Dal 2000 il Prof. D. Stranges è Prof. Associato di Chimica Fisica presso il Dip.Chimica dell'Univ. La Sapienza e responsabile del Lab. di Dinamica delle Reazioni Chimiche.
La sua attività di ricerca riguarda principalmente lo studio della dinamica di fotodissociazione UV di specie radicaliche e molecole stabili, della decomposizione di molecole termicamente instabili e delle reazioni bimolecolari tra atomi di ossigeno e carbonio e idrocarburi (in collaborazione con i Proff. P. Casavecchia e N. Balucani dell'Università di Perugia). Tali studi sono di interesse nei processi di combustione, nella chimica dell'atmosfera terrestre e di quelle planetarie e nello sviluppo di nuovi materiali.
Nel 1988 ha ricevuto il “Premio Federchimica - Per un futuro intelligente” (sezione neolaureati) e nel 1999 ha vinto lo stesso premio per la sezione professori universitari e ricercatori.
Attività di ricerca all'estero:
1) Univ. of California at Berkeley (USA) presso il gruppo del Prof. Yuan T. Lee (Premio Nobel per la Chimica, 1986): 1990-91 (6 mesi) e 1992-95 (3 anni). Si è occupato dello studio della dinamica delle reazioni chimiche unimolecolari e di quelle bimolecolari utilizzando tecniche sperimentali d'avanguardia (Spettroscopia Traslazionale dei Fotoframmenti e quella dei fasci molecolari incrociati). Un importante risultato ottenuto è stato lo sviluppo di una nuova sorgente pirolitica per fasci molecolari impulsati per produrre fasci molto intensi di specie radicali. Tale sorgente è stata utilizzata con successo per studiare la fotodissociazione UV del radicale allilico.
2) Max Planck Institut für Dynamik Und Selbstorganisation Göttingen (Germania) presso il gruppo del Prof. Jan P. Toennies: 1998 (6 mesi). Si è occupato della caratterizzazione di fasci di cluster giganti (droplets) di He e dello studio dei processi di electron attachment.
Nel 1999 ha cominciato a realizzare un complesso apparato sperimentale non commerciale per lo studio di processi di fotodissociazione utilizzando la tecnica della Spettroscopia Traslazionale dei Fotoframmenti. Questo apparato è stato completato 2003 poichè ha richiesto un investimento di circa 750.000 Euro.
E' stato co-organizzatore del XIX Int. Symposium on Molecular Beams (Roma 2001).
E' stato coordinatore scientifico di unità di ricerca di progetti nazionali finanziati dall' ASI, dal MIUR, dall'Univ. La Sapienza (Ateneo, Facoltà, AST ed Università), dal CNR ed è stato responsabile scientifico di una borsa di studio individuale Marie Curie della Comunità Europea. E' stato invitato a dare contributi orali, quali plenary lecture, invited lecture ed hot topic, in conferenze ed istituzioni internazionali di notevole prestigio.
Dal 2009 è membro del Comitato Scientifico Internazionale del “Int. Symposium on Molecular Beams”.
Ha svolto attività in qualità di referee per prestigiose riviste internazionali ed è stato revisore di progetti di ricerca per Enti americani e per il PRIN.

Contributi orali del Prof. D. Stranges a Conferenze Internazionali (dal 2007 ad oggi):

Plenary Lecture:
D. Stranges, “Thermal and Photoinduced decomposition of highly reactive species”, International Workshop on Atomic, Molecular and Ionic Processes, Alcochete (Pr), 29/06-02/07, 2008 (pp 23 - PL 3.2).

Invited Lectures:
1) ) D. Stranges, G. Scotti, E. Ripani, “Ultraviolet Photodissociation Dynamics of Hydrocarbon Free radicals”, XXIV International Symposium on Molecular Beams, Bordeaux (Francia), 23-26 Maggio, 2011, p. 17.
2) D. Stranges, G. Scotti, E. Ripani, “Ultraviolet photodissociation dynamics of the allyl and isopropyl radicals”, XVII Symposium on Atomic, Cluster and Surface Physics, Obergurgl (Austria), 24-29 Gennaio, 2010, p. 43.
3) P. O'Keeffe, P.L. Houston, R. Di Santo, D. Stranges, “Evidence for two competing mechanisms in the C2H2+CH3 dissociation channel from excited allyl radicals”, Molecular and nanodynamics: from atoms to biomolecules. Rome (Italy). 12-13 ottobre, 2007. (pp. R.7).

Hot Topics:
1) D. Stranges, G. Scotti, E. Ripani, “UV Photodissociation of Hydrocarbon Free Radicals: Allyl and Isopropyl Radical”, XXIII International Symposium on Molecular Beams. Dalian (China), 1-5 Giugno, 2009, p. 17.
2) P. O'Keeffe, P.L. Houston, R. Di Santo, D. Stranges, “Evidence for Two Competing Mechanisms in the C2H2 + CH3 Dissociation Channel from Excited Allyl Radicals”, 29th International Symposium on Free Radicals. Big Sky, Montana (USA). 12-17 agosto, 2007. (pp. 33).

