State-dependent Photoionization Cross-sections Of3d Transition Metal Atoms

The photoionization cross-section (PCS) of an excited atom is a veryimportant parameter in the atomic photoionization dynamics，it refers tothe probability of an electron being emitted from its electronic state whileatoms and photons interact with each other. Using the saturation methodwe accurately measured the absolute photoionization cross-sections ofseveral excited states of titanium, vanadium, Chromium, iron, and cobalt.We coupled a laser-ablated metal target with a supersonic molecular beamto produce a pulsed atomic beam，studied photoionization of excitedatomic states by using Resonance-enhanced multiphoton ionization; thephotoions were collected by a standard TOF mass spectrometer. Scanninglaser wavelength in the range of278-361nm, we obtained the REMPIspectra of the transition metals atoms. The absolute photoionization crosssection of atomic resonance excited state was extracted from the ionyields as a function of the laser intensity. The measured values range from0.4±0.1Mb to6.9±2.0Mb. The results show that the photoionizationcross-section strongly depends on the atomic state and not just on theelectronic configuration.