Printer Friendly

Shape of things to come: molecular STM.

The scanning tunneling microscope's (STM] needle-like probe enables researchers to image the electron clouds surrounding atoms. Making sense of those images, however, requires detailed calculations that predict the shape of electron clouds for individual atoms. The task is even more difficult for molecules.

Now, a team led by Vickie M. Hallmark and Shirley Chiang at IBM's Almaden Research Center in San Jose, Calif., has come up with a simple calculation technique that provides accurate shapes of the electron clouds surrounding molecules deposited on platinum. They used this prediction method along with high-resolution STM to distinguish among closely related chemicals called isomers - molecules containing the same number and kinds of atoms but built in different geometric arrangements.

As part of a report in the June M PHYSICAL REVIEW LETTERS, the group looked at three isomers of monomethylazulene [a-c, top]. They calculated the shape of each isomer's electron cloud using a conventional technique (a-c, center) and their new approach (ac, bottom). In an STM image of a mixture of molecules (d), they marked isomer a with a square and isomer b with a circle; the image of isomer c is shown at right (e). The shapes predicted by the new calculations - which include the influence of the platinum substrate - more accurately reflect those seen in the high-resolution STM images, Chiang and Hallmark assert. This advance brings researchers a step closer to using STM to track the reactants, intermediates, and products of chemical reactions on metal surfaces.
COPYRIGHT 1993 Science Service, Inc.
No portion of this article can be reproduced without the express written permission from the copyright holder.
Copyright 1993, Gale Group. All rights reserved. Gale Group is a Thomson Corporation Company.

Article Details
Printer friendly Cite/link Email Feedback
Title Annotation:calculation technique developed to aid identification of isomers imaged by scanning tunneling microscope
Publication:Science News
Article Type:Brief Article
Date:Jun 26, 1993
Words:244
Previous Article:Clinton backs scaled-down space station.
Next Article:Prolonged nursing and the risk of bone loss.
Topics:


Related Articles
Scanning the surface: from gold atoms to benzene molecules, the scanning tunneling microscope probes the intricate structure of surfaces.
Unique atomic views from STM's new kin.
Digging ditches in molecular strata.
STM tip builds golden mounds.
Microscope writes beneath a metal surface.
STM scientists strong-arm silicon atoms.
Microtools for scaling nanomountains.
Building structures molecule by molecule.
Atom tinkerer's paradise: innovations to atom-imaging microscopes create labs on tips.
Writing with warm atoms.

Terms of use | Copyright © 2016 Farlex, Inc. | Feedback | For webmasters