NUCLEAR ENERGY USED TO EXCITE ATOMS. A multinational team of physicists has observed for the first time a process in which the energy freed up by a nucleus relaxing to a lower state is used to excite an electron in the surrounding atom to a higher energy state. Normally atomic and nuclear phenomena are separate, mainly because the energies typifying atomic transitions (an electron moving from one quantum state to another) is measured in electrons volts (eV) or less, whereas analogous nuclear transitions are typically on the order of thousands or millions of eV. But for some heavy ions, which have been relieved of many their electrons (making the attraction between the nucleus and the remaining unshielded electrons all that much more powerful), the spacing between atomic states can actually exceed the spacing between nuclear states. In the case of a Bordeaux-Gif sur Yvette-Darmstadt-Orsay-Manchester-Caen-Stanford experiment (Jean-Francois Chemin, Center for Nuclear Studies at Bordeaux-Gradignan, chemin@cenbg.in2p3.fr, 011-33-55-712-0874) conducted at the GANIL accelerator in France, tellurium atoms, with 47 or even 48 electrons removed, are smashed into a target. In these collisions, energy from the nucleus serves to promote a deeply bound electron (in the 1s electronic, or "K shell" state) into a barely bound "Rydberg" orbit.
This observation has extraordinary implications. It means that energy can pass resonantly between the nuclear and electronic parts of the atom by a resonant process similar to that which operates between an inductor and a capacitor in an LC circuit. Furthermore, this transfer of energy is suspected to play a role in the anomalous lifetime of certain nuclear species; thus the concept of nuclear lifetime, normally thought to be immune from atomic effects, has to be modified to take into account charge states of the atom.
If this is true then inside stars, where atoms often exist in an ionized state, the lifetime of various nuclear species might well be affected by this process of internal conversion between atomic states, thus modifying the chain by which elements are synthesized in the stellar environment. (Carreyre et al., Physical Review C, 1 August; see also Japanese work ona related subject, Kishimoto et al. Physical Review Letters, 28 August: Select Articles.)
