Electron capture primary products

D. Chambers, Extractive derivatization of primary amines and beta-aminoalcohols with aromatic aldehydes to form Schiff base or oxa-zolidine products for analysis by electron capture gas chromatography, Diss. Abstr. Int. b. 44(7) 2148, (1984). 

AjH at 298.15 K is -35.035 kcal mol", and the primary bond dissociation energy (Products P(g) + P (g)) is 53.1 kcal mol". The latter value can be compared with Dq (PF) = 106.1 kcal mol" ( ), indicating that the P-F bond is much weaker in the anion relative to the neutral molecule. This is consistent with MO predictions (2-4) which indicate that the electron captured by PF occupies an antibonding orbital located primarily on the phosphorus atom. 

Flash Photolysis of Ba2+, Nap2 . Another example of mechanistic studies of disproportionation is furnished by flash photolysis of Ba2+,Nap2. The equilibrated system of Nap and Ba2+,Nap2" contains an extremely low concentration of radical anions present in the form of an equimolar mixture of Nap - and Ba2+,Nap. A flash of light ejects electrons from Ba2+,Nap2, which are then captured by Nap. Thus, Nap - and Ba2+,Nap " are the primary products of photolysis. The return to equilibrium results either from the collision of Nap " with Ba2+,Nap from the right... 

Other Studies Using Flash Photolysis. Flash photolysis allows the study of direct electron capture (17). A flash of light may eject an electron from A ",Cat+, for example. The primary products are a solvated electron (e ) and an adduct (A,Na+). The adduct may dissociate before electron capture and lead to the following reaction ... 

The primary decay products are neodymium and samarium isotopes. Promethium-146 decays to neodymium and samarium ( " Nd and "" Sm), the lighter isotopes generally to neodymium via positron decay and electron capture, and the heavier isotopes to samarium via beta decay. Exceptions are °Pm and Pm which give rise to Pr ( Pr and respectively) via positron emission. The isotope Pm decays to both Nd and Pr via positron emission, although the majority leads to Nd (Oliveira 2011). 

Attention has been centered on the haiogenated derivatives of primary amines. This development started with the introduction of electron capture detection systems. With pentafluoro-derivatives for example, detection by electron capture is over 1000 times more sensitive than by flame ionization. If hydroxyl groups are present, they are usually trimethylsilylated, which augments the electron affinity of the product. Picogram amounts of catecholamines have been separated on methylsilicone phases and detected by electron capture after derivatization with pentafluorobenzaldehyde and silylation [37,43]. Such methods can be a great aid in the ultra-trace analysis of primary amines in biological specimens. 

The yields of these so-called primary species, present at the time when radical combination in, and diffusive escape from, the spurs is complete, were obtained by adding solutes to the water to capture the radicals and by measuring the stable identifying products. It was from a number of these studies that it became clear that the reducing radical must exist in two forms, which turned out to be the hydrogen atom and the hydrated electron (e q). For example, Hayon and Weiss [6] found that the yields of H2 and Cl produced by irradiating solutions of chloroacetic acid varied with pH in a manner that was consistent with the following reactions ... 

The beta-current neutron detector is a solid state ion chamber which is used in nuclear reactor technology. It consists of an emitter in which a nuclear reaction occurs, leading to the emission of primary /3 particles (e.g. through the reaction ( Rh(n,7) Rh(/8 , 4.2 s) Pd) or secondary electrons (e.g. through absorption of the prompt y s emitted in the neutron capture). These electrons represent a current and are collected by a collector. The radioactive decay type detectors have a response time depending on the product half-life, which the capture-y detectors lack. These detectors have a limited lifetime for the Co(n,y) Co it amounts to 0.1 % per month at 10 n cm s . The lifetime depends on... 

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