EXCHANGE-REACTION BETWEEN INTERCALATED NA AND K STUDIED BY SYNCHROTRON-RADIATION

An exchange reaction between intercalated Na and K has been observed w ith core-level spectroscopy using synchrotron radiation. Both alkali m etals were found to intercalate the layered compound VSe2, when deposi ted onto the sample (0001) surface in UHV at room temperature, althoug h the rate of intercalation was markedly different. Sodium intercalate d easily, leaving only a small amount trapped at the surface, while fo r potassium a much larger part remained at the surface and the rate of intercalation was significantly lower. When Na was deposited onto VSe , intercalated with K, an exchange reaction was observed, in that Na r eplaced most of the intercalated K, which was forced to deintercalate back to the surface. For a similar deposition of K onto VSe2 intercala ted with Na, some of the K did intercalate, forcing some of the Na to larger intercalation depths but not hack to the surface, where the lar gest part of the deposited K was found.