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Per Jensen - One of the best experts on this subject based on the ideXlab platform.
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Rotational spectrum of so3 and theoretical evidence for the formation of sixfold Rotational Energy level clusters in its vibrational ground state
Journal of Chemical Physics, 2014Co-Authors: Daniel S Underwood, Sergei N Yurchenko, Jonathan Tennyson, Per JensenAbstract:The structure of the purely Rotational spectrum of sulphur trioxide 32S16O3 is investigated using a new synthetic line list. The list combines line positions from an empirical model with line intensities determined, in the form of Einstein coefficients, from variationally computed ro-vibrational wavefunctions in conjunction with an ab initio dipole moment surface. The empirical model providing the line positions involves an effective, Watsonian-type Rotational Hamiltonian with literature parameter values resulting from least-squares fittings to observed transition frequencies. The formation of so-called 6-fold Rotational Energy clusters at high Rotational excitation are investigated. The SO3 molecule is planar at equilibrium and exhibits a unique type of Rotational-Energy clustering associated with unusual stabilization axes perpendicular to the S–O bonds. This behaviour is characterized theoretically in the J range from 100–250. The wavefunctions for these cluster states are analysed, and the results are compared to those of a classical analysis in terms of the Rotational-Energy-surface formalism.
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Rotational Energy cluster formation in xy3 molecules excited vibrational states of bih3 and sbh3
Journal of Molecular Spectroscopy, 2006Co-Authors: Sergei N Yurchenko, Walter Thiel, Per JensenAbstract:Abstract Previous theoretical work on Energy cluster formation at high Rotational excitation in the vibrational ground state of PH3 [S.N. Yurchenko, W. Thiel, S. Patchkovskii, P. Jensen, Phys. Chem. Chem. Phys. 7 (2005) 573] is extended to BiH3 and SbH3. By means of variational calculations of the rotation–vibration energies based on ab initio potential Energy surfaces, we analyze the Rotational Energy clustering of BiH3 and SbH3 at J ⩽ 70 for a number of vibrational states. We show that BiH3 and SbH3, with their pronounced local mode behaviour, exhibit cluster formation already at moderate Rotational excitation. In addition, owing to its quasi-spherical-top character, BiH3 undergoes an imperfect bifurcation at high J. This gives rise to an Energy cluster type not present in PH3 and SbH3. We present a semi-classical approach to the construction of the Rotational Energy surfaces for vibrationally excited states.
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theoretical evidence for the formation of Rotational Energy level clusters in the vibrational ground state of ph3
Physical Chemistry Chemical Physics, 2005Co-Authors: Sergei N Yurchenko, Walter Thiel, Serguei Patchkovskii, Per JensenAbstract:We investigate theoretically the Rotational dynamics of pyramidal XY3 molecules in highly excited Rotational states. Towards this end we compute, by a variational method, the Rotational Energy levels in the vibrational ground state of PH3 for J ≤ 80. At J ≥ 50 the calculated Energy levels show a distinct cluster pattern. By monitoring the cluster formation we follow the various stages of the Rotational dynamics. We analyze the wavefunctions for the cluster states and compute expectation values which show that the C3v geometrical symmetry of PH3 is broken at high Rotational excitation. The conclusions drawn from the quantum-mechanical calculations are confirmed by semi-classical theory, i.e., by an analysis of the stationary points on the Rotational Energy surface.
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CHIRALITY IN Rotational Energy LEVEL CLUSTERS
Journal of Molecular Spectroscopy, 2004Co-Authors: Philip R. Bunker, Per JensenAbstract:Abstract Hougen’s role in developing our understanding of the symmetry classification of the Energy levels of molecules is briefly reviewed. For chiral molecules the application of these symmetry ideas shows that chiral states have mixed parity. High angular momentum states of H 2 X molecules, in which Rotational Energy level clusters form, do have mixed parity and are chiral. We show here that such states can have long lifetimes.
Sergei N Yurchenko - One of the best experts on this subject based on the ideXlab platform.
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Rotational spectrum of so3 and theoretical evidence for the formation of sixfold Rotational Energy level clusters in its vibrational ground state
Journal of Chemical Physics, 2014Co-Authors: Daniel S Underwood, Sergei N Yurchenko, Jonathan Tennyson, Per JensenAbstract:The structure of the purely Rotational spectrum of sulphur trioxide 32S16O3 is investigated using a new synthetic line list. The list combines line positions from an empirical model with line intensities determined, in the form of Einstein coefficients, from variationally computed ro-vibrational wavefunctions in conjunction with an ab initio dipole moment surface. The empirical model providing the line positions involves an effective, Watsonian-type Rotational Hamiltonian with literature parameter values resulting from least-squares fittings to observed transition frequencies. The formation of so-called 6-fold Rotational Energy clusters at high Rotational excitation are investigated. The SO3 molecule is planar at equilibrium and exhibits a unique type of Rotational-Energy clustering associated with unusual stabilization axes perpendicular to the S–O bonds. This behaviour is characterized theoretically in the J range from 100–250. The wavefunctions for these cluster states are analysed, and the results are compared to those of a classical analysis in terms of the Rotational-Energy-surface formalism.