Dati Bibliometrici del Prof. D. Stranges:

n. totale pubblicazion i = 33
H-Index = 19 (18 senza autocitazioni)
Tolale citazioni = 1024 (991 senza auto citazioni)
Numero di citazioni medie per articolo = 31.03
H-Index / n. pubblicazioni = 0.576 (valore più elevato di tutti gli afferenti al Dipartimento di Chimica).

Personal: Born 1962 in Washington, D.C.

Education: B.A., Chemistry, The Johns Hopkins University
Graduated with Departmental and General Honors (1983).

Ph.D., Physical Chemistry, University of California,
Berkeley (1989).
Thesis Advisor: Professor Yuan T. Lee

Appointments:

Research Assistant and Chemist, Gas and Particulate Science Division, National Bureau of Standards, Gaithersburg, MD, with Dr. Lloyd A. Currie (1978-1983).

Postdoctoral Research Associate, University of California Berkeley, Department of Chemistry, with Professor Daniel M. Neumark (1989-1992).

Assistant Professor, Department of Chemistry and Biochemistry UC San Diego (1992-1997).

Associate Professor, Department of Chemistry and Biochemistry UC San Diego (1997-1999).

Professor, Department of Chemistry and Biochemistry UC San Diego (1999-present).

Visiting Scientist, Combustion Research Facility, Sandia Nat’l Laboratory, Livermore, CA (2000).

Kurt Shuler Scholar in Physical Chemistry (2006–2011).

Chair, Department of Chemistry and Biochemistry (2006–2012)

Honors and Awards:

UC Berkeley Chemistry Department Fellowship (1983-1984).
Amoco Graduate Fellow, U.C. Berkeley (1988-1989).
Phi Beta Kappa (1989).
Camille and Henry Dreyfus New Faculty Awardee (1992).
UCSD Chancellor's Summer Faculty Fellowship (1993).
David and Lucile Packard Fellow in Science and Engineering (1994-1999).
Camille Dreyfus Teacher-Scholar (1996-2001).
Alfred P. Sloan Research Fellow (1997-1999).
Warren College Outstanding Teacher Award (1997).
Fellow, American Physical Society (2000).
UCSD Diversity Champion Award (2012).
ACS Division of Physical Chemistry Award in Experimental Chemistry (2012).

Professional Affiliations:

Fellow, American Physical Society
Member, American Chemical Society
Project Kaleidoscope Faculty for the 21st Century

Research Interests:

Molecular reaction dynamics, including dynamics of three-body collisions.
Dissociation dynamics and energetics of reactive intermediates.
Photodissociation of ions, transient molecules and clusters.
Photoelectron spectroscopy, photodetachment and dissociative photodetachment dynamics of negative ions.
Dissociative recombination and charge-exchange processes of positive ions.
Novel techniques in mass spectrometry and ion traps.
High-throughput analytical methods.
Gas-surface interactions, chemistry of supercritical solutions.

Current Research Support:

1. Dynamics and energetics of elementary combustion reactions and transient species, Department of Energy, $500,000 total costs, 11/10-10/13.
2. Acquisition of a 500 MHz NMR Spectrometer, National Science Foundation, $602,745 total costs, 2/08–1/13.
3. Energetics and dynamics of biofuel intermediates, American Chemical Society Petroleum Research Foundation New Directions Grant, $100,000 total costs, 9/11–9/13.

Professional Service Activities (Since 2008):

Member, External Advisory Panel, Keck Foundation Project, UH Manoa, HI (2008–2011).
External Review Panel, Office of Research Affairs, Ohio State University (2008).
Editorial Advisory Board, Journal of Physical Chemistry A (2008-2010).
Secretary, International Committee for the Int’l Symposium on Free Radicals (2009–present).
Participant, Second China-US Chemistry Deans-Chairs Forum, Beijing, China July 11-15, 2009.
International Program Committee, Electrostatic Storage Devices 2011 Conference, Gatlinburg, TN, June 9-13, 2011.
Academic Program Review Committee, Univ. of Arizona Dept. of Chem. and Biochem. Feb 22 – 24, 2011.

Lecturer on Reaction Dynamics of Transient Species, Conference Universitaire de Suisse Occidentale (Basel, EPFL Lausanne, Geneva, Fribourg), April 4–13, 2011.
Lecturer on Spectroscopy in Complex Systems: Photoelectron Spectroscopy, Pan-American Advanced Studies Institute, Cartagenas, Colombia, June 6 – 12, 2011.
Academic Program Review Committee, Chapman University Department of Chemistry, February 1 – 3, 2012.
Elected Member-at-Large, Division of Chemical Physics, American Physical Society 2012-2015.
Lecturer on Applications of Photoelectron Spectroscopy, 1st Colombian School on Theory and Computation in the Molecular Sciences, Universidad del Valle, Cali, CO April 29-May 1, 2012.

