Photoionization Studies of Atoms, Molecules and Clusters. From Synchrotron to FEL radiation at Elettra, Trieste

VUV and Soft-X-Ray radiation is a valuable tool for the investigation of electronic properties of matter. Photon flux and energy resolution achievable at third generation facilities, such as the Gas Phase beamline of the Elettra storage ring (Trieste, Italy) [1], enable studies of inner-shell electron photoionization, however with intrinsically low signal level due to the low density of targets such as biomolecules [2] and clusters [3]. I will discuss recent experiments where photoionization techniques have been applied to gas phase molecular targets of increasing complexity, ranging from molecules of biological interest, to metal containing molecules and clusters. Fourth generation light synchrotron sources such as the FERMI Free Electron Laser (whose commissioning has just started at Elettra) aim at extending the investigation of the electronic structure of matter to the temporal domain by means of pump-probe techniques. In this perspective, the development of diagnostic and spectroscopic techniques in the gas phase at a small scale test facility is of paramount importance. I will briefly present results obtained at EUFOS, the Elettra storage ring FEL [4], where the concept of laser seeding of an electron bunch was exploited to perform a proof of principle pump-probe experiments with sub-ps time resolution. References [1] K.C. Prince, et al J. Synch. Rad. 5, 565-568 (1998). See also at http://www.elettra.trieste.it/beamlines/GAPH/ . [2] V. Fever, O. Plekan, R. Richter, M. Coreno , K.C. Prince, V. Carravetta, J. Phys. Chem. A 113, 10726-10733 (2009). [3] P. Piseri, T. Mazza, G. Bongiorno, M. Devetta, M. Coreno, P.Milani, J. Electron Spectrosc. Relat. Phenom. 166-167, 28-37 (2008). [4] G. De Ninno, et al. Phys. Rev Lett. 101, art. no. 053902 (2008).