Abstract:
Formation of monatomic (K$^+$) and cluster potassium ions (K$_2^+$, K$_3^+$, K$_4^+$, K$_5^+$, K$_6^+$) in the process of field desorption from the spherical surface of a tungsten single crystal was detected. The studies were carried out in a field emission microscope, which provides for measuring the mass of ions desorbed by an electric field using time-of-flight mass analysis. The electric field strength required for potassium ions desorption corresponded to the calculated values obtained in the image force model for field desorption of alkali metals. For all detected potassium cluster ions, there is a minimum in the dependence of the number of desorbed ions on the electric field strength. For monatomic ions, such a minimum is not observed. The discovered patterns are explained by a shift in cluster desorption zones from the center of the sample to the periphery with increasing voltage.
Keywords:adsorption, field desorption, microscopy, ions, mass spectrometry.
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