Laser-based diagnostics applied to the study of BN nanotubes synthesis.

The boron nitride nanotubes (BNNTs) synthesis, using CO2-laser vaporization of a BN target under nitrogen gas, is investigated by UV-laser induced fluorescence (LIF) of the vapor phase and UV-Rayleigh scattering (RS) of the gas-suspended nanoparticles. The LIF signal from B atoms is mainly detected in the 1.5 mm-thick region above the BN target.

Purification of single-walled boron nitride nanotubes and boron nitride cages.

Continuous laser vaporization of a BN target under N2 atmosphere is up to now the unique route to single-walled boron nitride nanotubes (BN-SWNTs). Although grams of product can be obtained by this technique, the raw material contains in addition to the BN-SWNTs, different by-products made of boron and nitrogen. Since these materials are undesirable for the studying of the intrinsic properties of the nanotubes, we have undertaken a purification process using chemical and physical methods to separate the different components.

Self-assembly of precursors in single-crystal growth of biopolymers.

Self-assembly of precursors in dilute solution single-crystal growth of poly[(R)-3-hydroxyvalerate] (PHV) and the fungal polysaccharide mycodextran were studied by transmission electron microscopy, especially at the early stages of crystallization. Precursors for PHV, such as small primary nuclei and tiny square tiles, consolidate to a large square crystal composed of orthogonally arranged tiles. By contrast, the precursors of mycodextran were lath-shaped, which suggests that the crystal growth is mainly in the longitudinal direction.