Based on the nanostructured surface model that the(platinum,Pt) nanocones grow out symmetrically from a plane substrate,the local electric field near the conical nanoparticle surface is computed and discussed.On the basis of these results,the adsorbed CO molecules are modelled as dipoles,and three kinds of interactions,i.e.interactions between dipoles and local electric field,between dipoles and dipoles,as well as between dipoles and nanostructured substrate,are taken into account.The spatial configuration of CO molecules adsorbed on the nanocone surface is then given by Monte-Carlo simulation.Our results show that the CO molecules adsorbed on the nanocone surface cause local agglomeration under the action of an external electric field,and this agglomeration becomes more compact with decreasing conical angle,which results in a stronger interaction among molecules.These results serve as a basis for explaining abnormal phenomena such as the abnormal infrared effect(AIRE),which was found when CO molecules were adsorbed on the nanostructured transition-metal surface.
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.
In view of the disadvantages of the traditional phase space reconstruction method,this paper presents the method of phase space reconstruction based on the wavelet decomposition and indicates that the wavelet decomposition of chaotic dynamical system is essentially a projection of chaotic attractor on the axes of space opened by the wavelet filter vectors,which corresponds to the time-delayed embedding method of phase space reconstruction proposed by Packard and Takens.The experimental results show that,the structure of dynamical trajectory of chaotic system on the wavelet space is much similar to the original system,and the nonlinear invariants such as correlation dimension,Lyapunov exponent and Kolmogorov entropy are still reserved.It demonstrates that wavelet decomposition is effective for characterizing chaotic dynamical system.
