Towards an anthrax detector using the femtosecond adaptive spectroscopic technique for coherent anti-Stokes Raman Spectroscopy: Coherent anti-Stokes Raman spectroscopy signal from dipicolinic acid in bacterial spores

Abstract

We present experimental evidence of a resonant coherent anti-Stokes Raman spectroscopy (CARS) signal from dipicolinic acid, a marker molecule in anthrax spores. We also show some evidence of resonant CARS signal associated with the 1000 cm^?1 resonance from Bacillus Globigii spores which are similar to anthrax spores. These results constitute a first step towards developing a rapid identification technique for bacterial spores.     

Thermal stability of Al/AlGaAs and Al/GaAs/AlGaAs (MBE) Schottky barriers

Outstanding stability has been observed in Al/Al/sub x/Ga/sub 1-x/As and Al/GaAs/Al/sub x/Ga/sub 1-x/As (x=0.25) Schottky barriers prepared by depositing Al in situ by MBE on annealing up to 400 degrees C. Conventionally evaporated barriers have been fabricated and compared with epitaxial ones. The changes in barrier height and ideality factor induced by annealing are reported.<>     

Relaxation and recombination in ultrasmall InAs quantum dots

We report a photoluminescence study of self-organized nanometer-size InAs quantum dots grown by molecular beam epitaxy on a GaAs substrate. High optical excitation has been used in order to observe emission from higher states of the quantum dots. The energy difference between adjacent states turns out to be of the order of 40–50 meV for dot diameters around 20 nm. The photoluminescence decay time at the fundamental transition is found to be of the order of 700 ps, decreasing down to 100 ps for the highest confined states. Finally, a cascade-like mechanism for the carrier relaxation in these structures is strongly suggested by the time resolved data.     

On the role of Soft Computing in microelectronics technology

 This note discusses the potential of Soft Computing (SC) in microelectronics. Though the SC applications to this field have been so far rather marginal, the present trends of microelectronics technology strongly suggest that the techniques of soft computing, (fuzzy logic, neural networks, genetic algorithms, expert systems, etc.), synergistically combined with more conventional approaches, will play an increasingly relevant role.     

Electrooptic sampling of a packaged high-speed GaAs integratedcircuit

The authors describe the use of electrooptic sampling to characterize the performance of a packaged 1.7-GHz GaAs planar integrated decision circuit. To study the packaged device, it was necessary for the optical probe beam to impinge on the circuit from the front (active) side. This geometry enabled effective evaluation of the circuit, in spite of reduced spatial resolution and voltage sensitivity compared to a backside probing geometry. Using a gain-switched InGaAsP laser source, waveforms have been measured in the D flip-flop within the circuit and propagation delays of about 25 ps in the input buffers. Apparent crosstalk has been measured when the probe is positioned between adjacent active circuit lines and it is found that this crosstalk depends sensitively on the position of the probe beam     

Engineered Schottky barriers on n-In0.35Ga0.65As

The Schottky barrier height in Al/n-In_0.35Ga_0.65As was engineered using thin p-type near-interface In_0.35Ga_0.65As layers grown by molecular beam epitaxy. The effect of the thickness and doping level of the p-type layer on the barrier height was also studied by computer simulation. A good agreement was obtained between the calculated and experimental barrier height values. An experimental Schottky barrier height of 0.67 eV with an ideality factor of 1.15 has been achieved.