The double Auger (DA) decay of a $K$ hole has been observed directly by detecting the two emitted electrons in coincidence. The hole was created in ${}_{}{}^{37}{}_{}{}^{}\mathrm{Cl}$ following the electron-capture decay of ${}_{}{}^{37}{}_{}{}^{}\mathrm{Ar}$. The probability of DA decay, per Auger decay, with the two electrons both having an energy greater than 250 eV was found to be 3.7±0.2%. The DA probability was found to decrease exponentially as the energy partitioning between the two electrons changed from the asymmetric case ($E_1\gg E_2$) to the symmetric case ($E_1\approx E_2$). The DA probability accounts for the bulk of the intensity of high charge states previously measured in ${}_{}{}^{37}{}_{}{}^{}\mathrm{Cl}$.

• Received 12 September 1995

DOI:https://doi.org/10.1103/PhysRevA.53.R3716