J. Sokolov

Enrichment depth profiles in polymer blends measured by forward recoil spectrometry

A novel time‐of‐flight detector system for He+ forward recoil spectrometry which improves the depth resolution to better than 35 nm has been used to investigate the form of the surface enrichment profile in a protonated (normal) polystyrene (PS)/deuterated polystyrene (d‐PS) blend. The volume fraction φ of d‐PS depends on the depth z as φ(z)=φ∞+(φ1−φ∞) exp(−z/ξ), where φ1 and φ∞ are the surface and bulk volume fractions of d‐PS, respectively, and ξ is approximately the bulk correlation length, as predicted by theory.

Charge Transport in Mesoscopic Carbon Network Structures

The charge transport and quantum interference effects in low-dimensional mesoscopic carbon networks prepared using self-assembling were investigated. The mechanism of conduction in low-dimensional carbon networks was found to depend on the annealing temperature of the nitrocellulose precursor. The charge transport mechanism for carbon networks obtained at T ann =750 0 C was found to be the hopping conductivity in the entire investigated temperature range. The Coulomb gap near the Fermi level in the density of states was observed in the investigated carbon networks. The width of the Coulomb gap was found to be decreased with the annealing temperature of the carbon structures. The crossover from the strong localization to the weak localization regime of the charge transport in the carbon structures, obtained at T ann =950 0 C and T ann =1150 0 C, was observed in the temperature range T>100 K and T>20 K, respectively.