Educational Activities:

Former Ph.D. Students (Completed Ph.D.): 12
Current Doctoral Students: 4
Current Postdoctoral Associates: 1
Former Postdoctoral Associates: 13

Bibliography – Robert E. Continetti

Peer-Reviewed Publications (Selected, 84 Total)

2. R.E. Continetti, B.A. Balko and Y.T. Lee, Symmetric stretch excitation of CH3 in the 193.3 nm photolysis of CH3I, J. Chem. Phys. 89, 3383-3384 (1988).
10. R.E. Continetti, B.A. Balko and Y.T. Lee, Crossed molecular beams study of the reaction D + H2 * DH + H at collision energies of 0.53 and 1.01 eV, J. Chem. Phys. 93, 5719-5740 (1990).
16. R.E. Continetti, D.R. Cyr, D.L. Osborn, D.J. Leahy and D.M. Neumark, Photodissociation dynamics of the N3 radical, J. Chem. Phys. 99, 2616-2631 (1993).
18. C.R. Sherwood, M.C. Garner, K.A. Hanold, K.M. Strong and R.E. Continetti, Communication: Energy and angular distributions in dissociative photodetachment of O4−, J. Chem. Phys. 102, 6949-6952 (1995).
21. M.C. Garner, C.R. Sherwood, K.A. Hanold and R.E. Continetti, Photodissociation dynamics of O3− at 523 nm, Chem. Phys. Lett. 248, 20-26 (1996).
23. K.A. Hanold, M.C. Garner and R.E. Continetti, Photoelectron-photofragment angular correlation and energy partitioning in dissociative photodetachment, Phys. Rev. Lett. 77, 3335-3338 (1996).
26. M.C. Garner, K.A. Hanold, M. Sowa Resat and R.E. Continetti, Stability and dissociation dynamics of the low-lying excited states of ozone, J. Phys. Chem. A 101, 6577-6582 (1997).
29. K.A. Hanold, A.K. Luong and R.E. Continetti, Complete kinematic measurement of three-body reaction dynamics: Dissociative photodetachment of O6− at 532 nm, Journal of Chemical Physics, 109, 9215-9218 (1998).
30. K.A. Hanold and R.E. Continetti, Photoelectron-photofragment coincidence studies of the dissociative photodetachment of O4−, Chemical Physics 239, 493-509 (1998).
31. K.A. Hanold, A.K. Luong, T. Clements and R.E. Continetti, Photoelectron-multiple-photofragment-coincidence spectrometer, Review of Scientific Instruments 70, 2268-2276 (1999).
32. J.A. Davies, J.E. LeClaire, R.E. Continetti and C.C. Hayden, Communication: Femtosecond time-resolved photoelectron-photoion coincidence imaging studies of dissociation dynamics, J. Chem. Phys. 111, 1-4 (1999).
33. A.K. Luong, T.G. Clements and R.E. Continetti, Three-body dissociation dynamics of excited states of O3(D2O), J. Phys. Chem. A 103, 10237-10243 (1999).
34. L.S. Alconcel, H.J. Deyerl, V. Zengin and R.E. Continetti, Structure and energetics of vinoxide and the X(2A") and A(2A') vinoxy radicals, J. Phys. Chem. A 103, 9190-9194 (1999).
35. H.-J. Deyerl, A.K. Luong, T.G. Clements and R.E. Continetti, Transition state dynamics of the OH + H2O hydrogen exchange reaction studied by dissociative photodetachment of H3O2−, Discussions of the Faraday Society, No. 115, 147-160 (2000).
37. J.A. Davies, R.E. Continetti, D.W. Chandler and C.C. Hayden, Femtosecond time-resolved photoelectron angular distributions probed during photodissociation of NO2, Phys. Rev. Lett. 84, 5983-5986 (2000).
40. H.-J. Deyerl, L.S. Alconcel and R.E. Continetti, Photodetachment imaging studies of the electron affinity of CF3, J. Phys. Chem. A 105, 552-557 (2001).
41. A.K. Luong, T.G. Clements, M.S. Resat and R.E. Continetti, Energetics and dissociative photodetachment dynamics of superoxide-water clusters: O2−(H2O)n , n = 1-6, J. Chem. Phys. 114, 3449-3455 (2001).
43. L.S. Alconcel, H.-J. Deyerl, M.S. DeClue and R.E. Continetti, Dissociation dynamics and stability of cyclic alkoxy radicals and alkoxide anions, J. Am. Chem. Soc. 123, 3125-3132 (2001).
46. H.-J. Deyerl, T.G. Clements, A.K. Luong and R.E. Continetti, Transition state dynamics of the OH + OH  O + H2O reaction studied by dissociative photodetachment of H2O2−, J. Chem. Phys. 115, 6931-6939 (2001).
47. T.G. Clements and R.E. Continetti, Communication: Predissociation dynamics of HCO2/DCO2 studied by the dissociative photodetachment of HCO2−/DCO2− + h  H/D + CO2 + e−, J. Chem. Phys. 115, 5345-5348 (2001).
52. T.G. Clements and R.E. Continetti, Four-body reaction dynamics: Complete correlated fragment measurement of the dissociative photodetachment dynamics of O8−, Phys. Rev. Lett. 89, 033005-1 – 033005-4 (2002).
