Chlorobenzene Cation Research Articles

Assignment of the B̃+ State of the Chlorobenzene Cation Using Photoinduced Rydberg Ionization (PIRI) Spectroscopy

The photoinduced Rydberg ionization (PIRI) spectra of the B̃+ state of the chlorobenzene cation were recorded via the origin, 6b, and 16a16b vibrations of the cation ground state (X̃+). The resonance-enhanced multi photon dissociation spectroscopy (REMPD) spectrum of the B̃+←X̃+ transition of the chlorobenzene cation was also obtained. To date it has been thought that B̃+←X̃+ is an electronically forbidden transition (C2v symmetry), taking place from the 2B1 ground state to a 2B2 excited state. The ability of PIRI to provide spectra from specific lower-state vibrational levels allowed this hypothesis to be tested, because the 16a vibration would be the primary inducing mode in the transition. Assuming a forbidden transition, a comparison between the spectrum from the ground-state origin and that from the 16a16b vibration would necessitate an assignment that gives unlikely vibrational frequencies. It is therefore concluded that the B̃+←X̃+ transition of chlorobenzene is electronically allowed. Configuration interaction of singles (CIS) and complete active space multiconfigurational self-consistent field (CASSCF) calculations with 6-31G** basis sets were performed to ascertain the symmetry assignments of the excited ionic states. These calculations resulted in the possibility that at least one excited state of the cation of 2B1 symmetry lies below any state of 2B2 symmetry. Hence, we propose that the ionic transition observed in the acquired PIRI/REMPD spectra of the cation is an allowed transition to a 2B1 state, thus giving rise to the observation of the origin of the B̃+ state at 18 219 cm-1.

Two-color threshold photoionization spectroscopy of chlorobenzene- h5 and chlorobenzene- d5

The photoionization efficiency spectra of chlorobenzene- h 5 and chlorobenzene- d 5. have been obtained by two-color laser photoionization spectroscopy. The spectra consist of direct ionization steps and display Franck-Condon-like behavior. The adiabatic ionization energies of the two species have been determined to be almost identical (73176±10 cm −1) indicating similar stability of the molecular structure of the ground neutral and ion states. In addition, some precise frequencies of vibrational modes of the ground state chlorobenzene cation have been measured.

Characterization of the B̃←X̃ transition of the chlorobenzene cation prepared in non-equilibrium rotational population distributions by resonance-enhanced multiphoton ionization

The technique of resonance-enhanced multiphoton ionization has been used to prepare the chlorobenzene cation in a series of different non-equilibrium rotational population distributions in its ground state. The ion is probed by a second laser leading to dissociation into fragments detected mass spectrometrically. The varied rotational contours resulting from this experiment provide valuable extra information for characterization of the ion transition.

Unimolecular decay rates for laser induced Cl loss from energy selected chlorobenzene cations

Abstract The unimolecular dissociation rates for chlorobenzene cations with selected internal energy have been determined with 5% precision within a range between 3 × 10 5 and 1.5 × 10 6 s −1 . The ions have been formed by resonance-enhanced two-photon ionization. The kinetics of the laser induced fragmentation has been studied by fragment shape analysis in a time-of-flight mass spectrometer. The high precision of the measurements is due to improvement in the working conditions and data analysis. The rate energy dependence has been critically compared with the results of previous one- and multiphoton studies. From Rice-Rampsperger-Kassel-Marcus calculations, the activation energy and entropy for the dissociation process of the chlorobenzene cation have been determined. The value of the heat of formation of C 6 H + 5 deduced from E 0 is 259.5 kcal mol −1 .

ChemInform Abstract: Unimolecular Dissociation Rate Constants: Chlorobenzene Cations Revisited by Using a New Method.

ChemInformVolume 21, Issue 33 Preparative Organic Chemistry ChemInform Abstract: Unimolecular Dissociation Rate Constants: Chlorobenzene Cations Revisited by Using a New Method. R. J. STANLEY, R. J. STANLEY Dep. Chem., Pa. State Univ., University Park, PA 16802, USASearch for more papers by this authorM. COOK, M. COOK Dep. Chem., Pa. State Univ., University Park, PA 16802, USASearch for more papers by this authorA. W. JUN. CASTLEMAN, A. W. JUN. CASTLEMAN Dep. Chem., Pa. State Univ., University Park, PA 16802, USASearch for more papers by this author R. J. STANLEY, R. J. STANLEY Dep. Chem., Pa. State Univ., University Park, PA 16802, USASearch for more papers by this authorM. COOK, M. COOK Dep. Chem., Pa. State Univ., University Park, PA 16802, USASearch for more papers by this authorA. W. JUN. CASTLEMAN, A. W. JUN. CASTLEMAN Dep. Chem., Pa. State Univ., University Park, PA 16802, USASearch for more papers by this author First published: August 14, 1990 https://doi.org/10.1002/chin.199033104AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article. Volume21, Issue33August 14, 1990 RelatedInformation

Unimolecular dissociation rate constants: chlorobenzene cations revisited by using a new method

Unimolecular dissociation rates of metastable molecular ions formed at the laser focus of a time-of-flight mass spectrometer (TOFMS) have been determined by measuring the relative concentrations of «parent» metastable ions and the «daughter» fragment ions as a function of their retained kinetic energies upon dissociation. This is accomplished by the use of a simple one-stage ion mirror/energy analyzer. For a given reflection potential on the ion mirror, only those ions with a kinetic energy equal to or less than the reflection potential are detected

Rotational band contours from non-equilibrium energy distributions: Application to chlorobenzene and chlorobenzene cation

A computer program PROFIL has been written for the computation of rotational band contours of asymmetric rotor molecules prepared under non-equilibrium, adiabatic conditions, with a rotational energy distribution that is far from the Boltzmann distribution. The resulting contours differ markedly from the more familiar equilibrium contours. To illustrate the use of the program, we present data from an experiment in which chlorobenzene cations are produced with a non-equilibrium rotational energy distribution, and which are then excited to produce a spectrum with bands having a rotational contour, characteristic of that energy distribution.

