C<scp>ROSSED</scp>-B<scp>EAM</scp> S<scp>TUDIES OF</scp> R<scp>EACTION</scp> D<scp>YNAMICS</scp>

Casavecchia, Piergiorgio; Balucani, Nadia; Volpi, G. G.

doi:10.1146/annurev.physchem.50.1.347

Cited by 106 publications

(62 citation statements)

References 231 publications

(238 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…47,48 Briefly, two well collimated supersonic beams of the reagents are crossed at 90°in a large scattering chamber with background pressure in the 10 Ϫ7 mbar range, which assures the single collision conditions, and a mass spectrometer, contained in a triply differentially pumped ultrahigh-vacuum chamber, serves as detector of the reaction products. The mass spectrometer can be rotated in the collision plane around an axis passing through the collision center and the velocities of the particles can be derived from time-of-flight ͑TOF͒ measurements.…”

Section: A the Crossed Molecular Beam Experimentsmentioning

confidence: 99%

Crossed molecular beams and quasiclassical trajectory studies of the reaction O(1D)+H2(D2)

Alagia

Balucani

Cartechini

et al. 1998

The Journal of Chemical Physics

View full text Add to dashboard Cite

Articles you may be interested inDynamics of the C ( D 1 ) + D 2 reaction: A comparison of crossed molecular-beam experiments with quasiclassical trajectory and accurate statistical calculationsThe O ( 1 D)+ H 2 reaction at 56 meV collision energy: A comparison between quantum mechanical, quasiclassical trajectory, and crossed beam results Probing the effect of the H 2 rotational state in O ( 1 D)+ H 2 →OH+H : Theoretical dynamics including nonadiabatic effects and a crossed molecular beam studyThe dynamics of the reactions O( 1 D)ϩH 2 →OHϩH and O( 1 D)ϩD 2 →ODϩD have been investigated in crossed molecular beam experiments with mass spectrometric detection at the collision energies of 1.9 and 3.0 kcal/mol, and 5.3 kcal/mol, respectively. From OH͑OD͒ product laboratory angular and velocity distribution measurements, center-of-mass product translational energy and angular distributions were derived. The angular distributions are nearly backwardforward symmetric with a favored backward peaking which increases with collision energy. About 30% of the total available energy is found to be channeled into product translational energy. The results are compared with quasiclassical trajectory calculations on a DIM ͑diatomic-in-molecules͒ potential energy surface. Related experimental and theoretical works are noted. Insertion via the 1 1 AЈ ground state potential energy surface is the predominant mechanism, but the role of a second competitive abstraction micromechanism which should evolve on one of ͑or both͒ the first two excited surfaces 1 AЉ and 2 1 AЈ is called into play at all the investigated energies to account for the discrepancy between theoretical predictions and experimental results.

show abstract

Section: A the Crossed Molecular Beam Experimentsmentioning

confidence: 99%

Crossed molecular beams and quasiclassical trajectory studies of the reaction O(1D)+H2(D2)

Alagia

Balucani

Cartechini

et al. 1998

The Journal of Chemical Physics

View full text Add to dashboard Cite

show abstract

“…A number of methods exist for preparing molecules with large, well-defined, and controllable amounts of energy in electronic, translational, and vibrational degrees of freedom, but until recently, it has been much more difficult to exert control over the rotational energy of molecules (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14). Traditional methods for optically preparing rotationally hot molecules are limited by strict selection rules that constrain angular momentum changes to small values (15,16).…”

mentioning

confidence: 99%

Dynamics of molecules in extreme rotational states

Yuan

Teitelbaum

Robinson

et al. 2011

Proc. Natl. Acad. Sci. U.S.A.

122

View full text Add to dashboard Cite

We have constructed an optical centrifuge with a pulse energy that is more than 2 orders of magnitude larger than previously reported instruments. This high pulse energy enables us to create large enough number densities of molecules in extreme rotational states to perform high-resolution state-resolved transient IR absorption measurements. Here we report the first studies of energy transfer dynamics involving molecules in extreme rotational states. In these studies, the optical centrifuge drives CO 2 molecules into states with J ∼ 220 and we use transient IR probing to monitor the subsequent rotational, translational, and vibrational energy flow dynamics. The results reported here provide the first molecular insights into the relaxation of molecules with rotational energy that is comparable to that of a chemical bond.carbon dioxide | rotational dynamics | transient spectroscopy | high-energy molecules | strong optical fields C ontrol of molecular energy for use in chemical and physical transformations requires tools for exciting specific degrees of freedom in molecules. A number of methods exist for preparing molecules with large, well-defined, and controllable amounts of energy in electronic, translational, and vibrational degrees of freedom, but until recently, it has been much more difficult to exert control over the rotational energy of molecules (1-14). Traditional methods for optically preparing rotationally hot molecules are limited by strict selection rules that constrain angular momentum changes to small values (15, 16). Microwave spectroscopy has been used to a limited degree for walking molecules up a rotational ladder, but only small amounts of rotational energy (ΔJ ∼ 5) could be imparted to molecules with this approach (17, 18). Static electric fields have been explored for orienting molecules, but this approach is impractical for rotating molecules into high-energy states due to the high angular velocity and voltages required (19). Rotational motion in molecules can be induced with strong optical fields leading to rotational recurrences, but the amount of rotational energy obtained with this method is fairly modest (19)(20)(21)(22)(23)(24)(25). In some cases, photochemical reactions and inelastic collisions can be used to produce rotationally hot molecules, but the products generally have broad and poorly controlled rotational energy distributions (26).An important development in the area of light-matter interactions is the optical centrifuge for molecules (27,28). In this device, powerful ultrafast chirped laser pulses deposit rotational excitation in molecules that is comparable to, and in some cases even exceeds, interatomic binding energies. The optical centrifuge was proposed by Corkum and coworkers in 1999 and was first demonstrated in 2000 (27, 28). They used an optical centrifuge to spin Cl 2 molecules into J ∼ 420 and used a time-of-flight mass spectrometer to detect Cl radicals that resulted from rotationally induced dissociation. The dissociation energy of Cl 2 is 3.5 eV, but rotational...

