EXCEPTIONAL STRUCTURES IN THE ODD-ODD NUCLEUS 250Md

The low-energy two-quasiparticle bandhead energies for the odd-odd Z=101 nucleus 250 Md are evaluated using a zero range residual neutron-proton interaction. The 250Md ground state is seen to have the spin-parity Iπ=0- corresponding to the singlet band from the configuration {p : 7/2[514]⊗n:7/2[624]} in violation of the Gallagher-Moszkowski (GM) coupling rule. The situation here is shown to be almost identical to that for the rare-earth nucleus 166 Ho , which is the only well-established exception to the GM rule known so far. Analysis of the expected low energy spectrum, including the rotational levels, for 250 Md reveals the occurrence of an as-yet-unobserved long-lived high-spin Iπ = 7- isomeric state around (80±30) keV with dominant ε and α decay modes.

Determination of opacity data bases for TiO and H2O

Current ab initio methods for determining potential energy surfaces are discussed in relation to the TiO and H2O molecules, both of which make important contributions to the opacity of M-type stars. For the TiO molecule we discuss the determination of the radiative lifetimes of the excited states and band oscillator strengths for both the triplet and singlet band systems. While the theoretical radiative lifetimes for TiO agree well with recent measurements, the band oscillator strengths differ significantly from those currently employed in opacity calculations. For the H2O molecule we discuss the current results for the ground state potential energy and dipole moment surfaces generated at NASA Ames. We show that it is necessary to account for such effects as core-valence correlation to generate a potential energy surface of near spectroscopic accuracy. The current status of our effort to establish opacity data bases for both TiO and H2O is described.