By using a simple method to factorize the recursion operator, the inverse recursion operator of the variable coefficient KdV cquqtion is exhibited explicitly. Thee new sets of symmetries of the variable coefficient KdV equation arc given in addition to the known K symmetries and τ symmetries. Starting from these three sets of symmetries, we obtained three hierarchies of the variable coefficient KdV integro-differential equations.

It is shown that there is a simpler relationship between the energy eigenstates of a d-dimensional hydrogen atom and those of a D-dimensional harmonic oscillator, which is important in application.

By using the Wei-Norman's method, the deflection of an atomic beam with a large period quantized standing light wave is analyzed for the case with two-level atom and single-mode cavity field. It is concluded that after passing through the standing light wave in cavity, the atomic beam is split into infinite beams symmetrically, and each momentum shift for a split component is proportional to the interaction time. It is also shown that the output momentum distribution of atoms is sensitive to the statistical properties of the cavity field.

We report the cumulative reaction probabilities (CRP) of the three-dimensional Cl+H₂ → H+HCl calculated on the Stern-Persky-Klein potential energy surface, using the generalized Newton variational principle, for total angular momentum J =0, over a total reaction energy range from 9 to 19 kcal/mol. The relation between CRP and reaction rate constants, as well as the calculation for complete reaction rates (summed over all J), bypassing the direct calculation of the CRP's for J>0, are also discussed.

Si_l-xGe_x/Si single-mode rib waveguides with 0.5dB/cm losses have been fabricated, in which the SiGe layers are grown by molecular beam epitaxy. The single-mode waveguide dimensions determined experimentally are consistent with the single-mode theory of SiGe waveguides.

By using a simple transformation approach, we solve the higher-order nonlinear Schrödinger equation under another condition. The obtained exact soliton solutions have the following prominent features: The bright soliton can propagate in both the normal and anormal regions; the soliton travelling speed is proportional to its amplitude square; the phase of the soliton is independent of its amplitude or width; and the component solitons of the bound soliton have the same phase.

A scanning Fabry-Perot interferometer has been used to measure the H_α and D_α lines obtain the H/H+D ratio in ion cyclotron resonance heating HT-6M tokamak for determing the energy absorption mechanism. The recycling is observed by changing the working gas from deuterium to hydrogen.

A model for the source-free, collisional, cathodic plasma sheath in both spherical and cylindrical geometries is developed. The analytic expressions for the sheath scaling law, electric potential profile, ion density and average ion velocity spatial variation in the sheath are derived.

Using a 2-D hybrid model, the authors have found that external currents play an important role in the plasma parameters in the reactor. The plasma density, temperature and electrostatic potential would be significantly influenced by the applied external currents.

Surface relaxation and lattice dynamics of (100)Si have been studied using Tersoff-Dodson type Si potential. The average temperature of the lattice is studied as well. The temperature fluctuates with a frequency of 9.5x10¹² Hz,, that is about the average frequency of the optical phonons in Si. The (100) Si surface relaxes inward by 0.86 Å, and a reduction of 19% in the first interlayer spacing is found.

By using the extensive Pekar's variational method, the strong coupling polaron energy and the effective mass in a slab of polar crystal including both LO- and SO-phonons are derived as a function of the thickness of slab and the coupling constant. When the slab is thin, the SO-phonons not only influence the ground state energy, but also make the polaronic effective mass become non-isotropic.

We present photoluminescence studies on highly dense two-dimensional electron gases in selectively Si δ-doped GaAs/ln_0.18Ga_0.82 As/Al_0.25 Ga_0.75,As quantum wells (N_s = 4.24 x 10¹² cm^-2). Five well-resolved photoluminescence lines centered at 1.4194, 1.4506, 1.4609, 1.4695 and 1.4808eV were observed, which are attributed to the subband exciton emission. The subband separations clearly exhibit the feature of a typical quantum well with triangle and square potential. These very intensive and sharp luminescence peaks with linewidths of 2.2 to 3.5meV indicate the high quality of the structures. Their dependence on the excitation intensity and temperatures are also discussed.

We have observed transverse electric (TE) and transverse magnetic (TM) intersubband infrared absorption peaks in GaAs/AlGaAs step multiquantum wells (SMQW). The energy splitting between TE and TM is 13meV. The high conversion efficiency of second harmonic signal due to intersubband transition in the GaAs/AlGaAs SMQW with a waveguiding surface-emitting structure have been obtained. The second harmonic generation (SffG) obeys wave vector conservation and propagates perpendicular to the waveguide surface which shows that the nonlinear polarization field for SHG may be TE as well as TM active. The existence of strong surface-emitting second harmonic signal also offers solid evidence of TE polarization active intersubband transition in GaAs/AlGaAs SMQW structure.

The electrical properties of C₆₀-tetracyanoquinodimethane (TCNQ) thin films fabricated by using an ionized-cluster-beam method in a high vacuum system were investigated. The films were characterized by transmission electron microscopy (TEM) and electronic spectroscopy. The spectroscopic results evidenced the formation of the charge-transfer complex system in C₆₀-TCNQ thin films and the TEM results revealed the microstructure of the films. The film thickness is of about 100nm. The electromotive intensity at the transition point is a few 10⁷ V/m. The possible mechanism of the electrical phenomena of the films is discussed in the paper.

The thermoelectric power (TEP) and l/f noise of a series of YBa₂Cu₃O_7-δ/PrBa₂Cu₃O_7-δ YBCO/PrBCO) superlattice samples have been measured from 80 to 270K. The TEP of the superlattices has large and positive values. For samples with thick YBCO layers, it varies linearly with temperature and has a positive slope. The noise power of superlattice samples is about two orders of magnitude lower than that in bulk YBCO film.

The dynamical susceptibility of the two-dimensional spin fluctuations of local-moment antiferromagnets is proposed and studied self-consistently. The anomalous behaviors of high-T_c cuprates in the normal state are explained in the quantum critical regime, and the momentum averaged dynamical susceptibility reduces to the basic hypothesis of the marginal Fermi liquid theory.

A giant magnetoresistive effect in as-deposited Fe/Ag multilayer films with ultrathin Fe layers has been observed. The magnetoresistance in this system is presented first as a function of Fe layer thickness t_Fe. The sample with Fe layer thickness of 4Å exhibits a magnetoresistance ratio as large as 14.3% at 4.2K. The magnetoresistance ratio decreases approximately an order of magnitude with increasing t_Fe from 4 to 10Å and then changes slightly with further increasing t_Fe. From the hysteresis loop measurement, it is found that the interlayer coupling changes from antiferromagnetic to ferromagnetic with increasing t_Fe. The feature of material at the interface might be responsible for all these findings.

Lattice matched GaInP/GaAs heterostructures were grown by atmospheric pressuremetal organic vapor phase epitaxy (AP-MOVPE). Compositional intermixing of As/P and Ga/In near the heterointerfaces was studied by photoluminescence (PL) spectroscopy. Indium segregation, memory effect of In into GaAs and the carry-over of As in the GaInP layer during the growth process were considered as three major factors giving rise to the anomalous emissions in the PL spectra. Both thermal annealing and zinc doping strongly enhanced the compositional interdiffusion near the heterointerfaces.

Diamond films have been successfully deposited on a low carbon steel substrate without graphite codeposition. Graphite formation is suppressed by the interlayer formed in situ in pre-treatment process. Grain boundary serves as the preferential site for diamond nucleation.