53. T.G. Clements, R.E. Continetti and J.S. Francisco, Exploring the OH + CO  H + CO2 potential surface via dissociative photodetachment of (HOCO) −, J. Chem. Phys. 117, 6478-6488 (2002).
56. M.S. Bowen and R.E. Continetti, Photodetachment imaging study of the vinoxide anion, J. Phys. Chem. A 108, 7827-7831 (2004).
57. Z. Lu and R.E. Continetti, Dynamics of the acetyloxyl radical studied by dissociative photodetachment of the acetate anion, J. Phys. Chem. A 108, 9962-9969 (2004).
58. C.M. Laperle, J.E. Mann, T.G. Clements and R.E. Continetti, Three-body dissociation dynamics of the low-lying Rydberg states of H3 and D3, Phys. Rev. Lett. 93, 153202-1 – 153202-4 (2004).
59. H.J. Deyerl and R.E. Continetti, Photoelectron-photofragment coincidence study of OHF−: transition state dynamics of the reaction OH + F  O + HF, Phys. Chem. / Chem. Phys. 7, 855-860 (2005).
61. M.S. Bowen, M. Becucci and R.E. Continetti, Dissociative photodetachment dynamics of the iodide-aniline cluster, J. Chem. Phys. 125, 133309-1 – 133309-9 (2006).
63. Z. Lu, Q. Hu, J.E. Oakman and R.E. Continetti, Dynamics on the HOCO potential energy surface studied by dissociative photodetachment of HOCO− and DOCO−, J. Chem. Phys. 126, 194305-1 – 194305-11 (2007).
64. Z. Lu and R.E. Continetti, Alignment of a molecular anion via a shape resonance in near-threshold photodetachment, Phys. Rev. Lett. 99, 113005-1 – 113005-4 (2007).
65. Z. Lu, J.E. Oakman, Q. Hu and R.E. Continetti, Photoelectron-photofragment angular correlations in the dissociative photodetachment of HOCO−, Molec. Phys. 106, 595-606 (2008).
66. J.E. Mann, Z. Xie, J.D. Savee, B.J. Braams, J.M. Bowman and R.E. Continetti, Communication: Probing the Structure of CH5+ by Dissociative Charge Exchange, J. Am. Chem. Soc. 130, 3730-3731 (2008).
67. J.D. Savee, V.A. Mozhayskiy, J.E. Mann, A.I. Krylov and R.E. Continetti, The role of excited state topology in three-body dissociation of sym-triazine, Science 321, 826-830 (2008).
68. V. Mozhayskiy, J.D. Savee, J.E. Mann, R.E. Continetti and A.I. Krylov, Conical for stepwise, glancing for concerted: The role of the excited state topology in three-body dissociation of sym-triazine, (Cover Article) J. Phys. Chem. A 112, 12345-12354 (2008).
69. G. Piani, M. Becucci, M.S. Bowen, J. Oakman, Q. Hu and R.E. Continetti, Photodetachment and dissociation dynamics of microsolvated iodide cluster, Physica Scripta 78, 058110 (2008).
70. S. De Dea, D.R. Miller and R.E. Continetti, Cluster and solute velocity distributions in free jet expansions of supercritical CO2, J. Phys. Chem. A 113, 388 (2009).
71. J.E. Mann, Z. Xie, J.D. Savee, J.M. Bowman and R.E. Continetti, Communication: Production of vibrationally excited H2O from charge exchange of H3O+ with cesium, J. Chem. Phys. 130, 041102-1-4 (2009).
73. J.D. Savee, J.E. Mann and R.E. Continetti, Three-body dissociative charge exchange dynamics of sym-triazine, J. Phys. Chem. A 113, 3988-3996 (2009).
75. J. D. Savee, J.E. Mann and R.E. Continetti, Two-body dissociative charge exchange dynamics of sym-triazine, J. Phys. Chem. A 113, 8834-8838 (2009).
76. J.D. Savee, R.D. Thomas and R.E. Continetti, Dissociative charge exchange dynamics of HN2+ and DN2+, J. Chem. Phys. 131, 134301-1-8 (2009).
77. C.J. Johnson and R.E. Continetti, Dissociative photodetachment studies of cooled HOCO¯ anions revealing dissociation below the barrier to H + CO2, J. Phys. Chem. Lett. 1, 1895-1899 (2010).
78. J.E. Mann, Z. Xie, J.D. Savee, J.M. Bowman and R.E. Continetti, Dissociation dynamics of isotopologs of CH5 studied by charge exchange of CH5+ with Cs and quasiclassical trajectory calculations, J. Phys. Chem. A, 114, 11408-11416 (2010).
79. C.J. Johnson, B.L.J. Poad, B.B. Shen and R.E. Continetti, Communication: New insight into the barrier governing CO2 formation from OH + CO, J. Chem. Phys. 134, 171106-1-4 (2011).
80. C.J. Johnson, B.B. Shen, B.L.J. Poad and R.E. Continetti, Photoelectron-photofragment coincidence spectroscopy in a cryogenically cooled electrostatic ion beam trap, Rev. Sci. Instrum. 82, 105105-1-9 (2011).
81. C.J. Johnson, M.E. Harding, B.L.J. Poad, J.F. Stanton and R.E. Continetti, Communication: The electron affinities, well depths and vibrational spectroscopy of cis- and trans-HOCO, J. Am. Chem. Soc. 133, 19606-19609 (2011).

