A modular end-station for atomic, molecular, and cluster science at the low density matter beamline of FERMI@Elettra

Abstract

The low density matter end-station at the new seeded free electron laser FERMI@Elettra is a versatile instrument for the study of atoms, molecules and clusters by means of electron and ion spectroscopies. Beams of atoms, molecules and helium droplets as well as clusters of atoms, molecules and metals can be produced by three different pulsed valves. The atomic and molecular beams may be seeded, and the clusters and droplets may be pure, or doped with other atoms and molecules. The electrons and ions produced by the ionization and fragmentation of the samples by the intense light of FERMI can be analysed by the available spectrometers, to give mass spectra and energy as well as angular distributions of charged particles. The design of the detector allows simultaneous detection of electrons and ions using velocity map imaging and time-of-flight techniques respectively. The instruments have a high energy/mass resolution and large solid-angle collection efficiency. We describe the current status of the apparatus and illustrate the potential for future experiments.

Determining the polarization state of an extreme ultraviolet free-electron laser beam using atomic circular dichroism

“…The VMI spectrometer includes a 75 mm diameter imaging quality multichannel plate (MCP) stack with a high quality camera for the MCP image readout 31 . Its electron optics were set to work optimally for the kinetic energies of the He 1s electrons given by E kin ¼ E hn (48.4 eV) À E He(1s) (24.6 eV) ¼ 23.8 eV.…”

“…Calibration was achieved by analyzing the electron emission of different noble gas targets at various photon energies. A pulsed, supersonic helium injection beam produced with a commercial Even-Lavie valve (aperture 100 mm) was used to provide sufficient gas density (about 10 12 atoms per cm 3 ) in the interaction region for a shot-to-shot analysis of the VMI-spectra 31 .…”

“…The sCMOS camera readout acquires pictures of two dimensional projections of electron angular distributions with a 2,560 Â 2,160 pixels (6.5 mm) resolution 31 . These images (see for example, Fig.…”

Observation and Control of Laser-Enabled Auger Decay

“…This oscillates as a function of the relative phase η between the two harmonics, and its amplitude is approximately √ c( c) instead of c. The experiment was performed at the Low Density Matter beamline [17] of FERMI. The sample consisted of a mixture of neon and helium (for calibration purposes) and was exposed to a bichromatic beam of temporally overlapping first and second harmonic radiation with controlled phase relationship [14].…”

Polarization measurement of free electron laser pulses in the VUV generated by the variable polarization source FERMI

“…For this reason, three dedicated experiments were carried out at two different FERMI beamlines, namely DiProI [9] and LDM. Activity on DiProI is focused on coherent imaging techniques, LDM is the FERMI beamline for atomic, molecular and cluster physics studies [21]. DiProI hosted two experimental setups: an optical VUV polarimeter [15][16][17]19] (see also Figure 2) and a polarimeter based on the measurement of the angular distribution of photoelectrons (form He 1s core level).…”