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.

Science 21 January 2005:
Vol. 307. no. 5708, pp. 364 - 365
DOI: 10.1126/science.1108159
Prev | Table of Contents | Next

Perspectives

CHEMISTRY:
Short and Sharp--Spectroscopy with Frequency Combs

Thomas Udem

Many researchers have long assumed that continuous (or single-mode) lasers are sharper than pulsed lasers and are thus better able to resolve narrow spectral features of atoms and molecules. However, single-mode lasers are difficult to construct at short wavelengths, for example in the extreme-ultraviolet. Sharp lasers at these wavelengths have thus been difficult or impossible to come by. In his Perspective, Udem highlights an approach that may circumvent this problem. He discusses the report by Witte et al., who have used a train of coherent laser pulses rather than just a single laser pulse. The resulting spectral lines are narrower than the spectral width of a single pulse. This use of the laser's "harmonics" may enable high-resolution spectroscopy at wavelengths where no single-mode lasers are available.

The author is at the Max-Planck-Institut für Quantenoptik, 85748 Garching, Germany. E-mail: thu{at}mpq.mpg.de

Read the Full Text

To Advertise     Find Products

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