The surface pressure-area isotherms of a new type of two legged inert amiphiphilic molecule 1. 10-bistearyl-4.6.13.15-tetraene-8-nitrogen-6(abbreviated as NC) monolayers at the air-water interface in the subphase containing divalent ions (Cd2+,Ba2+,Co2+) and the effects of divalent ions in the subphase on the UV-visible absorption spectroscopy, steady-state fluorescence spectroscopy and optical nonlinear properties of Y-type hemicyanine/NC interleaving Langmuir-Blodgett multilayers were investigated. The π-A isotherms of NC molecules are strongly dependent on the divalent ions in the subphase. It was found that the peak positions of absorption and steady state fluorescence spectra of the alternating multilayers and the optical second harmonic intensity varied with the divalent ions in the subphase. The 2ω resonance effect of β was responsible for the observed χ(2) enhancement.