Book/Report

FZJ-2016-04869

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Festkörperreaktionen von energetischen Kohlenstoffatomen aus dem Kernprozess $^{14}$N (p, $\alpha$) C-011

Vogt, M. (Corresponding author)FZJ*

1983
Kernforschungsanlage Jülich GmbH, Zentralbiliothek, Verlag Jülich

Please use a persistent id in citations: http://hdl.handle.net/2128/12349

Report No.: Juel-1855

Abstract: The chemical reactions of recoil $^{11}$C (T$_{1/2}$ = 20.38 min) from the nuclear reaction $^{14}$ N(p,$\alpha$)$^{11}$ C were tested in simple inorganic solids such as alkali halides, LiH, LiNH$_{2}$ , solid NH$_{3}$, ammonium halides and methyl substituted ammonium chlorides. The aim was to obtain information on reaction mechanisms of hot carbon atoms in solids as well as to optimize the production of precursors for the syntheses of $_{11}$C-labelled compounds for nuclear medical application. The salts were irradiated with 13 MeV protons at 298 K and 77 K, and ammonia in the frozen state at 77 K. The nitrogen free alkali halides and LiH were doped with $^{11}$C by nuclear recoil implantation in a mixture with BN. The dependence of the $^{11}$C product formationon proton dose (10$^{-3}$ to 10$^{2}$ eV/_molecule), beam intensity (0.01 to 3o $\mu$A) and irradiation temperature was studied. $^{11}$C products were identified after outgasing or dissolution of the samples using radio-GC and radio-HPLC. The following products were observed (maximum radiochemical yields in brackets) : $^{11}$CH$_{4}$ (6o %), $^{11}$C-halomethanes (4o %), $^{11}$C-methylamine (84 %), $^{11}$C-formamidine (3o %), $^{11}$C-cyanamide (8o %), $^{11}$C-guanidine (65 %) and, in addition, the side products $^{11}$CH$_{2}$0, $^{11}$C-formiate, $^{11}$CO and $^{11}$CO$_{2}$ (< 10 %). In methyl substituted ammonium chlorides, products with increased methyl substitution at the nitrogen atom and chain prolongation (ethyl group) were formed. Two characteristic groups of $^{11}$C products are primarily formed at low doses in systems containing hydrogen, nitrogen and halogen: methane, halomethanes and methylamine and compounds with two nitrogens attached to the $^{11}$C (cyanamide and formamidine). The first group of products can be explained by classical H-abstraction and insertion reactions via CH, CH$_{2}$ and CH$_{3}$ radicals. The product formation is partially determined by thermody namic factors, in particular bond energies. In methylammonium chlorides the carbon atoms can undergo competitive reactions with C-H and N-H bonds. In contrast to the C-H bonds, the N-H bonds are attacked statistically. [...]

---

Contributing Institute(s):

1. Publikationen vor 2000 (PRE-2000 ; Retrocat)

Research Program(s):

1. 899 - ohne Topic (POF3-899) (POF3-899)

---

Database coverage:

---