Photoemission study of matrix isolated Cu atoms and clusters

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Abstract
Ultraviolet photoemission spectra of Cu atoms and clusters isolated at 7 K in Ar, Kr, and Xe matrices have been measured using He I and He I I radiation. For single matrix‐isolated Cu atoms, d‐level emission around 5.1 eV below EF (9.3 eV below Evac) has been observed in all three matrices. Comparison with respective gas phase data yields a relaxation shift (for the 3d94s1 final state) of about 1.3 eV. For matrix‐isolated Cu clusters the emission peak due to d‐band emission is independent of the matrix gas, indicating that the relaxation is solely determined by the cluster itself, rather than by the surrounding matrix. In the matrices doped with clusters the emission from the np levels of the noble gas atoms is markedly modified by the dopant. It is shown that the relaxation of the np levels is dominated by the Cu clusters, yielding emission spectra similar to those from physisorbed noble gases.