Plasma-enhanced synthesis of thin fluoropolymer layers with low Raman and fluorescence backgrounds

Radio-frequency (RF) plasma enhanced chemical vapor deposition (PECVD) provides a promising way to deposit extremely hydrophobic, highly adherent nanometer- to micrometer-thick films with thermal stability, a low coefficient of friction, a low dielectric constant, and a low value of surface energy. We describe the synthesis of these fluorinated thin films using hexafluoropropene as starting material and discuss their properties. These coatings, applied to stainless steel, provide ideal substrates for Raman spectroscopy, when extremely low backgrounds are required. Raman spectroscopy measurements of a low-concentration protein film are used to demonstrate sensitivity and level of detectability.