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275. Investigations on ion absorption and corrosion using radioactive indicators
246
Abstracts 268-278 33
33
268. Microscopic Examination of Interior of Highly Curved Surfaces by Means of Replica~. United States. Replicas of cellulose acetate film have been
272. High-temperature X-ray Diffraetometer. Great Britain. A vacuum furnace designed for use with a
taken for surface studies of inaccessible places or highly curved surfaces. In order to increase the contrast for electron microscopy, a carbon replica was made from the cellulose acetate replica, and shadowed with platinum. In order to increase the contrast for optical microscopy, the cellulose replicas were coated with gold by evaporation. G.S. Note by A. P. Young, Rev. Sci. lnstrum. 29, 661, July 1958.
commercial diffractometer is described. It uses a high-current heater made from tantalum foil, and allows the full Bragg spectrum to be recorded whilst satisfying the Bragg-Brentano focusing condition. The specimen temperature is uniform and can be measured accurately; the furnace has been operated successfully at temperatures up to 1100 °C, and it is believed that considerably higher temperatures can be achieved. (Author) J. Spreadborough and J. W. Christian, J. Sci. Instrum. 36, 116-118, March 1959.
33
269. Photoconductivity and the Visual Receptor Process. United States. Measurements were made using B-carotene melted and cooled between two conductive glass plates in a vacuum. It was shown that B-carotene glass qualifies as a highly photoconductive organic material. Some of the properties were determined. Letter by H. Steffen Peiser, J. Opt. Soc. Amer. 48, 581-582 Aug. 1958. 33 270. Improved, Single Flash, Continuum Source for use below
2000 A. United States.
A high intensity low energy flash lamp for use below 2000 A_ is described. The radiation from a single flash at 4000 V and 15 mfd produces an emission continuum to 1500 A which is of sufficient intensity to be used with either photographic or photomultiplier techniques. A densitometer trace of the Schumann-Range Oe absorption band system is shown. Also, oscilloscope traces are presented which were taken at 1700 ~k. These show attenuation of the signal as a function of oxygen concentration. The associated vacuum technique is described. (Author) Joseph A. Golden and Albert L. Myerson, J. Opt. Soc. Amer. 48, 548-552, Aug. 1958. 33
271. High-Sensitivity Crystal Infrared Detectors. United States. The intrinsic photosensitivity of germanium and indium antimonide disappears at wavelengths greater than 1.8 and 7t~ respectively. In Ge this upper limit can be extended by doping the crystals with impurities, the activation energies of the impurity centre then become the determining factor for the maximum infra-red wavelength that can be absorbed. In this work Ge infrared detectors are cut from a large zone levelled crystal. Compensation with antimony donors is used to obtain n-type material. The gold-antimony doped detectors have a long wavelength cutoff at 6~ and a photoconductive time constant which is dependent on the wavelength of the incident radiation. A table is given which shows the sensitivity characteristics of a number of these detectors. Indium antimonide detectors have been made with sensitivities comparable to those of the gold-doped Ge. The indium antimonide detector is made either by alloying or diffusing a thin layer of impurities into the surface layer of a single crystal of material. Cadmium is now being used, giving a thin p-type surface on n-type indium antimonide. If light is allowed to fall on the front surface of the alloyed material, a photo-voltage may be measured between the n and p parts of the detector. The cutoff wavelength for this type of detector when cooled to liquid nitrogen temperature also is of the order of 6t~. A comparison is made between the characteristics of the two types of cells and a description is given of a multiple contact cell which can locate a target as well as detect it. A section is included on the standard measuring techniques used in evaluating infrared detectors, c.s. M. E. Lasser, P. Cholet and E. C. Wurst, Jr., J. Opt. Soc. Amer. 48, 468-473, July 1958.
