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The photolysis and the fluorescence of C2F5COC2F5 have been studied at various temperatures, concentrations, and wavelengths. There is a strong dependence of the photochemical yield and to a lesser extent of the relative fluorescence yield on these factors. The reaction products are solely CO and C4F10. The fluorescence is excited by light of the wavelength region between 2537 Å and 3650 Å. The fluorescence band lies in almost the same wavelength region as that of CF3COCF3 and the relative fluorescence yield is slightly less in the higher concentration region. This behavior closely follows the pattern for CF3COCF3 and, hence, may be discussed by the same mechanism. A comparison is made of the primary photochemical reaction among fluorinated ketones.

The measurement of the fluorescence and photochemical yields of hexafluoroacetone previously made at 3130 angstrom and at room temperature is extended to various other wavelengths and temperatures. Relative fluorescence yields at room temperature increase with decrease of excitation energy. This wavelength dependence is smaller at higher concentrations. The yields increase with concentration eventually converging almost to a single value. On the other hand, the photochemical yields measured show the opposite trends with respect to variations in concentration and excitation energy. As concentration increases they also converge to a value almost identical with that at 3130 angstrom. The temperature effect on the fluorescence yield is also opposite to the one on the photolysis at 3130 angstrom. The fluorescence decreases with increase in temperature, the variation being much bigger at higher concentrations. The intensity distribution of the fluorescence band is independent of temperature. It seems difficult to interpret the observed temperature dependence for fluorescence quenching and for dissociation at infinite concentration on the basis of a single excited state. Two modes of dissociation are postulated arising respectively from low and from high vibrational levels of different electronic states.

Sono stati registrati gli spettri di risonanza paramagnetica elettronica degli ioni radicalici negativi del benzofenone e delle tre bezoilpiridine isomere ottenuti con il metodo elettrochimico. Le densita di spin determinate dalla struttura iperfine vengono discusse nel caso del benzofenone.

Vengono calcolati i primi livelli di energia degli elettronin e π per la molecola HFCO con il metodo LCAO, MO, SCF nella versione semiempirica di Pople-Pariser-Parr. Viene discussa principalmente la frequenza della transizionen → π prevista dal calcolo, confrontandola con il valore sperimentale recentemente trovato e con quello, gia noto da tempo, dell’analoga transizione della formaldeide.

The energy of the H2 molecule is calculated by using an « open shell » function analogous to the one used by Hylleraas for the He atom. In this way radial correlation is introduced without explicit inclusion of terms containing the interelectron distancer12. The calculated dissociation energy (4.17 eV) is one of the best values obtained in this approximation. A comparison with a similar wave function suggested by Muller and Eyring is made.

The rate constants and activation energies for the reactions of C3F7 radicals with methane and ethane have been measured by photolyzing mixtures of C3F7COC3F7 and hydrocarbon with 3130 Å light. Photolysis of mixtures of the ketone, methane, and deuterium has been used to check previous measurements on the reaction of C3F7 and deuterium.

Visible and ultra-violet absorption spectra have been taken for complexes of the type NiX2·2PR3 (X = NCS, Cl, Br; R = n-propyl, i-propyl, s-butyl, cyclohexyl). An assignment of the various transitions is suggested. Frequency shifts depending on alkyl substitution are shown to be due either to steric effects or to non-bonded group perturbations.

Nitrogen and hydrogen h.f.s. constants have been calculated for the NH3 + radical by using SCF molecular orbitals obtained from Hartree-Fock type atomic orbitals and performing an extensive configuration interaction calculation. The nitrogen constant agrees with experiment within the uncertainty of the values of the Hartree functions at the nucleus. The hydrogen constant (predicted of the opposite sign) is 10 per cent higher than the experimental value.

The ESR spectra of Cr 3+ -doped single crystals of urea and thiourea adduct compounds of Al- and Co-acetylacetonate have been recorded. The parameters of the spin Hamiltonian indicate that the chemical environment of the Cr 3+ atom is the same as that in the compounds without urea or thiourea. The analysis of the spectra allows definite conclusions on the crystal structure of the adducts to be drawn.

The proton magnetic resonance features of poly-(N-γ-carbobenzoxy-L-α-γ-diaminobutyric acid) are consistent with a special secondary structure of this polymer when compared with the structure of its higher homologs and of other uncharged polypeptides in the same solvent systems. The pure conformational shift of the peptide α-CH proton in going from helix to random coil is for the first time isolated from the solvent shift.

I primi livelli elettronici π del cloranile, della p-fenilendiammina e dei loro radicali ioni rispettivamente negativo e positivo, sono stati valutati col metodo LCAO, MO, SCF semiempirico. I risultati sono in buon accordo con i dati spettroscopici.

A mathod is described for the purification, on an industrial scale, of influenza viruses grown in allantoic cavity of embryonated eggs. The mehtod consists of combining continuous-flow centrifugation with zonal centrifugation in a sucrose (36.6 per cent-52.5 per cent w/v) density gradient. The sample flow rate is approximately 3.7 litres/h and the volumes treated vary between 3 and 33 litres of allantoic fluid. Both the recovery of the virus and the degree of concentration and purification result satisfactory.

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The nature of the radicals formed from citric acid after reaction with ˙OH radicals at different pH values is investigated by e.s.r. Three paramagnetic species are identified in acid solution, only one surviving when the pH is raised to 6. The formation of the radicals and their hyperfine structures are discussed.