The kinetics of the two-photon ionization of N,N,N′,N′-tetramethylbenzidine (TMB) in dichloromethane (CH2Cl2)-doped solid argon using 254 nm high-pressure Hg-lamp radiation is investigated by means of UV/VIS absorption spectroscopy. The experimental findings, especially the incomplete running of the ionization reaction, can be quantitatively understood on the basis of a kinetic model which includes dissociative electron attachment to CH2Cl2 and associative photodetachment of the corresponding radical anion. The model implies that the underlying electron transfer reactions reach the photoequilibrium TMB+CH2Cl2⇌hν2hνTMB•++ClHCH•⋯Cl−. The ionization cross-section of TMB in the lowest triplet state, the cross-section of associative photodetachment and the rate constant of cation electron recombination are obtained by adapting calculated to measured irradiation time dependent concentrations of the radical cation.

The kinetics of the two-photon ionization (TPI) of N,N,N′,N′-tetramethylbenzidine (TMB) in CH2Cl2-doped solid argon using 313 nm Hg lamp radiation is investigated by means of ultraviolet/visible (UV/VIS) absorption spectroscopy. The experimental findings can be quantitatively understood on the basis of a rate equation model. The ionization cross-section of TMB in the lowest triplet state and the rate constant of cation–electron recombination are obtained by adapting calculated to measured irradiation time-dependent concentrations of the cation.

Persistent contact ion pairs (CIPs) have been obtained by one-photon-induced electron transfer from N,N,N′,N′-tetramethyl-p-phenylenediamine (TMPD) to tetrachloromethane (CCl4) in solid argon, in addition to TMPD⋅+ free radical cations (FRCs) generated by two-photon ionization of TMPD as the primary process. The first UV/VIS absorption band of the CIPs is tentatively explained on the basis of the corresponding band of the FRCs.

A preceding study on persistent contact ion pairs (CIPs) which had been produced by Hg lamp irradiation of solid argon doped with N,N,N′,N′-tetramethyl-p-phenylenediamine and tetrachloromethane is extended to N,N,N′,N′-tetramethylbenzidine as a further donor and xenon as an additional solid medium. Experimental and theoretical ultraviolet/visible absorption spectroscopic and photokinetic investigations as well as energetic considerations lead to a more detailed understanding of the formation and properties of the CIPs.

Fluorescence spectroscopic studies have been performed on the radical cations of tetrathiafulvalene (TTF), 4,4′-dimethyl-5,5′-diphenyltetrathiafulvalene (DMDP–TTF), bis-(4,5-dihydronaphtho-[1,2d]-tetrathiafulvalene) (BDHN–TTF) and bis-(ethylenedithio)-tetrathiafulvalene (BEDT–TTF) in low-temperature organic glasses. For the first time emission and excitation spectra have been obtained for radical cations of this class of compounds. Only in the case of BEDT–TTF·+ fluorescence could not be detected. The luminescence spectra have been related to the corresponding UV/Vis/NIR absorption spectra and absorption data obtained using the LNDO/S PERTCI method. For DMDP–TTF·+ the fluorescence lifetime (1.09 ns) has been measured and the fluorescence quantum yield (5×10−3) has been estimated.

Photoionization of N,N,N′,N′-tetramethyl-p-phenylenediamine in CCl4- and CH2Cl2-doped solid argon using 313 (3.96) and 254 nm (4.88 eV) Hg lamp radiation, respectively, has been studied by UV/Vis absorption spectroscopy. According to the observed relation between the radical cation production and applied light intensity, the ionization proceeds as a sequential two-photon process.

The electron attachment products of CCl4 due to photoinduced electron transfer (using the 4.88 eV photons of a Hg lamp) from N,N-dimethylaniline and N,N,N′,N′-tetramethyl-p-phenylenediamine were investigated by FTIR spectroscopy in solid argon along with extensive ab initio calculations. Two attachment products have been detected by IR spectroscopy for the first time, i.e. the anions of CCl4 and CCl3, which are characterized by the complex structures Cl2CCl··Cl− and ClCCl·Cl−, respectively.