33
273. Electron Microscope and Electron Diffraction Study of Optically Transparent Electrically Conducting Coating on Glass and Acrylic Plastics. United States. An abstract of the above unpublished Finishing Report is given. The report is issued by the U.S. Air Force under No. P.B.118266. Note by Anon, Product Finishing 11, 73, August 1958. 33
274. Some Properties of Thin Barium-Strontium-Titanate Single Crystal Layers Evaporated in the Presence of an Electrical Field. In this paper an attempt is made to achieve the growth of single crystals of the ferro electrical Barium-strontium-titanate from the gas phase where this has as yet not been technically possible to carry out from the melt. After developing two evaporation devices for barium-strontium-titanate evaporation is carried out mainly in the presence of an electric field. The oriented single crystals formed at an adjustable condensation temperature of around 200 °C are investigated in detail. The dependance of dielectric constant on thickness of layer is notable and approaches the limit e --~ 9000 in the frequency range 1000 to 2000 Mc/s as the thickness is reduced. A discontinuous ageing process was observed only in the thicker deposits and is explained by the increase in the number of lattice errors and the resulting displacement of the domain boundaries. The breakdown strength of the layers achieved a maximum value of 5 × l0 s V/cm. (Authors) A. Moll, Z S . f. angew. Phys. 10, 410--416, 1958. 33
275. Investigations on Ion Absorption and Corrosion using Radioactive Indicators. K. Schwabe, Chemische Technik 10, 469--474, 1958. 33 276. Investigations of a High Frequency Ion Source. The optimal operating conditions for an ion-beam apparatus consisting of a high frequency ion source, ion accelerator and mass separator were determined. Under certain conditions an anomalous differential ionization of the in hydrogen was observed (probably due to metastable ions). R. Holz u. H. L6b, ZS..f. Naturforschung 13, 602-608, 1958. 33
277. Vacuum Sampling Device. Devices designed to take liquid samples in vacuum from an evacuated reaction vessel. S. Lesek and M. Sytar, Chemische Technik 10, 421, 1958. 33
278. Note on the Observation of Molecules by Field Emission Microscopy. Note by R. J. Hill and P. W. M. Jacobs, J. Chem. Phys. 30, 853-854, March 1959.
Abstracts 268-278 33
33
268. Microscopic Examination of Interior of Highly Curved Surfaces by Means of Replica~. United States. Replicas of cellulose acetate film have been
272. High-temperature X-ray Diffraetometer. Great Britain. A vacuum furnace designed for use with a
taken for surface studies of inaccessible places or highly curved surfaces. In order to increase the contrast for electron microscopy, a carbon replica was made from the cellulose acetate replica, and shadowed with platinum. In order to increase the contrast for optical microscopy, the cellulose replicas were coated with gold by evaporation. G.S. Note by A. P. Young, Rev. Sci. lnstrum. 29, 661, July 1958.
commercial diffractometer is described. It uses a high-current heater made from tantalum foil, and allows the full Bragg spectrum to be recorded whilst satisfying the Bragg-Brentano focusing condition. The specimen temperature is uniform and can be measured accurately; the furnace has been operated successfully at temperatures up to 1100 °C, and it is believed that considerably higher temperatures can be achieved. (Author) J. Spreadborough and J. W. Christian, J. Sci. Instrum. 36, 116-118, March 1959.
33
269. Photoconductivity and the Visual Receptor Process. United States. Measurements were made using B-carotene melted and cooled between two conductive glass plates in a vacuum. It was shown that B-carotene glass qualifies as a highly photoconductive organic material. Some of the properties were determined. Letter by H. Steffen Peiser, J. Opt. Soc. Amer. 48, 581-582 Aug. 1958. 33 270. Improved, Single Flash, Continuum Source for use below
