Mark R. Winkle

Infrared photoacoustic spectroscopy of undoped polyacetylene

Photoacoustic infrared spectroscopy has been applied to undoped polyacetylene powders and films and the results are compared to transmission infrared spectra obtained on both types of samples. the photoacoustic technique has been found to be particularly suitable for the study of polyacetylene powders which are more sensitive to air exposure than films, due to their higher surface area. The method yields spectra whose major features are essentially identical to transmission spectra, but allows more flexibility with respect to sample thickness, size, and shape. A band near 1920 cm−1, also observed but not discussed in previous studies, is assigned to the presence of cumulative carbon double bonds. Bands observed near 1375 and 890 cm−1 on films and, more prominently, on powders are assigned to the incorporation of small amounts of oxygen during preparation and handling, resulting in inadvertent doping. The large surface area of powders also results in more pronounced oxidation of the polymer backbone.

Novel acid-hardening positive photoresist technology

A newly developed positive photoresist technology which produces a crosslinked image is described. This resist has demonstrated high sensitivity and resolution for e-beam and X-ray applications. The resist uses conventional novolak polymers and melamine crosslinking agents with thermal acid generators to achieve acid-catalyzed crosslinking in the unexposed areas of the resist. An amine base is photochemically generated in the exposed areas which inhibits the crosslinking reaction. The exposed area remains soluble in conventional aqueous base developers. Chemistry of the thermal acid generators as well as examples of the photobase generators is discussed. Lithographic results focus on e-beam and X-ray synchrotron applications in which the crosslinked positive image has high contrast and high resolution.