Mass-selective two-color photoionization of benzene clusters

Hopkins, J. B.; Powers, D. E.; Smalley, R. E.

doi:10.1021/j150625a003

Cited by 229 publications

(132 citation statements)

References 4 publications

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“…Given the fact that the basis functions in eqn (7) are already adapted to C 6 (M) A #C 6 (M) B by choosing a specific combination of k A and k B (modulo 6) values, it is easy to use the relations in eqn (8) to construct a set of projection operators that produce symmetry-adapted basis functions for all irreps of G 576 . We use the so-called Wigner or matrix-element Table 3 Effect of the G 576 group generators on the angular coordinates defined in the text Table 4 Projection operators and k A , k B values for the G 576 irreps …”

Section: B Symmetry Adaptationmentioning

confidence: 99%

“…The partners in a symmetry-adapted basis carrying a multi-dimensional irrep yield the same energies. If needed, the partner wave functions can be obtained by the action of those generators in eqn (8) that are not contained in the projectors in Table 4. Operating with these projectors on the basis functions of eqn (7), with the application of eqn (8), yields the symmetry-adapted basis functions for all G 576 irreps.…”

Section: B Symmetry Adaptationmentioning

confidence: 99%

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Vibration–rotation-tunneling states of the benzene dimer: an ab initio study

Avoird

Podeszwa

Szalewicz

et al. 2010

Phys. Chem. Chem. Phys.

152

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An improved intermolecular potential surface for the benzene dimer is constructed from interaction energies computed by symmetry-adapted perturbation theory, SAPT(DFT), with the inclusion of third-order contributions. Twelve characteristic points on the surface have been investigated also using the coupled-cluster method with single, double, and perturbative triple excitations, CCSD(T), and triple-zeta quality basis sets with midbond functions. The SAPT and CCSD(T) results are in close agreement and provide the best representation of these points to date. The potential was used in calculations of vibration-rotation-tunneling (VRT) levels of the dimer by a method appropriate for large amplitude intermolecular motions and tunneling between multiple equivalent minima in the potential. The resulting VRT levels were analyzed with the use of the permutation-inversion full cluster tunneling (FCT) group G 576 and a chain of subgroups that starts from the molecular symmetry group C s (M) of the rigid dimer at its equilibrium C s geometry and leads to G 576 if all possible intermolecular tunneling mechanisms are feasible. Further information was extracted from the calculated wave functions. It was found, in agreement with the experimental data, that for all of the 54 G 576 symmetry species (with different nuclear spin statistical weights) the lower VRT states have a tilted T-shape (TT) structure; states with the parallel-displaced structure are higher in energy than the ground state of A + 1 symmetry by at least 30 cm À1 . The dissociation energy D 0 equals 870 cm À1 , while the depth D e of the TT minimum in the potential is 975 cm À1 . Hindered rotation of the cap in the TT structure and tilt tunneling lead to level splittings on the order of 1 cm À1 . Also intermolecular vibrations with excitation energies starting at a few cm À1 were identified. A further small, but probably significant, level splitting was assigned to cap turnover, although in scans of the potential surface we could not find a plausible 'reaction path' for this process. Rotational constants were extracted from energy levels calculated for total angular momentum J = 0 and 1, and from expectation values of the inertia tensor. Although the end-over-end rotational constant B + C agrees well with the measured microwave spectra, there is disagreement with the measurements concerning the (a)symmetric rotor character of the benzene dimer. It is concluded from calculations for the 54 nuclear spin species that the microwave spectrum should show overlapping contributions from many different species. Another interesting conclusion regards the role of the quantum number K, for a prolate near-symmetric rotor the projection of the total angular momentum on the prolate axis. For the benzene dimer, K has a substantial effect on the energy levels associated with the intermolecular motions of the complex.

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Section: B Symmetry Adaptationmentioning

confidence: 99%

Section: B Symmetry Adaptationmentioning

confidence: 99%

Vibration–rotation-tunneling states of the benzene dimer: an ab initio study

Avoird

Podeszwa

Szalewicz

et al. 2010

Phys. Chem. Chem. Phys.

152

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“…2-color HS data have already been published for benzene clusters, 8 and this same energy vas employed for h 6 :h 8 Using an ionization beam wavelength of 2789 _ for h and do :h""n fragmentation was observed. This observation suggests that the binding energy of (h%:h 6 )* is sore than 2200 cm-1.…”

Section: Ionization Energy Dependencementioning

confidence: 99%

Dimers of aromatic molecules: (Benzene)2, (toluene)2, and benzene–toluene

Law¹,

Schauer²,

Bernstein³

1984

The Journal of Chemical Physics

210

137

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The optical absorption spectra of the first excited singlet states of the benzene, toluene, and toluene–benzene dimers, created in a supersonic molecular jet, are reported. The absorption spectra are detected through two-color time of flight mass spectroscopy; this method eliminates fragmentation of dimers and higher clusters and the dimer spectra are uniquely observed. The benzene dimer observed in this experiment is suggested to have a parallel stacked and displaced configuration of C2h symmetry. Both the toluene and toluene–benzene dimers have two configurations: parallel stacked and displaced [based on (benzene)2] and perpendicular. (Benzene)2, (toluene)2, and toluene–benzene form excimers in the excited state for the parallel stacked displaced configurations. The transformation of (benzene)2 to the excimer takes place at the 00 with a ∼0 cm−1 barrier while the excimer is formed for toluene–benzene with a ∼900 cm−1 barrier. An exciton analysis of the (benzene)2 000 and 610 yields M12, the excitation exchange interaction, equal to ∼1.6 cm−1.

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“…The lack of homogeneous nucleation in Ben(C 2 H 6 ) 2 and Ben(C Hs) 2 indicates that the number of solvent monomers relative .. to dimers and larger solvent clusters is probably small for ethane and propane solvents. However, based on the calculated binding energies the relative number of methane monomers should also be small.…”

Section: Simentioning

confidence: 99%

“…Minimum energy geometries of Ben C 5 H 8 1 1 and Ben(C H 8) 2 ' Atomic positions are given in Table IX. Note that the 3-fold symmetry of benzene is nearly preserved by the atoms closest to benzene for both 'S species.…”

Section: Figurementioning

confidence: 99%

Molecular jet study of the solvation of benzene by methane, ethane, and propane

Schauer

Bernstein

1985

The Journal of Chemical Physics

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: :86 2 1 9 00 5 SECURITY CLASSIFICATION OF THIS PAGE (Wen SCHEDULE DISTRIBUTION STATEMENT (of this Report)This document has been approved for public release and sale; its ,.distribution is unlimited. ..'Two color time of flight mass spectroscopy studies of benzene solvated by methane, ethane, and propane in a molecular jet _ha' been carried out. Absorption ha. been characterized for'both the 0 and 61transitions of benzene (alkane)x(X=1,2,3...). Atom-atom exponential-6 potentials have been employed to calculate cluster geometry and binding energy. Comparisons between calculations and experiments allow the identification of specific configurations for the " cluster spectroscopic transitions. Cluster spectral shifts can also be identified and a correlation between the size of the cluster red shift and geometry .

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Mass-selective two-color photoionization of benzene clusters

Cited by 229 publications

References 4 publications

Vibration–rotation-tunneling states of the benzene dimer: an ab initio study

Vibration–rotation-tunneling states of the benzene dimer: an ab initio study

Dimers of aromatic molecules: (Benzene)2, (toluene)2, and benzene–toluene

Molecular jet study of the solvation of benzene by methane, ethane, and propane

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