Rotational band contour analysis in the B̃←X̃ system of chlorobenzene cation prepared by resonance enhanced multiphoton ionization

The rotational structure of some vibronic bands of the B̃←X̃ system of the chlorobenzene cation (φCl +) has been studied by computation of rotational band contours. For the first time contours for ions prepared by resonance enhanced multiphoton ionization (REMPI), with a restricted (or non-equilibrium) rotational excitation have been analysed. Using the mass selectivity of the REMPI method, the relative contributions from the two principal isotopes 35Clφ and 37Clφ have been taken into account. For this purpose the excited state rotational constants of 37Clφ have been determined. The ionic bands are shown to be A type which agrees with our vibrational assignments.

Ion trap method combined with two-color laser spectroscopy of supersonic molecular beams: Photodissociation of trapped C 6H 5Cl +

The cylindrical ion trap (CIT) method has been applied to two-color laser spectroscopy in combination with supersonic molecular beams. Ions generated by resonant multiphoton ionization of chlorobenzene with a nanosecond-pulsed dye laser were stored in a CIT cell for more than 10 ms after the ionization. With this technique the photodissociation of the selectively trapped chlorobenzene cation was observed by using a second dye laser. The yield spectrum of the dissociation to phenyl radical cation was obtained under the ideal condition of no background fragments.

Absorption Spectra of Benzene Cation Radical, Chlorobenzene Cation Radical, and Fluorobenzene Cation Radical in Perfluorocarbon Polymer Film at 77K

Abstract Absorption spectra of benzene cation radical, chlorobenzene cation radical, and fluorobenzene cation radical have been obtained in perfluorocarbon polymer at 77 K. Cation radicals are formed in good yields and less perturbed electronic absorption spectra are obtained. Results demonstrate that perfluorocarbon polymer is suitable as matrix for spectroscopic investigation of the cation radicals formed by γ-irradiation.

Resonance-enhanced multiphoton dissociation spectroscopy of the forbidden B̃←X̃ transition of the gas phase chlorobenzene cation

Well-resolved absorption spectra of the B̃←X̃ forbidden transition of the chlorobenzene cation have been obtained for the first time by two-photon induced dissociation of the ground state ion. The φ + fragment ions are detected with a time-of-flight mass spectrometer. The wavelength dependence of the fragment ion yield reflects the spectroscopy of the φCl + B̃ intermediate state reached by the first photon. Chlorobenzene cations are formed by resonance-enhanced two-photon ionization (R2PI) process. B̃←X̃ vibronic transitions are observed due to vibronic interactions between the nearby B̃ and C̃ states. A preliminary analysis of the spectra is proposed.

ChemInform Abstract: UNIMOLECULAR DISSOCIATION RATES OF THE CHLOROBENZENE CATIONS PREPARED BY MULTIPHOTON IONIZATION

Chemischer InformationsdienstVolume 15, Issue 27 Preparative Organic Chemistry ChemInform Abstract: UNIMOLECULAR DISSOCIATION RATES OF THE CHLOROBENZENE CATIONS PREPARED BY MULTIPHOTON IONIZATION J. L. DURANT, J. L. DURANTSearch for more papers by this authorD. M. RIDER, D. M. RIDERSearch for more papers by this authorS. L. ANDERSON, S. L. ANDERSONSearch for more papers by this authorF. D. PROCH, F. D. PROCHSearch for more papers by this authorR. N. ZARE, R. N. ZARESearch for more papers by this author J. L. DURANT, J. L. DURANTSearch for more papers by this authorD. M. RIDER, D. M. RIDERSearch for more papers by this authorS. L. ANDERSON, S. L. ANDERSONSearch for more papers by this authorF. D. PROCH, F. D. PROCHSearch for more papers by this authorR. N. ZARE, R. N. ZARESearch for more papers by this author First published: July 3, 1984 https://doi.org/10.1002/chin.198427106AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article. Volume15, Issue27July 3, 1984 RelatedInformation

Unimolecular dissociation rates of the chlorobenzene cation prepared by multiphoton ionization

We have studied the unimolecular reaction C6H5Cl+→C6H+5 +Cl as a function of internal energy by using multiphoton ionization (MPI) on a supersonically cooled jet of chlorobenzene to prepare the excited parent ion. Specific rate constants k(E) were obtained from an analysis of the distorted C6H+5 peak shape in a time-of-flight (TOF) mass spectrometer. Decomposition in the wavelength region 265–270 nm is shown to proceed by two-photon ionization followed by one-photon absorption. The internal energy of the excited parent ion is characterized in a separate experiment which measures the photoelectron kinetic energy distribution, obtained over the same wavelength range. The specific rate constants found in this study compare well with previous literature values, thus validating this MPI TOF technique for the determination of ion decomposition rates.