功率谱估计在扫描隧道显微术中的应用  

Application of Power Spectral Density Analysis in STM

作　　者：苏小平[1] 王少峰[1] 杨学恒[1] 

机构地区：[1]重庆大学数理学院,重庆400030

出　　处：《重庆大学学报（自然科学版）》2007年第4期129-133,共5页Journal of Chongqing University

摘　　要：扫描隧道显微镜(简称STM)所采集到的隧道电流信号,不仅包含着表征样品的表面形貌和分子结构的有效信号,而且还隐含着整个扫描隧道显微系统的动态特性.针对STM采集的信号,运用短时傅立叶变换对其波形数据进行功率谱密度估计,对信号在频率域中的特征向量加以提取.结果表明:基于谱空间的特征向量,准确地分辨出了工频在信号中的干扰,也能有效地解释和分析STM系统的动态特性,进而认为存在一小阻尼系统对信号施以影响;此外,分析的结果可以为STM扫描过程的控制,诊断以及扫描图像的重建和解释提供有力的理论指导.The tunneling-current signals which acquired by STM, include both the sample＇s molecular structure and the dynamic characteristics of STM system. The Short Time Fourier Transform （STFT） is utilized to estimate the power spectral density （PSD）of the tunneling-current signals and the data＇s feature vector was extracted in the frequency space. The results obtained by PSD estimation reveal that spectral-space-based feature vector can distinguish the interference from power line （50 Hz） , and it can explain and analyze the dynamic characteristics of STM efficiently by using a damped harmonic oscillator model. Meanwhile, the recognition is helpful in the control of the practice scanning condition of STM and the 3-D recreation for the images of STM.

关 键 词：扫描隧道显微镜(STM) 功率谱密度 特征提取 

分 类 号：O433[机械工程—光学工程]