It is shown that various spectroscopic methods based on measurements of X-ray spectra radiated from cluster targets can be used for estimation of the destruction degree of clusters by laser prepulses. These methods allow insight to be gained regarding the important issue of preservation of the dense cluster core at the moment of the arrival of the main laser pulse. In addition, they can be used for quantitative estimation of the size of the undestroyed parts of the clusters and also for measuring the temperature and density of the preplasmas produced by the laser prepulses.

Using deep level transient spectroscopy (DLTS) measurements with zero-bias and reverse-bias cooling, we have observed new metastable defects (EM1, EM2 and EM3) in n-type silicon by hydrogen implantation at temperature as low as 88 K. We have investigated the trap parameters of these metastable defects and their concentration depth profiles. Hydrogen ion implantation was performed with energies of 80 keV, 90 keV, and 100 keV to a dose of 2 × 1010 cm−2. The silicon substrate temperature was kept at as low as 88 K during hydrogen implantation and then was raised naturally to room temperature. From analysis of Arrhenius plots, the energy levels of EM1, EM2 and EM3 are obtained to be Ec-0.29 eV, Ec-0.41 eV and Ec-0.55 eV, respectively. The depth profiles of metastable defects in 90-keV samples have a peak in the concentration around the depth of 0.68 µm, which is shallow compared with the projected range of 90 keV hydrogen. The peak position becomes deeper as the energy of ion implantation increases. This indicates that the production of metastable defects is caused by ion implantation. Additionally, comparison with helium-implanted samples suggests that implanted hydrogen is included in these metastable defects.

We report on the transformation behaviour of metastable defects labelled EM1 (Ec-0.29 eV), EM2 (Ec-0.41 eV) and EM3 (Ec-0.55 eV) which are induced in n-type silicon by hydrogen implantation. Hydrogen implantation was performed at 88 K with an energy of 90 keV to a dose of 2 × 1010 cm−2. After fabrication of Schottky diodes on the implanted surfaces, deep level transient spectroscopy measurements were made to monitor metastable behaviour of defects. All three metastable defects are regenerated with reverse-bias cooling and removed with zero-bias cooling. 10-min isochronal annealing reveals that EM1 is regenerated around 270 K and is removed around 220 K. The EM2 (EM3) regeneration temperature is around 270 K (270 K) and its removal temperature 220 K (260 K). Isothermal annealing treatments for EM1 show that its transformation follows first order kinetics for both regeneration and removal. An activation energy is 0.94 eV and a frequency factor 6 × 1014 s−1 for regeneration of EM1, and 0.73 eV and 3 × 1013 s−1 for its removal.

Icosahedral quasicrystals Al71.5Pd20.3Mn8.2, Al70.7Pd21.34Re7.96, Al62.5Cu25.5Fe12.5, and α-Al68.31Mn21.21Si10.48 1/1- approximant were investigated by using a monoenergetic slow positron beam. The structural vacancy densities in the first three samples were determined to be 5.0×1020, 7.7×1020, and 4.7×1020 cm−3, respectively, by analyzing the measured S-parameter.

We explored the formation of holographic gratings by means of a polymer azobenzene liquid crystal (PALC). When two writing beams (argon-ion laser, 488 nm, unpolarized) were interfered on the surface of the PALC film (thickness, 500 ∼ 600 nm), multiple diffraction beams were observed immediately, resulting from grating formation. Such generation of the diffraction beams was assumed to be due to a periodic induction of photochemical phase transition in the bright fringes of the interference pattern. The grating is namely made up of a periodic arrangement of nematic (N, dark fringes) and isotropic (I, bright fringes) phases. Observation of recorded interference patterns under a cross-polarized optical microscope supported our speculation for the structure of the grating. On the basis of these results, we succeeded in recording an image hologram of a photomask as an object.

The use of preceramic polymers in diverse ceramic applications requires control of a complex set of chemical characteristics to ease processing and develop suitable ceramic properties. The desirable characteristics of a good precursor system are controllable viscosity (preferably without the use of solvents), inhibition of curing during fabrication followed by rapid curing, minimal release of volatiles during curing, high ceramic yield, and controllable final composition and stoichiometry.

This paper describes the use of chemical concepts to synthesize, modify, and manipulate polymeric precursors to silicates and the importance of curing (crosslinking) mechanisms and processing conditions as critical elements in developing ceramic matrix composites.