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Current Research Interests

We are interested in understanding structure and reactivity of ionic systems in gas and condensed phase. In particular we are interested in : (1) Uni- and bi-molecular reaction dynamics of molecular ions and (2) Solvation dynamics around ions in different environments.

Reaction dynamics of biological molecular ions

We study the gas phase reactivity of molecular ions due to collisions with rare gas by chemical dynamics simulations. These data are coupled with information obtained by statistical RRKM theory to obtain the overall picture at different reaction time-lengths. We are interested in particular in understanding fragmentation mechanisms responsible to the formation of peaks observed in ESI-MS/MS experiments. We apply this approach to understand biological molecules collision induced dissociation : from urea to poly-peptides. The collision dynamics between precursor molecule (ion-molecule reaction) is used to understand the formation of organic and molecular ions in astrophysical conditions.

This research was supported by the Labex (Excellence Laboratory) Charmmmat (2013-2014). Since 2015 this project is supported of the ANR-NSF project DynBioReact, for which I am the France PI, in collaboration with the group of prof. W.L.Hase (Texas Tech, USA PI).

Selected articles :

  • R.Spezia, Y.Jeanvoine, W.L.Hase, K.Song and A.Largo. Synthesis of formamide and related organic species in the interstellar medium via chemical dynamics simulations. Astroph. J. 826, 107 (2016).
  • A.Martin-Somer, M.Yanez, M.-P.Gaigeot and R.Spezia. Unimolecular Fragmentation Induced By Low Energy Collision : Statistically Or Dynamically Driven ? J. Phys. Chem. A 118, 10882-10893 (2014).
  • D.Ortiz, P.Martin-Gago, A.Riera, K.Song, J.-Y.Salpin and R.Spezia. Gas-Phase Collision Induced Dissociation Mechanisms of Peptides. Theoretical and Experimental Study of N-Formylalanylamide Fragmentation. Int. J. Mass Spectrom. 335, 33-44 (2013).
  • R.Spezia, A.Cimas, M.-P.Gaigeot, J.-Y.Salpin, K.Song and W.L.Hase. Collision Induced Dissociation of Doubly-charged Ions : Coulomb Explosion vs Neutral Loss in [Ca(urea)]2+ Gas Phase Unimolecular Reactivity via Chemical Dynamics Simulations. Phys. Chem. Chem. Phys. 14, 11724 – 11736 (2012).
  • R.Spezia, J.-Y.Salpin, M.-P.Gaigeot, W.L.Hase and K.Song. Protonated Urea Collision-Induced Dissociation. Comparison of Experiments and Chemical Dynamics Simulations. J. Phys. Chem. A 113, 13853–13862, 2009.

Solvation of Very Heavy Metals

We are developing polarizable classical potential to study via molecular dynamics solvation of lanthanoids and actinoids in different environments. We have studied the hydration of lanthanoids(III) and actinoids, and we were able to rationalize different experimental data, EXAFS in particular. This project was supported (2010-2014) by ANR-JCJC "AcLaSolv" (Actinoids and Lanthanoids Solvation) grant.

Selected articles :

  • M.Montagna, Y.Jeanvoine, R.Spezia and E.Bodo. Structure, Stability and Electronic Properties of DMSO and DMF clusters containing Th4+. J. Phys. Chem. A. 120, 4778-4788 (2016).
  • P.D’Angelo, F.Martelli, R.Spezia, A.Filipponi and M.A.Denecke. Hydration properties and ionic radii of actinide(III) ions in aqueous solution. Inorg. Chem. 52, 10318–10324 (2013).
  • P.D’Angelo and R.Spezia. Hydration of Lanthanoids(III) and Actinoids(III) : a Theoretical/Experimental Saga. Chem. Eur. J. 18, 11162 – 11178 (2012). Review article.
  • F.Martelli, R.Vuilleumier, J.-P.Simonin and R.Spezia. Varying the charge of small cations in liquid water : Structural, transport and thermodynamical properties. J. Chem. Phys. 137, 164501 (2012).
  • M.Duvail, F.Martelli, P.Vitorge and R.Spezia. Polarizable Interaction Potential for Molecular Dynamics Simulations of Actinoids(III) in Liquid Water. J. Chem. Phys. 135, 044503 (2011).
  • M.Duvail, P.Vitorge and R.Spezia. Building a polarizable pair interaction potential for lanthanoids(III) in liquid water : a molecular dynamics study of structure and dynamics of the whole series. J. Chem. Phys., 130, 104501, 2009.
  • M.Duvali, R.Spezia and P.Vitorge. A dynamical model to explain hydration behaviour through Lanthanide series. ChemPhysChem, 9, 693-696, 2008.

Photoreceptive systems

The vibrational and electronic properties of photoreceptive systems are studied in collaboration with different experimental and theoretical groups. In particular we are interested to dynamical effects on vibrational properties and the understanding of IR and Resonance Raman spectra.

Selected articles :

  • E.Kish, M.M.Mendes Pinto, D.Bovi, M.Basire, L.Guidoni, R.Vuilleumier, B.Robert, R.Spezia and A.Mezzetti. Fermi Resonance as a Tool for Probing Peridinin Environment. J. Phys. Chem. B. 118, 5873-5881 (2014).
  • D.Carbonera, M.Di Valentin, R.Spezia and A.Mezzetti. The unique photophysical properties of the Peridinin-Chlorophyll-a-Protein. Current Proteins & Peptide Science 15, 332-350 (2014). Special issue on “Sensors and trasductors in the landscape of photosynthesis”. Review article
  • D.Bovi, A.Mezzetti, R.Vuilleumier, M.-P.Gaigeot, B.Chazallon, R.Spezia and L.Guidoni.Environmental Effects on Vibrational Properties of Carotenoids : Experiments and Calculations on Peridinin. Phys. Chem. Chem. Phys. 13, 20954-20964 (2011).

Research stages at different levels are welcome on our different subjects : force field developments for migration and sequestration of heavy metals, direct dynamics of collision induced dissotiation, RRKM theory and applications, theoretical study of solvation effects. Both applicative and developping research field are possible, depending on the personal feeling.

Other Research Interests

The Role of Local Environment in Ultrafast Non-Adiabatic Dynamics

Studying the influence of environment on the ultrafast dynamics of biologically relevant chromophores, especially the effect on the localization of conical intersections and on the reactivity associated with these particular topological features. This was my post-doctoral work in the group of prof. J.T. Hynes at ENS-Paris. We have recently published part of this work on the G.Fleming Festschrift :

  • J.P.Malhado, R.Spezia and J.T.Hynes. Dynamical Friction Effects on the Photoisomerization of a Model Protonated Schiff Base in Solution. J. Phys. Chem. A 115, 3720–3735 (2011).

Present external collaborations

  • Bill Hase, Department of Chemistry, Texas Tech University, USA.
  • Ki Song, Korea National University of Education, South Korea.
  • Manuel Yanez, Universidad Autonoma de Madrid, Spain.
  • Laura Gagliardi, Department of Chemistry, University of Minnesota, USA.
  • Paola D’Angelo, Dipartimento di Chimica, Università di Roma "La Sapienza", Italy.
  • Christophe Den Auwer, Université de Nice, France.
  • Enrico Bodo, Università di Roma "La Sapienza", Italy.
  • Rodolphe Vuilleumier, ENS-Paris, France.
  • Jos Oomens, FELIX & Radabout Univeristy, Netherlands.
  • Antonio Largo, Universidad de Valladolid, Spain.
  • Benedetta Mennucci, Università di Pisa, Italy.
  • Emilio Martinez-Nunez, Universidad de Santiago de Compostela, Spain.