists strong dependence on the distance of the H−2 from the surface and also on the separation of atomic centers of H−2. The results show strong oscillations for smaller values of distances, whereas for larger values the oscillating structure disappears.

Detached Electron Spectra from H− near a Partially Reflecting Spherical Surface

The photodetachment of a hydrogen negative ion (H−) near a partially reflecting surface with a spherical shape is investigated by a theoretical imaging method. Analytical expressions for the detached electron flux and total photodetachment cross section are derived. It is found that two parameters, i.e. curvature radius rc and reflection parameter K, control the photodetachment spectra. Furthermore, these parameters can be used for the classification, identification and revelation of minor details like curvature of different types of surfaces.

PHOTODETACHMENT OF

Photodetachment of near a soft reflecting surface is investigated by using theoretical imaging method. Analytical expressions are derived for detached electron flux and photodetachment cross section. The surface strongly affects the results and induces oscillation in the detached electron spectra. The photodetachment cross section is double of the H- near a plane wall. For a very large distance between the surface and (R → ∞) the cross section reduces to the cross section of two center system in free space.

{\rm H}_2^-

We investigate half metallicity in a chromium (Cr)-substituted AlN dilute magnetic semiconductor using the full-potential linearized augmented plane-wave method. Our results show that Al0.75Cr0.25N is half metal and holds a net integer magnetic moment of 3μβ with lattice compression. The half-metallic nature is maintained from the relaxed lattice constant 4.36 A to 4.09 A. An abrupt change of the physical properties is observed at a robust transition lattice constant of 4.09 A, and the material transforms from half metal to metal. We find that up to 6% compression, the material maintains its half-metallic nature. Furthermore, we also confirm that the origin of ferromagnetism in Al0.75Cr0.25N is double exchange.

NEAR A SOFT REFLECTING SURFACE

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 (H-) 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.

Robust Half-Metallicity in a Chromium-Substituted AlN

Using traditional theoretical imaging method, we predict invisible oscillations in the photodetachment cross section of

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

{\rm H_{2}^{-}}

THE INVESTIGATION OF NON-OSCILLATING STRUCTURE OF THE PHOTODETACHMENT CROSS SECTION OF MOLECULAR ANION USING TRADITIONAL THEORETICAL IMAGING METHOD

near a thin soft surface. A laser which is polarized parallel to the surface is used to knock off electron from

The Effects of Spherical Surface and Laser Polarization on the Photodetachment Cross Section of H

{\rm H_{2}^{-}}

Cr-Doped III–V Nitrides: Potential Candidates for Spintronics

. Analytical expressions are derived for detached electron flux and photodetachment cross section. The results depend on the inter ion surface distance and separation of the atomic centers of the molecular anion. It is found that the surface strongly affects the detached electron flux and the photodetachment cross section. Unlike the detached electron flux the cross section displays non-oscillating structure. The non-oscillating structure is attributed to the parallel orientation of the laser polarization direction with the thin elastic surface.