The interaction of large Xe clusters with a soft x-ray laser pulse having a wavelength of 13.9 nm and an intensity of up to $2\times {10}^{10}\mathrm{W}/{\mathrm{cm}}^2$ was investigated using a time-of-flight ion mass spectrometer. The corresponding laser photon energy was sufficiently high to photoionize Xe $4d$ innershell electrons. It was found that ${\mathrm{Xe}}^{3+}$ ions (which result from double Auger decay of $4d$ vacancies) became the dominant final ionic product with increasing cluster size and x-ray intensity. This is in contrast to the results of synchrotron radiation experiments involving free Xe atoms, in which ${\mathrm{Xe}}^{2+}$ is the dominant resultant ion species. Possible mechanisms responsible for the enhancement of the double Auger transition probability in x-ray laser and cluster interaction are discussed.

• Received 22 November 2006

DOI:https://doi.org/10.1103/PhysRevLett.99.043004