Optical-pumping-induced population-grating transfer between hyperfine levels of the cesium D2 line is observed through four-wave mixing in a sample of cold atoms. Diffraction efficiencies of order of 1% have been measured for a large range of angular apertures. We have studied the angular dependence of the diffracted signal in the limit of small atomic velocities and discussed its application f...

An atomic version of the Millikan oil drop experiment is performed computationally. It is shown that for planar molecules, the atomic version of the Millikan experiment can be used to define an atomic partial charge that is free from charge flow contributions. We refer to this charge as the Millikan-Thomson (MT) charge. Since the MT charge is directly proportional to the atomic forces under a u...

In this paper we develop a three-element vector model to describe the stimulated Raman interaction in a L system. This model is valid over the range of interaction energies for which the excited state follows the ground states adiabatically. We use the model to present simple physical interpretations of the generation of Raman-Ramsey fringes in a separated field excitation, the ac Stark shift i...

We use a three-state model for an atom or molecule in which two transitions are simultaneously driven by the oscillating electric fields of two laser beams. The amplitudes and detunings of the applied oscillating fields vary during the optical pulse, which can cause transitions from one state to another. For some special cases not previously known, the transition probabilities and probabilities...

Abstract. We present a recently developed code for detailed NLTE calculations of accretion disc spectra of cataclysmic variables and compact X-ray binaries. Assuming a radial structure of a standard α-disc, the disc is divided into concentric rings. For each disc ring the solution of the radiation transfer equation and the structure equations, comprising the hydrostatic and radiative equilibriu...

Two simultaneous three wave mixing processes are analyzed, where an input frequency is converted to an output frequency via an intermediate stage. By employing simultaneous phase-matching and an adiabatic modulation of the nonlinear coupling strengths, the intermediate frequency is kept dark throughout the interaction while obtaining high conversion efficiency. This feat is accomplished in a ma...

Proton transfer across single-layer graphene proceeds with large computed energy barriers and is therefore thought to be unfavourable at room temperature unless nanoscale holes or dopants are introduced, or a potential bias is applied. Here we subject single-layer graphene supported on fused silica to cycles of high and low pH, and show that protons transfer reversibly from the aqueous phase th...

Atomic force microscopy has been used to determine how M0O3(010) surfaces with controlled defect populations evolve during reactions with MeOH/N2 mixtures. The structural evolution of the freshly cleaved surface is compared to surfaces reduced in 10%H 2/N2 at 400 *C. While the freshly cleaved surfaces are flat and nearly ideal, the reduced surfaces contain voids bounded by step loops where Mo a...

We have employed a classical molecular dynamics simulation for the direct pick-up reaction of adsorbates by very low energy (1-60 eV) ions scattered at a surface. The system investigated is the reactive ion scattering (RIS) of Cs+ with an adsorbate on a Pt(111) surface. The ion-dipole attraction between the projectile and the physisorbed adsorbate drives the abstraction reaction, in which the i...

A simple method has been employed to synthesize Copper and Copper oxide nanoparticles from Copper (II) succinate precursor by thermal decomposition method using oleylamine as a capping agent. The particles synthesized with oleylamine and triphenylphosphine were well dispersed nanoparticles obtained from X-ray Diffraction (XRD). The Synthesized copper nanoparticles were characterized by UV-Visib...