Key Experimental Features Research Articles

Downstream instabilities of electronegative plasma discharges

Relaxation oscillations are observed in low-pressure inductive plasma discharges operated with argon and SF6 gas mixtures. The data suggest that instabilities may develop periodically at some downstream location. Linear fluid and kinetic calculations predict ion two-stream instabilities when the positive and negative ions develop sufficiently large drift velocities of opposite sign in the downstream region. The thresholds and the growth rates of the instabilities are calculated and are found in fair agreement with the observations. The instability models can explain several key experimental features.

Scintillation decay time and pulse shape discrimination of binary organic liquid scintillators for the Borexino detector

The installation of a massive liquid scintillator detector, Borexino, devoted to the real time detection of low energy solar neutrinos, has been recently proposed at the Laboratory of Gran Sasso. The key features of this next generation solar neutrino experiment crucially rely upon the properties of the liquid scintillator used as detection medium. Thus a careful evaluation of these properties has been carried out. In particular we describe here the results of the measurements performed to determine the decay time of the scintillation light pulse for alpha and electron excitation in different solvents and solutes suitable to be used in the detector.

High Temperature (77–300 K) Photo- and Electroluminescence in Si/Si1-xGex Heterostructures

The photo- and electro-luminescence of strained Si1-x Gex /Si heterostructures on Si(100) substrates from 77 K to 300 K has been investigated both experimentally and by quantitative modelling. The key experimental features are very broad linewidths and an exponential drop in the luminescence at high temperatures, with a larger Ge fraction corresponding to a higher temperature before the drop begins. These phenomena were accurately explained by an electron-hole plasma from high carrier densities in the quantum well and by an excessively low effective lifetime in the silicon cladding region.

THE HOT-ELECTRON PROBLEM IN SUBMICRON MOSFET

A review of the hot electron problem in MOSFET is given. This includes: Key experimental features, the problem of modelling hot carrier transport in Si and SiO 2 after injection into the oxide, and an evaluation of technological measures to obtain hot carrier resistant structures.

Crystal-field model study of the xenon hexafluoride molecule. III. Electronic transitions and band shapes

The application of a two-electron crystal-field model to the electronic structure of xenon hexafluoride is extended to include the calculation of oscillator strengths for absorption transitions to the largely spin singlet and the largely spin triplet excited states. Band shapes are calculated in terms of their spectral moments by obtaining vibrational energies and wavefunctions for the mixed quadratic-quartic potential energy functions calculated from the crystal-field model. The key experimental features of the absorption spectrum of the vapor are reproduced, namely the pronounced red shift and the increased bandwidth with rising temperature. The over-all similarity of the vapor spectrum to that of the isovalent hexahalotellurate (IV) complexes in solids in noted. It is concluded that the experimental data of Claassen, Goodman, and Kim are compatible with the pseudo-Jahn-Teller model of Gillespie as developed by Bartell and Gavin and by Wang and Lohr, and that the data do not require the use of the electronic isomers model of Goodman, although the latter model is not excluded.