Surface plasmon resonance studies on spin coated films of azobenzene-substituted calix-4-resorcinarene molecules

Thin films of tetra-undecyl-tetra-p-nitrophenylazocalix(4)resorcinarene (Azol) molecules were deposited on different substrates by the spin coating method. The refractive index of spun films is found to be 1.494 from surface plasmon resonance (SPR) experiments on the sample in contact with two different dielectric media: air and high purity water. The thickness of films decreases with the increase in the spin speed as a -2/3 power law but rises linearly with the concentration. These observations are in agreement with hydrodynamic theory for spinning of a low-viscosity and highly volatile liquid.