SELECTIVE IONIZATION OF GROUP-I ELEMENTS FROM LASER-ABLATED PLUMES OFRB.GA.SB, K3GA3AS4, AND K4IN4AS6

Experimental results are reported on the I-III-V Zintl compounds Rb . Ga . Sb, K3Ga3As4, and K4In4As6 With respect to laser ablation and sub sequent laser ionization/removal processes. The approach takes advanta ge of the low ionization potentials of the group I elements to achieve selectivity and exert a measure of control over neutral mixtures. A 3 08 nm laser pulse is used to ablate a I-I-II-V Zintl compound, while a second laser is used to selectively ionize the ejected species within the extraction region of a time-of-flight mass spectrometer. With the second laser operating at 248 nm (in the case of Rb Ga Sb) and at 266 nm (in the case of K3Ga3As4 and K4In4As6), selective gas-phase ioniza tion and removal of the group I elements is clearly demonstrated. (C) 1998 American Institute of Physics.