Offline inelastic scattering with ultraviolet radiation

The IUVS beamline is devoted to the study of inelastic scattering with ultraviolet radiation, in a time-space domain not available at present at other facilities. In the inelastic scattering process, an incident photon interacts with the matter. In this interaction, the photons can be diffused. “Elastic scattering” can be defined as when the incident photon energy is the same as the diffused one, while “inelastic scattering” refers to when there is an energy variation. The beamline is specialized into the physics of disordered systems, such as molecular liquids, aqueous solutions, glasses and gels. More recently, the IUVS beamline also provides a new experimental set-up that enables the performance of UV resonance Raman scattering experiments by using synchrotron radiation in the energy range of wavelengths 200-270 nm as the excitation source. The possibility of having a continuous tunable wavelength in the UV range allows Raman scattering studies in many important fields of research, such as spectroscopy on molecules of biological interest (polymers, peptides DNA etc.), hydration shell in biological solutions, low energy excitations in highly correlated electronic systems, nanotubes and nanostructures.

Contact: Claudio Masciovecchio
Tel: +39 040 375 8093 (office) | +39 040 375 8516 (beamline)

Technical specifications

The inelastic light scattering spectrometer uses an undulator source. The incident photon energy is tuned to the 5-11 eV range by the monochromator, with a relative energy resolution in the 10-5 to 10-6 range. The analyzer allows analysis of the energy of the photons diffused in the sample, with an energy loss or an energy gain in the energy region typical of phonon-like excitations in the considered momentum region. The momentum transfer, Q, will be in the 0.02 to 0.25 nm-1 range, as determined by the incident photon energy, by the choice of the scattering angle and by the refraction index of the sample. The typical momentum resolution will be ΔQ/Q = 0.05, with some degree of tunability by varying the analyzer collection angle .For UV Raman setup, a Silicon mirror deviates the beam coming from the heat load chamber and directed at the conventional Brillouin scattering systems. The deviated beam is focalized at the entrance of a CT monochromator in order to increase the resolution to 0.1 nm. The beam is collimated and directed at the Raman system, which works in a backscattering geometrical configuration. The analyzer system consists of a three-grating CT spectrometer, working both in additive and subtractive modes. The system has been employed to allow measurements by using all three gratings or a single one. Two CCD are available.

Sample environment/Information for users

The endstation allows the generation of various sample environments. Measurements in vacuum down to a pressure range between 10-5 mbar and 10-10 mbar are possible. A temperature bath and an N2 cryostat allow measurements between 400 K and 77 K.

This instrument is also available for single instrument proposals in offline mode (with conventional light sources)

For more detailed information visit the beamline’s main homepage.