Difference between revisions of "PAA Selenium"
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<math>{76 \atop\; }Se (\gamma,n){75 \atop \; }Se</math> | <math>{76 \atop\; }Se (\gamma,n){75 \atop \; }Se</math> | ||
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| + | The prominent photons emitted have the following energies | ||
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| + | 136, 264, and 279 keV | ||
Revision as of 22:21, 10 December 2015
Using PAA ro measure Selenium concentrations.
According to Krouse<ref name="Krous1962"> H.R. Krause and H.G. Thode,"Thermodynamic Properties and Geochemistry of Iosotopic Compounds of Selenium",.Can. J. Chem., vol 40, pg 367</ref> , the fractional concentration of Se-82/Se-76 in plant material is observed to be less than from primordial (meteoric) concentrations by as much as 1.2%. Anaerobic bacteria are known to reduce selenates and senelites in biological systems. This may be the reason plant material has fractionation of selenium isotopes. They also observe excess concentrations of up to 0.4% in soil.
Plant material appears to be detect environmental selenium.
Can one use plant material to measure the provenance of selenium?
Can one perform PAA measurements of Se-82 and Se-76?
Neutron knockout of Se-82
If you knock a neutron out of Se-82 you produce the unstable isotope Se-81 which has a half life of 18 min and a meta-state with a 57 minute half life.
The prominent photons emitted have the following energies
262,276 keV for the 18 minute half life
and
260 & 276 keV for the 57 minute half life isotope
Neutron knockout of Se-76
If you knock a neutron out of Se-76 you produce the unstable isotope Se-75 which has a half life of 119 days.
The prominent photons emitted have the following energies
136, 264, and 279 keV