Distortion of He emission lines after fast-ion collisions

After excitation by fast ions (velocity = 2 to 5 au) the emission line profiles of doubly-excited helium atoms are observed to differ significantly from the normal shape of Beutler-Fano resonances. This difference is attributed to the Coulomb interaction between the emitted electron and the ion used to excite the atom. We explain the effect quantitatively with a simple classical model combined with a post-collision-interaction theory. 4 refs., 4 figs

DETERMINATION OF THE (0, 1) - (0, 3) ROTATIONAL SPLITTING OF H2+H_{2}{^{+}} FROM MICROWAVE SPECTROSCOPY OF H2H_{2} RYDBERG STATES.∗STATES.^{\ast}

$^{\ast}$Supported by NSF under Grant PHY-87-09707 $^{1}$L. Wolniewicz and J.D. Poll, Mol. Phys. 59, 953 (1986)Author Institution: Dept. of Physics, Univ. of Notre DameThe 1-3 rotational splitting of the ground vibrational state of $H_{2}^{+}$ has been $calculated^{1}$ to be $288.861(1) cm^{-1}$. As a consequence, the (0, 1)28L and (1, 3)16L Rydberg states of $H_{2}$ are separated in energy by only about 7 GHz. Electric dipole transitions between the two series, which would normally be forbidden, are weakly allowed by virtue of mixing between the two series. This allows a direct determination of the energy difference between states of the two series by microwave spectroscopy, from which the core rotational splitting may be inferred with high precision. Preliminary results of such a determination based on observation of the $(0, 1)28H_{6} - (0, 3)161_{7}$ transition, and other similar transitions will be described