A three-dimensional rendering of an ultra-high vacuum scanning tunneling microscope (STM) image of individual 2, 2, 6, 6-tetramethyl-1-piperidinyloxy (TEMPO) molecules on a Si(100) surface. The STM tip, which is used to address individual TEMPO molecules, is also schematically depicted. Room temperature STM charge transport measurements reveal negative differential resistance (NDR) through individual molecules that can be controlled through substrate doping. Representative current-voltage curves that clearly show NDR make up the background tiles.

Reference: N. P. Guisinger, M. E. Greene, R. Basu, A. S. Baluch, & M. C. Hersam, "Room temperature negative differential resistance through individual molecules on silicon surfaces," Nano Letters, 4, 55 (2004).

Reference: N. P. Guisinger, R. Basu, M. E. Greene, A. S. Baluch, and M. C. Hersam, “Observed suppression of room temperature negative differential resistance in organic monolayers on Si(100),” Nanotechnology, 15, S452 (2004).

This figure contains a three-dimensional rendering of an ultra-high vacuum scanning tunneling microscope image of individual 2,2,6,6-tetramethyl-1-piperidinyloxy (TEMPO) molecules on a Si(100) surface.

Reference: M. E. Greene, N. P. Guisinger, R. Basu, A. S. Baluch, and M. C. Hersam, “Nitroxyl free radical binding to Si(100): A combined STM and computational modeling study,” Surface Science, 559, 16 (2004).

This figure schematically depicts a femtosecond laser pump-probe spectroscopy measurement on surfactant encapsulated single-walled carbon nanotubes. This measurement is used to study photobleaching and stimulated emission of infrared radiation in these nanomaterials.

Reference: M. S. Arnold, J. E. Sharping, S. I. Stupp, P. Kumar, and M. C. Hersam, “Band Gap Photobleaching in Isolated Single-Walled Carbon Nanotubes,” Nano Letters, 3, 1549 (2003).

Reference: L. S. C. Pingree, M. C. Hersam, M. M. Kern, B. J. Scott, and T. J. Marks, “Spatially resolved electroluminescence of operating organic light-emitting diodes using conductive atomic force microscopy,” Appl. Phys. Lett., 85, 344 (2004).

Reference: Unpublished data courtesy of Mark Greene, Jon Widom, and Mark C. Hersam.

Reference: E. T. Foley, N. L. Yoder, N. P. Guisinger, and M. C. Hersam, “Cryogenic variable temperature ultra-high vacuum scanning tunneling microscope for single molecule studies on silicon surfaces,” Rev. Sci. Instrum., 75, 5280 (2004).

This figure contains a photograph of the cryogenic variable temperature ultra-high vacuum scanning tunneling microscope constructed in the Hersam Laboratory.

Reference: E. T. Foley, N. L. Yoder, N. P. Guisinger, and M. C. Hersam, “Cryogenic variable temperature ultra-high vacuum scanning tunneling microscope for single molecule studies on silicon surfaces,” Rev. Sci. Instrum., 75, 5280 (2004).

Reference: E. T. Foley, N. L. Yoder, N. P. Guisinger, and M. C. Hersam, “Cryogenic variable temperature ultra-high vacuum scanning tunneling microscope for single molecule studies on silicon surfaces,” Rev. Sci. Instrum., 75, 5280 (2004).