Innershell photoionisation spectroscopy of NaCl clusters

X-ray absorption near edge spectroscopy (XANES) was used to investigate the size dependent development of XANES structures from free molecules and clusters up to the solid NaCl. For measurements on clusters a new type of cluster source was designed in order to provide an intense and continuous cluster beam for inner shell absorption experiments on tightly bound clusters. Partial ion yield absorption spectra at the Cl 2p-edge were recorded for different NanCln−1 ions using a time-of-flight mass spectrometer at the high flux and high resolution undulator beamline BW3 at HASYLAB. The absorption spectra revealed a gradual evolution from the NaCl molecule and cluster to the solid. A comparison with recently performed multiscattering calculations indicates that the bond length even for rather small clusters (n=4) is increased by approximately 50% of the bond length change from the molecule to the solid