Die Bildung von 32PCl3 und andere Reaktionen heißer Phosphoratome aus den Kernprozessen 31P(n, γ) und 35Cl(n, α)

Abstract

HENGLEIN und Mitarb., Die Bildung von Sí PCl 8 und andere Reaktionen heißer Phosphoratome Our thanks are due to Mrs. J. A. B. GOODALL and Miss M. P. EDWAKDS for the e.m.f. measurements. AppendixCs 3e Cl Stock Solution The 3e Cl, contained in the equivalent of 4.05 mis of Ν · HCl, was neutralised with 0.67 g of Cs 2 C0 3 and made to 5.0 mis as stock. Per 1.0 ml of stock, Cs = 0.67 • 266/326 . 1/5 = 109 mg. Cl = 0.0355 . 4.05 • 1/ 5 = 28.8 mg. Assay (end-window GM counter) = 7.0 X 10 e c.p.m. Whence 3e Cl specific activity = 7.0 · 10 e /28.8 = 2.43 · 10® c.p.m./mg. CsCl Stock SolutionThe 137 Cs was made to 5.0 mis as stock after adding an amount of inactive CsCl corresponding to the inactive Cs present in the Cs 36 Cl stock. 19Per 1.0 ml of stock, Cs = 109 mg.Assay (end-window GM counter) = 8.12 χ 10 e c. p. m.Whence 137 Cs specific activity = 8.12 · 10 e /109 = 7.45 · 10 4 c.p.m./mg. Immersion of Steel DiscsThe 2.2 litre solution in which the discs were exposed was at p H 10.5 (approx. 20 p.p.m. KOH, = approx. 3.6 · 10 _4 M potassium) with addition of 1.0 ml of either stock solution, giving a concentration of 109/2.2 = 50p.p.m. = 3.76 · 10~4M caesium. The deposition discs were 2.0 cm diameter; hence each face has a plane area of 3.14 cm 2 . Weight of Element Deposited (mg/cm 2 ) c. p. m. on disc face 3.14 · specific activity c.p.m. on disc face i. e. CI deposited = 3 14 . 2 43 . 10 s mg/cm 4 c.p.m. on disc face Cs deposited = 3 14 . ΊΛ5 . 10 4 m g/ om2 • Assumed Cs + Κ deposited = twice the Cs value, since Cs + and K+ are approximately equimolar in the solution. Zusammenfassung In Phosphortrichlorid entfallen 85% (flüssig) bzw. 75% (gasförmig) der durch den 31 P(», y)-Einfang induzierten 32 P-Aktivität auf die 32 PCl 3 -Retention, während der Rest in einer polymeren Form des Phosphors vorliegt. Halogene erhöhen die Retention auf fast 100% ; Tetrachlorkohlenstoff wirkt ebenfalls fördernd. Ein Teil der Retention (47% der Gesamtaktivität in der Gasphase) stammt aus Reaktionen heißer Rückstoßatome, der restliche Teil (28% der Gesamtaktivität) kommt durch die Rückchlorierung thermalisierter Phosphoratome zustande. Der erstere Anteil wird durch Argon und andere Moderatoren in hoher Konzentration unterbunden, der letztere durch kleine Mengen von Kohlenwasserstoffen, welche Cl-Atome abfangen. In der Gasphaae erfolgt der Zerfall der PCl 3 -Molekel in 99,8% aller Neutroneneinfänge. In flüssigen Lösungen des Phosphortrichlorids mißt man eine scheinbar höhere primäre Retention, was auf Rekombinationen der Fragmente unter der Käfigwirkung der umgebenden Molekeln zurückgeführt wird. Die Käfig-Rekombination findet um so leichter statt, je geringer die Reaktivität des Lösungsmittels mit Chloratomen ist. 2· Brought to you by | provisional account Unauthenticated Download Date | 6/23/15 8:07 AM Brought to you by | provisional account Unauthenticated Download Date | 6/23/15 8:07 AM

The Chemical Effects of Radiophosphorus Recoiling from Nuclear Reactions

“…The radiative thermal neutron capture in solutions of phosphorus trichloride has been studied (50,51). In mixtures of phosphorus trichlorides with carbon tetrachloride, the observed retention (activity recovered as PC13) was about 65%, just as in pure phosphorus trichloride.…”

“…By this theory, assuming the radiative neutron capture of phosphorus to yield three equal -quanta per cascade of 7.92/3 = 2.64 Mev., the primary retention should be 0.6%. The observed retention of P32 as P32C13 after neutron activation of gaseous phosphorus trichloride was partly due to hot recoil atoms (47%), which could be inhibited by argon and other moderators at high concentrations, and partly due to rechlorination of thermal phosphorus atoms (28%), which could be inhibited by small amounts of hydrocarbon scavengers of chlorine atoms (51).…”