Digital Instruments Multimode SPM with a Nanoscope III controller:
Surface probe microscopies (SPM) allow one to image the direct surface of a material with nanometer to sub-nanometer resolution. The Multimode capabilities include tapping mode atomic force microscopy (AFM), contact mode AFM, and scanning tunneling microscopy (STM). Two piezoelectric scanners are available for use with the Multimode; the J scanner is capable of measuring areas up to 120 μm x 120 μm with a vertical range of ~ 5 μm, and the E scanner is capable of imaging areas up to 10 μm x 10 μm with a vertical range of ~ 2.5 μm. Sample size is limited to a 10 mm in diameter in order to be easily mounted on the magnetic steel mounting disk.
The role of water in carbon feed on the surface-guided growth of horizontally aligned single-walled carbon
nanotubes (HA-SWCNTs) was investigated. It is shown that the amount of water can be optimized to favor HA-SWCNT growth, which is proposed to be due to selective etching of carbon deposits at carbon–metal interface. Without water, nanotube–nanotube interaction and carbon accumulation at the interface are disproportionately large compared to the rate of nanotube growth, leading to catalyst deactivation. With excess water, suppression of nanotube growth occurs, resulting in reduced carbon yield on the surface.
Intermediate carbon/water feed ratios achieve cleaner growth with high efficiency.