Abstract: The molecular orientation and thermal stability of the Langmuir-Blodgett film of Cd salt of 10, 12-tricosadiynoic acid was studied using linear dichroism FT-IR spectroscopy. It was found that orientation angles between the transition moments of major characteristic groups in the film and the substrate surface normal line N are different. A molecular configuration like that of folding chain was evaluated, the closer to the hydrophobic end the more small the orientation angle is, this satisfies structural stability of LB films. The experiments on thermal stabiliyt showed that the structural stability of the LB film mainly depends on the hydrocarbon chain. After heated the tilt of the hydrocarbon chain was most serious and was irreversible on cooling back to the original room temperature.

Key words: Langmuir-Blodgett film of Cd salt of 10,12-tricosadiynoic acid, Molecular orientation, FT-IR linear Dichroism spectra