The Photo-Electric Effect of Caesium Vapor

Abstract

Long wave-length limit for photo-electric emission from caesium vapor.-Using a special quartz tube and taking precautions to avoid photo-electric emission from the electrodes, a narrow beam of nearly monochromatic light of gradually decreasing wave-length, was focused on the hot caesium vapor, and it was found that above 3220 A the emission was zero, between 3220 and 3145 A the emission changed linearly because of the width of the slit used, and below 3145 A the emission was practically constant. The mean, 3180 A, is taken as the critical wave-length. This is evidently identical with the convergence wave-length 3184.28 A, which is related to the ionization potential V{ according to the equation Vi=hc/e\{. Therefore the separation of an electron from a caesium atom requires the same amount of work whether produced by an impinging electron or by absorption of light.

3He induced reactions

“…At higher energies the predicted cross sections are significantly smaller than those observed consistent with the appearance of contributions from other levels in the compound system. Figure 8 shows the excitation function for this reaction as measured by Kunz ( , 1955. The observation of the radiative capture process 3He (d, y ) 5Li at the same resonance with a cross section of 0.05 mbn corroborates the surprisingly large value of the SHe width (Blair, Hintz and Van Patter 1954, Kunz, Butler and Holmgren 1955.…”

“…Use of 3He ions facilitates detailed measurements in isobaric multiplet states as has been noted previously. T o date only measurements in the A = 5, 6, 7 , 9,11,12,14,23 and 27 systems have been reported. Extension of these measurements in detail and scope will provide additional evidence on the validity of the charge independence hypothesis and on the extent to which isobaric spin may be considered as a good quantum number throughout the periodic table.…”

Ionization of Caesium Vapor by Light

“…Following the detection of the ionization produced by the absorption of ultraviolet light by caesium vapor by Kunz and Williams, 1 Mohler, Foote and Chenault, 2 Little, 3 Mohler and Boeckner, 4 and Lawrence and Edlefsen 5 have determined the shape of the ionization curve on both sides of the principal series limit of caesium. Little used the "direct" method, while the others used the sensitive method of neutralization of the spacecharge surrounding a heated filament.…”