Abstract
IN the course of a more extensive investigation of the phenomenon of photophoresis1–3, sunlight was focused vertically downward into an intense, sharply converging–diverging beam within a chamber containing air at a reduced pressure ranging from 5 to 15 torr. Graphite powder having particles mostly in the 0.1–1.0µ diameter range was dispersed as a dilute aerosol within the chamber. Particles in the beam exhibited both positive and negative photophoresis, that is, some of them moved along the rays of the beam away from the light source (positive) and some moved toward it (negative). The particles were also settling under the influence of gravity, and, as a result, some of them eventually came to the beam boundary, There they displayed a behaviour previously unreported; that action is described here.
Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
