Particle characterization using THz spectroscopy
  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. 
Philip Born, Karsten Holldack, and Matthias Sperl
cond-mat.dis-nn physics.optics