Search

The electron emission properties of a single C[sub 60] molecule supported on a W field emission tip are reported. Using standard models, values for the size, effective work function, and desorption temperature of C[sub 60] were obtained. Energy distributions of electrons emitted from C[sub 60] exhibit a narrow two-peaked spectrum and indicate a splitting of the highest occupied molecular-orbital level.

We investigate the mechanical properties of cantilevered silver-gallium (Ag2Ga) nanowires using laser Doppler vibrometry. From measurements of the resonant frequencies and associated operating deflection shapes, we demonstrate that these Ag2Ga nanowires behave as ideal Euler-Bernoulli beams. Furthermore, radial asymmetries in these nanowires are detected through high resolution measurements of the vibration spectra. These crystalline nanowires possess many ideal characteristics for nanoscale force and mass sensing, including small spring constants (as low as 10(-4) N m(-1)), high frequency bandwidth with resonance frequencies in the 0.02-10 MHz range, small suspended mass (picograms), and relatively high Q-factors (similar to 2-50) under ambient conditions. We evaluate the utility of Ag2Ga nanowires for nanocantilever applications, including ultrasmall mass and high frequency bandwidth piconewton force detection.

Epitaxial carbon was grown by heating (000 (1) over bar) silicon carbide (SiC) to high temperatures (1450-1600 degrees C) in vacuum. A continuous graphene surface layer was formed at temperatures above 1475 degrees C. X-ray photo-electron spectroscopy (XPS) and scanning tunneling microscopy (STM) were extensively used to characterize the quality of the few-layer graphene (FLG) surface. The XPS studies were useful in confirming the graphitic composition and measuring the thickness of the FLG samples. STM studies revealed a wide variety of nanometer-scale features that include sharp carbon-rich ridges, moire superlattices, one-dimensional line defects, and grain boundaries. By imaging these features with atomic-scale resolution, considerable insight into the growth mechanisms of FLG on the carbon face of SiC is obtained.

Poster from Birck Nanotechnology Center's 2008 Research Review

A correlation between growth temperature and electrical resistance of multiwalled carbon nanotubes (MWNTs) has been established by measuring the resistance of individual MWNTs grown by microwave plasma-enhanced chemical vapor deposition (PECVD) at 800, 900, and 950 degrees C. The lowest resistances were obtained mainly from MWNTs grown at 900 degrees C. The MWNT resistance is larger on average at lower (800 degrees C) and higher (950 degrees C) growth temperatures. The resistance of MWNTs correlated well with other MWNT quality indices obtained from Raman spectra. This study identifies a temperature window for growing higher-quality MWNTs with fewer defects and lower resistance by PECVD.