Restoration and pictorial representation of scanning-tunneling-microscope data

Abstract

Assuming a linear Gaussian resolution function, topographic and other data from a Scanning Tunneling Microscope (STM) or similar instruments like the Atomic-Force Microscope (AFM) can be deconvoluted using a Wiener filter to eliminate blurring and to suppress noise. Shot noise, owing to quantized electron transfer, becomes important at the picoamp level but can be easily filtered out. More care is required with 1/f-like noise which, however, leads to characteristic artifacts and can be estimated from an independent measurement. Salient features are easily recognized in processed three-dimensional surface profiles generated on a high-resolution graphics station by simulating shading with judiciously placed sources. To enhance the topography or to superpose information from spectroscopic, barrier-height or potentiometric measurements, colors can be combined with shading, or contour lines can be displayed. With these tools we can convey the essence of STM and related measurements to nonexperts, or exhibit correlations between properties recorded simultaneously. © 1988.