Review Articles (Selected, 7 Total)

2. R.E. Continetti, Photoelectron-photofragment coincidence studies of dissociation dynamics, Int. Rev. Phys. Chem. 17, 227-260 (1998).
3. R.E. Continetti, Dissociative photodetachment studies of transient molecules by coincidence techniques, in Advanced Series in Physical Chemistry Vol. 10B: Photoionization and Photodetachment Part 2, ed. C.Y. Ng, World Scientific, Singapore (2000), pp. 748-808 .
5. R.E. Continetti, Coincidence spectroscopy, in Annual Reviews of Physical Chemistry, Vol. 52, (2001), pp. 165-192.
6. R.E. Continetti and C.C. Hayden, Coincidence imaging techniques, in Modern Trends in Reaction Dynamics, ed. X. Yang and K. Liu, World Scientific (Singapore) 2004. pp. 475-528.
7. J.D. Savee, J.E. Mann, C.M. Laperle and R.E. Continetti, Experimental probes of transient neutral species using dissociative charge exchange, Int. Rev. Phys. Chem. 30, 79-113 (2011).

Invited Talks at National and International Meetings, 2009 – present (61 Total)

51. Dissociative photodetachment studies of exotic species: Double Rydberg anions, Gordon Research Conference on Molecular Energy Transfer, Ventura, CA January18-22, 2009
52. Photoelectron-photofragment coincidence studies of the NH4¯ double Rydberg anion and the excited states of NH4, 23rd International Symposium on Molecular Beams, Dalian, China June 1-5, 2009
53. Progress towards a cryogenically cooled ion trap for coincidence studies of molecular anions, 3rd International Workshop on Electrostatic Storage Devices, Aarhus, Denmark, June 21-25, 2009
55. Coincidence studies of dissociative photodetachment processes in a cryogenic ion trap, Telluride Symposium on Ion Traps and Guides for Chemistry and Spectroscopy, Telluride, CO, July 19-23, 2010.
56. Dissociative photodetachment studies of cooled HOCO¯ anions: Dissociation below the barrier to H + CO2, Telluride Symposium on Spectroscopy and Dynamics on Multiple Potential Energy Surfaces, Telluride, CO, July 26-30, 2010.
57. Coincidence studies of dissociation dynamics in a cryogenic ion trap, 8th International Conference on Dissociative Recombination, Lake Tahoe, CA, August 16-20, 2010.
58. Photoelectron-photofragment coincidence studies of NO–-X clusters (X=H2O, CD4), Faraday Discussion 150 on Frontiers in Spectroscopy, Basel, Switzerland, April 8, 2011.
59. Spectroscopy and dynamics of the HOCO radical, 66th Symposium on Molecular Spectroscopy, Ohio State University, June 20-24, 2011
60. Spectroscopy and dynamics of the HOCO radical, 31st Intl. Free Radicals Symposium, Port Douglas, Australia, July 25 – 29, 2011.
61. Spectroscopy and dynamics of the HOCO and DOCO radicals, International Conf. on Molecular Energy Transfer, Oxford, UK, September 11 – 16, 2011.

Other Invited Talks (not listed, 127 total)

Abstracts and Contributed Talks (not listed, 87 total)

ENERGETICS AND DYNAMICS OF COMBUSTION INTERMEDIATES

This proposal describes a collaboration between the University of California, San Diego (UCSD) Department of Chemistry and Biochemistry (Continetti) and the Department of Chemistry at the Univ. La Sapienza (Stranges) that will apply complementary state-of-the-art experimental techniques to understanding the energetics and dynamics of combustion intermediates. The chemistry of transient combustion intermediates is central to our understanding of the efficiency of fossil fuel combustion and its environmental impacts, including the formation of soot and other aerosols. At UCSD, pioneering work using negative ion precursors and fast beam translational spectroscopy has been carried out to characterize neutral alkoxy radicals [1,2] and most recently the essential hydroxycarbonyl radical (HOCO), the intermediate in the fundamental reaction of OH + CO ---> H + CO2 [3,4], using the technique of Photoelectron-Photofragment Coincidence (PPC) Spectroscopy. At La Sapienza, Prof. Stranges has established a state-of-the-art laboratory using Photofragment Translational Spectroscopy (PTS) with universal mass-spectrometric detection, and has made a number of important discoveries concerning the photochemistry of the allyl radical [5-7]. This collaborative effort will be initiated with the visit of Professor Continetti to La Sapienza from January – April 2013, and will lay the foundation for further exchange of students and postdoctoral fellows as well as the PI’s, as time permits, in the future.

