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Semiclassical theories and quantum hardwall calculation of atom surface scattering
Classified
abstracts
1959-l
967
36 1959. Semiclassical theories and quantum hardwall calculation of atom surface scattering. (USA) A semiclassical formalism for atom and electron scattering from solid surfaces is presented and compared to exact quantum calculations for scattering from a sinusoidal hardwall and to experimental scattering distributions for thermal helium and neon beams scattered from W(I12). The helium results are well represented by elastic calculations, but large inelastic effects are evident in the neon scattering. The semiclassical calculations for the hardwall are in agreement with the exact quantum results to within a few percent. Qualitatively, either a specularly dominated distribution or a rainbow pattern is predicted, depending on the k vector and the amplitude of the surface periodicity. A preliminary attempt to apply this formalism to lowenergy electron scattering from Ni(lOO) is also presented. The results, while not in exact agreement with more conventional dynamic LEED calculations, do reproduce absolute peak positions to within 7 v. R I Masel et al, J Voc Sri Tcchnol. 13 (I), 1976, 355-359. 36 1960. Energy dependence of scattered ion yields in ISS. (USA) Scattered ion yields as a function of primary ion energy in the range from 200 to 2500 eV have been measured for He+, Ne+, and Ar+ scattering from a variety of solid surfaces. The energy dependence of the yield curves contains information about the electronic states of surface atoms which complements normal ISS data. In addition, changes in the surface-atom chemical environment can be manifested as changes in the yield curve. A preliminary classification of yield curve shapes is proposed based on two considerations. First, does the target atom have an electronic state with a binding energy within approximately k IO eV of the bombarding species’ first ionization potential? Second, if the first criterion is satisfied, what are the orbital symmetries of this electronic state and the vacant ionic state? T W Rusch and R L Erickson, J Vuc Sri Techno/, 13 (I ) 1976 374-377. 36 1961. AES compositional profiles of mobile ions in the surface region of glass. (USA) Measurements have been made of the AES Na signal decay from a soda-lime silicate glass at both room temperature and liquid-nitrogen temperature and for various exciting electron-beam currents. Assuming a “residence” time which varies with temperature and beam current, all decay curves have been found to fit a single expression. Using a low temperature technique, “compositional profiles” have been measured on soda-lime silicate glasses which have reacted with water vapor. A discussion is included concerning the factors involved in the detailed interpretation of these AES, ion-milling profiles. C C Pantano et al, J Vuc Sci Technol, 13 (I), 1976, 414-418. 36 1962. Hydrogen and helium implantation in vitreous silica. The effects of 150-300-keV He+ and H+ implantation in vitreous silica have been examined by optical absorption spectroscopy, optical and scanning electron microscopy, gas reemission measurements, and microtopography. No surface blistering or exfoliation was observed at any implant temperature (6200” to -8OO”C), at Ruences in excess of lOi ions cm-2. The amount of compaction of the implanted layer was determined for high-fluence ion implantation and compared with existing data. Optical absorption studies show evidence for beam-assisted chemisorption, defect formation, and, with hydrogen implantation, the formation of large (~IOz2 cm-‘) concentrations of hydroxyl. Experimental results are correlated with gas diffusivity and solubility. Implications for fusion reactor applications are discussed. P L Mattern et al, J Vuc Sci Technol, 13 (I), 430-436. 36 1963. Surface analysis using complementary electronic and chemical measurements. (USA) Surface electronic properties using scanning low energy electron probe- (SLEEP) techniques have been studied in conjunction with surface chemical properties using Auger electron spectroscopy (AES). Some examples of SLEEP measurements such as scanning TV surface work function and secondary emission displays, work function and surface field distributions using sampling techniques, and determination of thin film dielectric constant and resistivity will
be described. Observed correlation between the variation function from SLEEP and changes in surface chemical using AES will be shown for some electronic applications. of SLEEP as a means for determining surface changes other techniques such as AES will also be discussed. G A Haas, J Vat Sci Technol, 13 (I), 1976, 479486.
