ESR absorption of adsorbed oxygen on zine oxide were .measured at 77∼210°K in vacuum to inverstigate the absorbed species of oxygen. The results are as follows:
(1) ESR spectra of adsorbed oxygen on zine oxide at g=2.003∼4, g=2.014, g≒2.04 and g≒2.06 are detected at 77°K in vacuum. Here, g is the spectroscopic factor of ESR absorption.
(2) All of the relative intensities of ESR spectra are decreased with incresing temperature at 77∼210°K. Above all, the spectrum at g=2.014 is disappeared at 100∼106°K. These will mean that the adsorbed oxygen on zinc oxide is desorbed.
(3) At 77°K, all of the relative intensities of ESR spectra are decreased by UV-irradiation. These are caused by photo-desorption of the absorbed oxygen on zinc oxide. And also, since the relative intensities are gradually increased after UV -irradiation, the adsorption of oxygen on zinc oxide is reversible.
(4) The ESR spectrum at g=2.003∼4 is due to an O^- (ads) -type oxygen that is formed by the following process: 1/2 O₂ (g) +Θ→O^- (ads). Here, the symbol, Θ indicates an electron in the conduction band of zinc oxide.
(5) The ESR spectrum at g=2.014 will be due to an ozonide-type oxygen, O₃^- (ads), since the value is nearly equal to the g-value of ESR spectrum observed in NaO₃ (g_∥=2. 003, g_⊥=2. 015).

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Spectral sensitization of zinc oxide electrophotographic layers by a series of merocyanine dyes was studied. Although the dyes used in the experiment are much different in adsorption characteristics onto the zinc oxide surface according to the property of the substituent introduced in the dye molecule, all these dyes have the same fundamental structure (5-〔(1-ethyl-4 (H) -quinolylidene-ethylidene〔-rhodanine.) and also have practically the same optical absorption.
From the result of the electrostatic surface potential measurement of the layers it has been shown that the dyes which have polar substituent such as C₂H₄S0₃Na or CH₂COOH are highly efficient spectral sensitizers.
However, in the case of electrodynamic measurement of the layers by using surface type photoconductive cells, these dyes are found to be almost ineffective as spectral sensitizers. This contradiction may be explained by assuming a shorter range of the mobile elctrons liberated by the photoexcited dye molecules, compared with that of mobile electrons excited by the intrinsic absorption of UV light. This is also confirmed by the fact that the time ef rise and decay of photocurrents observed in the dye sensitized wavelength region is shorter than that of the photocurrents in the intrinsic region.

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This paper describes the results obtained in our experiment on electical dispersion of liquid. The field strength (dc), the volume of liquid dispersed and the discharge current were measured and the correlations among them are discussed for various liquids; water, ethanol, water-ethanol mixtures and ethanol-benzene mixtures. When the distance between electrodes was fixed constant within 1∼5 cm, the volume of liquid dispersed was obseved to increase with the applied voltage within the experimental range of 6∼10 kV.
As to the discharge current during the electrical dispersion, the conductivity of the liquid seemed
to play a dominant role. The volume of liquid dispersed Q depended on the discharge current I, as represented by the following equation, Q=kI^α, where k and α are constants related to the property of liquid.

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