| The work presented in this thesis is focused on the electronic and optical properties of single wall carbon nanotubes (swCNs). In a first set of experiments we investigate the local electronic properties of swCNs using novel scanning probe microscopies. We use Scanning Gate Microscopy (SGM) to measure the energy of the resonant scattering centers in metallic swCNs, and to show the local nature of the memory effect observed in swCN field effect transistors (swCN-FETs). We also combine Impedance Spectroscopy and SGM to measure the high frequency properties of swCN-FETs. These experiments provide the first observations concerning the role of individual defects at high frequencies. The results are consistent with a simple parallel R-C circuit model for the swCN-FET. Furthermore, we present a quantitative model for the phase shifts observed in Scanning Conductance Microscopy (SCM) and demonstrate that this can be used to investigate the electronic properties of nanoscale samples without requiring electrical contacts. We provide a general method based on SCM that can be used to measure the dielectric constant of nanoscale objects.; In a second set of experiments we demonstrate that swCN-FETs functionalized with single stranded DNA (ss-DNA) act as highly sensitive chemical sensors. The ss-DNA decorated swCN-FETs are sensitive to chemical species (odors) that do not cause a detectable response in non-functionalized swCN-FETs. Moreover, odor responses of these devices are different in sign and magnitude for different odors, and the odor response characteristics are dependent on the base sequence of the ss-DNA used to decorate the swCN. These results suggest that swCN-FET functionalized with ss-DNA and related molecules (RNA, aptamers, etc) are extremely promising candidates for sensing applications.; Finally, we present photoluminescence measurements on individual swCNs, freely suspended across open apertures. These experiments show asymmetric peak line shapes, with line widths smaller than the thermal energy at room temperature, and strongly polarized emission and absorption along the nanotube axis. For particular samples we report the first observation of abrupt blueshifts in the emission energy due to small changes in the excitation position. |
