Production and Mass-Spectroscopic Characterization of Multiple Metal-Rich Alkali Halide Ion Clusters: Novel Structures and Properties

Abstract

Abstract Multiple metal-rich ion alkali halide clusters from solid crystals of NaF and CsI have been produced and characterized for the first time by a newly developed high-pressure laser-vaporization cluster source. The observed positive metal-rich clusters are NanFm+ (n ≈ 40, n-m = 1—9) and CsnIm+ (n ≈ 60, n-m = 0—5), which have enhanced intensities at n = 14, being independent of m, indicating the existence of multiple excess electrons. For negative clusters, NanFm- (n ≈ 40, n-m = -1—10) and CsnIm- (n ≈ 60, n-m = -2—3) have been observed. The NaF metal-rich negative clusters show two types of distinct magic numbers at n-m = 7 ((NaF)mNa7-) and n = 14 (Na14F13-x-, x = 0—4). The former and latter magic-number ions suggest the existence of a negative core ion of Na7- and a cubic 3×3×3 structure with multiple excess electrons, respectively. The present high-pressure laser-vaporization cluster source is suitable to produce these unstable clusters with a unique stoichiometry.