The complementary approaches to the study of radical photochemistry and dissociation dynamics available in the two laboratories will provide a more complete understanding of the role played by the radicals in complex systems, such as combustion and atmospheric oxidation. The PTS experiments at La Sapienza allows the probing of the dissociative states of hydrocarbon radicals in photodissociation experiments in the UV (248 nm, 5 eV). The focus of experimental efforts during the period of this collaboration will turn to more complicated prototypical hydrocarbon radicals, in particular the n-propyl radical and the 2-methyl-allyl radical. Once clean sources for these radicals are developed, as discussed further below, the capability of the Rome PTS spectrometer to examine with excellent mass resolution the dissociation pathways using the universal mass spectrometric detection approach will provide some of the first information available on the photochemistry of these radicals to date, with the exception of a prior study on H-atom elimination from the n-propyl radical [8]. Complementary experiments on the 2-methyl-allyl radical will be initiated during this period in Continetti’s laboratory at UC San Diego. Lineberger and co-workers have already shown that the 2-methyl-allyl radical anion can be generated in the gas-phase, and the electron affinity of the radical has been measured to be 0.5 eV [9]. With the light sources (up to 4.8 eV) available in the Continetti group, photodetachment of the radical anion will allow preparation of excited states nearly as high as the photoabsorption from the ground state neutral radical at 248 nm used in the PTS experiements. This will yield complementary insights into optically forbidden states (accessible in anion photodetachment) and also providing an alternative route to examining H-atom elimination pathways that are more difficult to study in the PTS experiment owing to large background signals in the mass spectrometer at m/e = 1. These experimental efforts in the two laboratories, conducted in concert and catalyzed by the presence of Continetti at La Sapienza will constitute an important advance in the study of these prototypical free radicals.

An additional direction for the PTS experiments in Rome will be the extension to oxygenated species, including the tert-butoxy (CH3)3CO and allyloxy C3H5O radicals. Alkoxy radicals are essential intermediates in the oxidation of hydrocarbons. In addition, oxygenated carbon radicals are becoming increasingly of interest as the use of biofuel sources, including ethanol, butanol and long-chain saturated and unsaturated acids and esters. Oxygenated species in general are amenable to study using negative ion precursors, owing to the stability of alkoxide anions, so a number of experiments have been carried out using PPC spectroscopy at UCSD, as noted above. However, the challenge with those experiments is indeed the stability of the alkoxide anions. Alkoxy radicals have significant electron affinities, in the 1.8 – 2.5 eV range, so photodetachment of the corresponding alkoxide anions even at 258 nm (4.8 eV) can only produce radicals with ~ 2.5 eV of internal excitation, considerably below the excitation energies available by photoabsorption from the radical ground state with the light sources available in the laboratory at La Sapienza. The key to carrying out experiments on the oxygenated species in Rome will be the demonstration of bright and stable source for these oxygenated radicals, as further discussed below.

In summary, this proposal describes a complementary program of research on prototypical free radicals of interest in atmospheric oxidation, combustion and the combustion of oxygenated biofuels. Using PTS spectroscopy in Rome, the photochemistry of alkyl and alkenyl radicals will be characterized during the visit of Professor Continetti of UCSD. In addition, complementary experiments involving the dissociative photodetachment of the 2-methyl-allyl radical anion will be carried out in Continetti’s laboratory during this period. In addition, research will be carried out in Rome to extend the PTS experiments to oxygenated radicals that have been studied, at lower excitation energies, using PPC spectroscopy on the corresponding anions at UCSD. These PTS experiments will extend our knowledge of the chemistry of these reactive species to higher lying excited states for the first time.

1. L.S. Alconcel, H.-J. Deyerl, M.S. DeClue and R.E. Continetti, Dissociation dynamics and stability of cyclic alkoxy radicals and alkoxide anions, J. Am. Chem. Soc. 123, 3125-3132 (2001).
2. L.S. Alconcel and R.E. Continetti, Dissociation dynamics and stability of cyclopentoxy and cyclopentoxide, Chem. Phys. Lett. 366, 642-649 (2002).
3. C.J. Johnson, B.L.J. Poad, B.B. Shen and R.E. Continetti, New insight into the barrier governing CO2 formation from OH + CO, J. Chem. Phys. 134, 171106-1-4 (2011).
4. C.J. Johnson, M.E. Harding, B.L.J. Poad, J.F. Stanton and R.E. Continetti, The electron affinities, well depths and vibrational spectroscopy of cis- and trans-HOCO, J. Am. Chem. Soc. 133, 19606-19609 (2011).
5. D. Stranges, P. O’Keeffe, G. Scotti, R. Di Santo and P.L. Houston, Competing sigmatropic shift rearrangements in excited allyl radicals, J. Chem. Phys. 128, 151101 (2008).
6. C. Chen, B. Braams, D.Y. Lee, J.M. Bowman, P.L. Houston and D. Stranges, Evidence for vinylidene production in the photodissociation of the allyl radical, J. Phys. Chem. Lett. 1, 1875 (2010).
7. C. Chen, B. Braams, D.Y. Lee, J.M. Bowman, P.L. Houston and D. Stranges, The dynamics of allyl radical dissociation, J. Phys. Chem. A 115, 6797 (2011).
8. Z. Wang, M.G. Mathews and B. Koplitz, Direct evidence for preferential β C-H bond cleavage resulting from 248 nm photodissociation of the n-propyl radical using selectively deuterated 1-bromopropane precursors, J. Phys. Chem. 99, 6913 (1995).
9. P.G. Wenthold, M.A. Polak and W.C. Lineberger, Photoelectron spectroscopy of the allyl and 2-methyl-allyl anions, J. Phys. Chem. 100, 6920 (1996).

