Based on the experimental results of abnormal infrared effects(AIREs) for molecules adsorbed on transition-metal nanostructured surfaces,the interactions and the polarizability of the adsorbed molecules are analyzed theoretically.By numerical simulations,the normal absorption spectrum,the Fano-like bipolar spectrum and the anti-absorption spectrum of the adsorbed CO molecules are obtained respectively.The results show that the adsorbed molecules on a metal nanostructured surface can accumulate together dues to the effect of local external electric field,which leads to a change in imaginary part of the molecular polarizability within a certain range of frequency,and even a negative value may appear.
Based on the nanostructured surface model,where conical nanoparticle arrays grow out symmetrically from a plane metal substrate,a theoretical model of the local electric potential near nanocones is built when a uniform external electric field is applied.In terms of this model,the electric potential distribution near the nanocone arrays is obtained and given by a curved surface using a numerical computation method.The computational results show that the electric potential distribution near the nanocone arrays exhibit an obvious geometrical symmetry.These results could serve as a basis for explaining many abnormal phenomena,such as the abnormal infrared effects(AIREs) which are found on nanostructured metal surfaces,as well as a reference for investigating the applications of nanomaterials,such as nanoelectrodes and nanosensors.
