Luminescence and nonradiative energy transfer to surfaces

Luminescent molecules near metal surfaces can have dramatically decreased quantum efficiencies and lifetimes. For example, decreases of ∼${10}^3$ in quantum efficiency and in lifetime occur for nitrogen atoms within 3 nm of potassium surfaces. This paper presents experimental decay curves for light emission from nitrogen atoms in a ${\mathrm{N}}_2$ matrix of varying thickness (3 to 1000 nm) on sapphire, silver, and potassium substrates. Theoretical decay curves are derived and found to be in agreement with the experimental curves. Both experiment and theory agree that for potassium there is near-resonant coupling between excited nitrogen atoms and potassium surface plasmons. For metal films, both film thickness and surface roughness affect the decay curves.