Grazing angle reflectance spectroscopy of organic monolayers on nanocrystalline diamond films

The nanocrystalline diamond (NCD) layers were grown by the large area (linear plasma) MWCVD on polished silicon substrates with and without intermediate mirror-like metallic coatings. The optical reflectance and Raman spectroscopy in the ultraviolet, visible and near infrared region (UV–VIS–NIR) reveals the thickness and the optical quality of NCD layers. The modified grazing angle reflectance (GAR) spectroscopy is applied in the mid infrared region 800–4000/cm to detect the molecular vibrations (functional groups) at the functionalized NCD surface. The optical absorbance of functionalized NCD surface is evaluated from p-polarized reflectance spectra measured at Brewster angle of incidence (BAR) to eliminate the interference fringes. We report a significant enhancement of sensitivity of BAR using NCD growth on metal mirrors.

Research highlights
► NCD growth on metalic substrate is demonstrated.
► The metallic coating of the substrate significantly enhances the IR reflectivity of NCD layer.
► We evaluated the optical absorbance spectra of silanized NCD surface from p-polarized reflectance spectra measured at Brewster angle of incidence to eliminate the interference fringes in NCD film.