Microwave Spectrum of Chlorine Dioxide. IV. Determination of Centrifugal Distortion Effects and Potential Constants

Pillai, M. G. Krishna; Curl, R. F.

doi:10.1063/1.1733118

Cited by 66 publications

(6 citation statements)

References 10 publications

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“…In particular, evolution along the symmetric stretch coordinate results in a bond length increase of 0.15 Å, and relaxation along the asymmetric stretch results in a bond-length change of (0.06 Å. The sign of the displacement along the symmetric stretch (i.e., bond elongation) has been established by rotational spectroscopy 24,27,46,47 and is supported by ab initio theoretical work. 35, 36 The experimentally determined double-well potential along the asymmetric stretch can be envisioned as resulting in ClO bond compression or elongation by 0.06 Å such that the combined evolution along both stretch coordinates results in an equilibrium excited-state structure in which ClO bond lengths are unequal.…”

Section: Discussionmentioning

confidence: 66%

“…Numerous investigations on the gas-phase reactivity of OClO have established that in this phase, photoexcitation leads predominately to the formation of ClO and O. 8,9,16,[18][19][20]22,25,26,[45][46][47] The minor reaction pathway corresponding to Cl + O 2 formation is believed to proceed via photoisomerization of OClO to ClOO with subsequent decomposition of this species resulting in product formation. 4,12,28,29,[33][34][35][36] The gas-phase photochemical quantum yield for this process remains the subject of debate with values ranging from 0.15 to ∼0.…”

Section: Introductionmentioning

confidence: 99%

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Excited-State Dynamics of Chlorine Dioxide in the Condensed Phase from Resonance Raman Intensities

et al. 1997

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Resonance Raman spectra of chlorine dioxide (OClO) dissolved in cyclohexane obtained with excitation throughout the 2 B 1 -2 A 2 electronic transition are presented. Resonance Raman intensity corresponding to all vibrational degrees of freedom (the symmetric stretch, bend, and asymmetric stretch) is observed, demonstrating that excited-state structural evolution along all three coordinates occurs upon photoexcitation. The electronic absorption and absolute resonance Raman cross sections are reproduced employing the time-dependent formalism for Raman scattering using an anharmonic description of the 2 A 2 , excited-state potential-energy surface. Analysis of the resonance Raman cross-sections demonstrates that both homogeneous and inhomogeneous broadening mechanisms are operative in cyclohexane. Comparison of the experimentally determined, gas-phase 2 A 2 surface to that in solution defined by the analysis presented here shows that although displacements along the symmetric stretch and bend are similar in both phases, evolution along the asymmetric stretch is dramatically altered in solution. Specifically, employing the gas-phase potential along this coordinate, the predicted intensity of the overtone transition is an order of magnitude larger than that observed. The analysis presented here demonstrates that the asymmetric stretch overtone intensity is consistent with a reduction in excited-state frequency along this coordinate from 1100 to 750 ( 100 cm -1 . This comparison suggests that differences in evolution along the asymmetric stretch may be responsible for the phase-dependent reactivity of OClO. In particular, the absence of substantial evolution along the asymmetric stretch in solution results in the ground-state symmetry of OClO being maintained in the 2 A 2 excited state. The role of symmetry in defining the reaction coordinate and the nature of the solvent interaction responsible for modulation of the excited-state potential energy surface are discussed.

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Section: Discussionmentioning

confidence: 66%

Section: Introductionmentioning

confidence: 99%

Excited-State Dynamics of Chlorine Dioxide in the Condensed Phase from Resonance Raman Intensities

et al. 1997

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“…The equilibrium geometry of ground-state OClO corresponds to ClO bond lengths of 1.471 Å and O-Cl-O bond angle of 117.35°. 70 The displacements along the symmetric stretch (∆ ) 5.63) and bend (∆ ) 0.4) in water correspond to a 2 A 2 excited-state equilibrium geometry with Cl-O bond lengths of 1.68 Å and O-Cl-O bond angle of 108.8°. Since resonance Raman intensities depend on ∆ 2 , the calculation is performed such that the sign of ∆ along the symmetric stretch or bend corresponds to Cl-O bond elongation and reduction of the O-Cl-O bond angle in agreement with both gas-phase experimental and theoretical results.…”

