James Donald Targove

Flowing afterglow synthesis of polythiophene films

Penning ionization of thiophene and 2,5‐dichlorothiophene by metastable argon in a flowing afterglow leads to the deposition of dense, uniform polythiophene films. Homogeneous kinetics have been examined using quadrupole mass spectrometry. The films have been characterized by spectroscopic ellipsometry, optical absorption, Rutherford backscattering spectrometry, and scanning force microscopy. The polymer, which has a nonlinear optical susceptibility χ(3)=10−11 esu at 602 nm, has been deposited on Si, quartz, and metal substrates.

Optical and structural characterization of mixed LaF3BaF2 thin films

Abstract Mixed LaF3ue5f8BaF2 thin films with a range of compositions have been deposited by co-evaporation, with the resulting films being a solid solution of the two constituents. The large tensile stress of pure LaF3 films was greatly reduced by the addition of BaF2. The mixed films exhibit the fluorite crystalline structure of BaF2, with the lattice parameter varying linearly with composition. Several cubic semiconductors can therefore be lattice matched by the appropriate mixed fluoride films. The refractive index of the mixed films was an approximately linear function of stoichiometry, allowing the fabrication of gradient index films by varying the relative deposition rates. The example of an antireflection coating with a sinusoidal refractive index profile is presented.