Research

Organic ultra thin films

 

Collaborations with the Dipartimento di Ingegneria dei Materiali e dell'Ambiente e Dipartimento di Chimica Università di Modena e Reggio Emilia (L. Pasquali et al.), and the Saha Institute of Nuclear Physics Kolkata (A. Datta and M. Mukherjee)

X-ray reflectivity (XRR) offers a powerful tool to study a wide class of surfaces and buried interfaces with molecular scale resolution. Resonant soft x-ray reflectivity exploits the characteristic absorption spectra of atoms and molecular states to access element- and bond-specific information beyond the pure electron density distributions. In contrast to established absorption spectroscopy techniques which are based on electron/photon yield, resonant reflectivity is quantitative in nature and the data carry full depth-dependent information with nanometer resolution through structures up to several hundred nm thickness ranging from buried interfaces to the free surface. Reflectivity data recorded in s and p incidence across carbon K-edge absorption resonances allow to study oriented functional groups in an ultrathin self-assembled monolayers. The dielectric tensor and the molecular orientation can be obtained from polarization-dependent resonant XRR experiments using an indigenously developed simulation code OPAL.
This technique open the possibility to study single molecules electronic devices, that has attracted much attention in recent decades. It is known that the detailed geometrical configuration of metal−molecule−metal junctions plays a key role in the charge transport properties. For instance, self-assembled monolayers of dithiols are promised to have different applications and have been extensively studied. However, the accurate determination of the configuration of dithiols adsorbed on a surface is a long-standing and interesting problem.

The 1,4 benzenedimethanethiol (BDMT) molecule

Experimental results compared to calculations