Many properties of single wall carbon nanotubes (SWNTs) are unique and advantageous. The electrical, thermal, and strength properties of SWNT are highly desirable for many applications. To take advantage of these properties it is necessary to remove the impurities that are inevitability produced during the growth of the nanotubes. High gradient magnetic separation techniques have been used to separate the magnetic catalyst particles from the nanotubes. Even if all the impurities were removed there would still be many different types of SWNTs in a sample. For the first time, different types of SWNTs have been observed acting as individual chemical species by changing the pH of surfactant stabilized suspensions of SWNTs. In the future, one can expect this scheme to play an important role in the separation of SWNTs by type.

Iron catalyzed gas-phased disproportionation of carbon monoxide under high pressure is known to produce carbon Single Walled Nano-Tubes (SWNT). Non-tubular carbon by products and iron encapsulated-graphitic shelled nano-particles are produced concomitantly under conditions optimized for SWNT production, are undesirable bi-products. Differences in oxidation thresholds of the constituents and acid leaching of iron particles have been exploited in the co-development of Laser Desorption Ionization Mass Spectroscopy (LDI) evaluation and SWNT purification. LDI threshold conditions have been established for the analysis of non-SWNT carbon species. It has been shown that neither photochemical decomposition nor photo assisted molecular self-assembly contribute to the mass spectra. Raw, processed materials and molecular specific extractions are evaluated. Laser Desorption Ionization mass spectroscopy, Transmission Electron Microscopy, Raman and TGA results are reported.

The far infrared dielectric properties of confined water were measured with terahertz time-domain spectroscopy. Inverse micelles with anionic, cationic, as well as non-ionic surfactants were used to confine the water with excellent size control from water pool radii of 5 to 75 angstroms. The normally flat far infrared absorption spectra of water is profoundly disrupted by confinement, yielding spectra with very large absorption peaks between 0.2 and 1.0 THz. These peaks are present in all surfactant systems as well as in samples formulated with various brine concentrations or glycerol in place of the water. The origin of the THz absorptions of these liquid pools is assigned to surface oscillations of the water pool opposed by the interfacial tension of the water-surfactant-oil interface. The implications of the existence of this peak are quite important. The far infrared dielectric properties of confined water are important in many biological and inorganic systems ranging from protein folding to zeolite chemistry. Additionally, the spectral position and lineshape of these absorption peaks are suggestive of a similar phenomenon in glass forming materials known as the Bose peak. This peak in the far infrared is believed to be due to coherent scattering off of various domains of homogeneity within the inhomogeneous glass. A size-dependent study of these domains in glasses is frustrated by an inability to control domain size within a single glass system. The amenability of inverse micelles to a size dependent study, and the surprising degree of correlation between the lineshapes of the Bose peak with the absorption spectra of micellar confined water, indicate that these results could have great importance in understanding the origins of the Bose peak in glassy materials.

Single walled carbon nanotube (SWNT) researchers have many obstacles to overcome before SWNTs become commercially applicable including two equally important but separate issues: suspending pristine, individual SWNTs in water and chirality controlled synthesis. The first part of this thesis describes how to suspend, analyze, and manipulate individually suspended SWNTs in twenty four different surfactants and polymers. The second part of this thesis explains how to attach a metal nanoparticle to the open end of a short SWNT and seamlessly grow the same chirality SWNT. Suspending pristine, individual SWNTs in water is critical for some composite material applications and any biological application. This research characterizes the spectral properties and the ability to suspend individual SWNTs for over twenty surfactants and polymers. In addition, methods for concentrating and purifying the SWNT suspensions are detailed. Finally, three examples applications of these SWNT suspensions in material and biomedical application are described. Being able to synthesize chirality-specific SWNTs in bulk quantities is critical for chirality specific SWNT applications. Currently, the problem lies with the initial SWNT nucleation; there is no control. The method for controlling SWNT chirality proposed in this thesis is a templated growth model using an existing SWNT as the template. A new catalyst particle is attached to the end of a SWNT creating a SWNTcat. During growth the carbon addition is directed through the catalyst to the existing SWNT resulting in seamless, chirality consistent growth. To test the models validity, a proof of concept was carried out on surfaces where the growth could be monitored by atomic force microscopy (AFM). The SWNTcats were prepared with a variety of catalysts in several solvents. Straight, seamless growth of the SWNTcat was seen with a variety of growth conditions proving this is a viable route to large scale synthesis of chirality-specific SWNT production.

Advances in the computation of the Coulomb, exchange, and correlation contributions to Gaussian-based Hartree-Fock and density functional theory Hamiltonians have demonstrated near-linear scaling with molecular size for these steps. These advances leave the ${\cal O}(N\sp3)$ diagonalization bottleneck as the rate determining step for very large systems. In this work, a conjugate gradient density matrix search (CG-DMS) method has been successfully extended and computationally implemented for use with first principles calculations. A Cholesky decomposition of the overlap matrix and its inverse, which can be formed in near linear time for sparse systems, is used to transform to and back from an orthonormal basis. Linear scaling of CPU time for the density matrix search and crossover of CPU time with diagonalization is demonstrated for polyglycine chains containing up to 493 atoms and water clusters up to 900 atoms.

