On the INDO calculations of N32− and N4− free radicals

?-tensors as well as anisotropic and isotropic hyperfine coupling constants have been calculated for the N₃^2? and N₄^? free radicals. The adequacy of the INDO method is discussed in relation with the results of a previous ab initio calculation.     

Quantized ν = 5/2 state in a two-subband quantum hall system

The evolution of the fractional quantum Hall state at filling 5/2 is studied in density tunable two-dimensional electron systems formed in wide wells in which it is possible to induce a transition from single- to two-subband occupancy. In 80 and 60 nm wells, the quantum Hall state at 5/2 filling of the lowest subband is observed even when the second subband is occupied. In a 50 nm well, the 5/2 state vanishes upon second subband population. We attribute this distinct behavior to the width dependence of the capacitive energy for intersubband charge transfer and of the overlap of the subband probability densities.     

Temperature Dependence of the Amplitude of Minima of Absorption of Microwave Radiation at Cyclotron Resonance Harmonics

JETP Letters - The temperature dependence of microwave absorption minima observed at cyclotron resonance harmonics in a two-dimensional electron system implemented in a GaAs/AlGaAs heterostructure...     

Femtosecond vibrational nuclear dynamics in the electronically excited state of the I2 molecule

Dynamics of the nuclear motion in the bound electronic B-state of the I₂ molecule was studied in the real time scale. Experiments were performed by the femtosecond pump-probe technique, which measured the dependence of the intensity of fluorescenceP(t) in the highly excited f-state on the time delay between pump and probe pulses. TheP(t) dependence observed has an oscillating character with a period of –300 fs. The pump pulse was generated by a femtosecond dye laser and amplified in a pulse dye laser amplifier; its spectral width was 5.6 nm, the wavelength in the center of the spectrum was 614 nm, and the duration was 90 fs. The probe pulse was generated in a KDP crystal due to duplication of the light frequency; its spectral width was 1.2 nm, the wavelength in the center of the spectrum was 307 nm, and the duration was 120 fs. TheP(t) dependence on the parameters of the probe and pump pulses was theoretically analyzed in terms of the quantum model based on the known energies of electronic vibrational-rotational states in the X-, B-, and f-terms of the iodine molecule. Experimental and calculatedP(t) plots at time delays of up to l.5 ps and time resolution of less than 100 fs were compared. Values of potentials in the X-, B-, and f-terms of the iodine molecule, spectra, and durations of pump and probe pulses are sufficient data for quantitative calculation of the experimentally obtainedP(t) plot.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 594–600, March, 1996.     

Evolution of quasiparticle charge in the fractional quantum hall regime

The charge of quasiparticles in a fractional quantum Hall (FQH) liquid, tunneling through a partly reflecting constriction with transmission t, was determined via shot noise measurements. In the nu = 1/3 FQH state, a charge smoothly evolving from e(*) = e/3 for t(1/3) congruent with 1 to e(*) = e for t(1/3)<1 was determined, agreeing with chiral Luttinger liquid theory. In the nu = 2/5 FQH state the quasiparticle charge evolves smoothly from e(*) = e/5 at t(2/5) congruent with 1 to a maximum charge less than e(*) = e/3 at t(2/5)<1. Thus it appears that quasiparticles with an approximate charge e/5 pass a barrier they see as almost opaque.     

Absorption spectrum around nu=1: evidence for a small-size Skyrmion

We measure the absorption spectrum of a two-dimensional electron system (2DES) in a GaAs quantum well in the presence of a perpendicular magnetic field. We focus on the absorption spectrum into the lowest Landau level around nu=1. We find that the spectrum consists of bound electron-hole complexes, trionlike and excitonlike. We show that their oscillator strength is a powerful probe of the 2DES spatial correlations. We find that near nu=1 the 2DES ground state consists of Skyrmions of small size (a few magnetic lengths).     

General properties of lasing effect in chiral liquid crystals

Numerical simulations and experimental studies of the lasing effect in chiral liquid crystals are presented. It is shown that ring-like light emission, which is often observed experimentally, is a true lasing effect. Lasing condition and different modes in thin liquid crystal layers are discussed.     

Electrical transport and magnetic ordering in R 2Ti3Ge4 (R=Dy, Ho and Er) compounds

New R ₂Ti₃Ge₄ (R=Dy, Ho and Er) intermetallic compounds have been synthesized and characterized by X-ray diffraction and low temperature ac magnetic susceptibility, electrical resistivity and thermoelectric power measurements were carried out. The compounds crystallize in the parent, Sm₅Ge₄-type orthorhombic structure (space group Pnma) and lanthanide contraction is observed as one moves along the rare-earth series. The changeover from paramagnetic to antiferromagnetic phase happens at low temperatures and the ordering temperature scales with the de Gennes factor. The electrical resistivity is metallic with a negative curvature above 100 K. Thermopower displays a weak maximum at temperatures less than 50 K signifying the possible phonon and magnon drag effects.