ABSTRACT
We summarize in section 5.1 how atoms are arranged in a solid and in section 5.2 what holds them together. In section 5.3, we study the atomic structure and bonding in the two major dust constituents: silicate and carbon grains, and in section 5.4, we present their optical constants as well as absorption and extinction efficiencies for typical grain sizes. Finally, we discuss the size distribution of grains which is able to explain the observed interstellar extinction curve and sketch how grains can acquire such a distribution in grain-grain collisions.
