Optical limitng and field emission studies of carbon nanotubes

Abstract

In this research, we investigate two of carbon nanotubes most well known properties: optical limiting and field emission. Our aim is to modify the carbon nanotubes using physical and chemical means to modify their optical limiting and field emission characteristics. In the first part of this thesis, we coat randomly aligned multi-walled carbon nanotubes (MWNTs) with a-Au and a-Ag nanoparticles. The optical limiting characteristics of as-grown MWNTs and the coated MWNTs are then measured and compared at 532nm and 1064nm using a nanosecond laser. In the second part of the thesis, we modify the MWNTs by plasma etching with N2 and Ar for 10min and 20min each. The field emission characteristics of the etched samples are then measured using a custom-made chamber and compared to that of MWNTs. Various methods of characterization, such as XPS, PES, SEM and Raman spectroscopy are used to investigate these observations and an explanation to our results is proposed.