The initial objectives during the proposed visit to La Sapienza will be to extend earlier work on the photodissociation dynamics of hydrocarbon radicals in the Stranges laboratory to experiments on hydrocarbon radicals including the n-propyl radical, C3H7, and the 2-methyl allyl radical, H2CC(CH3)CH2. These measurements will be made using the existing flash pyrolysis radical beam source currently available in the laboratory [1], using the readily synthesized nitrite precursors CH2C(CH3)CH2ONO (for the 2-methyl-allyl radical) and CH3CH2CH2CH2ONO (for the n-propyl radical). Nitrites like these are expected to exhibit pyrolysis chemistry involving production of the target radicals in concert with formaldehyde and nitric oxide: R-CH2-ONO ---> R + CH2O + NO. These experiments are expected to take the first two months of the proposed visit. In the case of the n-propyl radical, the methyl radical elimination channel yielding CH3 + C2H4 (ethylene) is expected to play an important role. In addition the H-atom elimination channel yielding H + CH3CHCH2 (propene) is likely to also be significant, however this will be more difficult to measure in the present configuration of the PTS spectrometer. The PPC experiment at UCSD has been demonstrated to measure H atom elimination channels, however, in the case of the n-propyl radical that will not be a successful approach as the n-propyl radical is believe to have a negative electron affinity (the anion is not stable). The 2-methyl allyl radical is likely to exhibit a methyl radical elimination channel (CH3 + H2CCCH2). This channel will be easily measured in the PTS experiment, providing important information on the bond dissociation energies and partitioning of energy in this dissociation channel. Complementary experiments examining the potential H-atom elimination channel yielding H + the conjugated diradical (H2C)2CCH2 will be carried out for this system in the laboratory at UCSD using the PPC approach since it has been shown that the anion can be synthesized by Lineberger and co-workers, and with the low electron affinity for the radical, reasonably high levels of excitation (4.3 eV) can be achieved at 258 nm.

During the second half of the visit to La Sapienza, Continetti will explore the production of oxygenated radicals. For the tert-butoxy and allyloxy radicals, the corresponding tert-butyl nitrite and allyl nitrite species may prove to be effective precursors in the pyrolytic source already available in Rome. These nitrites do not have available to them a low-energy pathway to the production of R + H2CO + NO, and are thus expected to primarily yield RO + NO. Tert-butyl nitrite is commercially available, and allyl nitrite can be easily prepared [2], and has already been used to produce the allyloxide anion in Continetti’s laboratory at UCSD [3]. In addition, it will be useful to examine the efficacy of a pulsed discharge ion source for producing neutral radicals from these nitrite precursors. There is extensive experience with pulsed discharge ion sources in the Continetti laboratory, and they are straightforward and can be implemented with the existing pulsed valves in the Stranges laboratory without a significant investment in either apparatus or electronics. For a ‘universal’ PTS spectrometer like that available in the Stranges laboratory the development of new beam sources for reactive species is the key to opening up whole new classes of photochemical reactions for study, so these experiments will be of great interest.

One of the most important outcomes of this collaborative proposal will be the forging of strong scientific bonds between the UCSD and La Sapienza research programs. Continetti has had long term support from the US DOE for his research program on combustion intermediates, and the Stranges laboratory likewise has an outstanding record in this regard. An important goal will be further exchange of researchers at the graduate and postdoctoral levels between the two laboratories. On the US side, this support will be sought from the National Science Foundation, and European sources for support will also be investigated.


1. H. Clauberg, D.W. Minsek and P. Chen, Mass and photoelectron spectroscopy of C3H2, J. Am. Chem. Soc. 114, 99 (1992).
2. S.G. Lee, L. Breeze, R.K. Bohn and N.S. True, Four conformers characterized in allyl nitrite, Chirality 14 232 (2002).
3. M.S. Bowen, Photodetachment dynamics of oxygenated organic anions and solvated iodide clusters, Ph.D. Thesis, UC San Diego (2005).

Questa ricerca non è ancora inserita in un progetto internazionale.

