Theoretical surface-enhanced Raman spectra study of substituted benzenes II. Density functional theoretical SERS modelling of o-, m-, and p-methoxybenzonitrile.

The SERS modelling of o-, m-, and p-methoxybenzonitrile has been performed following the same methodology that in Part I. Optimized structure obtained from DFT calculations in a B3LYP-LANL2DZ level of calculation shows different tilted positions for the isomers under study. From correlations obtained by comparison of Raman and SERS spectra concerning geometrical parameters, frequency shifting, change in band intensity, and force constants is possible to give insight about the different effect of the metal surface on these molecules and the structural reasons of this behaviour.

Theoretical surface-enhanced Raman spectra study of substituted benzenes I. Density functional theoretical SERS modelling of benzene and benzonitrile.

This paper reports a DFT modelling of SERS spectra for benzene and benzonitrile on the basis of a simple noncoordinate substrate-adsorbate model. Assignment of normal modes was obtained from internal force constants and potential energy distribution matrices and used to identify, according the SERS selection rules, the orientation of the optimized molecules on the metallic surface. Calculated band enhancements are in good agreement with experimental observations.