show abstract

“…We still do not have a suitable method for directly obtaining structural information about the reaction site or active intermediates through the reaction itself. In gas-phase reactions, methods for approaching the potential energy surface (PES) have been established using both chemical kinetics and reaction dynamics [7]. This paper reviews energy partitioning requisite for surface reaction dynamics in both reactant adsorption and product desorption.…”

mentioning

confidence: 99%

“…The structural information on surface-reaction sites and the configuration of the transition state will be found in reaction dynamics dealing with energy partitioning as well as the product velocity distribution in terms of the PES, as is usually the case in gas-phase reactions. Information on the transition state conformation (TS) in gas-phase reactions is deduced from the spatial and energy distributions of emitted products before energy dissipation for various collision energies [7] or by femto-second spectroscopy during molecular transformation [8]. In the case of surface reactions, such information, if obtained, will be able to provide the structure of active sites or intermediates which have been surveyed for nearly a century.…”

mentioning

confidence: 99%

Surface reaction dynamics and energy partitioning

Matsushima

Shobatake

2010

Journal of Molecular Catalysis A: Chemical

View full text Add to dashboard Cite

New approaches to surface reactions are reviewed in comparison with reaction dynamics in the gas phase. These are commonly based on product analysis before energy dissipation, in contrast to the chemical kinetics of surface reactions. Information of energy partitioning during reaction events is requisite to approach to reaction sites. In reactant adsorption, electronic excitations are exemplified to take place, showing non-adiabatic processes. On the other hand, in product desorption, spatial and energy distributions of desorbing products with hyperthermal energy can deliver the most direct structural information of the transition state including active intermediates and product formation sites. Typical analyses are shown in both N 2 O decomposition and CO oxidation on noble metals.Keywords; Surface reaction dynamics, Energy partitioning, Angular distribution, N 2 O decomposition, NO reduction, CO oxidation, Palladium, Rhodium, Platinum Chemical kinetics and reaction dynamicsThe mechanisms of chemical reactions on solid surfaces have been mostly examined from the viewpoint of chemical kinetics. The resultant mechanism is frequently short-lived because surface chemical kinetics describes the reaction rate in a phenomenological way as a function of the reactant coverage and surface temperature, proposing a consistent reaction mechanism.Most of the mechanisms deduced on ill-defined surfaces along these lines were discarded in the 1960s after re-examination by surface science techniques including vibration and photoelectron spectroscopies on well-defined surfaces [1,2]. This passive status of surface chemical kinetics has not changed even after the examination of many simulations for the description of the inhomogeneous reactivity of surface species from a mean-field approximation [3] or Monte Carlo simulations on lattice gas models [4]. Fortunately, surface 3 science has explained the mechanism of the remarkable sensitivity of chemical reactions toward surface structures, for example, in the synthesis of ammonia (N 2 +3H 2 →2NH 3 ) on iron surfaces [5] and CO oxidation (CO+O 2 →CO 2 ) on platinum metals [6]. Our understanding is, however, still far from that of gas-phase reactions. We still do not have a suitable method for directly obtaining structural information about the reaction site or active intermediates through the reaction itself. In gas-phase reactions, methods for approaching the potential energy surface (PES) have been established using both chemical kinetics and reaction dynamics [7]. This paper reviews energy partitioning requisite for surface reaction dynamics in both reactant adsorption and product desorption. In the former, electronic excitations take place, showing non-adiabatic processes. In the latter, knowledge of this partitioning opens reaction dynamics focusing on spatial and energy distributions of desorbing products, which can deliver structural information of active intermediates and product formation sites.In general, a chemical reaction must be characterized with respect to not...

show abstract

CROSSED-BEAM STUDIES OF REACTION DYNAMICS

Cited by 106 publications

References 231 publications

Crossed molecular beams and quasiclassical trajectory studies of the reaction O(1D)+H2(D2)

Crossed molecular beams and quasiclassical trajectory studies of the reaction O(1D)+H2(D2)

Dynamics of molecules in extreme rotational states

Surface reaction dynamics and energy partitioning

Contact Info

Product

Resources

About