| In this thesis, we study the properties of alkali doped single walled carbon nanotubes (SWNT). SWNT are crystallized into ropes, which display the one-dimensional electronic properties of the constituent nanotubes. Using x-ray diffraction, we show that the alkali atoms invade the channels in the triangular rope lattice and determine the structure of the doped ropes. We show that the diffraction profile of the doped SWNT is best described by a model where the alkali ions surround each tube in an ordered fashion by dilating the channels.; Alkali doped SWNT exhibit colors similar to alkali doped graphite (GIC). We study their electronic structure with IR reflectivity; the alkali dopants donate their valence electron to the SWNT host, so the free carrier concentration increases, shifting the Drude-edge into the visible spectral range. This is accompanied by a large shift of the Fermi-level, so the characteristic transitions between the 1D van Hove singularities of the undoped SWNT diminish.; The presence of the alkali ions around the SWNT breaks the translational symmetry and increases coupling between parallel tubes within ropes. We find that the momentum relaxation time shortens as the ropes become more three dimensional. We also find that alkali disorder contributes to the scattering.; In p-type, HNO3 doped SWNT, the charge transfer is smaller; only the first subband of the semiconducting tubes gets depleted, shown by the disappearance of the first van Hove transition. This indicates a Fermi-level shift of ∼0.3 eV. The reflectivity has structure at low energy, which moves the Drude-peak to a sharp, intense peak at 0.1 eV in the optical conductivity, reminiscent of quasi-1D TTF-TCNQ.; The DC conductivity also increases ∼80-fold during doping. The low temperature divergence of undoped SWNT disappears in alkali doped SWNT. However, we find that oxygen can modulate the low-T divergence. After outgassing, the divergence becomes ∼10 times stronger. We interpret the low-T resistivity in terms of the barrier height modulation model of Derycke. The oxygen modulates the tunneling barriers within the bulk sample.; Alkali doped SWNT show the hallmark feature of metals, conduction electron spin resonance. We study this with in situ electrochemical doping. The spin susceptibility and conductivity increase with K concentration as the Fermi-level shifts to higher density of states regions due to charge transfer. However, the spin relaxation rate and g-factor are independent of K-concentration, indicating a microscopically inhomogeneous doping process, where fully doped regions grow at the expense of undoped ones. We develop a method of determining the microwave conductivity in situ, based on changes in the skin depth, utilizing the ferromagnetic resonance of the catalyst impurities. |
