Effect of crossed electric and magnetic fields on donor impurity binding energy

By using an appropriate coordinate transformation, we have calculated variationally the ground state binding energy of a hydrogenic donor impurity in a quantum well in the presence of crossed electric and magnetic fields which are applied tilted at an angle to the layers. The dependence of the donor impurity binding energy on the well width, on the strength of the electric and magnetic fields, on the impurity position and on the directions of the external fields is discussed. PACS 71.55.Eq; 71.55.-i     

The electric field dependence of a donor impurity in graded <Emphasis Type="Bold">GaAs</Emphasis> quantum wires

The effect of the electric field on the binding energy of the ground state of a shallow donor impurity in a graded GaAs quantum-well wire (GQWW) was investigated. The electric field was applied parallel to the symmetry axes of the wire. Within the effective mass approximation, we calculated the binding energy of the donor impurity by a variational method as a function of the wire dimension, applied electric field, and donor impurity position. We show that changes in the donor binding energy in GQWWs strongly depend not only on the quantum confinement, but also on the direction of the electric field and on the impurity position. We also compared our results with those for the square quantum-well wire (SQWW). The results we obtained describe the behavior of impurities in both square and graded quantum wires. PACS 68.65.-k; 71.55.-i; 71.55.Eq     

Electronic structure of two coupled Si δ-doped GaAs as dependent on the donor thickness

For the uniform distribution we have theoretically investigated the influence of donor thickness on two coupled Si -doped GaAs structure, at T=0 K. Electronic structure have been calculated by solving the Schrödinger and Poisson equations self-consistently. We thus find the confining potential, the electronic density, the subband energies and their eigen envelope functions, the subband occupations and Fermi energy. From the self-consistent calculation, we have seen that the effective potential profile and the electronic density of two coupled Si -doped GaAs structure are sensitive to the donor thickness while the subband energies and the subband occupations are not sensitive to the donor thickness . PACS 73.20.Dx; 73.20.At; 73.90.+f     

Landau transitions at higher gaps in InSb and GaSb

Landau levels have been resolved at the E₁ + Δ₁ gap in InSb and at the E₁ edge in GaSb. Transverse reduced masses of 19 ± 3 and 21.4 ± 1.5 have been obtained at the respective edges. Using band gaps determined from the experiment, the spin-orbit splitting Δ₁ has been measured as 0.500 ± 0.013 eV in InSb. Combined with a measurement of the zone center spin-orbit splitting, this gives a ratio of 0.623 ± 0.02 of slightly less than $\text{2}\text{3}$.     

Modification of cycloolefin copolymer and poly(vinyl chloride) surfaces by superimposition of nano- and microstructures

Cycloolefin copolymer (COC) and poly(vinyl chloride) (PVC) surfaces were patterned with nanopillars or with microbumps on which nanopillars were superimposed. The area of patterned surfaces was several square centimeters. Patterning was achieved by applying nanoporous anodized aluminum oxide (AAO) membrane as a mask in injection molding or imprinting. Nanostructures superimposed on microstructures were achieved by patterning the AAO mask with microstructures before anodization. Micro- and nanometer-sized structures could then be transferred simultaneously to polymer surfaces. Structures were characterized by SEM, AFM, and contact profilometry. The effect of different-sized structures on properties of the polymer surface was studied by contact angle measurements. Relative to the smooth surface, the increase in water contact angle on a COC surface with nanostructures superimposed on microstructures was up to 50°.     

Synthesis,structure and in vitro anticancer activity of ruthenium(II) and platinum(II) complexes with chiral aminophosphine ligands

Transition Metal Chemistry - (R)-[Ru(η6-p-MeC6H4iPr)Cl2{Ph2PNHCH(CH3)(C6H4-4-F)}] (1) and cis-(R,R)-[PtCl2{Ph2PNHCH(CH3)(C6H4-4-F)}2] (2) have been obtained by the reaction of the chiral...     

Synthesis and nicotinic acetylcholine receptor affinity of bivalent tropane‐3‐carboxylates

A series of diol di‐(tropane‐3α‐carboxylate) esters and diol di‐(tropane‐3β‐carboxylate) esters were synthesized from 3‐tropene‐3‐carboxylic acid and tropane‐3β‐carboxylic acid, respectively. The bivalent tropane‐3‐carboxylates were evaluated for their ability to inhibit [³H]cytisine binding at rat brain nicotinic acetylcholine receptors (nAChRs). In general the (3β,3β')‐isomers were more potent than (3α,3α')‐isomer and the (3β,3β')‐decyl derivative (n = 10, K_i = 145 nM) exhibited the most potent affinity for nAChRs of the series.