A new surface for surface-enhanced infrared spectroscopy: Tin island films

For the first time, it has been observed that tin island films used in surface infrared experiments give rise to an electromagnetic enhancement of the infrared absorption spectrum. The surface enhancement of the infrared (SEIR) absorption by tin island films is shown for evaporated nanometric films of 5,14-pentacenedione (Q2) and naphthalic 1,8:4,5-dianhydride (NTCDA). The experiments and spectral characteristics demonstrating the ability of tin to produce SEIR of organic molecules physically adsorbed onto tin structures are described. Tin island films of varying mass thickness were fabricated to ascertain maximum enhancement. Their morphology was determined by transmission electron microscopy. Comparisons are made between the SEIR spectra on rough tin and on silver surfaces and the corresponding reflection-absorption spectra (RAIRS) obtained for the same organic molecules on reflecting surfaces of tin and silver.