Knowledge Bank

The photographic absorption spectra of HCl and DCl have been analyzed above the 1st ionization potential ($750-950$ \AA). Rydberg series converging to the 2nd ionization limit ($\mathrm{<mrow\; data-mjx-texclass="ORD">2</mrow>}\Sigma +$) have been identified with quantum defects of 1.8 and 2.2. No rotational structure was observed in either series, indicating that the autoionization rate is faster than the rotational period (about $1013sec-1$ for the lowest members of the two series). The symmetries of the Rydberg states cannot be determined conclusively since the rotational fine structure is obscured. Photoelectric studies of the absorption spectrum are underway in order to determine the relative intensities and lineshapes of the individual transitions.