Thermopower as a tool for characterization of metal-molecule junctions

INOR 61

Kanhayalal Baheti1, Jonathan A. Malen, jonmalen@newton.berkeley.edu2, Peter Doak1, T. Don Tilley1, Arun Majumdar2, and Rachel A. Segalman, segalman@berkeley.edu3. (1) Department of Chemistry, University of California, Berkeley and Lawrence Berkeley National Laboratories, Berkeley, CA 94720, (2) Department of Mechanical Engineering, University of California, Berkeley and Lawrence Berkeley National Laboratories, Berkeley, CA 94720, (3) Department of Chemical Engineering, University of California Berkeley and Lawrence Berkeley National Laboratories, 201 Gilman, Berkeley, CA 94553
Thermopower measurements offer an alternative to conductance measurements that are insensitive to the number of molecules in the junction. We use a simple two-point probe technique, based on the scanning tunneling microscope break junction method, to measure thermopower of metal-molecule-metal junctions. This measurement can uniquely distinguish whether transport in the junction is dominated by the HOMO (if measured value is positive) or LUMO (if it is negative) level in the molecule, which cannot be easily obtained from other measurements. This method is also amenable to statistical analysis without any need for data preselection. The application of this technique for the measurement of various small molecules between gold contacts will be discussed.
 

Nanoscience - Characterization and Applications
9:00 AM-1:00 PM, Sunday, April 6, 2008 Morial Convention Center -- Rm. 221, Oral

Division of Inorganic Chemistry

The 235th ACS National Meeting, New Orleans, LA, April 6-10, 2008