Open AccessThe absorption coefficient for slow electrons in the vapours of mercury, cadmium and zinc
Author(s) -
Robert B. Brode
Publication year - 1925
Publication title -
proceedings of the royal society of london. series a, containing papers of a mathematical and physical character
Language(s) - English
Resource type - Journals
eISSN - 2053-9150
pISSN - 0950-1207
DOI - 10.1098/rspa.1925.0134
Subject(s) - electron , atomic physics , attenuation coefficient , chemistry , cathode ray , path length , mean free path , molecule , vapours , beam (structure) , physics , optics , quantum mechanics , organic chemistry , neuroscience , biology
According to the classical dynamics, the molecules in the path of a beam of electrons will, by virtue of their electric fields, deflect the electrons constituting the beam. This deflection, while not perceptible for the electrons which pass at large distances from the molecule, may cause those which approach more closely to disappear from the beam. The effective area, within which an electron will be deflected from the beam, can be calculated from the equation I = I0 e -αxp , where I0 is the number of electrons initially present in the beam, I the number remaining at the end of the pathx ,p the pressure of the gas, and α the absorption coefficient or the effective stopping area of all the molecules in a unit volume of gas at unit pressure. The mean effective area of a single molecule is obtained by dividing a by 3·56 × 1016 , when the units chosen are millimetres of Hg and centimetres. Using this equation, Lenard and others have determined the absorption coefficients for most of the common gases.