Supplementary Material:
Conductance Switching in Single Molecules through Conformational Changes

Z. J. Donhauser,1 B. A. Mantooth,1 K. F. Kelly,1 L. A. Bumm,1 J. D. Monnell,1 J. J. Stapleton,1 D. W. Price Jr.,2 D. L. Allara,1J. M. Tour,2 and P. S. Weiss1

1Department of Chemistry, The Pennsylvania State University, University Park, PA 16802-6300, USA

2Department of Chemistry and Center for Nanoscale Science and Technology, Rice University, Houston, TX 77005, USA

Movies of a number of inserted molecules recorded with the STM at high gap impedance show stochastic switching of conductance.  Supplementary movies 1-3 show examples of several such movies.  Movie 2 is particularly illuminating in that disorder in the alkanethiolate matrix sweeps through the lower region of the images.  When this happens the switching rate rises very dramatically and can no longer be tracked on the time scale of imaging.

Supplementary Movie 1 (3.2 MB)
Dodecanethiolate film with 4,4'-di(ethynylphenyl)-2'-nitro-1- benzenethiolate (2') inserted.  Approximately 45% of the visible molecules undergo at least one switching event.

200 frames, 8.2 min/frame, Sample bias: +1.4 V, Current: 4.0 pA, 1500 Å x 1500 Å.
Total Time: Approx. 27 hr

Supplementary Movie 2 (4.4 MB)
Dodecanethiolate film with 4,4'-di(ethynylphenyl)-1-benzenethiolate (1') inserted.  Note the effect of matrix disorder on switching rate as the movie progresses.

240 frames, 5.0 min/frame, Sample bias: +1.0 V, Current: 1.0 pA, 1000 Å x 1000 Å.
Total Time: Approx. 20 hr.

Supplementary Movie 3  (4.1 MB)
Dodecanethiolate film with 1' inserted.  The film has been vapor annealed to reduce switching; note the stability of the inserted molecules. 

200 frames, 5.3 min/frame, Sample bias: -1.0 V, Current: 1.0 pA, 1500 Å x 1500 Å.
Total Time: Approx. 18 hr.

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Last updated: May 8, 2001 zjd
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