The nature and structure of electron attachment products in the photoinduced electron transfer reaction DMA + CH2Cl2→hvDMA+ + (electron attachment products) in solid argon has been studied by FTIR spectroscopy (DMA = N,N-dimethylaniline, hν = 4.88 eV Hg lamp radiation) along with extensive ab initio calculations. Two attachment products have been identified: the radical anion of CH2Cl2 and the dichloromethane anion (HCCl2−. The radical anion turns out to have a C1 hydrogen bridged structure (ClHCH…Cl−1). This structure as well as the species of HCCl2− have not been detected before.

Electron correlation effects on the electronic structure of atoms were investigated by means of a variety of position and momentum space related properties such as radial one-electron densities and radial electron momentum densities, Compton profiles and radial electron pair distributions. The results were obtained from MR-SDCI wavefunctions utilizing very large basis sets and are discussed in a comparative manner, analysing characteristic features and trends.

Inelastic (or X-ray incoherent) scattering factors for Li to Ar are presented which take into account electron correlation to a large extent. The scattering factors were derived from MR-SDCI (multi-reference singly and doubly excited configuration interaction) calculations which recover between 90 and 99% of the estimated total correlation energy. Experimental high-energy electron and X-ray scattering cross sections available for Ne and Ar are compared with the corresponding calculated results.

The kinetics of the photobleaching process o-thiobenzoquinone methide (1) → benzo[b]thiete (2), i.e. the forward reaction of the optically switchable 1⇌2 system, in a solid argon layer has been investigated experimentally by measuring the time-dependent photon flux density (photon irradiance) of the transmitted photolysis light. A kinetic model is presented which simultaneously accounts for both the anisotropy of the light absorption and variation of the photon flux density in the layer with position and time. Good agreement between theory and experiment is achieved.

High-energy electron and X-ray scattering cross-sections of O2, F2, CO and CO2 have been calculated within the framework of the first Born approximation from MR-SDCI wavefunctions recovering up to 92% of the estimated correlation energy. In contrast to the fair agreement found for X-ray scattering cross-sections, comparison with available experimental data shows large deviations in the case of electron scattering. Possible causes for the observed discrepancies are discussed.

The LNDO/S PERTCI method for treating vertical valence electronic transitions and ionizations of chiefly organic molecules has been reparametrized for molecules containing N and O atoms and extended to systems containing F and S atoms including d AOs for sulfur. The quality of results is statistically judged on utilizing appropriate groupings of the transitions and ionizations considered.

ChemInformVolume 21, Issue 1 Physical Organic Chemistry ChemInform Abstract: 1,2-Dithiete is More Stable than 1,2-Dithioglyoxal as Evidenced by a Combined Experimental and Theoretical IR Spectroscopic Approach. F. DIEHL, F. DIEHL Fachbereich Phys. Chem., Univ. Marburg, D-3550 MarburgSearch for more papers by this authorH. MEYER, H. MEYER Fachbereich Phys. Chem., Univ. Marburg, D-3550 MarburgSearch for more papers by this authorA. SCHWEIG, A. SCHWEIG Fachbereich Phys. Chem., Univ. Marburg, D-3550 MarburgSearch for more papers by this authorB. A. JUN. HESS, B. A. JUN. HESS Fachbereich Phys. Chem., Univ. Marburg, D-3550 MarburgSearch for more papers by this authorJ. FABIAN, J. FABIAN Fachbereich Phys. Chem., Univ. Marburg, D-3550 MarburgSearch for more papers by this author F. DIEHL, F. DIEHL Fachbereich Phys. Chem., Univ. Marburg, D-3550 MarburgSearch for more papers by this authorH. MEYER, H. MEYER Fachbereich Phys. Chem., Univ. Marburg, D-3550 MarburgSearch for more papers by this authorA. SCHWEIG, A. SCHWEIG Fachbereich Phys. Chem., Univ. Marburg, D-3550 MarburgSearch for more papers by this authorB. A. JUN. HESS, B. A. JUN. HESS Fachbereich Phys. Chem., Univ. Marburg, D-3550 MarburgSearch for more papers by this authorJ. FABIAN, J. FABIAN Fachbereich Phys. Chem., Univ. Marburg, D-3550 MarburgSearch for more papers by this author First published: January 2, 1990 https://doi.org/10.1002/chin.199001046AboutPDF 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 onFacebookTwitterLinkedInRedditWechat No abstract is available for this article. Volume21, Issue1January 2, 1990 RelatedInformation

