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  • 1
    Electronic Resource
    Electronic Resource
    Vibrational predissociation of the Ar⋅⋅⋅Cl2 van der Waals complex: The small molecule limit for intramolecular vibrational redistribution (1992)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 97 (1992), S. 341-354 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: A converged three-dimensional quantum treatment of vibrational predissociation in the Ar⋅⋅⋅Cl2(B3Π0u+,υ′) van der Waals complex is presented. The potential energy surface used is a sum of pairwise Morse atom–atom interactions adjusted asymptotically to a C6/R6+C8/R8 anisotropic van der Waals form. Calculations have been performed in the energy region of Ar⋅⋅⋅Cl2(B,υ'=6, 10, and 11) excited levels. In agreement with the experimental findings, the final rotational distribution of Cl2 is found to be strongly dependent on the initial υ' state being excited, as well as on the number of vibrational quanta lost in the vibrational predissociation process. The role of intramolecular vibrational redistribution for υ'=10 and 11 for which the Δυ=−1 channel is closed is also studied. It is found that the vibrational predissociation (VP) dynamics are dominated by the coupling of the zero-order "bright'' state with a single "dark'' state from the υ'−1 manifold of van der Waals vibrationally excited states which then decays to the continuum, and that the product state distribution is determined by the dissociation of the dark state. This is characteristic of the sparse limit for intramolecular vibrational redistribution. It also implies that the dissociation rate is not governed by a simple function of the initial quantum numbers such as the one given by the energy gap law. The golden rule approximation gives surprisingly accurate results for Ar⋅⋅⋅Cl2 dynamics. This will be very useful for fitting a potential energy surface to experimental results.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.463579
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  • 2
    Electronic Resource
    Electronic Resource
    Intramolecular vibrational relaxation in a triatomic van der Waals molecule: ArCl2 (1992)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 96 (1992), S. 2404-2407 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Exact quantum mechanical calculations of the vibrational predissociation of ArCl2 are reported. The results confirm the hypothesis that Δv=−2 dissociation of the B state, v'=10 level occurs by preliminary coupling to the Δv=−1 manifold followed by coupling to the Δv=−2 continuum. The intensity borrowing due to the coupling is consistent with intramolecular vibrational relaxation (IVR) in the sparse limit, ρV≤1.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.462038
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  • 3
    Electronic Resource
    Electronic Resource
    Coherence effects between intramolecular vibrational relaxation and dissociation in triatomic van der Waals systems (1993)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 99 (1993), S. 1035-1049 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Time-independent [Halberstadt and co-workers, J. Chem. Phys. 96, 2404 (1992); 97, 341 (1992)] and time-dependent quantum mechanical calculations that describe the intramolecular vibrational relaxation (IVR) of Ar...Cl2 are used to develop analytical models for this process. It is shown that time-resolved experiments should reveal an oscillatory dissociation rate. It is found that the oscillations will be different for different rotational levels, and may tend to wash out if insufficient state selection is achieved in the initial excitation step. This may explain why no such oscillations were observed for Ar...I2. It is also predicted that the observed product state rotational distribution will change with the initially excited rotational state.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.465403
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  • 4
    Electronic Resource
    Electronic Resource
    Vibrational predissociation of ArCl2: Toward the determination of the potential energy surface of the B state (1996)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 105 (1996), S. 5830-5841 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Accurate quantum mechanical calculations are carried out to test the sensitivity of the spectroscopy and dynamics of the B state of ArCl2 to the steepness of the Morse term, α, of an atom–atom potential. It is discovered that the predissociation dynamics for this molecule are very complicated even in the Δv=−1 regime due to resonances in the continuum manifold of states. In both the Δv=−1 regime and the Δv=−2 regime the rate of vibrational predissociation and the product rotational distribution are extremely sensitive to the value chosen for α, but not in a regular way. For the Δv=−2 regime the variations can be attributed to spacings between resonances and the overlaps of the bright state wave functions with nearby dark states as expected from the intramolecular vibrational relaxation model. In the Δv=−1 regime, the variations are shown to originate from resonances in the v−1 continuum set of states. Although this makes it difficult to determine the value for α, a value of 1.8 A(ring)−1 is probably close to the true value. The most useful new data to determine the potential would be measurements of the lifetimes for as many vibrational levels as possible and rotational distributions for excitation to low vibrational levels of the B state. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.472425
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  • 5
    Electronic Resource
    Electronic Resource
    Vibrational Predissociation and Intramolecular Vibrational Energy Redistribution: Three-Dimensional Quantum Dynamics of ArI2 (1995)
