Single-molecule observations of azobenzene photo-switching in controlled nanoscale environments

COLL 195

Ajeet Kumar, ajeet@psu.edu1, Tao Ye1, Tomohide Takami2, Byung-Chan Yu3, A. K. Flatt3, James M. Tour3, and Paul S. Weiss, stm@psu.edu1. (1) Departments of Chemistry and Physics, The Pennsylvania State University, 104 Davey laboratory, University Park, PA 16802, (2) Visionarts Research Inc, Tokyo, 107-0062, Japan, (3) Department of Chemistry and Center for Nanoscale Science and Technology, Rice University, Houston, TX 77005
Molecules that control position and conduction at the nanometer scale have great promise for future devices. Azobenzene molecules having two conformational isomers (trans and cis) are well known examples of molecular photo-switches. We study the reversible photo-isomerization of azobenzene derivatives in precisely tailored nanoscale environments with the scanning tunneling microscope (STM). Matrices have been prepared to assemble isolated, chains and islands of molecules. We report the OFF and ON switching of single azobenzene derivative molecules from trans to cis and vice versa on photoillumination with ultraviolet (UV, ~350 nm) and visible (Vis, ~440 nm) light, respectively. We also observe that the efficiency of photo-switching decreases from isolated molecules to chains of molecules to islands of molecules. Figure: Azobenzene molecules switch ‘OFF/ON' on irradiation with UV and Vis light, respectively. Vbias = -0.6 V; Itunneling = 2 pA.

 

Fundamental Research in Colloid and Surface Chemistry
6:00 PM-8:00 PM, Monday, August 20, 2007 BCEC -- East Registration, Poster

Division of Colloid & Surface Chemistry

The 234th ACS National Meeting, Boston, MA, August 19-23, 2007