2010 July

Editor’s suggestion for PRB

Thursday, 29th July 2010Publication highlights

Fig: Comparison of the experimental IR spectrum of Fe4O6+ with the calculated IR spectra for two different geometries. Kirilyuk et al.

An article from the Fritz Haber Institute’s Molecular Physics department has been selected as an Editor’s Suggestion in the July issue of Physical Review B. The scientists, including collaborators from France and The Netherlands, report on the vibrational spectra of several cationic iron-oxide clusters in the gas phase. Clusters, which contain only a few atoms, are of interest to study as they straddle the boundary between gas-phase and condensed matter physics. The possibilities to tailor the magnetic properties of iron oxide particles by their size and composition make them promising candidates for many applications, for instance in data storage.

The spectra were measured using infrared multiphoton dissociation (IR-MPD), where the fragmentation of the clusters after absorption of multiple IR photons is detected; single photons in the infrared spectral range are usually not energetic enough to result in fragmentation. The vibrational spectra obtained by IR-MPD provide a distinct fingerprint of the original cluster. The researchers compared their experimental data to calculations to learn more about the clusters’ properties. In this way, they could ascertain the geometric and magnetic structure for Fe4O6+. Their report can be found here.

(Published: 19 July 2010 |Phys. Rev. B 82, 020405(R)).

Further Information: André Fielicke

Here Comes the Sun

Thursday, 22nd July 2010General science information, Miscellaneous

An exhibition about the sun and its energy will be presented in Berlin between September 6 until October 31. There will be multimedia displays, interactive experiments, and games appropriate for children 7 year and older. Come and learn about the sun, its potential for energy, and its influence on life on our planet.

Location: UferHallen, Uferstraße 8, 13357 Berlin
Opening Hours: daily from 11am to 6pm

more information can be found here (in German):

Call for “Gerhard Ertl Young Investigator Award”

Tuesday, 20th July 2010General science information, Miscellaneous

Young surface science researchers (less than 6 years since their PhD), with no restrictions to nationality or home institution, are invited to apply for the “Gerhard Ertl Young
Investigator Award”. More details can be found here.

A new microwave lens for polar molecules

Friday, 2nd July 2010Publication highlights

A team of international scientists led by P.I. Melanie Schnell has successfully demonstrated a microwave lens for neutral polar molecules at the Fritz Haber Institute. Their findings have been published in Physical Review Letters. Already in the 1920’s external electric and magnetic fields were used to manipulate neutral molecules. Yet analogous devices involving electromagnetic radiation, such as optical and microwave fields, were only developed much later. For example, in 1975 a rectangular microwave resonator was used to deflect a beam of CsF molecules. However these results were never fully understood.

In the present work, scientists combined a cylindrically symmetric microwave cavity with the so-called Stark decelerator, a device used to decelerate a packet of molecules by time-varying electric fields to a desired velocity. Once in the resonator, the molecular packet is confined in the transverse directions by the applied microwave field. In other words, the microwave field acts like a positive lens for the polar molecules. In contrast to optical (laser) fields, strong interaction forces can be reached using microwaves since very small detunings of the resonator frequency from the molecular resonance frequency are possible. Moreover, by changing the sign of this detuning, molecules in quantum states with completely different behavior in external fields can be addressed, which demonstrates the great versatility of this method. These experiments lay the groundwork for future microwave devices, which are promising for controlling larger more complex molecules that are otherwise difficult to manipulate.

(Published: 23 June 2010 |Phys. Rev. Lett. 104, 253001).

Further information: Melanie Schnell