The absolute sub-monolayer surface number densities sensitivity was determined using evanescent-wave cavity ring-down spectroscopy (EW-CRDS) and conventional CRDS. The absolute surface coverages were found from conservation of the integrated band intensities using average molecular tilt angles that were derived from the polarization anisotropies of the adsorbate spectra. The monolayer coverages were probed without the need for ultra-high vacuum as long as the total system intrinsic loss was small. The detection limit achieved using an unclad folded resonator was comparable to that obtained using an optimized planar waveguide with an analyte-enriching surface coating.
ASJC Scopus subject areas
- Physics and Astronomy(all)
- Physical and Theoretical Chemistry