Finite slice analysis (FINA) of sliced and velocity mapped images on a Cartesian grid

Contains fulltext : 187488.pdf (publisher's version ) (Open Access)9 p

Dynamics on the double morse potential: a paradigm for roaming reactions with no saddle points

In this paper we analyze a two-degree-of-freedom Hamiltonian system constructed from two planar Morse potentials. The resulting potential energy surface has two potential wells surrounded by an unbounded flat region containing no critical points. In addition, the model has an index one saddle between the potential wells. We study the dynamical mechanisms underlying transport between the two potential wells, with emphasis on the role of the flat region surrounding the wells. The model allows us to probe many of the features of the “roaming mechanism” whose reaction dynamics are of current interest in the chemistry community

Hot molecules-off the beaten path

Item does not contain fulltex

Pyrazine: supercollisions or simple reactions?

Photodissociation of 1,4 diazine ~pyrazine! following 248 nm ~S2 S0! and 308 nm ~S1 S0! excitation has been studied by photofragment translational spectroscopy. While the latter wavelength was inefficient at generating reactive products, the former wavelength afforded a rich variety of fragments, the most translationally energetic being HCN carrying up to 36 kcal/mol. The implications of this reactive mechanism toward interpretation of vibrational energy transfer experiments from hot ground state pyrazine are considered. The absolute quantum yields f~248 nm, 27-A!50.4060.10, f~248 nm, 27-B!50.086.02, f~308 nm, 27-B8!50.0036.001 and the two corresponding translational energy distributions are presented

The reactions of Na{sub 2} with O{sub 2}

The reactions of Na{sub 2} with O{sub 2} were studied in a crossed-beam experiment at collision energies (E{sub c}) of 8 and 23 kcal/mol. The formation of NaO{sub 2} + Na was observed at both collision energies, with the angular distributions of NaO{sub 2} in the center of mass coordinates peaking strongly forward with respect to the direction of the O{sub 2} beam, suggesting that the reaction is completed in a time scale that is shorter than one rotational period of the molecular system. From the velocity distribution of the products, the authors found that the newly formed NaO{sub 2} molecules are internally excited, with less than 20% of the available energy appearing in the translational motion of the separating products. These results indicate a ``spectator stripping`` mechanism for the reaction, with the O{sub 2} stripping one Na off the Na{sub 2} molecules. At E{sub c} = 23 kcal/mol the cross section for this reaction channel is estimated to be 0.8 {angstrom}{sup 2}. Another reaction channel which produces NaO + NaO was seen at E{sub c} = 23 kcal/mol. The angular distribution for NaO is broad and forward-backward symmetric in the center of mass frame. A substantial fraction of the available energy is released into the relative motion of the products. This reaction is likely to proceed on an excited potential energy surface since a charge transfer to the excited O{sub 2}{sup {minus}} orbitals seems necessary for breaking the O-O bond. The measurement yields a bond energy of 60 kcal/mol for the Na-O molecule, and a total cross section of 2 {angstrom}{sup 2} for this reaction channel at E{sub c} = 23 kcal/mol

Direct Extraction of Alignment Moments from Inelastic Scattering Images

Item does not contain fulltex

Imaging the inelastic scattering of vibrationally excited NO (v = 1) with Ar

Contains fulltext : 184179.pdf (Publisher’s version ) (Closed access