The synthesis methods we employ are widely varied: CVD, Laser assisted CVD, PLD, RF Magnetron sputtering, Kratchmer Generator growth, chemical synthesis, and electro-chemical templating. We grow and characterize all the materials used in the various programs of the Center. Of particular interest in the center:
- Electro-spun polymer fibers,
- Polymer nanospheres and nanowires
- Carbon Nanotubes, and their doped variants,
- Metal Nanoparticles,
- GaN, PbS, PbSe nanowires
Left: an assortment of the types of materials made and characterized at Nanotech. The top is an arc-grown SWCNT. The STM images shows the chiral nature of teh atomic structure of the nanotube. The tunneling spectroscopy and microscopy facilties at the Nanotech Center allow for imaging at very low current densities which opens the door to a wide range of macromolecular imaging without field-induced distortion.
The middle image is of metal nanoplates. We have extesnive experience in nanorod and nanoparticle synthesis in Ag and Au along with a few other metals. In the SEM shown the surfactant stabilizer on the surface (in this case CTAB) interacts across the surfaces of the particle from particle-to-particle. This leads to a form of sefl assembly. The scale overwhich these can be assembled seems to be dictated by nonequilibrium thermodynamic arguments.
The bottom image is of PPV nanotubes made through vapor phase polymerization in AAO templates. Notice the color chage as the tubes are bundled together. When separate, the tubes exhibit a blue-ish green, whereas after bundling they turn greenish-yellow. The self-absorption of singlet emission is well known in thick films but this demonstration at the nanosclae was unexpected.
A key aspect of any nanomaterials synthesis program is the characterization techniques utilized. We specialize in electron and scanning probe microscopies, scanning probe spectroscopies, and a number of optical techniques such as Raman, Luminscences, Pulse-Probe, Time-of-flight, and z-scan for nonlinear effects. We also have a number of long standing collaborations in Raman, HRTEM, EELS, and XPS-UPS, to further our characterization methods.