PAA Selenium

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 detect environmental selenium.

Can one use plant material to measure the provenance of selenium?

As shown in the Figure below, the Se-82/Se-76 ratio varies from -1.2% to +0.2% for plant materials but remains relatively constant for other materials. The variations in plant material has been described as being due to differences in the bacteria residing in the plant. The question to investigate is whether or not these variations in the concentration can be used to determine the provenance of the sample.

Below is a table listing the natural abundances of Selenium

Natural abundance of selenium

Isotope	Abundance
Se-74	0.86%
Se-76	9.23%
Se-77	7.60%
Se-78	23.69%
Se-80	49.80%
Se-82	8.82%

Below are possible PAA reactions that may be used to observe specific Se isotopes

Reaction	Half-life	Relative activity	Gamma-rays, keV (BR)
Se-74(gamma,n)Se-73	7.1 h	1.5E-1	361 (100)
Se-74(gamma,n)Se-73m	39 m	3.2	402 (4)
Se-74(gamma,np)As-72	26 h	1.0E-3	834 (100)
Se-76(gamma,n)Se-75	120 d	1.3E-2	265(29)
Se-77(gamma,p)As-76	26.4 h	4.4E-2	559(44)
Se-78(gamma,p)As-77	38.8 h	8.6E-2	239(2)
Se-80(gamma,n)Se-79m	3.9 m	5.9	96(10)
Se-80(gamma,np)As-78	1.5 h	2.2E-2	614(54)
Se-80(gamma,p)As-79	8.2 m	1.3	96(9)
Se-80(gamma,[math]a[/math]p)Ge-75	83 m	2.8E-1	265(11)

Can one perform PAA measurements of Se-82 and Se-76?

Se_PAA_Reactions

Experiments

PAA Selenium/Soil Experiments

LB Se PAA Horse Feed Experiment

Nickel Normalization

LB PAA Nickel Investigation

First Observation of Se lines

Using the 44 Machine at 7 kW power and 44 meV incident electron energy to produce a bremsstrahlung spectrum with a mean energy of 15 meV.

All runs lasting less than 214 seconds have time stamp that gives real time if you divide by clock frequency of 20 MHz.  The first 32 bits are used for a real time measurement.

MDA and Se mass Calculations

LB MDA/Se Mass Calculations

IAC Detector Efficiencies

LB PAA IAC Detector Efficiencies

Runlists

LB PAA Runlist 4/01/16 - 06/02/16

LB March 2017 Runlist

Data Analysis

Pure Se Sample

Observed lines

LB_Feb2017_Se_Investigations

Estimate of Se-79 activity

Using known efficiency to extrapolate initial activity

Use ratio with Nickel foil rate

Se spiked in Soil

Detection limit of Se in Soil

References

User_talk:Brenleyt

<references/>

File:Krouse CanJournChem 40 1962 p367.pdf

Goryachev, A. M., & Zalesnyy, G. N. (n.d.). The studying of the photoneutron reactions cross sections in the region of the giant dipole resonance in zinc, germanium, selenium, and strontium isotopes. Retrieved September 16, 2016, from http://www-nds.indcentre.org.in/exfor/servlet/X4sSearch5?EntryID=220070

Goryachev, B. I., Ishkhanov, B. S., Kapitonov, I. M., Piskarev, I. M., Piskarev, V. G., & Piskarev, O. P. (n.d.). Giant Dipole Resonance on Ni Isotopes. Retrieved October 26, 2016, from http://www-nds.indcentre.org.in/exfor/servlet/X4sGetSubent?reqx=119235&subID=220597006&plus=1

Handbook on Photonuclear data for applications, cross sections, and spectra. (2000, October). Retrieved November 4, 2016, from http://www-pub.iaea.org/MTCD/Publications/PDF/te_1178_prn.pdf

MSDS

Selenium shot, amorphous, 2-6 mm, Puratronic, 99.999% Alfa Aesar product # 10603 File:AlphaAesarSelenium MDSD.pdf

Informative links

http://www.deq.idaho.gov/regional-offices-issues/pocatello/southeast-idaho-phosphate-mining/southeast-idaho-selenium-investigations/

https://inldigitallibrary.inl.gov/sti/3169894.pdf

http://giscenter.isu.edu/research/Techpg/sisp/index.htm

PAA_Research