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Soft x-rays and secondary electrons

Becker, Joseph A. (1924) Soft x-rays and secondary electrons. Physical Review, 24 (5). pp. 478-485. ISSN 0031-899X. http://resolver.caltech.edu/CaltechAUTHORS:BECpr24

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Abstract

Velocity distribution of photo-electrons excited by soft x-rays.— The apparatus was similar to that used in the magnetic analysis of β rays. Soft x-rays excited by primary electrons with 150 to 1500 volts energy, fall on a radiator of W, Pt, Al, etc. The photo-electrons emitted in a plane approximately normal to the uniform magnetic field acting, each travel in a circle with a radius proportional to the speed; those of a given speed which pass through two fixed slits strike a photographic plate, after describing a semi-circle, along a line depending on their speed, thus giving a spectrum. The plates each show a sharp line with a considerable amount of energy right at the hν limit corresponding to the energy of the primary electrons. A band due to electrons which had lost from 4 to 11 volts in coming out of the radiator, was also observed. These lines and bands indicate that free or loosely bound electrons are more readily ejected than internal electrons by soft x-rays. However, other lines were obtained due to electrons from various levels of the radiator atoms, with energies diminished by amounts corresponding to the critical potentials. Critical potentials obtained by magnetic analysis of photo-electrons.—For aluminum radiator: L2L3, 70 volts; L1, 80 volts. For silver: N1, 134 volts; M6, 365-370 volts. When the target for the primary electrons got covered with tungsten oxide, x-rays corresponding to jumps between N and O levels produced photo-electrons of corresponding energy. In this way the following characteristic lines in the N spectrum of tungsten were observed: N3O5, 410; N2O4, 482; N1O3, 560; N5O3, 305; and N4O2, 312, all in volts. N4O6 is missing, indicating that the O6 level is not occupied. All the values agree well with the Bohr theory predictions and with other results.


Item Type:Article
Additional Information:©1924 The American Physical Society. Received 10 June 1924. In conclusion, the author wishes to express his thanks to Professor R. A. Millikan for his continued interest and stimulation in the work. He is also indebted to Mr. E. L. Rose, who is continuing the work, for his assistance in conducting some of the later experiments.
Record Number:CaltechAUTHORS:BECpr24
Persistent URL:http://resolver.caltech.edu/CaltechAUTHORS:BECpr24
Alternative URL:http://dx.doi.org/10.1103/PhysRev.24.478
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:2412
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:03 Apr 2006
Last Modified:26 Dec 2012 08:48

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