Extended view of the benzene 260-nm transition via single vibronic level fluorescence. I. General aspects of benzene single vibronic level fluorescence

Knight, Alan; Parmenter, C. S.; Schuyler, Michael

doi:10.1021/ja00841a001

Cited by 110 publications

(26 citation statements)

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“…Transitions are vibronically induced in the spectrum if they are of the right symmetry to mix in allowed character from higher-lying electronic states. As Knight, Parmenter, and Schuyler have detailed, 8 a Taylor series expansion of the electric dipole transition moment in terms of the normal coordinates for benzene gives rise to transitions which are first-order, second-order, The benzene-DCl transition is blue shifted from the benzene-HCl transition by 10 cm -I. In (b), the benzene-HCl transitions are also present due to isotopic exchange in our gas handling system.…”

Section: Resultsmentioning

confidence: 80%

The spectroscopy and dynamics of π hydrogen-bonded complexes: Benzene–HCl/DCl and toluene–HCl/DCl

Gotch

Zwier

1990

The Journal of Chemical Physics

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The benzene-HCI/DCl and toluene-HClIDCI complexes have been studied using both fluorescence and multi photon ionization detection. These complexes are prototypical of 1r hydrogen-bonded complexes involved in the chemically important proCeSS of electrophilic aromatic attack. Laser-induced fluorescence (LIF) etalon scans of the 66 rotational band contour are used to determine the SI state geometry of the benzene-HCI as one in which HCl is on the sixfold axis with a center-of-mass separation of 3.64±0.03 A. The lack of significant van der Waals' intensity points to the complex having a hydrogen-bonded geometry similar to that found in the ground state. Dispersed fluorescence scans are used to put crude bounds on the So and SI binding energies of the benzene-HCI complex of 1.8<,Do <, 3.8 kcallmol and 1.5<,D6<,3.5 kcallmol. The fluorescence lifetimes of bound levels of the complexes are factors of 7-12 times shorter than the corresponding levels of the free molecules. In contrast, the C 6 H 6 -CH 3 CI complex, which has a similar geometry and binding energy, has a fluorescence lifetime nearly as long as C 6 H 6 • We argue that the differences observed are consequences of the hydrogen bonding interactions present in benzene-HCI and toluene-HCl. Two-color multiphoton ionization experiments in which the delay between the So-S 1 laser and the ionization lasers is continuously scanned give evidence that the hydrogen bonding interactions lead to enhanced intersystem crossing to the triplet state. One-color RE2PI scans show that fragmentation of the [benzene-HCI] + and [toluene-HCI] + ionic complexes proceeds nearly quantitatively (;;;.98%) from the hydrogen-bonded Sl state. This fragmentation occurs by virtue of the repulsive geometry formed for the ionic complex in Franck-Condon excitation from the SI state.

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Section: Resultsmentioning

confidence: 80%

The spectroscopy and dynamics of π hydrogen-bonded complexes: Benzene–HCl/DCl and toluene–HCl/DCl

Gotch

Zwier

1990

The Journal of Chemical Physics

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“…The vibronic band system of type 6 1 1 n , in which the degenerate 6 (e 2g ) vibration is excited in the 1 B 2u state, is strongly observed by virtue of the intensity-borrowing through Herzberg-Teller coupling between the 1 B 2u and higher-lying 1 E 1u electronic states and favorable Franck-Condon factor for the 1 (a 1g ) mode. 14,15 The 0 0 0 transition in benzene cluster systems can have intensity, since the clustering can induce configurational mixing between the 1 B 2u and 1 E 1u states. In other words, the local environment characterized by ''site'' symmetry less than C 3v loosens the forbidden nature of the transition.…”

Section: Resultsmentioning

confidence: 99%

S 1 –S vibronic spectra of benzene clusters revisited. I. The tetramer

Iimori¹,

Ohshima²

2002

The Journal of Chemical Physics

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“…22 v6, an e2g in-plane ring elongation mode, is first-order allowed, and the 610 transition is one of the most intense vibronic transitions in the spectrum of free benzene. 23 Following complexation to a solvent molecule X, the reduced symmetry of the complex may induce intensity in vibronic transitions in benzene which are otherwise forbidden. ,5-7 In the course of this study, we have developed a more systematic procedure for using these transitions to deduce the symmetry of the complex.…”

Section: Methodsmentioning

confidence: 99%

The Spectroscopy and Photophysics of π Hydrogen‐BondedComplexes: Benzene–CHCl₃

et al. 1994

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A vibronic level study of the spectroscopy and photophysics of the C6H6–CHCl3 complex has been carried out using a combination of laser-induced fluorescence and resonant two-photon ionization (R2PI). In C6H6-CHCl3, the S1–S0 origin remains forbidden while the 1610 transition is weakly induced. Neither 610 nor 1610 are split by the presence of the CHCl3 molecule. On this basis, a C3vstructure is deduced for the complex, placing CHCl3 on the six-fold axis of benzene. The large blue-shift of the complex’s absorption relative to benzene (+178 cm–1) and the efficient fragmentation of the complex following one-color R2PI reflect a hydrogen-bonded orientation for CHCl3 relative to benzene’ π cloud. Dispersed fluorescence scans place a firm upper bound on the ground state binding energy of the complex of 2,024 cm–1. Both the 61and 61 11 levels do not dissociate on the time-scale of the S1 fluorescence and show evidence of extensive state mixing with van der Waals’ levels primarily built on the 00 level of benzene. The C6H6–(CHCl3)2 cluster shows extensive intermolecular structure beginning at +84 cm–1, a strong origin transition, and splitting of 61. A structure which places both CHCl3 molecules on the same side of the benzene ring is suggested on this basis. The vibronic level scheme used to deduce the structure of C6H6–CHCl3 is tested against previous data on other C6H6–X complexes. The scheme is found to be capable, in favorable cases, of deducing the structures of C6H6–X complexes based purely on vibronic level data. Finally, the results on C6H6–CHCl3 are compared with those on C6H6–HCl and C6H6-H2O to evaluate the characteristics of the n hydrogen bond.

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Extended view of the benzene 260-nm transition via single vibronic level fluorescence. I. General aspects of benzene single vibronic level fluorescence

Cited by 110 publications

References 3 publications

The spectroscopy and dynamics of π hydrogen-bonded complexes: Benzene–HCl/DCl and toluene–HCl/DCl

The spectroscopy and dynamics of π hydrogen-bonded complexes: Benzene–HCl/DCl and toluene–HCl/DCl

S 1 –S vibronic spectra of benzene clusters revisited. I. The tetramer

The Spectroscopy and Photophysics of π Hydrogen‐BondedComplexes: Benzene–CHCl₃

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Extended view of the benzene 260-nm transition via single vibronic level fluorescence. I. General aspects of benzene single vibronic level fluorescence

Cited by 110 publications

References 3 publications

The spectroscopy and dynamics of π hydrogen-bonded complexes: Benzene–HCl/DCl and toluene–HCl/DCl

The spectroscopy and dynamics of π hydrogen-bonded complexes: Benzene–HCl/DCl and toluene–HCl/DCl

S 1 –S vibronic spectra of benzene clusters revisited. I. The tetramer

The Spectroscopy and Photophysics of π Hydrogen‐BondedComplexes: Benzene–CHCl3

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The Spectroscopy and Photophysics of π Hydrogen‐BondedComplexes: Benzene–CHCl₃