Semiempirical valence electron calculations using the CNDO/S SECI, HAM/3 Cl, LNDO/S PERTCI, MNDOC PERTCI, and MNDO/S PERTCI methods have been applied to the interpretation of the recently reported UV/vis absorption spectrum of transiento-benzyne. Detailed calculations were performed for benzene,o-benzyne, cyclopentadienylidenecarbene, cyclopentadienylideneketene, and cyclopentadienylideneketone (6-fulvenone). From these calculations and experimental data for benzene,o-benzyne, and cyclopentadienylideneketone, an interpretation of the electronic absorption spectrum ofo-benzyne is proposed. The interpretation includes the proposal that the first band and a part of the third band originally assigned too-benzyne may be due to cyclopentadienylideneketene, a common byproduct (or intermediate) of the photolyses of benzocyclobutenedione and 3-diazobenzofuranone.

ChemInformVolume 21, Issue 1 Physical Organic Chemistry ChemInform Abstract: The Electronic Spectrum of o-Benzyne. Experiment and Theory, a Critical Evaluation A. SCHWEIG, A. SCHWEIG Fachbereich Phys. Chem., Univ. Marburg, D-3550 MarburgSearch for more papers by this authorN. + MUENZEL, N. + MUENZEL Fachbereich Phys. Chem., Univ. Marburg, D-3550 MarburgSearch for more papers by this authorH. MEYER, H. MEYER Fachbereich Phys. Chem., Univ. Marburg, D-3550 MarburgSearch for more papers by this authorA. HEIDENREICH, A. HEIDENREICH Fachbereich Phys. Chem., Univ. Marburg, D-3550 MarburgSearch for more papers by this author A. SCHWEIG, A. SCHWEIG Fachbereich Phys. Chem., Univ. Marburg, D-3550 MarburgSearch for more papers by this authorN. + MUENZEL, N. + MUENZEL Fachbereich Phys. Chem., Univ. Marburg, D-3550 MarburgSearch for more papers by this authorH. MEYER, H. MEYER Fachbereich Phys. Chem., Univ. Marburg, D-3550 MarburgSearch for more papers by this authorA. HEIDENREICH, A. HEIDENREICH Fachbereich Phys. Chem., Univ. Marburg, D-3550 MarburgSearch for more papers by this author First published: January 2, 1990 https://doi.org/10.1002/chin.199001048Read the full textAboutPDF 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, Issue1January 2, 1990 RelatedInformation

The electronic absorption spectra of benzo[b]thiete (1) and of transient o-thiobenzoquinonemethide (2) have been obtained. Semiempirical valence-electron calculations using the CNDO/S SECI, CNDO/S PERTCI and LNDO/S PERTCI methods and correlation diagrams using suitable reference compounds ad aniline, thiophenol, thioanisole, all-trans-octatetraene and o-xylylene are applied to the interpretation of the spectra. The results clearly reveal 1 as a typically donor-substituted benzene derivative and 2 as a polyene-like system closely related to o-xylylene.

Calculated electron pair distributions are presented for a series of small molecules, namely C2H2, N2, CO, O2 and F2, taking electron correlation and chemical binding effects into account. A novel empirically founded procedure is proposed for estimating the electron repulsion energy of a molecule from its one-electron density in a rather accurate way.

Differential cross sections for high-energy electron and X-ray scattering on H2O and NH3 molecules have been calculated in the first Born approximation using approximate Hartree—Fock and configuration-interaction wavefunctions. For non-linear molecules, the first theoretical inelastic and total cross sections with explicit inclusion of electron correlation are presented. A comparison between the theoretical and experimental scattering functions is made. Apart from minor discrepancies which can be due to deficiencies in the theoretical as well as the experimental procedures, agreement between theory and experiment is satisfactory.

Polyatomic vibrational effects on electron-molecule scattering have been studied by approximate Hartree-Fock calculations in the first Born approximation on the normal vibrational modes of H2O in the ground state. The harmonic and anharmonic effects, which are discussed in detail are small, lending credence to the practice of comparing cross sections calculated at a fixed geometry with (averaged) experimental data.