Selective ionization of group I elements from laser ablated plumes of Rb⋅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 subsequent laser ionization/removal processes. The approach takes advantage of the low ionization potentials of the group I elements to achieve selectivity and exert a measure of control over neutral mixtures. A 308 nm laser pulse is used to ablate a I–III–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 ionization and removal of the group I elements is clearly demonstrated.