THE SOFT X-RAY CONTINUOUS SPECTRUM FROM LOW ENERGY ELECTRONS IN THE 80A- 180A REGION
The intensity distributions in the low energy continuous x-ray spectrum from solid targets were studied by means of a calibrated vacuum spectrometer. The x-ray beam was incident upon a concave glass grating at a grazing angle of 4.642 deg , and the dispersed radiation was recorded on a photographic plate mounted along the Rowland circle. Knowledge of grating efficiency and instrumental dispersion made it possible to obtain a relative intensity distributron of the radiation emitted from the source. The target consisted of a freshly evaporated layer which was subsequently renewed at frequent intervals during expesure. Pressures below 3.0 x l0-6 mm of mercury were maintained in the x-ray tube during exposure. The experimental observations were confined to the wavelength interval extending from 80 to 180 A. The investigation indicated that the intensity per unit wavelength interval can be closely approxr-mated by a function of the form B/ lambda /sup alpha /. In particular, the values of alpha ranged from 1.9 for aluminum at an accelerating potential of 3.0 kv to a value of 3.0 for silver and gold at accelerating potentials of 3.0 kv. B is a normalization constant chosen for convenience to give a relative intensity of 100 at a wavelength of 80 A. Reduction of the accelerating potential below 3.0 kv resulted in a decrease in the observed value of alpha for both silver and manganese targets; i.e., as the observable range of wavelengths approached the short wavelength limit, the intensity per unit wavelength interval tended toward a l/ lambda /sup 2/ dependence. Observation of the spectrum at various angles of photon emergence showed variations in the spectral shape which are in accordance with theory, but there appeared to be no significant evidence of the effects of self-absorption of the x-ray photons by target material. Relative intensity distributions in the continuous spectrum for a magnesium target at a potential of 675 volts and a manganese target at a potential of 630 volts sgreed with the predictions of the basic Sommerfeld theory for the continuous spectrum. Published rangeenergy relations indicated that electrons with kinetic energies around 600 ev penetrate to a depth of less than 200 A; thus significant contributions to the spectrum come from interactions of electrons and stoms which lie essentially in the surface layers of the target. Since the theory is based upon one interaction between a given electron and a monolayer of atoms, the agreement of the experimental results with prediction indicated that use of the thin target model is applicable at these electron energies and x-ray wavelengths.
- Research Organization:
- cornell Univ., Ithaca, N.Y.
- NSA Number:
- NSA-16-023032
- OSTI ID:
- 4809989
- Journal Information:
- Dissertation Abstr., Vol. Vol: 22; Other Information: Orig. Receipt Date: 31-DEC-62
- Country of Publication:
- Country unknown/Code not available
- Language:
- English
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LOW-ENERGY CONTINUOUS X-RAY SPECTRUM IN THE 80 A TO 180 A REGION