Improvements in the determination of the continuously-scanned Raman excitation profiles (REP's) are described. The continuous-scanning technique is applied to ozone excited in the first continuum (the Hartley band). The Rayleigh excitation profile, which is required for intensity calibration, is obtained simultaneously. A theoretical calculation for the ozone Rayleigh excitation profile is also provided for comparison. REP measurements of the vibrational features up to 6 quanta are determined in the wavelength range of 238--271 nm. These spectra show oscillatory structures that are qualitatively but unambiguously identified as the Raman counterparts of those in the absorption spectrum. The use of overlapping dye mixtures to cover most of the Hartley band is required. Difficulties encountered in patching together these first-generation spectra are discussed in detail.

The high resolution infrared spectrum of the $\nu\sb1$ acetylenic CH stretch of the propargyl radical H$\sb2$CC$\equiv$CH has been obtained by the color center laser kinetic spectroscopy method. The propargyl radical is produced by flash photolyzing stable precursors propargyl bromide or propargyl chloride using the ArF excimer laser. The transient infrared absorptions of the propargyl radical are probed by the color center laser. More than 300 absorption lines were observed in the frequency region of 3304 cm$\sp{-1}$ to 3337.5 cm$\sp{-1}.$ Most of these lines were assigned to the different K subbands of the $\nu\sb1$ fundamental vibrational mode except those lines belonging to an unknown hot band. The upper state energies were obtained by adding the ground state energies appropriately to each observed P and R transitions. Then these upper state energies were fitted by a least squares fitting program and the upper state rotational constants A, B, C and centrifugal distortion constants $\rm\Delta\sb{K},\ \Delta\sb{NK}$ and $\rm\Delta\sb{N}$ together with the band origin $\nu\sb1$ were obtained from the fitting. K = 2$\pm$ sublevels were found perturbed by another vibrational mode so they were not used in the fitting. The nature of this perturbation was recognized as a Coriolis interaction.

The C-H stretching fundamental of the free radical HCCN has been investigated under high resolution using infrared kinetic spectroscopy. This transient molecule was produced by the flash photolysis of dibromoacetonitrile (Br$\sb2$HCCN) at 193 nm and its transient infrared absorption spectrum probed using a color center laser. Spectra of the molecule were collected between 3182 and 3274 cm$\sp{-1}$. The rotational analysis of the $\nu\sb1$ fundamental places its origin at 3246.657 cm$\sp{-1}$. Four hot bands associated with the bending vibrations have been observed; the vibrational and rotational assignment of three of these bands $\nu\sb1 + \nu\sb5 - \nu\sb5$, $\nu\sb1 + \nu\sb4 - \nu\sb4$, and $\nu\sb1 + 2\nu\sb5\sp{\pm 2} - 2\nu\sb5\sp{\pm 2}$ is definite. The $\nu\sb5$ energy was obtained by measuring the intensity of a line of the $\nu\sb1 + \nu\sb5 - \nu\sb5$ band relative to one of the fundamental and calculating the energy assuming a room temperature Boltzmann distribution. A comparison of this energy with that of quasilinear fulminic acid, HCNO, and with theoretical calculations suggests a similar floppy HCX bending potential.

Ab initio SCF Hartree-Fock calculations have been carried out on all the fullerene isomers of C$\sb{20}$ to C$\sb{36}.\ C\sb{20},\ C\sb{24},$ and C$\sb{26}$ have only one fullerene isomer each, of $C\sb{2h},\ D\sb6$ and $D\sb{3h}$ symmetry respectively. C$\sb{28}$ has two distinct fullerene isomers, C$\sb{30}$ has three, C$\sb{32}$ and C$\sb{34}$ have six, and C$\sb{36}$ has fifteen. Their lowest energy structures were found to be of $T\sb{d}\ C\sb{2v},\ D\sb3,\ C\sb2,$ and $D\sb{2d}$ symmetry respectively. All ground-state isomers have closed-shell electronic configurations except C$\sb{26}$-$D\sb{3h}$ (open-shell $\rm\sp5A\sp\prime\sb1)$ and C$\sb{28}$-$T\sb {d}$ (open-shell $\sp5{\rm A}\sb2).$ A new mechanism, called "peeling", is proposed in order to explain the end of the C$\sb2$ loss fragmentation pattern at C$\sb{32}$ observed in photodissociation studies. It consists of opening the fullerene surface and excising long carbon chains. MNDO calculations show the "peeling" channel to be more competitive than the C$\sb2$ loss fragmentation process for C$\sb{32}.$

The photophysics of higher fullerenes remain poorly characterized, partly because they may exist in many isomeric structures that are difficult to isolate. This project concerns the properties of C84 isomers. Using recycling HPLC methods, we separated a sample of purified C84 into three fractions. The first contains a mixture of the three most abundant isomers---D 2 (IV), D2d (II), and Cs (a). The second and third peaks were found to contain the C2 and Cs (b) isomers, respectively. A kinetics-based method was used to find the effective molar absorptivities of these fractions. Sensitive transient absorption measurements following optical excitation reveal widely differing triplet state lifetimes among these isomers. Quenching studies indicate that one C84 isomer has a triplet state energy below that of oxygen's 1Delta g state, while the others have higher energies. Further results, including fluorescence spectra and variable-temperature triplet decay kinetics, will also be presented.