Production and Decay of Double $L$ Vacancies in Argon and Phosphorus

Measurements have been made at two laboratories which indicate that the structure reported at 450-550eV in the electron spectrum from ${\mathrm{Ar}}^{+}$-Ar collisions by Ogurtsov, Flaks, and Avakyan is spurious. It is argued that the double $L$ vacancies which they invoke to explain the structure are more likely to decay by the two-step Auger process $L^{ 2}\to L{M}^{ 2}\to M^{ 4}$ than by the one-step process $L^{ 2}\to M^{ 3}$ suggested by these authors. Evidence supporting this is found in our electron spectra from ${\mathrm{P}}^{+}$-Ar collisions, where it is known from energy-loss and charge-state measurements that double $L$ vacancies are produced in phosphorus.