Deexcitation of sputtered metastable aluminum atoms

An experimental system was set up incorporating pulsed ion beam sputtering, two Nd:YAG pumped dye lasers and an imaging time-of-flight (TOF) analysis system. The system was used to perform state-selective analyses of neutral atoms sputtered from surfaces using resonant one-color and two-color ionization schemes. We have measured, for the first time, TOF mass spectra of Al atoms sputtered into the ground state 2 P 1 / 2 0 and first excited state 2 P 3 / 2 0 (with an excitation energy of 0.014 eV) from single crystals of Ni3Al and NiAl. The population ratio of the first excited state to the ground state in the sputtered flux was estimated to be 0.91 for Ni3Al and 0.95 for NiAl, respectively. This indicates that the magnitude of the excitation energy plays an important role even in the deexcitation rate of sputtered metastable state atoms with an open outer shell.