Rotationally Resolved Intramolecular Processes in Benzene

Neusser, H. J.; Schubert, Ulrich S.; Riedle, Eberhard; Kiermeier, A.; Kühlewind, H.; Schlag, E. W.

doi:10.1002/bbpc.198800069

Cited by 8 publications

(6 citation statements)

References 25 publications

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“…From Table II it is also seen that the theo- .. 2,12),( 14, 2,13) Quartic constants: (4,10,14,16), (5,10,14,17), (5,10,15,16) Coupling to 6 2 111 states i= 6 to 9: (6,6,i) i=6t09andj= 16 and 17: l1,j) i= 6 to 9 andj= 18 to 20: 14 contributing via an off-resonance in the coupling of these states. The present interpretation in terms of a perpendiculartype Coriolis coupling, involving (x,y) axes of rotation, is consistent with the experimental fact, noted by Neusser and co-workers, 7 that the splitting at the avoided crossing from different K 's varies with J in a way characteristic of a perpendicular Corio lis coupling, namely it varies as…”

Section: Discussionsupporting

confidence: 92%

“…Choosing e = 16 with r(QI6) = e 2u and r(QIO) = elg, then in kede the irreducible representation for the direct product r(Qe) ® r(Qd) ® r(Qe) = e lu ®e lg ®e 2u is a lg + a 2g + 3e 2g , which contains an al g component, ensuring that kede is not zero by symmetry. The four values of bC6, 7,8,9), together with the three values of c(l8, 19,20), indicates 12 independent, nonzero products kabekede;~J from this source.…”

Section: F2au a Qb(tb·mentioning

confidence: 97%

“…This (x,y) Coriolis coupling, a consequence of the selected states and the symmetry requirements, is supported later by experiment. 7 Due to symmetry present in a C N operation about the principal symmetry axis the following selection rule applies for coupling between two zeroth-order states for a symmetric top61:…”

Section: Contact Transformation Theory and Applicationmentioning

confidence: 99%

“…81 Noting that rCQs) = b 2g it is found that r( Qb) = e 2g . Thereby, it follows that b is restricted to being 6, 7,8,9 for a nonzero ;~J' Considering kabe next, there are three possible values of a, namely, 10, 14, and 16. Choosing a = 14 (similar reasoning would follow for the remaining two choices) then for r C Qa ) ® r C Qb ) ® r C Qe ) to have an a lg component,84 noting that rCQa) = r(QI4) = b 2u and, it was seen, r( Qb) = e 2g , it follows 81 that r( Qe) = e lu ' Thereby,7 = 18,19,20.…”

Section: F2au a Qb(tb·mentioning

confidence: 99%

“…Since the excess vibrational energy for the 141 state is only 1570 cm -I, the possibility of only a few "final" dark states being implicated in causing the spectral perturbations is a real one. 7 In Sec. II A the Hamiltonian for the higher order vibration-rotation interactions relevant to the 141 state are given.…”

Section: Introductionmentioning

confidence: 99%

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Theory of anharmonically modified Coriolis coupling in the S1 state of benzene and relation to experiment

Helman

Marcus

1991

The Journal of Chemical Physics

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A voided crossings between quasidegenerate rovibrational states in the Doppler-free twophoton excitation of the 141 mode in the SI excited state of benzene are treated theoretically. Two sets of avoided crossings in plots of spectral line frequency vs J at a given K and !::J( have been reported experimentally between an initially prepared "light" state (14 1 in zeroth order) and dark states, namely, one which in zeroth orderis a 5 1 10 1 16 1 state, the other being in zeroth order a 6 2 111 and/or possibly a 3 1 16 1 state, implicated earlier by Neusser et al. The identification of these states makes the phenomenon an excellent candidate for treatment of the avoided crossing via a Van Vleck transformation, no other basis set states being needed for the diagonalization in order to extract the important features. Two successive transformations are used for handling direct coupling and coupling via virtual states. The dominant calculated contribution to the coupling is, jointly, Coriolis plus cubic--cubic anharmonic interactions between vibrational modes. Playing less of a role are Coriolis terms in which the inverse moment of inertia tensor is expanded up to quadratic terms in the coordinates. There results a 5 X 5 (for coupling to 5 1 10 1 16 1 ) and a 3 X 3 (for coupling to 6 2 111 or 3 1 16 1 ) matrix of the transformed Hamiltonian, each of which can also be described, if desired, to a very good approximation by a 2 X 2 matrix. The coupling element Vo and the difference of the rotational constants for the light and dark states (AB) are obtained from the plots of line position vs J(J + 1) obtained. For the 141 to 5 1 10 1 16 1 and for the 141 to 6 2 111 couplings the theoretical results are in reasonable agreement with the experimental results, no adjustable parameters being employed. For a coupling of 141 to 3 1 16 1 the calculated Vo would be much too high compared with experiment (a factor of 10), the coupling involving the exchange of only three instead off our vibrational quanta. A situation in which the 141 state is coupled to the 6 2 111 state to yield an avoided crossing and off-resonantly coupled to the 3 1 16 1 state would be consistent with some experimental results and not affect the reasonable agreement of the slope difference and splitting for the avoided crossing plots. 872 J. Chem. Phys. 95 (2), 15

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Section: Discussionsupporting

confidence: 92%

Section: F2au a Qb(tb·mentioning

confidence: 97%

Section: Contact Transformation Theory and Applicationmentioning

confidence: 99%

Section: F2au a Qb(tb·mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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