Using an electromagnetically driven shock tube and rapid scanning Fabry-Perot spectrometer, the Lorentzian half-width of the 4663-Å line of singly ionized aluminum was measured and found to be 0.45 Å ± 20% for an environment corresponding to $N_e={10}^{17}$ ${\mathrm{cm}}^{-3\mathrm{}}$ and $T_e=18\mathrm{}500$ °K. Semiclassical and semiempirical calculations yielded values of 0.56 Å and 0.41 Å, respectively, while the distorted-wave approximation gave 0.51 Å. Our measurement and the calculated values fall a factor of 5 below the results of a previous experiment.

• Received 7 October 1974

DOI:https://doi.org/10.1103/PhysRevA.11.477