Spectroscopy and Dynamics of K Atoms on Argon Clusters

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• 作者：J. Douady ; S. Awali ; L. Poisson ; B. Soep ; J. M. Mestdagh ; B. Gervais
• 刊名：Journal of Physical Chemistry A
• 出版年：2015
• 出版时间：June 11, 2015
• 年：2015
• 卷：119
• 期：23
• 页码：6074-6081
• 全文大小：297K
• ISSN：1520-5215

文摘

We present a combined experimental and simulation study of the 4s 鈫?4p photoexcitation of the K atom trapped at the surface of Arb>Nb> clusters made of a few hundred Ar atoms. Our experimental method based on photoelectron spectroscopy allows us to firmly establish that one single K atom is trapped at the surface of the cluster. The absorption spectrum is characterized by the splitting of the atomic absorption line into two broad bands, a 螤 band associated with p orbitals parallel to the cluster surface and a 危 band associated with the perpendicular orientation. The spectrum is consistent with observations reported for K atoms trapped on lighter inert gas clusters, but the splitting between the 螤 and 危 bands is significantly larger. We show that a large amount of K atoms are transiently stuck and eventually lost by the Ar cluster, in contrast with previous observations reported for alkaline earth metal systems. The excitation in the 危 band leads systematically to the ejection of the K atom from the Ar cluster. On the contrary, excitation in the 螤 band leads to the formation of a bound state. In this case, the analysis of the experimental photoelectron spectrum by means of nonadiabatic molecular dynamics simulation shows that the relaxation drives the system toward a basin where the coordination of the K atom is 2.2 Ar atoms on the average, in a poorly structured surface.