Self-Diffusion in Core-Shell Composite 12CO2/13CO2 Nanoparticles

Abstract

A new technique for the generation of multilayered molecular nanoparticles is presented. Core-shell composite nanoparticles of CO2 with varied composition have been investigated by Fourier-transform infrared spectroscopy over 600 s at 78 K. The isotopically different zones of the particles turned out to have completely different spectra in the nu3 region: a tub structure (mantle) and a head-and-shoulders structure (core). From the aggregation behavior of both components the particle formation time was found to be 0.1 s. Low-temperature self-diffusion of airborne molecular nanoparticles has been monitored for the first time. The self-diffusion coefficient for 12CO2/13CO2 nanocomposites at 78 K was determined from the time evolution of the nu1 + nu3 combination band to about 7×10-20 m2/s. The work represents a major advance toward nanoengineering of molecular nanoparticles at low temperatures.