Science Letter
June 9, 2009
RADIOANALYTICAL AND NUCLEAR CHEMISTRY;
Research from V. Chaltikyan and co-authors provides new data about
radioanalytical and nuclear chemistry
According to recent research from Armenia, "The cesium isotope Cs-135
has an extremely long half-life (tau(1/2) = 2.3 center dot 10(6) y)
and its high water solubility leads to the anxiety of exudation to
ground water during geological disposal. Such a LLFP Cs-135 would be
converted into Cs-136 (Its half-life is 13.16 d and it becomes stable
Ba-136) by neutron capture reaction."
"However intermingling Cs-133 of which the natural abundance is 100%
disturbs this nuclear converting reaction because Cs-133 also absorbs
neutrons and produces Cs-135 again. For separating Cs-135 from other
cesium isotopes, laser-chemical isotope separation (LCIS) is believed
to be suitable mainly due to the light absorption and emission
stability. Isotope separation of alkali metal Rb-85/Rb-87 was
successfully achieved, showed 23.9 of head separation factor by
LCIS. The measured isotope shift of Cs D-2 line is within the reach
of available semiconductor lasers having emission line width of less
than 1 MHz, which shows that the selective excitation of Cs-135 may
turn to be possible. It is known that cesium excited to the
6(2)P(3/2) state may forms cesium hydride while ground-state cesium
does not. Therefore if the lifetime of 6(2)P(3/2) state is
sufficiently longer than the inverse rate of the chemical reaction,
Cs-135 can be extracted as cesium hydride," wrote V. Chaltikyan and
colleagues (see also Radioanalytical and Nuclear Chemistry).
The researchers concluded: "Applicability of the Doppler-free
two-photon absorption method for selective excitation and further
evaluation on Rydberg states and ionization should be investigated."
Chaltikyan and colleagues published their study in the Journal of
Radioanalytical and Nuclear Chemistry (Perspectives of laser-chemical
isotope separation of a long-lived fission product:
cesium-135. Journal of Radioanalytical and Nuclear Chemistry,
2009;280(2):343-352).
For additional information, contact V. Chaltikyan, National Academy
Science, Institute Physics Research, Ashtarak 0203, Armenia.
Publisher contact information for the Journal of Radioanalytical and
Nuclear Chemistry is: Springer, Van Godewijckstraat 30, 3311 Gz
Dordrecht, Netherlands.