Volume 120, Issue 13, 01 April 2004
Index of content:
120(2004); http://dx.doi.org/10.1063/1.1691403View Description Hide Description
Two recent papers presented calculations of the highly excited vibrational states of ozone [J. Chem. Phys. 119, 6512 (2003); 119, 6554 (2003)]. The nature and energies of these states may hold the key to the anomalous isotopic distribution of ozone in the atmosphere. Even though the same potential energy surface of Babikov et al. [J. Chem. Phys. 119, 2577 (2003)] was used in both calculations, the number of bound van der Waals states reported below dissociation differed significantly. In order to resolve the issue we present here the results of an independent computation of all the bound vibrational states of and up to dissociation. Our methods differ from both earlier calculations since we use hyperspherical coordinates and a direct product discrete variable representation of the Hamiltonian. The results of present work support the existence of several van der Waals states for on this potential energy surface.
120(2004); http://dx.doi.org/10.1063/1.1689634View Description Hide Description
The title reaction was studied in a crossed-beam experiment by imaging of state-selected products. The rotational state selection of the products was achieved using resonance-enhanced multiphoton ionization. The coincident information on the DF coproducts was revealed in a state-resolved manner from time-sliced velocity map images. Significant dependences of both the correlated differential cross sections and the DF vibrational branching ratios on the “tagged” rotation states were found. The dynamical implications of one of the major findings are discussed.
120(2004); http://dx.doi.org/10.1063/1.1689639View Description Hide Description
We report on the Raman spectra of water under high temperature and pressure conditions and show a discontinuity in the pressure dependence of the OH stretching frequency. As pressure increases, the strength of hydrogen bonding increases rapidly in the pressure ranges up to at 25 °C, at 100 °C, and at 300 °C and slowly above these pressures. This finding clearly demonstrates the existence of discontinuities in the pressure response of the hydrogen bonds of water, which suggests a possible structural change under these conditions.
Molecular orientation via a dynamically induced pulse-train: Wave packet dynamics of NaI in a static electric field120(2004); http://dx.doi.org/10.1063/1.1695315View Description Hide Description
We regard the rovibrational wave packet dynamics of NaI in a static electric field after femtosecond excitation to its first electronically excited state. The following quasibound nuclear wave packet motion is accompanied by a bonding situation changing from covalent to ionic. At times when the charge separation is present, i.e., when the bond-length is large, a strong dipole moment exists and rotational excitation takes place. Upon bond contraction, the then covalently bound molecule does not experience the external field. This scenario repeats itself periodically. Thus, the vibrational dynamics causes a situation which is comparable to the interaction of the molecule with a train of pulses where the pulse separation is determined by the vibrational period.