Luminescence of dye molecules on oxidized silicon and fluorescence interference contrast microscopy of biomembranes

The luminescence of dye molecules depends on their position in a layered optical system. Conversely, the luminescence can be applied to measure the position of dye molecules above an interface. We formulate the electromagnetic theory of stationary fluorescence in a layered optical system—of light absorption, light detection, and fluorescence lifetime—computing the angular dependence of dipole interaction with all plane waves by a classical Sommerfeld approach. The theory is checked by experiments with stained lipid membranes on silicon with 256 terraces of silicon dioxide. We apply the electromagnetic theory to fluorescence micrographs of living cells on oxidized silicon chips and evaluate distances between the cell membrane and the substrate in a range of 1–150 nm.