2000 A. United States.
A high intensity low energy flash lamp for use below 2000 A_ is described. The radiation from a single flash at 4000 V and 15 mfd produces an emission continuum to 1500 A which is of sufficient intensity to be used with either photographic or photomultiplier techniques. A densitometer trace of the Schumann-Range Oe absorption band system is shown. Also, oscilloscope traces are presented which were taken at 1700 ~k. These show attenuation of the signal as a function of oxygen concentration. The associated vacuum technique is described. (Author) Joseph A. Golden and Albert L. Myerson, J. Opt. Soc. Amer. 48, 548-552, Aug. 1958. 33
271. High-Sensitivity Crystal Infrared Detectors. United States. The intrinsic photosensitivity of germanium and indium antimonide disappears at wavelengths greater than 1.8 and 7t~ respectively. In Ge this upper limit can be extended by doping the crystals with impurities, the activation energies of the impurity centre then become the determining factor for the maximum infra-red wavelength that can be absorbed. In this work Ge infrared detectors are cut from a large zone levelled crystal. Compensation with antimony donors is used to obtain n-type material. The gold-antimony doped detectors have a long wavelength cutoff at 6~ and a photoconductive time constant which is dependent on the wavelength of the incident radiation. A table is given which shows the sensitivity characteristics of a number of these detectors. Indium antimonide detectors have been made with sensitivities comparable to those of the gold-doped Ge. The indium antimonide detector is made either by alloying or diffusing a thin layer of impurities into the surface layer of a single crystal of material. Cadmium is now being used, giving a thin p-type surface on n-type indium antimonide. If light is allowed to fall on the front surface of the alloyed material, a photo-voltage may be measured between the n and p parts of the detector. The cutoff wavelength for this type of detector when cooled to liquid nitrogen temperature also is of the order of 6t~. A comparison is made between the characteristics of the two types of cells and a description is given of a multiple contact cell which can locate a target as well as detect it. A section is included on the standard measuring techniques used in evaluating infrared detectors, c.s. M. E. Lasser, P. Cholet and E. C. Wurst, Jr., J. Opt. Soc. Amer. 48, 468-473, July 1958.
33
273. Electron Microscope and Electron Diffraction Study of Optically Transparent Electrically Conducting Coating on Glass and Acrylic Plastics. United States. An abstract of the above unpublished Finishing Report is given. The report is issued by the U.S. Air Force under No. P.B.118266. Note by Anon, Product Finishing 11, 73, August 1958. 33
274. Some Properties of Thin Barium-Strontium-Titanate Single Crystal Layers Evaporated in the Presence of an Electrical Field. In this paper an attempt is made to achieve the growth of single crystals of the ferro electrical Barium-strontium-titanate from the gas phase where this has as yet not been technically possible to carry out from the melt. After developing two evaporation devices for barium-strontium-titanate evaporation is carried out mainly in the presence of an electric field. The oriented single crystals formed at an adjustable condensation temperature of around 200 °C are investigated in detail. The dependance of dielectric constant on thickness of layer is notable and approaches the limit e --~ 9000 in the frequency range 1000 to 2000 Mc/s as the thickness is reduced. A discontinuous ageing process was observed only in the thicker deposits and is explained by the increase in the number of lattice errors and the resulting displacement of the domain boundaries. The breakdown strength of the layers achieved a maximum value of 5 × l0 s V/cm. (Authors) A. Moll, Z S . f. angew. Phys. 10, 410--416, 1958. 33
275. Investigations on Ion Absorption and Corrosion using Radioactive Indicators. K. Schwabe, Chemische Technik 10, 469--474, 1958. 33 276. Investigations of a High Frequency Ion Source. The optimal operating conditions for an ion-beam apparatus consisting of a high frequency ion source, ion accelerator and mass separator were determined. Under certain conditions an anomalous differential ionization of the in hydrogen was observed (probably due to metastable ions). R. Holz u. H. L6b, ZS..f. Naturforschung 13, 602-608, 1958. 33
277. Vacuum Sampling Device. Devices designed to take liquid samples in vacuum from an evacuated reaction vessel. S. Lesek and M. Sytar, Chemische Technik 10, 421, 1958. 33
278. Note on the Observation of Molecules by Field Emission Microscopy. Note by R. J. Hill and P. W. M. Jacobs, J. Chem. Phys. 30, 853-854, March 1959.