Production and ionization energies of K sub(n)F (n=2-6) clusters by thermal ionization mass spectrometry

RATIONALE The very small clusters of the type K sub(n)F are of particular importance since their first ionization energies (IEs) are lower than those of the alkali metal atoms. Theoretical calculation has demonstrated that this kind of cluster represents a potential 'building block' for cl...

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Bibliographic Details
Published in:Rapid communications in mass spectrometry 2012-08, Vol.26 (16), p.1761-1766
Main Authors: Veljkovic, F M, Djustebek, J B, Veljkovic, M V, Velickovic, SR, Peric-Grujic, A A
Format: Article
Language:English
Subjects:
Atomic properties
Clusters
Electronics
Fluorine
Ionization
Mass spectrometry
Potassium
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Summary:RATIONALE The very small clusters of the type K sub(n)F are of particular importance since their first ionization energies (IEs) are lower than those of the alkali metal atoms. Theoretical calculation has demonstrated that this kind of cluster represents a potential 'building block' for cluster-assembly materials with unique structural, electronic, optical, magnetic, and thermodynamic properties. To date, however, there have been no experimental results on the IEs of K sub(n)F (n >2) clusters. METHOD K sub(n)F (n=2-6) clusters were produced by the evaporation of a solid potassium fluoride salt using a modified thermal ionization source of modified design, and mass selected by a magnetic sector mass spectrometer where their IEs were determined. RESULTS Clusters K sub(n)F (n=3-6) were detected for the first time. The order of the ion intensities was K sub(2)F super(+)>>K sub(4)F super(+)>>K sub(3)F super(+)K sub(6)F super(+)>K sub(5)F super(+). The determined IEs were 3.99 plus or minus 0.20eV for K sub(2)F, 4.16 plus or minus 0.20eV for K sub(3)F, 4.27 plus or minus 0.20eV for K sub(4)F, 4.22 plus or minus 0.20eV for K sub(5)F, and 4.31 plus or minus 0.20eV for K sub(6)F. The IEs of K sub(n)F increase slightly with the increase in potassium atom number from 2 to 6. We also observed that the presence of a fluorine atom leads to increasing ionization energy of bare metal potassium clusters. CONCLUSIONS The modified thermal ionization source provides an efficient way of obtaining the fluorine-doped potassium clusters. These results also present experimental proof that K sub(n)F (n=2-6) clusters belong to the group of 'superalkali' species.
ISSN:0951-4198
1097-0231
DOI:10.1002/rcm.6284