Films of poly(methyl methacrylate), of varying thicknesses from near monolayer to 2 gm, on gold and silicon substrates have been examined by external reflection infrared spectroscopy. The shape of the 1731 cm'1 C=0 band has been determined as a function of film thickness, angle of incidence, and polarization of the incident beam. Theoretical calculations of the band shape distortions of the C=0 stretching mode are in good agreement with the observed spectra. Additional calculations, based on indices of refraction calculated from the Kramers-Kronig relation, demonstrate the effects of wavelength, extinction coefficient, and bandwidth on hypothetical reflection spectra. Some general conclusions are drawn with respect to the types of shifts and distortions one can expect in the reflection spectra of typical organic polymer films. These results suggest that significant care be taken in the assessment of chemical changes from band shifts and splitting in polymer/metal reflection spectra.

No abstract

A four-channel surface acoustic wave (SAW) chemical sensor array with associated RF electronics is monolithically integrated onto one GaAs IC. The sensor operates at 690 MHz from an on-chip SAW based oscillator and provides simple DC voltage outputs by using integrated phase detectors. This sensor array represents a significant advance in microsensor technology offering miniaturization, increased chemical selectivity, simplified system assembly, improved sensitivity, and inherent temperature compensation.

-An oscillator technology using surface acoustic wave delay lines integrated with GaAs These oscillators are also promising for other RF applications.

No abstract