摘要:

Coupling is considered between the lower3B1uand3E1ustates of benzene under the combined influence of substituents and the crystal field. A model is derived in which the value of the E.S.R. parameterE, the orientation of the zero-field axes relative to the molecular frame and the radiative properties of the upper two spin components of the lowest triplet state are interpreted in terms of an electronic wavefunction.

ISSN:0026-8976    

DOI:10.1080/00268977700101281

出版商:Taylor & Francis Group    

年代:1977

数据来源: Taylor

摘要:

The phosphorescence spectrum ofp-xylene-h10in ap-xylene-d10host is first presented. Secondly we report E.S.R. experiments performed onp-xylene-α,α′-d6inp-xylene-d10; from an analysis of the orientations of the principal axes in combination with the crystal structure and of the hyperfine splittings it is concluded that the in-plane principal axes of the zfs tensor make an angle of 68° with the molecular axes. Thirdly we discuss Microwave-Induced Delayed Phosphorescence (MIDP) experiments onp-xylene-h10inp-xylene-d10in which the relative radiative rate constants for decay from the zero-field spin components of the triplet state to single vibronic bands of the ground state have been obtained.

ISSN:0026-8976    

DOI:10.1080/00268977700101291

出版商:Taylor & Francis Group    

年代:1977

数据来源: Taylor

摘要:

E.S.R. experiments performed at 1·3 K by optical detection are reported for the photo-excited triplet state of palladiumporphin in a single crystal ofn-octane, and the observation of a level anticrossing signal is described.

ISSN:0026-8976    

DOI:10.1080/00268977700101301

出版商:Taylor & Francis Group    

年代:1977

数据来源: Taylor

摘要:

Force constants have been calculated for H2NF and HNF2fromab initioHartree-Fock wavefunctions by the force method, using 7s3p/1 gaussian basis sets. The force field of HNF2, obtained from a combination of the theoretical results with the experimental frequencies, can be considered as the most reliable one at present. Previous force fields are discussed critically. From a full optimization the predicted geometry of H2NF is: NF = 1·399 Å, NH = 1·018 Å, HNF = 102·9° and HNH = 105·9°.

ISSN:0026-8976    

DOI:10.1080/00268977700101311

出版商:Taylor & Francis Group    

年代:1977

数据来源: Taylor

摘要:

This paper describes and illustrates the characteristic types of rotational fine structure found in vibrational Raman bands of asymmetric top molecules. The first section contains a brief summary of the relevant theory leading to a formulation of the selection rules governing Raman spectra of asymmetric tops. They are presented in a concise, comprehensive and more useful form than hitherto. This is followed by a brief description of computer programmes which accurately simulate such Raman vibration-rotation band contours and enable individual transitions to be assigned. The final section illustrates the different band structures which can occur, namely,A,Ba,Bb, andBctypes, with possible mixtures of these in molecules of low symmetry. Attention is drawn to how information on the derivatives of elements of the polarizability tensor with respect to particular normal coordinates can be extracted from such spectra. Examples are given for ethylene and trans-1,2-dideuteroethylene.

ISSN:0026-8976    

DOI:10.1080/00268977700101321

出版商:Taylor & Francis Group    

年代:1977

数据来源: Taylor

摘要:

A detailed analysis of the Raman-activev1,v3(bothA-type) andv5(Bc-type) vibration-rotation bands of ethylene is presented. In addition to structural data simulation of the spectra yields values for the polarizability ratios of the totally symmetric bands, giving information on the polarizability ellipsoid as the molecule vibrates.v3is shown to be perturbed by ac-type Coriolis interaction which complicates the interpretation of the negative value of the polarizability ratio required to match the observed spectrum.

ISSN:0026-8976    

DOI:10.1080/00268977700101331

出版商:Taylor & Francis Group    

年代:1977

数据来源: Taylor

摘要:

Non-adiabatic transition probabilities in systems of three adiabatic molecular states of the same symmetry are calculated by the semiclassical/adiabatic technique and numerically. The terms considered are three 1g(or 1u) molecular states of alkali diatomM2; in the limit of three atoms these terms correlate with the ground2S1/2and excited2Pj(j= ½, 3/2) atomic states. The results are discussed in connection with the corresponding Massey parameter and can be used to estimate non-adiabatic effects in photodissociation ofM2*(B1Πu) and in collisional excitation ofM.

ISSN:0026-8976    

DOI:10.1080/00268977700101341

出版商:Taylor & Francis Group    

年代:1977

数据来源: Taylor

摘要:

A systematic computational study and Regge Pole (complex angular momentum) analysis of large-angle elastic scattering in chemically reactive systems has been carried out. Various new interference effects can appear in the large-angle scattering. In some cases, use of different parameters in theSmatrix results in very similar angular distributions, which would lead to ambiguities in the fitting of experimental data. Up to 15 000 partial waves are used in the calculations but no more than three terms are necessary in the Regge Pole analysis for the large-angle scattering. A physical interpretation in terms of direct elastic scattering and surface waves that propagate around the region of chemical reaction can be given. Experimental criteria for the detection of the interference effects are discussed.

ISSN:0026-8976    

DOI:10.1080/00268977700101351

出版商:Taylor & Francis Group    

年代:1977

数据来源: Taylor

摘要:

The spectra of hydrogen-oxygen and acetylene-oxygen flames have been recorded on a Fourier transform spectrometer in the region 6200–9100 cm-1with a resolution of 0·015 cm-1. In this region, we have performed a detailed analysis of the 2v2+v3,v1+v3,v1+v2+v3-v2andv1+v2+v3bands. A primary motive for this study was to obtain higher rotational energy levels for the (021), (101) and (111) vibrational states. Moreover an extensive set of rotational levels of the (010) vibrational state has been deduced from the combined study of hot bands involving the (011), (021) and (111) vibrational states. A room-temperature absorption spectrum of water recorded on a Fourier transform spectrometer in the region 1750–2300 cm-1(resolution 0·005 cm-1) has also been used to confirm the analysis.

ISSN:0026-8976    

DOI:10.1080/00268977700101361

出版商:Taylor & Francis Group    

年代:1977

数据来源: Taylor

摘要:

A pseudopotential method without parameters is proposed that takes advantage of the fact that in the Hartree-Fock-Slater (HFS) model core-valence exchange is already in suitable form for separating core and valence electrons. Various approximations in the scheme are tested and results are presented for the CO, Cl2and Ni2systems and compared to frozen core HFS results. Some implications for current Hartree-Fock pseudopotential schemes are discussed.

ISSN:0026-8976    

DOI:10.1080/00268977700101371

出版商:Taylor & Francis Group    

年代:1977

数据来源: Taylor