MSC Colloquium Sense Jan van der Molen
|07 October 2004||FWN-Building 5111.0080, Nijenborgh 4, 9747 AG, Groningen|
|Speaker:||Dr.ir. Sense Jan van der Molen|
|Affiliation:||Research Group Physics of Nanodevices, Materials Science Centre, Rijksuniversiteit Groningen|
|Title:||Photochromic molecules on gold: promising and intriguing nanodevices|
|Date:||Thu Oct 7, 2004|
|Start:||16.00 (Doors open and coffee available at 15.30)|
One of the most exciting and still rather unexplored fields of nanoscience is formed by single-molecule electronics. The increasing interest in this research direction has two main reasons. First, a single-molecule device has dimensions of a few nanometers only. Hence, true nanometer-size science becomes possible. Second, the rich possibilities of chemistry become available to device phyics.
We concentrate on creating a molecular nanodevice that can be manipulated with light. For this, we investigate photochromic molecules (1,2-bis[5'-(5''-acetylsulfanylthien-2''-yl)-2'-methylthien-3'-yl]) that are synthesized in Ben Feringa's group. In solution, these organic molecules can be switched reversibly between a conjugated, 'conductive' state and a non-conjugated, 'insulating' state by using light of the proper wave lengths.
Two ways to contact a molecule are chosen, both based on the Au-S bond. First, we use the mechanically controllable break junction (MCBJ) technique. Second, we study a diluted self-assembled monolayer (SAM) using scanning tunneling microscopy (STM). With both methods, we observe switching from the 'conductive' to the 'insulating' state. However, we do not observe the reverse process, which should occur upon illumination with UV light. Optical absorption experiments using gold colloids covered by switchable molecules confirm the latter observation. Furthermore, ultrafast spectroscopy measurements are performed at the MSC to elucidate switching dynamics. Finally, we discuss a possible way out, introducing newly synthesized organic molecules.
|Last modified:||22 October 2012 2.30 p.m.|