Lenard window
A Lenard window is a means of a thin aluminum covered foil opening in the glass of a cathode ray tube , of electrons may be passed. It is named after the German physicist Philipp Lenard , who received the Nobel Prize in Physics for his basic research in the field of cathode rays .
background
Lenard was able to use a cathode ray tube and an aluminum foil with a thickness of 0.5 µm, which corresponds to approx. 10,000 atomic layers, to prove that atoms are not impenetrable for electrons. The cathode ray is generated in the vacuum of the discharge tube, which is normally completely enclosed by glass , whereby the glass is impenetrable for the electrons. However, through the Lenard window, the electron beam can enter a gas atmosphere and can be used to carry out scattering experiments .
Lenard was able to investigate the impact of electrons with atoms of the foil and the gases outside the bulb and determine the influence of the test parameters foil thickness, foil material, pressure and composition of the ambient gas as well as the distance between foil and detector . The result was that mass and charge within atoms are not evenly distributed, but rather “grainy”. This finding was in contradiction to Thomson's atomic model and in agreement with the later developed atomic model according to Rutherford .
literature
- Hermann Haken , Hans Christoph Wolf : Atomic and Quantum Physics: Introduction to the experimental and theoretical basics . Berlin [u. a.]: Springer, 8th, updated and exp. Ed., 2004