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Some effects of cathode material and surface nature on work function and sparking potentials in hydrogen
Classified Abstracts being either in operation or not. It will be seen that the spectrum of the residual gas is considerably affected by the pumping action of the gauge. Mass No. 1 2 3 16 18 28 44
Source H H,f Ha+ CH4+ H,Q+ co+ COsf
Ion current (lo-IsA) Gauge off Gauge on 0.55 55 36 0.1 0.1
0.2 24 1.2 0.45 1.6 4.6 0.1
The author gives reasons molecules of CH,, Hz0 and hydrogen with the glass of hydrogen itself is probably by the incandescent tungsten V. J. Mimeault,
for supposing that the contaminant CO are due to interaction of atomic the containing vessel. The atomic produced from molecular hydrogen filament of the gauge. (U.S.A.) w. J. s. Vacuum, 13 (6), June 1963, 229-230.
16 : 41 894. Crystal field effects in the adsorption and desorption of oxygen at a nickel oxide surface. (Great Britain) The adsorption of oxygen on nickel oxide has been studied over the range of temperature from 20°C to 460°C. It is an activated process. The attainable coverage at 6 x lO-2 mm pressure passes through a maximum at 250°C. The coverage at this temperature is 10 per cent but it is only 1 per cent at 20°C. Illumination at 20°C of a surface carrying adsorbed oxygen gives rise to desotption, and experiments with filters show that the photo-activity is almost entirely confined to wavelengths between 650mp and 9OOmp. The kinetics of the photodesorvtion have been studied and the dependence on incident light intensity has been examined. Photodesorption at 20°C is more extensive when oxygen has been presorbed at room temperature (1 per cent coverage) than when it has been presorbed at higher temperatures (higher coverages). The absorption spectrum of nickel oxide is discussed and the correlation between the wavelengths active in photodesorption and those involved in internal d-d transitions of the Ni2+(d*) ion is emphasised. The changes in crystal field stabilization during chemisorption of oxygen on nickel ions in the three principal planes (lOO), (110) and (111) are outlined, and a model is presented which associates photodesorption with the change from six-fold to four-fold co-ordination initiated by absorption in the 3A2-ST1s band. The kinetics which follow from the The influence model are shown to conform to those observed. of coverage on photodesorption is discussed with reference to the role of NiS+ ions produced during oxygen chemisorption. (Great Britain) (Authors) J. Haber and F. S. Stone, Trans. Faraday Sot., 59 (l), Jan. 1963, 192-206. Surface contamination in kinetic pumping systems. No. 879. Sorption pumping at high and ultra-high vacua. No. 910.
16 : 11 See Abstr. 16 : 21 See Abstr.
16 : 22 Effect of adsorbed oxygen in measurements with ionization gauges. See Abstr. No. 920. Non-evaporatfng getters with diffusion. See Abstr. No. 974.
surface
adsorption
and
16 :47 pore-
894-899
383 18.
Gaseous
Electronics
18 : 33 895. Thermal recovery of inert gases ionicaily pumped into glass. (Italy) Inert gases (generally observed as common residuals in electron tubes) were ionically pumped into a glass surface and the spontaneous recovery observed with a mass spectrometer. The pumping was conducted under dynamic conditions such that a constant ion bombardment rate was maintained. The recovery rate was measured as a function of time after ending bombardment and was found to be related to this parameter by the expression : Rate at-“. The index n was found to decrease from - 1 at short pumping times to a lower value at long pumping times. The long pumping time values of n were observed to depend upon the pumping pressure, decreasing to -0.25 at pressures of lo-* tori-. This typical behaviour of recovery from metals (- 1 index) to that of “ pseudo equilibrium static pumping ” recovery (-0.5 index) were reproduced. An explanation of the recovery data is given in terms of thermal desorption from a heterogenity of capture sites near the glass surface. This is shown to agree with a previous theory of pumping into glass surfaces. (Great Britain) (Authors) G. P. Smeaton, J. H. Leek and G. Carter, 2nd Internat. Symp. residual gases in electron tubes, Milan, (March 1963), Nuovo Cimento (in press). 18 : 47 Interactions between ionizing discharges and getter films. See Abstr. No. 978. 18 : 31 : 52 Some effects of cathode material and surface nature on work function and sparking potentials in hydrogen. See Abstr. No. 933.
19. Radiation 19 896. Pulsed Laser operation in helium-neon mixtures. (Great Britain) In a previous paper, the authors reported pulsed infrared oscillations in the after glow of a helium-neon plasma at pressures of the order of 1 torr. The present communication describes results obtained at higher pressures. The gas mixture was excited by means of external ring electrodes to which were applied 1~ set pulses of up to 60 kV. Oscillation of the plasma occurs about 1~ set after the pulse with a half width of l-8 psec. Four wavelengths in the infrared were recorded, with a peak output of about 80 W and a mean power of about 25 mW. The discharge becomes unstable if the total gas pressure exceeds 240 torr (neon partial pressure 5 torr). (Great Britain) W. J. S.
H. A. H. Boot, et al., Nature, 198 (4882), 25 May 1963, 773-774. 19 897. Energy emitted in spectral lines by a plasma at equilibrium. (U.S.A.) L. M. Biberman, et al., Optics & Spectrosc., 14 (3), March 1963, 176. 19 898. Luminescence of anthracene crystal obtained by sublimation in an oxygen atmosphere under irradiation. (U.S.A.) V. L. Zima and A. N. Faidysh, Optics & Spectrosc., 14 (3), March 1963, 198. 19 899. Luminescence kinetics of chromium luminors. M. Composite AlIOI.Ga20,-Cr system and magnesium spine1 activated by chromium. (U.S.A.) N. S. Tolstoy and Liu Shun-Fu, Optics di Spectrosc., 14 (3), March 1963, 202.
