Slab optical waveguide (SOWG) was employed for obtaining absorption sp
ectra of rhodamine 6G (Rh6G) with the concentration of 1 mu mol/dm(3).
It was found that Rh6G existed as a monomer and dimer on SOWG surface
s. On the SOWG surfaces treated with octadecylsilane only the band ass
igned to a monomer of Rh6G was observed.