SILANE COATINGS FOR LASER-DRIVEN POLARIZED HYDROGEN SOURCES AND TARGETS

It is necessary to use special coatings on the surfaces of volumes con taining polarized atoms in order to minimize depolarizing spin interac tions during wall collisions. We are studying coatings of organosilico n compounds that preserve hydrogen and potassium polarizations and pre vent molecular recombination of hydrogen during wall collisions in a l aser-driven polarized hydrogen source. Continuing problems with coatin gs for these sources has been the reproducibility of high-quality surf aces and reliable assessment of surface quality before installation of coated parts in the laser-driven source. We have used an atomic force microscope to scan surfaces coated with different organosilicon compo unds with the goal of assessing surface quality and determining a meth od of preparing reproducible surfaces that do not degrade with time. H ere we show AFM scans of the different coatings, discuss the quality o f coatings made with different chemicals and application procedures, a nd present the results of coating stability tests as a function of tem perature and exposure to potassium. We find that a simple organosilico n afterwash gives a significantly improved surface.