Quantitative high-resolution microscopy on a suspended chain of gold atoms

High-resolution electron microscope images of a suspended gold chain were a nalyzed quantitatively. The images of the suspended gold chain were recorde d on videotapes, during in situ observation in an ultra-high-vacuum electro n microscope. The chain consisted of four gold atoms free from any substrat e. Image simulation verified that the gold chain has a center-top geometry. The simulation also showed that the chain has no glue atoms spinning aroun d the axis of the chain. A spinning gold atom was shown to give 50% of the stationary atom in gray scale. By comparing the noise level of the observed image and the gray scale of single atoms such as C, Si, S, Cu, and Au, we verified that the Si and S atoms have almost twice as large contrast as the noise (peak-to-peak), and C atoms have almost the same contrast as the noi se level. The analysis showed it critical to detect a single Si and S atoms . (C) 2001 Elsevier Science B.V. All rights reserved.