Section: T H I S C O N T E N T Imentioning

confidence: 96%

Excited-State Reaction Dynamics of Chlorine Dioxide in Water from Absolute Resonance Raman Intensities

Foster

Reid

1998

J. Phys. Chem. A

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Resonance Raman spectra of aqueous chlorine dioxide (OClO) are measured for several excitation wavelengths spanning the photochemically relevant 2B1−2A2 optical transition. A mode-specific description of the optically prepared, 2A2 potential energy surface is derived by simultaneous analysis of the absolute resonance Raman and absorption cross sections. The resonance Raman spectra are dominated by transitions involving the symmetric stretch and bend coordinates demonstrating that excited-state structural evolution occurs predominately along these degrees of freedom. Scattering intensity is not observed for transitions involving the asymmetric stretch, demonstrating that excited-state structural evolution along this coordinate is modest. The limited evolution along the asymmetric stretch coordinate results in the preservation of C 2 v symmetry on the 2A2 surface. It is proposed that this preservation of symmetry is responsible for the increase in Cl photoproduct quantum yield in solution relative to the gas phase. Analysis of the absolute scattering cross sections also demonstrates that the homogeneous line width for the 2B1−2A2 optical transition in water is essentially identical to that in cyclohexane; however, the extent of inhomogeneous broadening increases dramatically in aqueous solution. Comparison of the spectroscopic properties of OClO to the properties of isoelectronic O3 - is made to elucidate the origin of the solvent response to OClO photoexcitation. It is suggested that solvent−solute dipole−dipole coupling and intermolecular hydrogen bonding represent the largest components of the solvent coordinate.

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“…The Third-Law method is generally preferred over the van't Hoff (Second-Law method) in analysing equilibrium constant data if molecular constants for the equilibrium species are accurately known. Burkholder et al 11 used molecular constants from Herzberg and Huber 17 and Pillai and Curl 18 for ClO and OClO respectively. Rotational constants and ground electronic state degeneracy of Cl 2 O 3 were obtained from the data of Friedl et al 19 Experimental determinations of the vibrational frequencies of Cl 2 O 3 have yet to be made.…”

Section: The Equilibrium Constant As a Function Of Temperaturementioning

confidence: 99%

A discharge-flow study of Cl2O3

Green¹,

Islam²,

Guest³

et al. 2003

Phys. Chem. Chem. Phys.

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The discharge-flow technique coupled with UV-absorption spectroscopy has been used to study the production of dichlorine trioxide, Cl 2 O 3 , from the reaction between ClO and OClO radicals. The absorption cross section of Cl 2 O 3 was determined to be (1.44 AE 0.10) Â 10 À17 cm 2 molecule À1 at l max ¼ 267 nm (all errors reported are two standard deviations of the statistical error). The equilibrium constant for the process ClO þ OClO þ M Ð Cl 2 O 3 þ M was measured in the temperature range 243-298 K. A Second-Law analysis yielded values of D r H n ¼ À57.9 AE 2.1 kJ mol À1 and D r S n ¼ À132.6 AE 7.9 J K À1 mol À1. The rate coefficient for the formation of Cl 2 O 3 was measured with helium as the third body at a concentration of $7.3 AE 10 16 molecule cm À3 over the temperature range 243-283 K. Analysis of these data employing the conventional form of the rate equation for the low-pressure limit, k 0 (T) ¼ k 0 (300)Á(T/300) Àn , resulted in values of k 0 (300) ¼ (2.83 AE 0.04) Â 10 À32 cm 6 molecule À2 s À1 and n ¼ À4.32 AE 0.1. These spectroscopic, thermochemical and kinetic data are compared with previously reported values.

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Microwave Spectrum of Chlorine Dioxide. IV. Determination of Centrifugal Distortion Effects and Potential Constants

Cited by 66 publications

References 10 publications

Excited-State Dynamics of Chlorine Dioxide in the Condensed Phase from Resonance Raman Intensities

Excited-State Dynamics of Chlorine Dioxide in the Condensed Phase from Resonance Raman Intensities

Excited-State Reaction Dynamics of Chlorine Dioxide in Water from Absolute Resonance Raman Intensities

A discharge-flow study of Cl2O3

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