Abstract Experimental synchrotron radiation induced electron- and ion spectroscopies together with electron-ion and ion-ion coincidence techniques as well as electron energy loss spectroscopy have been used to study the electronic properties of several vapor phase samples. In this thesis studies of the electronic structure and fragmentation of Sb4 clusters, photo- and Auger electron spectroscopy of atomic Si and Pb as well as ultra high resolution VUV absorption of vapor phase KF molecules have been performed. The instrumentation and techniques used in the studies, especially the electron energy loss apparatus and the newly built ultra high resolution FINEST beamline branch, are presented.