Measurmennt of recoil proton polarization in the process of π− photoproduction from neutrons in the energy range between 700 and 1200 MeV

The recoil proton polarization for γn → π^?p was measured around the third resonance region. Both momentum vectors of the proton and the pion were determined by the magnetic spectrometers. The proton polarization was measured by means of proton-carbon scattering in the polarization analyzer located behind the proton spectrometer. Below 900 MeV incident photon energy, our data are consistent with the other existing experimental data ($\text{θ}{}_{\mathrm{\pi }}{}^1\text{= 90°}$) and the predictions of partial-wave analyses. Above 1000 MeV, however, a large discrepancy was observed between our data and the predictions of the partial-wave analyses. The discrepancy stands out as the pion c.m. angle increases. A new partial-wave analysis was made for γn → π^?p including our polarization data, and the accuracy of the experimentally determined electromagnetic coupling constant of the third resonances were greatly improved. In particular, a finite amount of the helicity $\text{3}\text{2}$ amplitude for the γn → F₁₅(1688) resonance was obtained against the predictions of the quark models, by Copley, Karl and Obryk and by Feynman, Kislinger and Ravendal but in agreement with the relativistic quark models of Sugimoto and Toya, and Kubota and Ohta.     

Studies of the optical properties of acridine orange-sodium carboxymethylcellulose complexes

Summary From the studies of ORD and CD spectra of AO-CMC complex, we have deduced that the molecule of CMC in aqueous solution is at least partly in a helical structure and the helical sections are coiled in one direction.AO bound CMC has a high stacking tendency and a dye molecule partly occupies an etheriflcated site adjacent to those already occupied by other dye molecules on the helical part. The bound AO in helical part may be constituted the superhelix.

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Zusammenfassung Aus Untersuchungen der ORD- und CD-Spektren des Acridine-orange-Natrium-carboxymethylcellulose-Komplexes (AO-CMC-Komplexes) folgern wir, daß die CMC-Moleküle in wäßriger Lösung wenigstens teilweise schraubenförmig vorliegen und einen einheitlichen Schraubensinn besitzen. AO an CMC gebunden hat eine starke Tendenz sich aufzurichten und ein Farbstoffmolekül besetzt teilweise eine verätherte Stelle benachbart zu einem schon von einem anderen Farbstoffmolekül besetzten Platz längs der Schraube. Das gebundene AO im Schraubenanteil dürfte die Superhelix bilden.

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The authors acknowledge the help of Dr.K. Tsuda (Research Institute for Polymers and Textiles) with useful suggestions and MissT. Kitagawa (Nippon Bunko Co.) for experimental work.     

Photochemische Reaktionen. 99. Mitteilung. Photochemistry of N-Acylimidazoles. IV. Structural Factors Leading to Norrish Type II Elimination and to Cyclobutanol Formation in the Photolysis of Acylimidazoles

Conformational factors leading to Type II elimination and to cyclobutanol formation were studied in the irradiation of N-acylimidazoles with simple acyl groups as well as of their photochemical acyl migration products.     

Ultrasonic relaxation and volumetric studies of micelle-monomer exchange process in aqueous solutions of sodium and cesium perfluorooctanoates

Ultrasonic absorption measurements of aqueous solutions of sodium perfluorooctanoate (SPFO) and of cesium perfluorooctanoate (CsPFO) were carried out in the frequency range 0.2–90 MHz at 25°C. A single ultrasonic relaxation process is observed in all solutions investigated. The observed relaxation process should be ascribed to a “fast” relaxation process due to an exchange of surfactant monomer between micelle and bulk solution. The mean dissociation rate constant and the magnitude of the volume difference due to the exchange process are determined by applying the relations derived by Aniansson and Wall and by Teubner, respectively. The ratio of the aggregation number of the micelle to the mean dissociation rate constant is reduced to about one-half and the volume difference decreases when the counterion of the perfluorooctanoate changes from Na⁺ to Cs⁺. Precise density measurements were also carried out to support information obtained from the ultrasonic relaxation study. Magnitudes of the volume difference estimated from the two independent studies above are in approximate agreement with each other. However, the volume difference determined from the density measurements is slightly larger than that determined by ultrasonic study and almost independent of the species of the counterion.     

Photoreactivity and emission properties of liquid-crystalline twin dimers containing cinnamic acid moieties at both ends of ethylene glycol spacers. II. Emission properties

Emission properties of liquid-crystalline twin dimers containing 4-methoxy-cinnamic acid moieties at both ends of various ethylene glycol derivatives (nEGMC), where n denotes the number of the ethylene glycol units in the spacers, have been explored by steady-state and time resolved fluorescence spectroscopy in relation to the morphology of the system. Characteristic emissions were observed in the twin dimers, particularly in 2EGMC and 5EGMC, which were ascribed to excimer emission, and the energy gap between the locally excited state (monomer emission) and the excimer state and could be correlated to the difference in the spatial orientation of the mesogenic 4-methoxycinnamate groups adopted in nEGMC in the ground state. The picosecond time resolved fluorescence spectroscopy revealed no observed rise in the excimer emission in any sample at any temperature, indicating that the excimer is most probably formed by direct excitation of the pair wise arrangement of the 4-methoxycinnamate moieties in the ground state; thus, the excimer formation behaviour reflects well the ground state morphology of the twin dimers.     

Spectroscopy of pico-second light pulses with a television camera system

A television camera system using a high-sensitivity image orthicon is constructed for spectroscopic measurements in the pico-second region. It is possible to fix the spectrum of a relatively weak pico-second light pulse as a static spectrum on the screen of an oscilloscope. Time-resolved luminescence spectra from a heavily-excited GaAs crystal in the pico-second region are demonstrated as examples of measurements using this system.