A theoretical study on the photodissociation of C3O2

The photodecomposition of C₃O₂ into C₂O and CO is studied with the ab initio MO calculation. It is found that, starting from the second excited state of C₃O₂ (_u), the ground-state C₂O (triplet) is yielded through the bent dissociation. The stable structure of the excited triplet state of C₃O₂ as an intermediate is also demonstrated.     

SCF calculations of aromatic hydrocarbons the variable β approximation

The transition energies and intensities of naphthalene, anthracene, phenanthrene, pyrene, and azulene are calculated with a variable modification of the Pariser-Parr-Pople method. In this procedure each is determined from the bond order after every iteration. The dependence of on bond order is given by = –0.51 p + A ₀ eV where A ₀ is –1.90 eV (naphthalene and azulene), –1.84 eV (anthracene and phenanthrene), and –1.82 eV (pyrene). Precise knowledge of the molecular geometry is not required and the results are in good agreement with experiment.

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Zusammenfassung Die elektronischen Anregungsenergien sowie die zugehörigen Intensitäten von Naphthalin, Anthrazen, Phenantren, Pyren und Azulen wurden mit der Modifikation der variablen der Pariser-Parr-Pople Methode berechnet, bei welcher die -Werte nach jedem Iterationsschritt als Funktion der Bindungsordnung neu berechnet werden. Ihre Abhängigkeit ist durch = –0,51 p + A ₀ eV gegeben, wobei A ₀ –1,90 (Naphthalin und Azulen), –1,84 (Anthrazen und Phenantren) bzw. –1,82 (Pyren) ist. Für das Verfahren ist die genaue Kenntnis der Geometrie des Moleküls nicht vonnöten und die Resultate befinden sich in guter Übereinstimmung mit dem Experiment.

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Résumé Nous avons calculé les énergies et intensités des transitions électroniques de naphthalène, Anthracène, phénanthrène, pyrène et azulène par une méthode PPP modifiée, où les sont déterminés des indices de liaison p après chaque itération: = –0,51 p + A ₀ eV, où A ₀ = –1,90 (pour naphthalène et azulène), –1,84 (anthracène et phénanthrène) et –1,82 (pyrène), respectivement. On n'a pas besoin des géometries exactes des molécules. Les résultats s'accordent bien à l'expérience.

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Supported by the U.S. Atomic Energy Commission and National Science Foundation.     

Kinetic spectrophotometric determination of antimony(III) based on induced oxidation of tris(1,10-phenanthroline)iron(II) by chromium(VI)

The method involves the measurement of the extent of the induced reaction, which ceases a few seconds after initiation. Antimony(III) can be determined in the range 0.4–10 μg ml^-1. The standard deviation is ±0.25 μg. The method is applied to marine sediments.     

Electron interaction in molecules

An idea of electron interaction in molecule has been applied to the SCF MO calculations of theπ-electronic structure of some complex aromatic hydrocarbons and their derivatives. The theoretical results for singlet and triplet transition energies, first ionization potentials and bond lengths agree fairly well with the experimental data. A correlation equation between the valence state ionization potential and the one center electron repulsion integral has been proposed. It has been shown that the electron repulsion in molecule is considerably smaller than in free atom. The present calculation shows that we can treat sulphur as a normal heteroatom analogous to oxygen and nitrogen.     

Partial structure analysis of conjugated systems I

A new method for analysing the partial structure of conjugated systems is proposed. The present method is applied to the most important partial structure, benzene, which is closely related to aromaticity. The calculated results are in accord with the previously proposed indices of aromaticity.     

94 GHz InP MMIC five-section distributed amplifier

A single-stage 94 GHz InP MMIC amplifier with 6.4 dB gain at 94 GHz has been developed, which is the highest-frequency MMIC amplifier reported to date. Lattice-matched GaInAs/AlInAs HEMTs with 0.1 mu m mushroom gates were the active devices. The CPW MMIC chip dimensions are 500 mu m*670 mu m.<>     

Carbon-13 nuclear magnetic resonance spectroscopy—VII:para-substituted fluorobenzenes

C-13 and F-19 NMR spectra of seventeen para-substituted fluorobenzenes were measured and the chemical shifts as well as coupling constants with respect to substituents were analysed. The chemical shifts of the fluorine, the C₁ and the C₂ atoms were found to depend on the total electron densities. In the case of the C₃ atom, the chemical shifts seem to depend on π-electron densities rather than the total electron densities. The present calculations also indicate that the chemical shift of the C₄ atom depends mainly on σ-electron densities due to the inductive effects of substituents. The strongest factor influencing the coupling constant, ⁿJ(C? F), is also considered to be the π-electron densities on the carbon atoms. In the case of the direct couplings, ¹J(C? F), the π-bond orders are important.     

An ab initio calculation on proton transfer in the benzoic acid dimer

We have made an ab initio calculation of the barriers for proton transfer in the hydrogen-bonded dimers of benzoic acid and acetic acid. Geometrical optimization values which are closer to the experiment one.