MOLECULAR BEAM GROUP OF PERUGIA

DEPARTMENT OF CHEMISTRY

UNIVERSITY OF PERUGIA

REACTION DYNAMICS NETWORK

Research Overview
Our main research activity is currently in the field of Chemical Reaction Dynamics. We aim at understanding “chemical reactivity” at the most fundamental level.
We use the Crossed Molecular Beam (CMB) scattering technique with rotating mass spectrometric detection and time-of-flight analysis to measure reactive differential cross sections for elementary chemical reactions of importance from a fundamental point of view and in areas of practical interest, such as atmospheric-, combustion- and astro-chemistry.    From measurements of product angular and velocity distributions in the laboratory frame, we derive product angular and translational energy distributions in the center-of-mass system. From these we get information on (a) primary reaction products and branching ratios, (b) reaction micro-mechanisms (i.e., "direct" or via "long-lived complex"), (c) intermediate lifetimes and their unimolecular decay dynamics, (d) product energy partitioning (between translation and internal degrees of freedom), (e) details of the potential energy surface(s) for reaction.
    The main thrust of our work during the last few years has been that of investigating the reactive scattering of (a) oxygen atoms, (b) nitrogen atoms, (c) chlorine atoms, (d) carbon atoms, (e) hydroxyl radicals, (f) dicarbon radicals, and (g) cyano radicals with both inorganic and organic molecules. Reactive scattering of gas-phase atomic species from a liquid hydrocarbon surface in the thermal collision energy range is also investigated. Very recently (2008), we have undertaken the investigation of the reaction dynamics of also sulfur atoms. Key to these studies is the ability to generate intense, continuous supersonic beams of these transient species.

    The experimental results for simple 3-atom and 4-atom prototype reactions are usually compared with those of dynamical calculations, both by quantum mechanical and quasiclassical trajectory methods, on the relevant potential energy surfaces within international collaborations with leading theoretical groups.

    Recently (2004), an improvement in the detection sensitivity of the CMB apparatus, based on the implementation, for the first time, of the "soft" electron-ionization method for product detection, has opened up the way to investigate the detailed dynamics of polyatomic multichannel reactions (as those of O-atoms with unsaturated hydrocarbons) and radical-radical reactions (as those of O-atoms with hydrocarbon radicals). At the same time, the CMB apparatus was equipped, for the first time in this kind of instruments, with the possibility of crossing the two reactant beams at angles both lower (45°) and higher (135°) than the usual 90°. This permits to extend the range of collision energies, both on the low and high-energy side, that can be attained, and it is of importance for astrochemistry and combustion relevant reactions, respectively. The investigation of the dynamics of polyatomic multichannel reactions and radical-radical reactions is our major current effort. Furthermore, a new laboratory has recently been set-up to characterize, by using Laser-Induced-Fluorescence (LIF) and Resonant-Enhanced-Multiphoton-Ionization (REMPI), the internal quantum state distributions of supersonic radical beams to be used in crossed molecular beam reaction dynamics studies.

Selected recent publications:

·       " Crossed-beam and theoretical studies of the S(¹D) + C₂H₂ reaction", J. Phys. Chem. A 113, 4330-4339 (2009) (DOI: 10.1021/jp810989p)

·         “Observation of organosulfur products (thiovinoxy, thioketene and thioformyl) in crossed-beam experiments and low temperature rate coefficients for the reaction S(¹D) + C₂H₄”, Phys. Chem. Chem. Phys. 11, 4701-4706 (2009) (Comm.) (DOI:10.1039/B900059C)

·         “Probing the dynamics of polyatomic multichannel elementary reactions by crossed molecular beam experiments with soft electron-ionization mass spectrometric detection”, Phys. Chem. Chem. Phys. 11, 46-65 (2009). (Perspective, Front Cover) (DOI: 10.1039/B814709D)

·         “Beyond the Lennard-Jones model: A simple and accurate potential function probed by high-resolution scattering data useful for molecular dynamics simulations”, Phys. Chem. Chem. Phys. 10, 5489–5503 (2008) (Perspective, Front Cover) (DOI: 10.1039/b808524b)

·          “The extent of non-Born-Oppenheimer coupling in the reaction of Cl(²P) with para-H₂”, Science 322, 573-576 (2008).

·         “Unraveling the dynamics of the C(³P,¹D) + C₂H₂ reactions by the crossed molecular beam scattering technique”, J. Phys. Chem. A 112, 1363-1379 (2008) (DOI: 10.1021/jp0776208)

·          “Crossed molecular beam studies of radical-radical reactions: O(³P) + C₃H₅ (allyl)”, Phys. Chem. Chem. Phys. 9, 1307–1311 (2007) (DOI:10.1039/ B618971G)

·         “Crossed molecular beam reactive scattering: From simple triatomic to multichannel polyatomic reactions”, Int. Rev. Phys. Chem. 25, 109-163 (2006).

