ENERGY SHIFT IN THE [(DT MU)-D]EE MOLECULE DUE TO THE FINITE SIZE OF THE MUONIC MOLECULAR ION (DT MU)+

The energy shift due to the presence of the extended (dt-mu)11 pseudonucleus (in its first excited state with one unit of angular momentum) in the quasihydrogenlike molecule [ (dt-mu)11 - d]ee is estimated using first-order perturbation theory. The quadrupole parts of the electron-(dt-mu)11 and deuteron-(dt-mu)11 interactions are found to give energy shifts of several meV. The result suggests that the normal practice of calculating the shift in [(dt-mu)11 - d]ee by scaling the shift calculated for (dt-mu)11e may be in error. Calculations of the formation rate of [(dt-mu)11 - d]ee, which plays an important role in muon-catalyzed fusion, require an accuracy of about 1 meV in the binding energy, and the present result indicates that a shift in this binding energy of several meV, due to the finite (dt-mu)11 size, cannot yet be excluded.