Photophoretic Spectroscopy
  M. Pope, S. Arnold and L. Rozenshtein
  Chem. Phys. Lett. 62, 589-591 (1979)
The action spectrum of the 
photophoretic force on a peryIene crystailite (~10 micron diameter) was 
determined in a static
configuration. The agreement between this action spectrum and that of the 
optical absorption spectrum was good.