A Determination of e/m from the Zeeman Effect

Values of e/m have been obtained from the Zeeman separations of the Cd line λ 6439 and the Zn line λ 6362, the g-factors of which have been carefully examined. Magnetic fields up to 7300 gauss are produced in a solenoid giving less than .1% variation in field strength over a length of 6 cm at the center. The current-field ratio K of the solenoid is determined, under operating conditions, in terms of the calculated ratios of measured single layer solenoids. The field strength. during exposure is given by the product of K and the solenoid current. Evaporation of Zn and Cd in the short (6 cm) positive column of a helium discharge gives the desired lines, the Zeeman patterns of which are photographed with a Fabry-Perot interferometer. Measurement of the separations at orders of interference in the neighborhood of 100,000 gives the following values: Cd λ 6439 : e/m = 1.7578 x 107 e m units ± .06% Zn λ 6362 : e/m = 1.7576 ± .05% These results are stated as e/m = (1.7577 ± .0017) x 107 abs e m units