A. Aydinli

Rotational Raman scattering in the instructional laboratory

We describe the use of a single spectrometer and a low power argon laser for the study of the pure rotational Raman spectra of H2, O2, N2, and CO2. Analyses of the spectra allow the student to obtain internuclear separations in the ground state, the rotational temperature of the gas, and the influence of nuclear spin on the allowed rotational states. The four molecules chosen for study have nuclei with spins of I=0 (O2), 1/2 (H2), and 1 (N2) and thus the discussion includes the effects of both Bose and Fermi exchange properties on the symmetry of the overall wave function. To fully illustrate the range of information available from the data, we provide spectra obtained with a high quality double spectrometer which allow even the lowest rotational states to be observed and show the stretching of the H2 molecule due to centripetal forces.

Fabrication of CdTe solar cells by laser-driven physical vapor deposition

Abstract Polycrystalline cadmium sulfide-cadmium telluride heterojunction solar cells were fabricated for the first time using a laser-driven physical vapor deposition method. An XeCl excimer laser was used to deposit both of the II–VI semiconductor layers in a single vacuum chamber from pressed powder targets. Results are presented from optical absorption, Raman scattering, X-ray diffraction, and electrical characterization of the films. Solar cells were fabricated by deposition onto SnO 2 -coated glass with top contacts produced by gold evaporation. Device performance was evaluated from the spectral quantum efficiency and current-voltage measurements in the dark and with air mass 1.5 solar illumination.

Time-Resolved Raman Scattering and Transmission Measurements during Pulsed Laser Annealing,

Abstract : Raman scattering from a 7 nsec pulsed dye laser has been used to determine the onset of recrystalization following an 8 nsec dye laser excitation pulse in ion-implanted silicon. We find essentially complete recrystallization 59 nsec after the first excitation pulse and from Stokes-anti-Stokes ratios we find at 59 nsec a crystalline lattice temperature of 600 + or - 200 C. Time-resolved transmission measurements at lambda = 1.15 microns also demonstrate that no molten phase has occurred even though the usual reflectivity enhancement is observed. (Author)