45 research outputs found
Phosphorus cluster production by laser ablation
Neutral and charged phosphorus clusters of a wide size range have been produced by pulsed laser ablation (PLA) in vacuum at 532, 337, and 193 nm ablating wavelengths and investigated by time-of-flight mass spectrometry. The neutral P_n clusters are even-numbered with local abundance maxima at n = 10 and 14, while the cationic and anionic clusters are preferentially odd-numbered with (P_7)+, (P_21)+, and (P_17)- being the most abundant ions. The dominance of the magic clusters is more pronounced at 337-nm ablation that is explained by efficient direct ejection of their building blocks under these conditions. Nanocrystalline phosphorus films have been produced by PLA in ambient helium gas
Local heating method for growth of aligned carbon nanotubes at low ambient temperature
We use a highly localised resistive heating technique to grow vertically aligned multiwalled nanotube
films and aligned single-walled nanotubes on substrates with an average temperature of less than 100°C. The
temperature at the catalyst can easily be as high as 1000 °C but an extremely high temperature gradient
ensures that the surrounding chip is held at much lower temperatures, even as close as 1μm away from the
local heater. We demonstrate the influence of temperature on the height of multi-walled nanotube films,
illustrate the feasibility of sequential growth of single-walled nanotubes by switching between local heaters
and also show that nanotubes can be grown over temperature sensitive materials such as resist polymer
Electronic and vibrational excitation in atom/molecule collisions
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