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nanotimes News in Brief

Nanoparticles // Heartbeat of Nanoparticles Made Visible

gether with his Ph.D. student Thorsten Schumacher achieved a breakthrough in the study of tiny gold nanoparticles. They used a nano-antenna, which has already been applied successfully as a nanosensor by Prof. Harald Giessen from the 4 . Physics Institute of the University of Stuttgart, Germany.

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Lippitz‘ dream is to investigate the mechanical properties of the smallest nanoparticles. “The sur- face to volume ratio would then be huge, and we would expect new nanomechanical properties,” he explains. To get one step closer to this dream, he placed a small antenna near the tiny particle. This nano-antenna focuses the laser light very tightly on the nanoparticle under examination. Consequently, the light modulation due to the nanomechanical vibrations are very efficiently coupled back into the laser beam. “This is the first time that someone uses nano-antennas to investigate ultrafast nonlinear optical effects. The whole thing works like a mobile phone, in which the antenna makes that the electro- magnetic waves are effectively coupled into the small electronic circuits of the phone,” Lippitz explains. Lippitz sees a huge potential for his new method: “In the future, we will be able to put the smallest nano- objects of a few nanometers in diameter in the focal point of a nano-antenna and study them using non- linear optical processes of only a few femtoseconds.

ssistant professor Markus Lippitz from the Max Planck Institute for Solid State Research, to-

Then we can make movies on the na- noscale, using the most extreme slow motion. Not only can we investigate nanoobjects such as semiconductor quantum dots, but also chemical and biological ob- jects, such as molecules and viruses.”

The head of the 4th Physics Institute, Prof. Harald Giessen, added: “The work by Markus Lippitz is a re- sults of the very successful collaboration between the Max Planck Institute and the University of Stuttgart. Markus Lippitz is an excellent young scientists, who also supports the Stuttgart Excellence Initiative in the Graduate School „Advanced Condensed Matter Science.”

Th. Schumacher, K. Kratzer, D. Molnar, M. Hentschel, H. Giessen, and M. Lippitz: Nanoantenna-enhanced ultrafast nonlinear spectroscopy of a single gold nanoparticle, In: Nature Communications, Vol. 2(2011), May 2011, Article Number: 333, DOI:10.1038/ncomms1334: http://dx.doi.org/10.1038/ncomms1334

Image: Assistant professor Markus Lippitz (left) with his PhD student Thorsten Schumacher. © University of Stuttgart, Germany

11-05 :: May/June 2011