Determination of traces of phosphorus in gallium arsenide by radiochemical neutron activation analysis

A radiochemical separation procedure has been developed to determine traces of phosphorus in gallium arsenide. In this procedure the indicator nuclide 32P is separated from all other long-lived activation products in high purity. The resulting eluate is sufficiently pure to allow β-counting. Because of the high β-energy of 32P (1710 keV) the activity can be measured via the Cerenkov effect, whereas most radionuclides, because they have essentially lower β-energies, are discriminated by this technique, so that the selectivity of the measurement of 32P is improved considerably. A detection limit of 1 ng/g was achieved when using samples of 50 mg, a thermal neutron flux of φth = 1*1013 n*cm-2*s-1, an irradiation time of 36 hours and a measuring time of 1 hour. (author) 13 refs.; 3 figs.; 1 tab