Foto del docente

Alberto Modelli

Adjunct professor

Department of Biological, Geological, and Environmental Sciences

Curriculum vitae

- Alberto Modelli, born in Conselice (Ravenna), Italy, on June 18, 1950.

- Position: Associate Professor, Department of Chemistry, University of Bologna, via Selmi 2,    40126 Bologna. 

- Teaching: Physical Chemistry (for the degree in Environmental Sciences).

- University Degree (Title): Doctor in Chemistry, University of Bologna, July 1974.

- Member of the Italian Society of Chemistry.

- Postdocs: University of Nebraska, Lincoln (USA), Department of Physics and Astronomy,

 March-September 1980 (with a N.A.T.O. grant).

- Visiting Professor Stays: University of Paris (France), Physical Chemistry Institute "Pierre et Marie Curie", May-June 1993.

- Research consultant at CNR (Consiglio Nazionale delle Ricerche) from 1981 to 2006.

- National scientific qualification as full professor in the sector 03/A2 - Models and Methods for Chemistry, as defined in DD 222 of July 20 2012.

Research activity

       The research activity is devoted to the study of electronic structures, orbital interactions and nature of chemical bonds in gas-phase molecular systems. Various electron spectroscopy techniques are used: photoelectron spectroscopy (PES, excited by X or UV radiations) supplies the ionization energy values from the filled orbitals, electron transmission spectroscopy (ETS) supplies the energies of electron attachment to empty orbitals, that is, the negative of the vertical electron affinity values, dissociative electron attachment spectroscopy (DEAS) measures the abundance of negative fragments produced by electron impact, as a function of the incident electron energy. The experimental data are interpreted with the aid of proper theoretical calculations.

       A complete picture of the electronic structure requires the knowledge of both the filled and the empty levels, equally important from the thoretical and the reactivity points of view. However, while ionization energy data are easily available in the literature, the complementary electron affinity data are still sparse. The ETS/DEAS apparatus built in Bologna is one of the few existing in the world, and favoured scientific collaborations with researchers of foreign Universities: P.D. Burrow (University of Nebraska, Lincoln,m USA),  K.D. Jordan (Università di Pittsburg, USA), H.D. Martin (University of Dusseldorf), M. Tronc (University Pierre et Marie Curie, Paris VI), A.P. Hitchcock (Uni­versity McMaster, Hamilton, Canada), J. Tamariz (University of Mexico City),  L. Szepes e L. Nyulaszi (University of Budapest), J.P. Schermann (University of Paris 13, Villetaneuse), J. Nixon (University of Sussex, Brighton), N.L. Asfandiarov (Academy os Sciences, Ufa, Russia).

We applied the above mentioned techniques to organic and organometallic compounds (a survey is given in A. Modelli, Trends in Chemical Physics (Research Trends) ,  6 (1997) 57-95).

X-ray photoelectron spectroscopy was used to determine ionization energies from inner pseudo-atomic orbitals, and the subsequent mechanisms of electronic relaxation and charge re-distribution, mainly through shake-up processes, i.e., core ionization accompanied by simultaneous excitation of a valence electron to an empty orbital.

UV photoelectron spectroscopy was mainly applied to conjugated p-systems and organometallic compounds to investigate on the mechanisms of orbital interactions, nature of chemical bonds, acceptor or donor properties of substituent functional groups, conformational problems.

Electron Transmission Spectroscopy (an electron-molecule scattering technique) was employed to characterize (in energy and localization properties) temporary anion states, following several lines of research: systematic investigation on the acceptor properties of hydrocarbons containing elements of the main groups (14-17); metal-ligand interactions and charge distributions in transitional complexes; frontier electronic structure in compounds of environmental and biochemical interest. When the anion energy is above the threshold for dissociation, the electron capture process (resonance) may follow a dissociative channel (in kinetic competition with simple detachment of the extra-electron). In this case, a long-lived negative fragment and a neutral radical are formed. DEA spectroscopy measures the yield of negative fragments (with a mass filter), as a function of the electron impact energy. In particular, we used DEAS to determine the efficiency of intramolecular electron transfer between non-bonded functional groups. A multidisciplinary approach, including all the above mentioned techniques and theoretical calculations, was employed to characterize the filled and empty level structures of organic monomers and oligomers, extrapolating the results to the corresponding conducting polymers.

Another field of research is devoted to the determination of the extent and rate of biodegradation of environmental pollutants. In particular, the ASTM D 5988-96 method was used to study the biodegradability of various polymeric materials and ionic liquids due to the action of microorganisms present in the soil, in aerobic conditions.

Moreover, the degree of polymerization of paper samples exposed to various ageing and oxidation conditions was measured as a function of time by viscometry to describe the rate laws and calculate rate constants and activation energies. The rate constants of recycled paper were found to be comparable with those of non-recycled paper within experimental limits.

An innovative survey was conducted of the collections of the historical Biblioteca Classense, located in the urban area of Ravenna (Northern Italy). This survey was carried out non-destructively by assessing degradation visually and by measuring NIR spectral data followed by multivariate data analysis. The survey aimed to evaluate the current conservation state of the book collections and predict the collection lifetimes in diverse environmental management scenarios.

       The research activity led to publication of about 180 papers on international journals.