Il Prof. Albert Stolow dello Steacie Institute for Molecular Sciences, National Research Council of Canada (Ottawa, Canada), ha visitato e collaborato con il mio gruppo di ricerca per 30 giorni, dal 03 Aprile 2010 al 01 Maggio 2010, in qualità di Professore Visitatore (anno finanziario 2007). Il titolo della ricerca proposta era “TIME- AND ENERGY-DOMAIN CHEMICAL REACTION DYNAMICS” ed il programma prevedeva l’utilizzo di due diverse tecniche sperimentali per raggiungere questi obbiettivi. Una tecnica, che utilizza un approccio basato sul dominio delle energie, è quella utilizzata a Roma dal Prof. Domenico Stranges ed è conosciuta come la Spettroscopia Traslazionale dei Fotoframmenti mentre la seconda, che utilizza un approccio basato sul dominio dei tempi (esperimenti pump-probe al femtosecondo) è la Spettroscopia Fotoelettronica al Femtosecondo Risolta in Tempo sviluppata ad Ottawa dal Prof. Albert Stolow. Questo approccio complementare fornisce informazioni sulla dinamica dello stato di transizione e sulle distribuzioni degli stati quantici dei frammenti formati nel processo di fotodissociazione. Il metodo della Spettroscopia Traslazionale dei Fotoframmenti, mediante la risoluzione dell’energia cinetica di rinculo dei fotoframmenti e la distribuzione angolare, fornisce una visione completa di tutti i canali primari di dissociazione e le loro abbondanze relative. La Spettroscopia Fotoelettronica al Femtosecondo Risolta in Tempo, invece, permette di ottenere informazioni sul decadimento ultraveloce degli stati elettronici eccitati inizialmente raggiunti, mediante la misura e l’analisi degli spettri fotoelettronici e della distribuzione angolare dei fotoelettroni.
Si è deciso di iniziare questa collaborazione con lo studio sulla dinamica di fotodissociazione UV di etileni metil sostituiti (cis- e trans-2-butene, 2-metil-2-butene, 2,3-dimetil-2-butene e 2-metil-propene) utilizzando le due tecniche sperimentali sopra citate. Durante il periodo di permanenza del Prof. A. Stolow a Roma si è iniziato lo studio sulla fotodissociazione del cis- e trans-2-butene e del 2,3-dimetil-2-butene a 193 nm utilizzando la tecnica della Spettroscopia Traslazionale dei Fotoframmenti. Ad oggi è stato completato lo studio del 2,3-dimetil-2-butene, mentre per tutte le altre molecole sono stati rivelati solamente i canali di dissociazione che portano alla formazione di idrogeno atomico e molecolare. Nel caso del 2,3-dimetil-2-butene, sono stati identificati diversi canali primari di dissociazione: 1) perdita di idrogeno atomico, 2) perdita di idrogeno molecolare e 3) perdita di CH3. Per tutti e tre i canali primari osservati, una frazione dei frammenti molecolari pesanti (C6H11 nel primo caso, C6H10 nel secondo e C5H9 nel terzo) vengono formati con una energia interna sufficientemente elevata da provocare un processo di dissociazione secondario.
Con l’assorbimento di un fotone a 193 nm il 2,3-dimetil-2-butene viene eccitato nello stato di valenza 1ππ* ma è possibile anche l’eccitazione nello stato di Rydberg 1π3s. E noto, comunque, che il decadimento dello stato di Rydberg 1π3s in quello di valenza 1ππ*, nel caso dei mono alcheni, è estremamente veloce (qualche decina di femtosecondo). Lo stato di valenza 1ππ*, a sua volta, decade nello stato fondamentale attraverso un’intersezione conica tra queste due superfici di energia potenziale. Quindi, i processi di dissociazione avverranno dallo stato elettronico fondamentale e, quindi, saranno di tipo statistico. Per questo motivo, sono stati eseguiti calcoli ab initio per caratterizzare i minimi e gli stati di transizione esistenti sulla superficie di energia potenziale dello stato elettronico fondamentale per poter poi calcolare, utilizzando la teoria RRKM, le costanti di velocità microcanoniche relative a tutti i processi di isomerizzazione e dissociazione per poter, infine, determinare le abbondanze relative dei vari canali primari di dissociazione e confrontarli con i valori ottenuti sperimtalmente.
Per le altre molecole rimane da misurare i canali primari di dissociazione originati dalla rottura di un legame C-C e di eventuali canali secondari di dissociazione.
Per studiare il decadimento non adiabatico e ultraveloce dello stato di valenza 1ππ* in quello fondamentale mediante intersezioni coniche esistenti tra questi due stati, il Dott. Enrico Ripani, strudente di dottorato presso il gruppo del Prof. Domenico Stranges, si è recato ad Ottawa dal Prof. A. Stolow per sette mesi (dal 1/9/2011 al 31/3/2012) per studiare questi processi di decadimento ultraveloce con la tecnica della Spettroscopia Fotoelettronica Ultraveloce Risolta in Tempo.
Lo studio sulla fotodissociazione del 2,3-dimetil-2-butene è stato concluso ed è quasi ultimata la stasura di un manoscritto da sottomettere ad una prestigiosa rivista scientifica internazionale nel campo della chimica fisica (D. Stranges, E. Ripani, A. Stolow, “Photodissociation of 2,3-dimethyl-2-butene at 193 nm”, in preparazione). Si prevede che anche i risultati sugli altri sistemi molecolari sopra citati, una volta ultimati l’acquisizione e l’analisi dei dati sperimentali, saranno oggetto di diverse pubblicazioni scientifiche su rinomate riviste scientifiche internazionali.