The Shimadzu UV 2450 is a dual beam spectrophotometer. The dual beam is used to minimize noise between the baseline and the sample. It can analyze both liquid and solid samples using absorbance and reflectance. A light source is shown onto a sample and is either partially absorbed or reflected and the changes in intensity are measured.
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.