    s.l. : American Chemical Society
    The @journal of physical chemistry 〈Washington, DC〉 99 (1995), S. 2512-2519 
    Details
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/j100009a008
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  • 6
    Electronic Resource
    Electronic Resource
    Quantum dynamics of ArI2 vibrational predissociation including low total angular momenta: The role of intramolecular vibrational energy redistribution (1996)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 104 (1996), S. 4999-5011 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Full-dimensional quantum dynamics calculations on ArI2(B,vi) vibrational predissociation with total angular momenta J=0, 1, and 2 are presented. Models based on a few interacting states are shown to reproduce important aspects of the dynamics, confirming that vibrational predissociation is mediated by a few-state intramolecular vibrational energy redistribution effect. As a consequence, vibrational predissociation rate constants exhibit large oscillations with vi, the initial I2 vibrational quantum number in the complex. The qualitative effect persists when alternative choices for the interaction potential parameters are considered. Similarly, despite the importance of Coriolis coupling, the effect persists as J is varied from 0 to 2. We also discuss how the effect may be difficult to observe in typical experiments that involve higher J values. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.471267
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  • 7
    Electronic Resource
    Electronic Resource
    Vector properties in photodissociation: Quantum treatment of the correlation between the spatial anisotropy and the angular momentum polarization of the fragments (1994)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 100 (1994), S. 3610-3623 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The dependence of the angular momentum polarization (orientation and alignment) of the fragments on the direction of ejection k, is studied quantum mechanically for molecular photodissociation into two fragments of which one carries an angular momentum j. Explicit expressions in terms of the transition matrix elements for electronic excitation into the final dissociative states are given in the axial-recoil limit and for different photon polarizations. The importance of interference effects due to coherent excitation of dissociative states with different helicity quantum numbers (the projection Ω of j on the recoil direction k) is stressed. It is shown that not only absolute magnitudes but also relative phases of individual transition matrix elements can be determined separately if the spatial anisotropy of the angular momentum polarization is measured.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.466402
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  • 8
    Electronic Resource
    Electronic Resource
    Energy levels and structure of tetra-atomic van der Waals clusters (1994)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 101 (1994), S. 2217-2230 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: A variational treatment is presented to study bound and quasibound states of X1...BC...X2 van der Waals clusters, where X1 and X2 are rare gas atoms and BC is a conventional diatomic molecule. The Hamiltonian operator, including all the degrees of freedom, is expressed in terms of the B–C relative vector and bond coordinates which describe the position of each rare gas atom with respect to the BC center of mass. In a body-fixed reference system, with the Z axis parallel to the diatomic axis, all the matrix elements of the Hamiltonian are evaluated in a basis set of functions which takes into account the symmetries of the system. Numerical applications to the He2...Cl2 and Ne2...I2 complexes are presented and discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.467662
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  • 9
    Electronic Resource
    Electronic Resource
    Global potential energy surfaces for the H+3 system. Analytical representation of the adiabatic ground-state 1 1A′ potential (2000)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 112 (2000), S. 1240-1254 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Adiabatic global potential energy surfaces, for singlet and triplet states of A′ and A″ symmetries, were computed for an extensive grid for a total of 8469 conformations of H3+ system at full configuration interaction ab initio level and using an extended basis set that has also been optimized for excited states. An accurate (root-mean-square error lower than 20 cm−1) global fit to the ground-state potential is obtained using a diatomics-in-molecules approach corrected by several symmetrized three-body terms with a total of 96 linear parameters and 3 nonlinear parameters. This produces an accurate global potential which represents all aspects of ground-state H3+ including the absolute minimum, the avoided crossing and dissociation limits, satisfying the correct symmetry properties of the system. The rovibrational eigenstates have been calculated up to total angular momentum J=20 using hyperspherical coordinates with symmetry adapted basis functions. The infrared spectra thus reproduced is within 1 cm−1 with respect to the experimental values for several transitions. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.480539
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  • 10
    Electronic Resource
    Electronic Resource
    Vector Correlations in the Photopredissociation of van der Waals Molecules (1994)
    s.l. : American Chemical Society
    The @journal of physical chemistry 〈Washington, DC〉 98 (1994), S. 3307-3316 
    Details
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/j100064a011
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