·          “Experimental and theoretical differential cross sections for the N(²D)+H₂ reaction”, J. Phys. Chem. A 110, 817-829 (2006)

·          “Dynamics of the O(³P)+C₂H₄ reaction: Identification of five primary product channels (vinoxy, acetyl, methyl, mthylene, and ketene) and branching ratios by the crossed molecular beam technique with soft electron ionization”, J. Phys. Chem. A 109 (16), 3527 (2005) (Letter, Front Cover)

·          “The dynamics of the prototype abstraction reaction Cl(²P_3/2,1/2) + H₂: A comparison of crossed molecular beam experiments with exact quantum scattering calculations on coupled ab initio potential energy surfaces”, Phys. Chem. Chem. Phys. 6, 5007-5017 (2004)

·         “Dynamics of the insertion reaction C(¹D) + H₂: A comparison of crossed molecular beam experiments with quasiclassical trajectory and quantum mechanical scattering calculations”, Phys. Chem. Chem. Phys. 6, 4957-4967 (2004)

·          “Soft electron impact ionization in crossed molecular beam reactive scattering: the dynamics of the O(³P) + C₂H₂ reaction”, J. Chem. Phys. 120, 4557-4560 (2004)

·         “Crossed molecular beam reactive scattering: towards universal product detection by soft electron-impact ionization”, In "Modern Trends in Chemical Reaction Dynamics, Part II: Experiment and Theory”, Advanced Series in Physical  Chemistry- Vol. 14, Ed. by Xueming Yang and Kopin Liu (World Scientific, Singapore, 2004), Ch. 7 (pp. 329-381).

·         “Differential cross sections from quantum calculations on coupled ab initio potential energy surfaces and scattering experiments for Cl(²P) + H₂ reactions”, Phys. Rev. Letters 91, 013201-1-013201-4 (2003)

Less recent:

·         "Chemical reaction dynamics with molecular beams", Rep. Prog. Phys. 63, 355-414 (2000)

·         "Cyanomethylene formation from the reaction of excited nitrogen atoms with acetylene: a crossed beam and ab initio study", J. Am. Chem. Soc. 122, 4443-4450 (2000)

·         "Crossed beam studies of reaction dynamics", Annu. Rev. Phys. Chem. 50, 347-376 (1999)

·         "Reactive scattering of oxygen and nitrogen atoms", Acc. Chem. Res. 32, 503-511 (1999)

·          “Reactive scattering of ground state and electronically excited oxygen atoms on a liquid hydrocarbon surface", Faraday Discuss. 108, 387-399 (1997)

·         "The dynamics of the reaction OH+D₂-> HOD+D: Crossed beam experiments and quantum mechanical scattering calculations on ab initio potential energy surfaces", Chem. Phys. 207, 389-409 (1996)

·         "Dynamics of the simplest chlorine atom reaction: An experimental and theoretical study", Science 273, 1519-1522 (1996)

·         "Reactive scattering of atoms and radicals", J. Chem. Soc. Faraday Trans. (Faraday Research Article) 91, 575-596 (1995)

·         “Crossed Beam Studies of Four-Atom Reactions: The Dynamics of OH + CO”,  J. Chem. Phys. 98, 8341-8344 (1993)

 Biography
1950 : Birth, Marsciano (Perugia), Italy
1974 : "Laurea" in Chemistry, University of Perugia (Italy).
1974-1977 : Research Fellow, Department of Chemistry, University of Perugia (Italy).
1977-1980 : Post-doctoral fellow with Professor Y.T. Lee, Department of Chemistry and Lawrence Berkeley Laboratory, University of California, Berkeley, CA (USA).
1980-1987 : Research Associate, Department of Chemistry, University of Perugia (Italy).
1987-2001 : Associate Professor of Physical Chemistry (Chemical Kinetics and Molecular Dynamics), University of Perugia (Italy).
2001- present : Full Professor of Physical Chemistry, University of Perugia (Italy).

1997: Professeur Invité, University of Paris-Sud, Orsay, France
2000: Miller Visiting Professor, University of California, Berkeley, USA
2002: Erskine Visiting Professor, University of Canterbury, Christchurch, New Zealand 

2007: Visiting Professor, Dalian Institute of Chemical Physics, CAS, Dalian, China

Member of the Editorial Board of PCCP (Physical Chemistry Chemical Physics)(2006- ).
Member of the International Advisory Board of the "Journal of Physical Chemistry" (2006-2008).
Member of the International Advisory Board of "Chemical Physics" (2007-).
Member of the International Advisory Board of "Chemical Physics Letters" (2009-).

Board Member of the Molecular Physics Section of the European Physical Society (EPS) (2004- ).

Scientific Secretary of the International Symposium on Molecular Beams (2002- ).
Fellow of the Royal Society of Chemistry (FRSC)

Chairman of the XVI International Conference on Molecular Energy Transfer - COMET XVI (Assisi, Italy, 20-25 June 1999).
Chairman of 26th International Symposium on Free Radicals (Assisi, Italy, 2-7 September 2001).
Chairman of XIV Symposium on Atomic and Surface Physics - SASP 2004 (La Thuile, 2004).

-  Team Leader in the European Training and Mobility of Researchers (TMR) Network (1997-2001) "ASTROPHYSICAL CHEMISTRY: Experiments, Calculations and Astrophysical Consequences of Reactions at Low Temperatures" (FP4)
-  Co-ordinator of the European Research Training Network (RTN) (2000-2004) "REACTION DYNAMICS: Experimental and Theoretical Studies on the Dynamics of Reactions of Atoms and Radicals of Fundamental and Practical Importance". (FP5)
-  Team Leader in the European Commission Marie Curie Research Training Network (2004-2008): “The Molecular Universe: An interdisciplinary programme on the physics and chemistry of molecules in space”. (FP6)

-  Team Leader in the European Commission Research Infrastructure Action (2004-2008): "European Planetology Network (EUROPLANET)". (FP6)

- AWARDS: Polanyi Medal 2008.
 
 

                                                                                                                                                                   last update: Feb 2009