Authors:D. Fetterolf, B. Lawson, D. Hoch and T. Pinkerton
Negative Ion Fast Atom Bombardment Mass Spectrometry is conducted on potassium pertechnetate evaporated onto a copper probe. The mass spectra of pertechnetate /TcO
/ reveal the presence of mononuclear and polynuclear technetium oxo species which form general series TcnO
,...TcnOn+4 with n=1 to 5. The polynuclear species are believed to be formed via gas phase reactions.
Enthalpies of solution of 1,4-dioxane, 12-crown-4 ether (12C4), 15-crown-5 ether (15C5) and 18-crown-6 (18C6) have been analyzed
from the point of view of preferential solvation of these cyclic ethers (crown ethers) by a molecule of acetone or dimethylsufoxide
in the mixtures of water with acetone or dimethylsulfoxide. It has been observed that the carbonyl carbon atom replacement
in acetone molecule by sulfur atom brings about completely different behavior of molecules of these solvents in relation to
cyclic ethers dissolved in mixed solvents. Crown ethers are preferentially solvated by acetone (ACN) molecules, which is not
observed in the case of dimethylsulfoxide (DMSO).
The enthalpies of solution of cyclic ethers: 1,4-dioxane, 12-crown-4 (12C4), and 18-crown-6 (18C6) in water–acetone mixtures
have been measured within the whole mole fraction range at 298.15 K. Based on the obtained data, the effect of base–acid properties
of water–acetone mixtures on the solution enthalpy of cyclic ethers in this mixed solvent has been analyzed. The strong dependence
of the enthalpy of solution (solvation) of cyclic ethers on basic properties of mixed solvent has been observed. The effects
of carbonyl atom replacement in acetone (ACN) molecule by sulfur atom (DMSO molecule) and base–acid properties of mixed solvent
on the solvation process of cyclic ethers have been analyzed.
The -recoil effect of239Pu has been observed in environmental samples and theN5P
/N5 ratio in these samples has been calculated. This ratio in atmospheric samples is in the range between 10–5 and 10–4 (atom/atom). For other contemporary terrestrial samples it is in the range between 10–7 and 10–6 (atom/atom), while that of uranium mineral is about 10–10 (atom/atom). The results further explain the radioactive fallout contamination of our environment by uranium and plutonium isotopes.
Hot atom chemistry in the past and at present is reviewed, and its future direction is considered. Though it has still important meanings in nuclear and radiochemistry studies, new ideas to improve the present situation are expected to emerge.
In muon catalyzed fusion /CF/ in the mixture of deuterium and tritium, there is a small probability of muon sticking on a fusion product4He and this causes a limit of cycle number of CF in the reaction system: D+T
4He+n. The sticking loss is, however, to be re-considered by a bond rupture model of hot atom chemistry because the process has similarity to hot atom chemical phenomena.
Some of the techniques used in atom-at-a-time investigations of both nuclear and chemical properties of transactinide elements
will be discussed. Constraints on the systems that are valid for exploring chemical properties when only a few atoms at a
time are available and recent developments in instrumentation are considered. The current status of investigations of the
chemical properties of the transactinides is summarized and prospects for additional studies are evaluated.
A much improved version of our gas-filled spectrometer for heavy-ion-induced fusion reactions is described. This instrument (SASSY II) is of the type D-Q-D wherein the dipoles are made with strong vertically-focussing gradients. The problems associated with experiments with cross sections in the picobarn range are discussed. In such experiments it is necessary to identify single atoms with a high degree of confidence.