  THz extinction spectroscopy extends UV-Vis and NIR-spectroscopy to
characterize particles from fine powders and dust to sand, grains and
granulated materials. We extract particle sizes from the spectral position of
the first peak of the interference structure and size distributions from the
visibility of the fine ripple structure in the measured extinction spectra. As
such, we can demonstrate a route for a quick determination of these parameters
from single measurements.
