The Infrared Spectroscopy Group at Sapienza University of Rome respecting Covid-19 social distancing (Feb 2021).

Towards a Silicon-germanium quantum well terahertz emitter (Appl Phys Lett 2021)

"Tip-Enhanced Infrared Difference-Nanospectroscopy of the Proton Pump Activity of Bacteriorhodopsin in Single Purple Membrane Patches." Nano Lett. 2019, 19, 5, 3104-3114

Infrared Nanospectroscopy with Quantum Cascade Lasers is used for nanoscale identification of substances and for investigation of deeply sub-wavelength volumes containing few molecules.

Scanning probe fabrication is carried out for improving the performances of infrared nano spectroscopy in terms of field enhancement, field confinement, spectral selectivity. Focused ion beam, Electron-beam induced deposition, Electron-beam lithography and Deep reactive-ion etching are employed.

The key tool for enhancing light-matter interaction at mid infrared and terahertz frequencies is Plasmonics.

Nanostructured metals and semiconductors can be both used to enhance electromagnetic fields in deeply sub wavelength volumes. Nanoantennas, nanoresonators, arrays with sub wavelength period can be designed, simulated, fabricated and finally used for surface-enhanced spectroscopy.

Plasmonic naoantenna hotspots can be imaged and their spectra can be measured by IR nanospectroscopy.

"Nanoscale thermal gradients activated by antenna-enhanced molecular absorption in the mid-infrared"

Appl. Phys. Lett. 114, 023105 (2019)

Nonlinear frequency mixing can profit from the enhanced fields. Overlap of the plasmon mode pattern with the interaction region is crucial for obtaining high device performances (sensors, detectors.. )

Three-dimensional antenna structures provide further degrees of freedom for multi-beam interactions.

Fourier-Transform Infrared Spectroscopy (FTIR) is the main analysis tool in our laboratory at Sapienza University of Rome.

Terahertz, Far-infrared, mid-infrared rages are fully covered. UV/vis spectroscopy is also available.

All kinds of optical configurations (reflection, microscopy, grazing-incidence, scattering, dichroism, cryogenic temperatures..) are already available or can be built.

Quasi-normal-incidence reflectivity setup built for infrared and terahertz spectroscopy of single crystals at low temperatures. The optical conductivity, the kinetic energy and the superconducting condensate energy are derived by Kramers-Kronig transformation of the reflectivity of novel superconductors (High-Tc cuprates, doped diamond, graphite-like hexagonal-lattice systems..). The system is now used for the determination of the dielectric function of doped semiconductors in the midinfrared and for the spectral analysis of nano antennas.

Synchrotrons and Free-electron lasers provide special beam conditions for infrared and terahertz spectroscopy (high brilliance for microscopy, low frequencies for spectroscopy, short pulses for pump-probe time-resolved analysis). We are users of the beam line IRIS at BESSY-II, Helmoltz Zentrum Berlin, and of the laser FELBE at Helmoltz Zentrum Dresden Rossendorf.