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Rotational Energy cluster formation in xy3 molecules excited vibrational states of bih3 and sbh3
Journal of Molecular Spectroscopy, 2006Co-Authors: Sergei N Yurchenko, Walter Thiel, Per JensenAbstract:Abstract Previous theoretical work on Energy cluster formation at high Rotational excitation in the vibrational ground state of PH3 [S.N. Yurchenko, W. Thiel, S. Patchkovskii, P. Jensen, Phys. Chem. Chem. Phys. 7 (2005) 573] is extended to BiH3 and SbH3. By means of variational calculations of the rotation–vibration energies based on ab initio potential Energy surfaces, we analyze the Rotational Energy clustering of BiH3 and SbH3 at J ⩽ 70 for a number of vibrational states. We show that BiH3 and SbH3, with their pronounced local mode behaviour, exhibit cluster formation already at moderate Rotational excitation. In addition, owing to its quasi-spherical-top character, BiH3 undergoes an imperfect bifurcation at high J. This gives rise to an Energy cluster type not present in PH3 and SbH3. We present a semi-classical approach to the construction of the Rotational Energy surfaces for vibrationally excited states.
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theoretical evidence for the formation of Rotational Energy level clusters in the vibrational ground state of ph3
Physical Chemistry Chemical Physics, 2005Co-Authors: Sergei N Yurchenko, Walter Thiel, Serguei Patchkovskii, Per JensenAbstract:We investigate theoretically the Rotational dynamics of pyramidal XY3 molecules in highly excited Rotational states. Towards this end we compute, by a variational method, the Rotational Energy levels in the vibrational ground state of PH3 for J ≤ 80. At J ≥ 50 the calculated Energy levels show a distinct cluster pattern. By monitoring the cluster formation we follow the various stages of the Rotational dynamics. We analyze the wavefunctions for the cluster states and compute expectation values which show that the C3v geometrical symmetry of PH3 is broken at high Rotational excitation. The conclusions drawn from the quantum-mechanical calculations are confirmed by semi-classical theory, i.e., by an analysis of the stationary points on the Rotational Energy surface.
Nicholas C. Handy - One of the best experts on this subject based on the ideXlab platform.
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The vibrational–Rotational Energy levels of silanone
Chemical Physics Letters, 1999Co-Authors: Jacek Koput, Stuart Carter, Nicholas C. HandyAbstract:Abstract The equilibrium structure and 6-dimensional potential Energy surface of silanone, H 2 SiO, has been determined from large-scale ab initio calculations using the coupled-cluster method, CCSD(T), with basis sets of double- through quintuple-zeta quality. The effects of core-electron correlation on the calculated structural parameters have been investigated. The anharmonic force field has been determined. The vibrational–Rotational Energy levels of the molecule have then been calculated using variational and perturbational methods. The calculated molecular properties are in good agreement with experimental data.
F. Fleming Crim - One of the best experts on this subject based on the ideXlab platform.
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State‐to‐state Rotational Energy transfer in highly vibrationally excited acetylene
The Journal of Chemical Physics, 1992Co-Authors: J. D. Tobiason, A. L. Utz, F. Fleming CrimAbstract:Vibrational overtone excitation of single rovibrational eigenstates in acetylene, followed by state‐resolved, laser‐induced fluorescence (LIF) interrogation of the collisionally populated quantum states, permits a direct determination of both the pathways and rates of state‐to‐state Rotational Energy transfer in a polyatomic molecule containing about 10 000 cm−1 of internal Energy. The data, which we acquire under single‐collision conditions, demonstrate the importance of Rotational Energy transfer, even at high levels of vibrational excitation. The observed state‐to‐state Rotational Energy transfer pathways populate a wide range of angular momentum states and account for about 70% of the total relaxation rate. About one‐third of the total relaxation occurs by ‖ΔJ‖=2 transitions, which are the smallest allowed, but there are also single‐collision Energy transfer pathways with ‖ΔJ‖ as large as 20 and ‖ΔE‖ as large as 600 cm−1 (≊3kT). The state‐resolved rate constants for Rotational Energy transfer decrease...
Jacek Koput - One of the best experts on this subject based on the ideXlab platform.
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The vibrational–Rotational Energy levels of silanone
Chemical Physics Letters, 1999Co-Authors: Jacek Koput, Stuart Carter, Nicholas C. HandyAbstract:Abstract The equilibrium structure and 6-dimensional potential Energy surface of silanone, H 2 SiO, has been determined from large-scale ab initio calculations using the coupled-cluster method, CCSD(T), with basis sets of double- through quintuple-zeta quality. The effects of core-electron correlation on the calculated structural parameters have been investigated. The anharmonic force field has been determined. The vibrational–Rotational Energy levels of the molecule have then been calculated using variational and perturbational methods. The calculated molecular properties are in good agreement with experimental data.
