Research interests of Prof. Franco Gianturco

1. Radiation Damage

One of the basic questions which has come up from the earliest stages of the study on the effects of the electromagnetic field on biological material, and on the living organisms, has been that of pinning down the way in which the ensuing radiation can alter, damage or kill the target organisms. Only very recently, however, it has become apparent, although not yet fully explained, that the emission of secondary electrons at energies below ionization thresholds is one of the most efficient (and lethal!) sources of damage to biomaterials.
The consensus which is beginning to build up, in fact, suggests that such fast electrons, before and in competition with undergoing solvation into the aqueous medium, are able to form a variety of Transient Negative Ions (TNIs) which in turn allow efficient excess energy deposition into the molecular bonding network, a feature which causes dissociative electron attachment into a broad variety of negative fragments:
M(v,j) + c-  ->  (TNI)  ->  Ma(v'j') +Mb-(v'',j')

2. Astrochemistry

The research group has recently become more involved with the theoretical and computational simulation of a variety of molecular/chemical processes which are of direct interest for the unravelling, at the nanoscopic level, of astrophysical events that involve molecules, neutral and ionized, electrons and photons. In particular, the group is currently studying the following mechanisms that could provide a better understanding of a broad range of astrophysical processes:

  1. The formation of increasingly larger Polycondensed Aromatic Hydrocarbons (PAHs) starting with the most likely molecular cornerstones like the benzene and benzyne, molecules which are suspected of forming metastable anionic states leading to ring-opening reactions;
  2. A further class of compounds that are also connected with the formation of metastable and possibly stable anions are the linear carbon chains terminated by either H or N, that have been recently observed in the Interstellar medium: C6H- , C4H-, C8H-, NC4N-, etc. They are all object of analysis and simulation in our group in order to isolate the most likely paths leading electron attachment and ensuing energy redistribution via molecular fragmentations;
  3. The study of exothermic reactions in the early Universe, and the role played by the chemistry of Lithium-containing species, is also one of the topics regarding the Chemical Cosmos which are pursued by the group. A further topic of studies in the realm of reactive events is also the analysis of ionic reactions containing He and/or H in order to establish possible preferential evolutionary paths leading to the survival of specific ionic compounds amenable to observation.

3. Helium Nanodroplets

The superfluid properties of bulk 4He and 3He gases have triggered, in the recent years, an additional field of studies based on the surprising discovery that finite aggregates of such weakly interacting atoms, the helium nanodroplets, can constitute a gentle, adaptive environment at very low temperatures (below 1 K) where one can study with great accuracy the properties of the molecules which are used as dopants of such clusters of atoms. In particular, it has become clear from experiments and from the relevant theoretical models that different molecular species, and different molecular ions, undergo solvation in the nanodroplets in different ways, which in turn tell us a great deal on the interplay between interaction forces and the dynamics of microsolvation.

4. Ultracold Chemistry

A series of recent experiments which have intended to attain Bose-Einstein Condensates (BEC) of molecular species, have also opened up a new field of research in the area of chemical physics, i.e. the study of chemical processes down to temperatures of the nanokelvins (nk), where it has become apparent that matter essentially behaves according to the law of quantum mechanics.
This has meant that the theoreticians interested in this area had to meet the challenges that this new class of experiments have provided and also had to develop, or to retool, some of the necessary machinery to study many of the processes involved.
Examples for this are: the collisional energy transfer processes down to the Wigner regime, the presence of chemical reactions at vanishing collision energies, the role of virtual states on both types of processes and the analysis of Feshbach resonances and of Efimov States.

5. Lepton Chemistry

According to the standard model, the two most stable leptonic particles are the electron and its antiparticle, the positron. In recent years these two particles have provided new varieties of experimental findings when interacting, at low energies, with molecular gases. In these situations “low energy” means from threshold up to 10 eV or thereabout. Il has become apparent, for instance, that positrons interact with molecules in a special way in the sense that new “reaction channels” become available through the formation of positronium, Ps:  M(v,j) + e+ → M+ (v’,j’) + Ps
or through annihilation processes:   M(v,j) + e+ → M+ (v’,j’) + 2γ
Both the above elementary mechanisms pose great challenges to theorists since one needs to unravel the actual nanoscopic dynamics of the processes, the efficiency of which changes greatly from molecule to molecule.

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