OVERTONES OF LONGITUDINAL ACOUSTICAL VIBRATION OF PALMITIC ACID ADSORBED ON SILVER

The SERS spectrum of palmitic acid adsorbed on silver colloid surfaces is reported. The high order overtones, up to the 6th, of the accordion mode in the C-C-C deformation region are observed. The calculated frequencies of the overtone transitions from the energy expression for the anharmonic oscillator, with that omega(e) is 104 cm-1 and omega(e)x(e) is 2 cm-1, are excellent in agreement with the observed ones. We suggest a conformation that the four carbons from the carboxylate group of palmitic acid have a gauche conformation and the other carbons have an all-trans conformation.