Gas Phase Photoemission beamline

Marcello Coreno -

Robert Richter (Elettra-ST)  

Michele Alagia (CNR-IOM) 

Kevin C. Prince (Elettra-ST) 

Fabio Zuccaro -

Monica de Simone (CNR-IOM) 

Cesare Grazioli (CNR-IOM) 

Lorenzo Avaldi -



Elettra Synchrotron - Trieste


Scientific Activity

The Gas Phase Photoemission beamline of the Elettra synchrotron radiation ring (Trieste, Italy) is the only one specifically devoted to gaseous systems. It is operated by a joint Research Team of Elettra Sincrotrone Trieste and Italian National Research Council, offering a multi-technique approach for investigation of electronic properties of free atoms, molecules and clusters in a wide energy range (CNR-IOM and CNR-ISM).
The source is a 36 period planar undulator. The monochromator is a Variable Angle Spherical Grating Monochromator, with five gratings and a photon energy range 13-900 eV(Iph> 1011 ph/s; E/E > 104 ). It delivers high flux (up to 1014ph/s, at100 eV, 0.1% bandwidth), with good resolving power (E/ΔE ≥ 10000) and small spot size (≈250 µm) at the target. At variance with other beam lines at the ELETTRA, the end-station is not fixed, but several interchangeable apparatuses are available for users’ experiments and users can also bring their own apparatus to perform experiments, provided that it is compatible with beamline requirements. Two exit ports are available for experiments: the GasPhase main line (hv range : 13-900 eV) and the GasPhase branchline (hv range: 13-250 eV). At both  main line and branch line a differential pumping section is settled, in order to decouple the UHV section of the mirror chambers from the high vacuum in the experimental end station (up to 5 orders of magnitude difference in pressure). On the branch-line, a ps-laser, tunable in the range 700-1000 nm (Tsunami, SpectraPhysics, ~83 MHz) is available. It can be synchronized to synchrotron radiation at 1/6th of the storage ring frequency (~83 MHz) for pump-probe experiments.
The active in-house and users' research program at GasPhase covers the following areas of activity:

  • high resolution studies of electronic structure and dynamics of atoms and molecules (with core level photoabsorption, photoemission and dispersed fluorescence);
  • characterization of reactive gases, radicals, transient species (electron and ion coincidence spectroscopies;
  • studies of complex molecules (biological and other organic molecules, and   organometallic complexes);
  • studies of inorganic and organic clusters;
  • studies of electron correlation in atoms and molecules   after   double photoionization, and inner shell ionization and decay;
  • novel instrumentation for investigation of many body interactions in complex systems.


The beamline is presently equipped with several distinct interchangeable set-ups:

  • Multi-coincidence experiments set up, for angle resolved and electron-electron coincidence experiments in a versatile multichannel configuration (fig. 2); PEPECO
  • VG-220i set up for photoemission and mass spectrometry of condensable vapours, equipped for ion-electron coincidences
  • Velocity Map Imaging  set up (VMI and PEPICo) PEPICO
  • Molecular beam set up, for PEPICo mass spectroscopy.
  • ARPES, angle-resolved photoemission experiments on aggressive molecular species (radicals, transients, reactive species).
  • SCIENTA SES-200 electron analyzer (Fig. 4; in collaboration with Uppsala University).
  • PIFS and XUV-PIK, for dispersed emission experiments with an UV-Vis monochromator and/or a compact XUV spectrometer (in collaboration with IFN-CNR, Padua) PIFS
  • CESyRa "Cluster Experiment with Synchrotron Radiation" for photoionization  of clusters of refractory materials, via electron-ion multicoincidence (in collaboration with prof. Paolo Piseri, University of Milan and NFFA).
Relevant Publications



