摘要:

AbstractThis paper reviews recent developments in ground state high resolution spectroscopy of high temperature radicals. The methods discussed include microwave absorption spectroscopy and microwave‐optical double resonance techniques. These methods have been used to study rotational spectra and hyperfine structure of earth alkaline monohalide

ISSN:0005-9021    

DOI:10.1002/bbpc.19820860902

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:1982

数据来源: WILEY

摘要:

AbstractMolecules with partly filled 3d or 4f shells have a surprisingly large number of low lying electronic states, resulting in incredibly complex spectra. This paper attempts to show that, although the spectra are complicated, the explanation of the global electronic structure is quite simple. Ligand Field Theory displays all of the important relationship between the dNor fNstructures in the free‐atomic‐ion and the molecule. The splitting of the core into numerous substates causes a gratuitous repetition and intermingling of the usual ϱ, π‐valence structures which are so familiar for molecules with filled‐shell cores. The 4f electron is shown to be a useful probe of the unknown structures of more diffuse valence orbitals. A semi‐empirical theory is described which allows important features of the molecular level diagram to be predicted using atomic energy level tables and a scrap of paper. The same theory provides a basis for detailed numerical parametrization and quantitative predictions of energy levels, perturbation matrix elements, hfs splittings, and transition

ISSN:0005-9021    

DOI:10.1002/bbpc.19820860903

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:1982

数据来源: WILEY

摘要:

AbstractThe rotation‐inversion spectrum of isocyanamide, H2N — NC, has been investigated in the frequency range 100 to 400 GHz. Due to the near C2vsymmetry of the inverting molecule two types of dipole transitions have been observed: 1) intrasystem a‐type transitions and 2) intersystem or rotation‐inversion c‐type transitions connecting the two energy manifolds of H2N — NC belonging to the inversion states O+and O−, respectively. The inversion splitting was found to be 0.369 cm−1, indicative of a high barrier to inversion. Pure inversion transitions are not allowed. The rotation‐inversion analysis was carried out for 240 a‐type and c‐type transitions using S‐reduced Hamiltonians according to Watson for the O+and O−inversion states separated by the inversion splittingE1nv. The analysis yielded the following spectroscopic constants:plus centrifugal distortion constants. The present data and their analysis provide an excellent basis for a radioastrono

ISSN:0005-9021    

DOI:10.1002/bbpc.19820860904

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:1982

数据来源: WILEY

摘要:

AbstractThe first‐ and second‐order rotational Zeeman effect was investigated in isobutane. The magnetic‐field induced birefringence was measured at room temperature in several gases formed by axially symmetric molecules using pressures up to 1 bar. For benzene vapour these measurements were extended to higher temperatures. The susceptibility anisotropies obtained from the Cotton‐Mouton constants of the gases agree well with those measured directly by the rotational Zeeman effect which indicates that hyperpolarizabilities are negligible. The corresponding temperature independent contribution to the Cotton‐Mouton effect of benzene vapour proves to be less than 3% of the Cotton‐Mouton constant at room

ISSN:0005-9021    

DOI:10.1002/bbpc.19820860905

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:1982

数据来源: WILEY

摘要:

AbstractInfrared spectrum of HNCO near 5 μm was measured by a diode laser spectrometer with source frequency modulation and Stark modulation methods. The subbands of thev2fundamental band were identified forKa= 0 to 4. The subband origins and the effective rotational constants for these subbands were determined. The rotational fine structure of thev2band suggests that the levels are perturbed by accidental resonances

ISSN:0005-9021    

DOI:10.1002/bbpc.19820860906

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:1982

数据来源: WILEY

摘要:

AbstractThe present work deals with the intensity analysis of rovibrationally resolved Raman spectra of natural and13C as well as18O isotopically enriched samples of CO2photoelectrically recorded in the Fermi resonance region (1100–1460 cm−1). Based upon Chedin's set of rovibrational data [1] and upon the polarizability theory of Raman scattering, we have successfully fitted our calculated intensities to the measured spectra of each isotopic species. — The procedure yields values for three parameters, namely (δ2ƒ‐I0/δq2,+;δq2,‐) (δƒ‐I0/δq1) = ‐ 0.200 and ‐ 0.100 (± 3%) fort= 0 andt= 2, respectively, and |(δƒ‐00/&dgr;q1/δ ƒ‐20/δq1)| ≈ 1.47 ± 2%, that are derived from the spherical polarizability tensor ƒ‐Iq. A spectroscopic temperature can be evaluated

ISSN:0005-9021    

DOI:10.1002/bbpc.19820860907

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:1982

数据来源: WILEY

摘要:

AbstractThe use of theoretical models in predictions of equilibrium geometries of molecules is reviewed. If the basis set is taken to the split‐valence + polarization level and if the electron is included by Møller‐Plesset perturbation theory to third order, theoretical structures are found to lie within experimental error ranges for the majority of small molecules that have been investigated. The application of the same techniques to unstable intermediates is illustrated by some studies on the vinylidene‐acetylene rearran

ISSN:0005-9021    

DOI:10.1002/bbpc.19820860908

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:1982

数据来源: WILEY

摘要:

AbstractThe dispersion of the refractive index of the gases He, Ne, Ar, H2, N2, O2, CH4, and C(CH3)4at low densities is determined in the visible wave length range 400 nm ≦ λ ≦ 700 nm by means of scanning‐wavelength interferometry. The measurements are fitted by one‐term Kramers‐Heisenberg dispersion relations and used to calculate some macroscopic and molecular properties like mean polarizabilities, effective eigenenergies and oscillator strengths, oscillator strength sums, Verdet and related constants, Rayleigh scattering cross sections and dispersion force constants. The theoretical background as well as the significance of the different relations between refractive index and these properties is presented and discuss

ISSN:0005-9021    

DOI:10.1002/bbpc.19820860909

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:1982

数据来源: WILEY

摘要:

AbstractThe difference of the Coulomb potential for a pointlike and for an extended nucleus is taken as a perturbation of the molecular energy. Correction terms, which are dependent on the mean square nuclear charge radius, are introduced for the molecular energies. The observability of the resulting isotope shift in the molecular spectra is discussed in comparison to the usual mass shift. Some examples for the pure electronic and rotational energy are presented using high precision laser and microwave experiments on Pb‐ and Tl‐compou

ISSN:0005-9021    

DOI:10.1002/bbpc.19820860910

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:1982

数据来源: WILEY

摘要:

AbstractPhotoelectron spectroscopy has proven valuable for the analysis and optimization of numerous gas phase reactions in flow‐systems — especially in search for heterogeneous catalysts, which can be tested within a single day using gas mixtures of varying composition over the temperature range from 300 K to 1300 K. In academic research, this real‐time measuring probe allows one to determine — with millimol quantities and within a few hours — the temperatures for different decomposition channels. Simultaneously, main products can be characterized by the comparison of their ionization fingerprints with calculated (SCF) eigenvalue sequences making use of Koopmans theorem. If need be, the yield of a certain reaction product e. g. a short‐lived intermediate can be improved by optimizing the reaction conditions aiming at maximum intensity of the corresponding bands. In this way, many short‐lived and/or reactive molecules such as thioformaldehyde, P2or silabenzene, which are discussed as examples, have been detected or reaction channels like vinyl azide→2H‐azirineacetonitrile visualized, PE‐spectrometers are well‐suited for on‐line connection to computers; portable instruments for laboratory us

ISSN:0005-9021    

DOI:10.1002/bbpc.19820860911

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:1982

数据来源: WILEY