Competitive phenomena between stimulated Raman scattering and resonant laser emission In atomic lead are studied through photodissociation of PbCI₂ with a UV laser. The different dependences of their intensities on the UV power, the density of PbC1₂ and the pressure of buffer gases are investigated. The results indicate that under the conditions of high pump intensity and low buffer gas pressure SRS can have the advantage of RLE.

An orthorhombic-to-tetragonal structural transition of high Tc Ba₂LaCu₃0_7-y samples was observed with transmission electron microscope( TEM). Two intermediate orthorhombic structures were discovered and discussed. Thus, the Ba₂LaCu₃0_7-y is another member of high Tc Ba₂LnCu₃0_7-y (Ln=Lathanides) family with lower structural transition temperature.

Nucleon-nucleon interaction is studied in the non-relativistic quark model with a flat bottom linear confinement potential. The results are consistent with the calculated ones from the lattice quantum chromodynamics. The quark-quark interaction also consists of those caused by the one gluon exchange and the one pion exchange. The phenomenological sigma meson exchange between two nucleons is also included to fit the S-wave N-N scattering data. The calculated NN channel S-wave phase shifts show that the flat bottom linear confinement potential can provide part of the medium range attraction.

The high Tc superconductor LaBa_2-xCa_xCu₃O_y has been studied and the composition dependence of Tc examined For x=1, T_c^onset = 94K,T_c^R=0 =80K. The structure of this system was refined utilizing the X-ray powder diffraction data, and it was found that the material is isostructural with YBa₂Cu₃O_y.

The expression of non-propagating solitary wave on surface of fluid with small viscidity excited by external drive has been obtained uing the method of multiple scales. Some discussions have been made on the result obtained, which is consistent with that of Larraza and Putterman with the external drive and viscidity being neglected.

An event of peripheral collision of a relativistic oxygen nucleus. which immediately disintegrates into four helium nuclei, a quarternary fragmentation event, has been measured exclusively, and the mechanism of this event is discussed. The quarternary fragmentation phenomenon may provide an experimental evidence for the cluster model of oxygen nucleus.

The Σ=9 grain boundary (GB) structures of α iron at different temperatures were simulated with a molecular dynamical method. Johnson's potential was used and constant volume assumption was made. The maximum number of atoms was 1376. Temperature effects on the relaxed GB structures at 600K and at 900K were detected, while the difference between structures at OK and at 300K was negligible. Some techniques for speeding up the computing process were developed and the criterion of equiliblium was discussed.

The temporal evolution of stark-broadening of H_β line in laser-induced plasma in methane is investigated and the electronic density is determined from the Stark-broadened linewidth of the Balmer beta line. The maximum half-width of the line is more than 100Å and the deduced electronic density is about 4x10¹⁷cm^-3.

Percolation structures of precipitated new phases were observed in Au-Ti and Ni-A1 amorphous films upon ion irradiation. The experimental evidences showed that the observed structures were formed in the surface layer, ca 20nm thick. It was revealed that the formation of percolation clusters was sensitive to alloy composition as well as irradiation dose.

Our experiment make the zeroing of the torsion balance easier at small distance. and the non-Newtonian force of α=0.01, λ=0.25cm can be detected.

The structure of N-heterocyclic complex formed by benzotriazole on silver colloidal surface is determined with SERS technique. It is found that the adsorption on silver surface is through the triazole part of the molecule. A new chemical reaction in this system is found with the SERS technique.

The influence of fluid flow on the dendritic growing tips in region close to the growth interface have been studied quantitatively. The effect of asymmetrical parabola tips and the crossover of diffusion-convection transport mechanisms on crystal growth behaviour have been found for the first time.