Note to users. If you're seeing this message, it means that your browser cannot find this page's style/presentation instructions -- or possibly that you are using a browser that does not support current Web standards. Find out more about why this message is appearing, and what you can do to make your experience of our site the best it can be.

Published Online November 10, 2005
Science DOI: 10.1126/science.1120693

Reports

Submitted on September 28, 2005
Accepted on October 25, 2005

Real-Time Observation of Molecular Motion on a Surface

Ellen H. G. Backus 1, Andreas Eichler 2, Aart W. Kleyn 3, Mischa Bonn 4

1 Leiden Institute of Chemistry, Leiden University, P.O. Box 9502, 2300 RA Leiden, Netherlands.
2 Institut für Materialphysik & Center for Computational Materials Science, Universität Wien, Sensengasse 8/12, A-1090 Wien, Austria.
3 Leiden Institute of Chemistry, Leiden University, P.O. Box 9502, 2300 RA Leiden, Netherlands; FOM Institute for Plasma Physics Rijnhuizen, P.O. Box 1207, 3430 BE Nieuwegein, Netherlands; FOM Institute for Plasma Physics Rijnhuizen, P.O. Box 1207, 3430 BE Nieuwegein, Netherlands.
4 Leiden Institute of Chemistry, Leiden University, P.O. Box 9502, 2300 RA Leiden, Netherlands; FOM Institute for Atomic and Molecular Physics, Kruislaan 407, 1098 SJ Amsterdam, Netherlands.

The laser-induced movement of CO molecules over a platinum surface is followed in real time using ultrafast vibrational spectroscopy. Because the CO molecules bound on different surface sites exhibit different C--O stretch vibrational frequencies, the site-to-site hopping, triggered by excitation with a laser pulse, can be determined from sub-picosecond changes in the vibrational spectra. The unexpectedly fast motion – characterized by a 500 femtosecond time constant – reveals that a rotational motion of the CO molecules, rather than pure translation, is required for this diffusion process. This conclusion is corroborated by density functional theory calculations.




To Advertise     Find Products

Science. ISSN 0036-8075 (print), 1095-9203 (online)