The paper reports on the comprehensive gas phase electronic structure characterization of PPT (2,8-bis(diphenylphosphoryl) -dibenzo[b,d]thiophene), a promising ambipolar phosphorescent host material recently introduced in organic light-emitting diodes (OLEDs). This system can be considered formed by two diphenylphosphine oxide (dPPO) moieties functionalizing the small dibenzothiophene (DBT) core. PPT is characterized by high triplet energy. The triphenyl phosphine oxide (TPPO) molecule has been chosen as the model compound of the dPPO groups in PPT. A combined experimental and theoretical study by density functional theory of the gas phase electronic structure of TPPO and PPT has been performed through X-ray photoelectron spectroscopy and near-edge X-ray absorption fine structure spectroscopy measured at the carbon and oxygen 1s regions.

with permission from {A. Guarnaccio, et al,  The Journal of Physical Chemistry C  124 ,9774}. Copyright {2020} American Chemical Society."
The NEXAFS spectra of 2-nitroimidazole measured at the C, N, and O K edge and the iso-surfaces for the LUMO and LUMO+1 orbitals at all calculated excitation channels. The white dots indicate the sites of excitation. .

Tunability and selectivity of synchrotron radiation have been used to study the excitation and ionization of 2-nitroimidazole at the C, N, and O K-edges. The combination of a set of different measurements (X-ray photoelectron spectroscopy, near-edge photoabsorption spectroscopy, Resonant Auger electron spectroscopy, and mass spectrometry) and computational modeling have successfully disclosed local effects due to the chemical environment on both excitation/ionization and fragmentation of the molecule.

"Reproduced from P. Bolognesi, et al. Frontiers in Chemistry, 7 (2019) 151 "
NEXAFS spectrum of 2-nitroimidazole measured at the K threshold for C, N, and O K and isosurfaces of the LUMO and LUMO + 1 orbitals


"Reproduced from S. Mandal et al. PCCP. 22(2020)10149 with permission from the PCCP Owner Societies."
Schematic of the VMI-PEPiCo experiment on acetylenic oligomers in He nanodrops

Gasphase Projects

  • CLAMPS - CITIUS-LDM Atomic and Molecular Physics Support laboratory at Elettra, Trieste +

    The projects aims at establishing the "General Laboratory for Atomic and Molecular physics" support laboratory (GLAM) at Elettra. Read More
  • AHEAD2020 - IIntegrated Activities for the High Energy Astrophysics Domain +

    AHEAD2020 has been approved to advance the integration of national efforts in high-energy astrophysics, keeping the community at the cutting Read More
  • PIK - Single-shot X-ray radiation emission experiments +

    The project deals with R&D and implementation of a prototype of an innovative XUV spectrometer for photon spectroscopy. Read More
  • A nanoview of radiation-biomatter interaction +

    The project aims to exploit new opportunities to study the structure and dynamics of complex biomolecules isolated. Read More
  • NANO-IBCT - Nano-scale insights in ion beam cancer therapy +

    To combine the unique experimental and theoretical expertise available within Europe to acquire greater insight at the nanoscopic and molecular Read More
  • XLIC - XUV/X-ray light and fast ions for ultrafast chemistry +

    The scientific objective of the Action is to understand, monitor and control the nuclear dynamics. Read More
  • EUROFEL - European Free Electron Lasers +

    Creation of a consortium of pan-European interest (FELs ‐ of ‐ Europe). Read More
  • Nanoscale insights in radiation damage +

    The objectives of the project are the study of elementary damage processes in prototype molecules  Read More
  • nanoTOOLS - New molecular tools for exploring the nanoscopic world +

    Development of intense ESI sources and Application of the new devices. Read More
  • Chimica ionica e neutra in fase gassosa +

    The aim of the research is the study of aspects of ionic chemistry in the gaseous phase, which are of Read More
  • DYNA CHIRO - Spectroscopy and Dynamics of Chiral Systems +

    Dyna Chiro aims to probe the dynamical behaviour of chiral molecules, with chiral sensitivity. Read More
  • GAUDETE - GAs phase Upgraded DETEctor +

    Elettra-ST project with CNR-ISM in-kind contribution, for the upgrade of the VG hemispherical photoelectron analyzer of the GasPhase Photoemission beamline. Read More
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