Study of small chlorine-doped potassium clusters by thermal ionization mass spectrometry

The theoretical calculations have predicted that nonmetal‐doped potassium clusters can be used in the synthesis of a new class of charge‐transfer salts which can be considered as potential building blocks for the assembly of novel nanostructured material. In this work, KnCl (n = 2–6) and KnCln−1 (n = 3 and 4) clusters were produced by vaporization of a solid potassium chloride salt in a thermal ionization mass spectrometry. The ionization energies (IEs) were measured, and found to be 3.64 ± 0.20 eV for K2Cl, 3.67 ± 0.20 eV for K3Cl, 3.62 ± 0.20 eV for K4Cl, 3.57 ± 0.20 eV for K5Cl, 3.69 ± 0.20 eV for K6Cl, 3.71 ± 0.20 eV for K3Cl2 and 3.72 ± 0.20 eV for K4Cl3. The KnCl+ (n = 3–6) clusters were detected for the first time in a cluster beam generated by the thermal ionization source of modified design. Also, this work is the first to report experimentally obtained values of IEs for KnCl+ (n = 3–6) and KnCln−1+ (n = 3 and 4) clusters. The ionization energies for KnCl+ and KnCln−1+ clusters are much lower than the 4.34 eV of the potassium atom; hence, these clusters should be classified as ‘superalkali’ species. Copyright © 2012 John Wiley & Sons, Ltd.