The oxidation of ethyl alcohol at platinum electrodes was studied by a‐c differential capacitance measurements, current density measurements, rates of change of current density with time, constant current, voltage‐time traces, and product analyses. Capacitance measurements can be interpreted as indicating that ethyl alcohol adsorbs on platinum electrodes in 1NH2SO4 as CH3C*HOH in the voltage range from +0.3 to 1.0v (NHE) and as CH3CH2O* in the voltage range from 0.9 to 1.4v. Above 1.2v platinum forms an irreversibly adsorbed oxide film which is not catalytically active and which weakly adsorbs ethyl alcohol. On reduction of this platinum oxide an “activation” occurs resulting in high catalytic activity. Current density peaks at 0.9 and 1.2v are consistent with postulated adsorption properties. Similar studies indicated that acetaldehyde reacts in an analogous manner. Thus, the suggestion of other investigators that the minimum in the alcohol curve arises because of poisoning by acetaldehyde appears to be refuted.

hydrogen events" were examined under high magnification to determine whether one or more light tracks were also associated. One example of a pair of light tracks, assumed to be electrons, was found (Fig. 1). s'~e++e +y.(2) followed by the direct decay of the neutral pion, as predicted by Dalitz4 and as observed by various authors'' CpĨ t~P rocess (1) is the charge-symmetric analog of the process which was used to explain the pairs in the negative pion beam: s. +~'+e.(3)Since there are approximately as many neutrons as protons in the emulsion the cross sections for (1) and (3) should be nearly the same, which is not inconsistent with the results reported here. The lack of a visible gap between the pair and the star is in agreement with the short lifetime reported earlier. FIG. 1. Electron pair produced by 113-Mev positive pion: u, incident pion; b, proton of 75&10 Mev or other fragment of same ionization; c1, c2 electrons of 27&9 and 56&14 Mev, respectively.The angle between the two electron tracks 8 is 5.2 1. 0' and the angle between the direction of the incident pion and the direction of the center of mass of the pair p is 62&2'. The energies of the two electrons are 27~9 Mev and 56&14 Mev. These data are consistent with the earlier results obtained on the negativepion-produced pairs' except for the angle g, which is smaller than any of the angles reported earlier and which seemed in the earlier work to have an improbably sharp distribution centered around 115' in the laboratory system. Since this is the only case in the positive beam, the significance of the occurrence of such an angle is not clear. In the area scanned for this experiment, there were (1.56+0.05)&&10' cm of pion track. ' Since the mean free path for pions at very nearly the same energy' is 33.6&17 cm, approximately 4600 interactions must have occurred. Approximately one-eighth of these would be "possible hydrogen events" as described earlier. Thus one pair was found in about 600 stars examined. There is no visible gap on this pair, and a gap would have been seen if it were as large as one micron. It is suggested that this pair can be interpreted as the result of the charge-exchange scattering of a pion on a neutron in a nucleus of the emulsion: vr++ m -+n'+ p, HERE are experimental' ' and theoretical~' indications of a state in Al" lying below the 6-second positron-emitting 0+ state. The ground state apparently4' lies 4.0 Mev above that of Mg" and is expected~to have a 5+ configuration. If the Mg' states at 1.83 and 2.97 Mev" both have 2+ configurations,Ap" should decay predominantly by positron emission to the 1.83-Mev state with a half-life estimated'' at 10' -10' years, with smaller amounts of electron capture to both states. We have sought radioactivity in aluminum carrier isolated from a target of commercial magnesium bombarded with 400 pa-hr of 15-Mev deuterons in the University of Pittsburgh cyclotron. After numerous NH4OH precipitations at pH 6, numerous NaOH precipitations of Fe(OH). -, and two 8-hydroxyquinoline precipi. tations, the a...

Die spezifische Aktivität des langlebigen isomeien Grundzustandes des 26Αl wurde gemessen und daraus die Halbwertszeit ermittelt. Die 26Al-Probe wurde durch Bestrahlung von reinstem Magnesium im Zyklotron des Oak Ridge National Laboratory mit Protonen erzeugt und chemisch ohne Träger abgetrennt. Die spezifische Aktivität einer Lösung dieser Probe wurde mittels eines 4 π-Geiger-Zählers gemessen, wobei ein Verzweigungsverhältnis von 84,6% zu 15,4% zwischen Positronenemission und Elektroneneinfang angewendet wurde. Die Konzentration des vorhandenen 26Αl ist massenspektrometrisch mit Hilfe der Isotopenverdünnungsmethode bestimmt worden, wobei 27Al als Verdünnungsmittel verwendet worden ist. Die Messungen ergaben einen Wert von (7,38 ± 0,29) · 105 a für die Halbwertszeit des langlebigen 26Αl.

The disintegration scheme of the long-lived ground-state isomer of Al 26 has been determined. It is based on the following observations.The maximum positron energy as determined by absorption measurements is 1.16±0.05 Mev; this agrees with the expected 1.17 Mev. The spectrum appears to be simple.The scintillation gamma spectrum shows intense positron annihilation radiation, a strong peak at 1.83 ±0.03 Mev, and weak peaks at 1.12=k0.03 Mev and 2.96±0.05 Mev, corresponding to transitions from the known Mg 26 states at 1.82 and 2.97 Mev. A peak at 0.68 Mev is from the addition of two annihilation photons, one being backscattered from the source and surroundings; the gamma of ^0.7-Mev energy reported by others is not present. The peak at 2.97 Mev is shown to result from 2.97-Mev photons as well as from addition of 1.82-and 1.15-Mev photons.The relative intensities of the annihilation and gamma radiations indicate that Al 26 undergoes (84.6 ±1.8)% positron emission to the 1.82-Mev state of Mg 26 ; (11.4±1.9)% electron capture to the same state; (3.7±0.3)% electron capture to the 2.97-Mev state followed by emission of 1.15-and 1.82-Mev gamma-rays; and (0.30±0.03)% electron capture to the same state followed by 2.97-Mev radiation. Other energetically possible transitions are apparently negligible in intensity.Auger electrons and x-rays were observed in a proportional counter spectrometer. Analysis of the spectra yielded iC-shell fluorescence yields of 0.008±0.003 for magnesium and 0.008±0.003 for aluminum.

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