Source H H,f Ha+ CH4+ H,Q+ co+ COsf
Ion current (lo-IsA) Gauge off Gauge on 0.55 55 36 0.1 0.1
0.2 24 1.2 0.45 1.6 4.6 0.1
The author gives reasons molecules of CH,, Hz0 and hydrogen with the glass of hydrogen itself is probably by the incandescent tungsten V. J. Mimeault,
for supposing that the contaminant CO are due to interaction of atomic the containing vessel. The atomic produced from molecular hydrogen filament of the gauge. (U.S.A.) w. J. s. Vacuum, 13 (6), June 1963, 229-230.
16 : 41 894. Crystal field effects in the adsorption and desorption of oxygen at a nickel oxide surface. (Great Britain) The adsorption of oxygen on nickel oxide has been studied over the range of temperature from 20°C to 460°C. It is an activated process. The attainable coverage at 6 x lO-2 mm pressure passes through a maximum at 250°C. The coverage at this temperature is 10 per cent but it is only 1 per cent at 20°C. Illumination at 20°C of a surface carrying adsorbed oxygen gives rise to desotption, and experiments with filters show that the photo-activity is almost entirely confined to wavelengths between 650mp and 9OOmp. The kinetics of the photodesorvtion have been studied and the dependence on incident light intensity has been examined. Photodesorption at 20°C is more extensive when oxygen has been presorbed at room temperature (1 per cent coverage) than when it has been presorbed at higher temperatures (higher coverages). The absorption spectrum of nickel oxide is discussed and the correlation between the wavelengths active in photodesorption and those involved in internal d-d transitions of the Ni2+(d*) ion is emphasised. The changes in crystal field stabilization during chemisorption of oxygen on nickel ions in the three principal planes (lOO), (110) and (111) are outlined, and a model is presented which associates photodesorption with the change from six-fold to four-fold co-ordination initiated by absorption in the 3A2-ST1s band. The kinetics which follow from the The influence model are shown to conform to those observed. of coverage on photodesorption is discussed with reference to the role of NiS+ ions produced during oxygen chemisorption. (Great Britain) (Authors) J. Haber and F. S. Stone, Trans. Faraday Sot., 59 (l), Jan. 1963, 192-206. Surface contamination in kinetic pumping systems. No. 879. Sorption pumping at high and ultra-high vacua. No. 910.
16 : 11 See Abstr. 16 : 21 See Abstr.
16 : 22 Effect of adsorbed oxygen in measurements with ionization gauges. See Abstr. No. 920. Non-evaporatfng getters with diffusion. See Abstr. No. 974.
surface
adsorption
and
16 :47 pore-
894-899
383 18.
Gaseous
Electronics
18 : 33 895. Thermal recovery of inert gases ionicaily pumped into glass. (Italy) Inert gases (generally observed as common residuals in electron tubes) were ionically pumped into a glass surface and the spontaneous recovery observed with a mass spectrometer. The pumping was conducted under dynamic conditions such that a constant ion bombardment rate was maintained. The recovery rate was measured as a function of time after ending bombardment and was found to be related to this parameter by the expression : Rate at-“. The index n was found to decrease from - 1 at short pumping times to a lower value at long pumping times. The long pumping time values of n were observed to depend upon the pumping pressure, decreasing to -0.25 at pressures of lo-* tori-. This typical behaviour of recovery from metals (- 1 index) to that of “ pseudo equilibrium static pumping ” recovery (-0.5 index) were reproduced. An explanation of the recovery data is given in terms of thermal desorption from a heterogenity of capture sites near the glass surface. This is shown to agree with a previous theory of pumping into glass surfaces. (Great Britain) (Authors) G. P. Smeaton, J. H. Leek and G. Carter, 2nd Internat. Symp. residual gases in electron tubes, Milan, (March 1963), Nuovo Cimento (in press). 18 : 47 Interactions between ionizing discharges and getter films. See Abstr. No. 978. 18 : 31 : 52 Some effects of cathode material and surface nature on work function and sparking potentials in hydrogen. See Abstr. No. 933.
19. Radiation 19 896. Pulsed Laser operation in helium-neon mixtures. (Great Britain) In a previous paper, the authors reported pulsed infrared oscillations in the after glow of a helium-neon plasma at pressures of the order of 1 torr. The present communication describes results obtained at higher pressures. The gas mixture was excited by means of external ring electrodes to which were applied 1~ set pulses of up to 60 kV. Oscillation of the plasma occurs about 1~ set after the pulse with a half width of l-8 psec. Four wavelengths in the infrared were recorded, with a peak output of about 80 W and a mean power of about 25 mW. The discharge becomes unstable if the total gas pressure exceeds 240 torr (neon partial pressure 5 torr). (Great Britain) W. J. S.
H. A. H. Boot, et al., Nature, 198 (4882), 25 May 1963, 773-774. 19 897. Energy emitted in spectral lines by a plasma at equilibrium. (U.S.A.) L. M. Biberman, et al., Optics & Spectrosc., 14 (3), March 1963, 176. 19 898. Luminescence of anthracene crystal obtained by sublimation in an oxygen atmosphere under irradiation. (U.S.A.) V. L. Zima and A. N. Faidysh, Optics & Spectrosc., 14 (3), March 1963, 198. 19 899. Luminescence kinetics of chromium luminors. M. Composite AlIOI.Ga20,-Cr system and magnesium spine1 activated by chromium. (U.S.A.) N. S. Tolstoy and Liu Shun-Fu, Optics di Spectrosc., 14 (3), March 1963, 202.