Characterizing the Effect of Surface Hydrophobicity on Depletion Layer

When water meets an extended hydrophobic surface a region of reduced density called the depletion layer forms, but this phenomenon has only been experimentally verified on surfaces with contact angles \textgreater 100$^{\circ}$. Using self-assembled monolayers of organothiols on gold we produce surfaces with contact angles between 55$^{\circ}$ and 107$^{\circ}$ and then use surface plasmon resonance spectroscopy to quantify the thickness of the depletion layer formed. These experiments allow for the understanding of how the depletion layer changes with the hydrophobicity of a surface which is one of the underlying mechanisms behind several biological systems.