of work properties The use caused by
36 1964. Versatile surface spectroscopy sample manipulator. (USA) This paper describes a UHV sample manipulator of nonmagnetic construction with six degrees of motion freedom and sample heating up to I200 K for use in uv photoemission, Auger, and related spectroscopies. The sample head, with continuously adjustable 0 and Z axis rotation can be used easily inside a retarding potential sphere for photoemission studies. The manipulator can be mounted in any orientation. It provides f3.2-mm linear motion in the X and Y directions, I l.4-cm linear motion in the Z direction, 360” rotation about the Z axis, and I lo” rotation about the 0 axis located 2.54 cm behind the sample surface. Several detent positions provide a set of rotational positions about an axis 4, 2.54 cm behind the 0 axis and perpendicular to both the 8 and Z axes. This motion (combined with appropriate linear motions) allows location of the sample in any one of a number of separate experimental ports-five in our case. Translational and rotational motions of the sample are available in each of the separate experimental areas. A liquid-nitrogen cooling attachment can be added with some loss of motion freedom but which yields a continuous thermal range from 80 to 1200 K. C J Russo and R Kaplow, J Vuc Sci Technol, 13 (I), 1976 487-489. 36 1965. Composition of binary alloys by simultaneous SIMS and ARS measurements. (USA) Simultaneous AES and SIMS measurements gave identical depth profiles for a thin Ni film on Cu. For a thin Al, Ti, or Ag film on Si, however, corresponding pairs of profiles obtained by AES and SIMS were different. To further study these discrepancies, binary alloy films of different composition ratios were then prepared by vacuum deposition from two evaporation sources. Alloy compositions measured by AES and SIMS showed a linear relationship for the Ni-Cu system; however, they deviated from the linear relationship for the Ti-Si system in the Ti-rich range. By use of composition dependent parameters in Shroeer’s model, the SIMS data could be partially explained for the Ti-Si system. The nonlinear relationship appeared to be caused by changes in the most probable ion energy, the shape of ion energy distribution curve, the work function, and the sputtering yield. (Japan) T Narusawa et al, J Vuc Sci Technol, 13 (I ), 1976, 5 14-5 I 8. 36 1966. Integral Auger spectra via tailored modulation techniques. (USA) A review of the properties of presently utilized display modes for broad-energy-range Auger electron spectra (from deflection-type analyzers) suggests that an N(E) presentation, stripped of its most troublesome backgrounds, would be an excellent mode in many respects. The general features of the instrument response function and the modulation waveform required to achieve such a result in real time are developed and applied to the spectra of several typical specimens. In addition to the practical advantage that the maximum possible sensitivity and resolution are simultaneously available from the analyzer employed, this approach also encourages modest realtime spectrum deconvolution to actually reduce the finite broadening associated with that analyzer. D J Poeker et al, .I Vuc Sci Technol, 13 (I ), 1976, 507-5 I I.
37. INORGANIC DISTILLATION
CHEMISTRY,
ANALYTICAL
CHEMISTRY,
37 1967. Adsorption and desorption of water on Au by the quarkrystaloscillator method. (USA) Initial water adsorption and de-sorption isotherms (Type II) are reported for Au-coated quartzcrystal substrates at temperatures of 15.5”, 23”, 30”, and 39” using a quartz-crystal oscillator with an ultimate sensitivity of -IO-* g/cm’. Hysteresis between adsorption and desorption is most probably related to Au porosity and thermal 361
abstracts
1959-l
967
36 1959. Semiclassical theories and quantum hardwall calculation of atom surface scattering. (USA) A semiclassical formalism for atom and electron scattering from solid surfaces is presented and compared to exact quantum calculations for scattering from a sinusoidal hardwall and to experimental scattering distributions for thermal helium and neon beams scattered from W(I12). The helium results are well represented by elastic calculations, but large inelastic effects are evident in the neon scattering. The semiclassical calculations for the hardwall are in agreement with the exact quantum results to within a few percent. Qualitatively, either a specularly dominated distribution or a rainbow pattern is predicted, depending on the k vector and the amplitude of the surface periodicity. A preliminary attempt to apply this formalism to lowenergy electron scattering from Ni(lOO) is also presented. The results, while not in exact agreement with more conventional dynamic LEED calculations, do reproduce absolute peak positions to within 7 v. R I Masel et al, J Voc Sri Tcchnol. 13 (I), 1976, 355-359. 36 1960. Energy dependence of scattered ion yields in ISS. (USA) Scattered ion yields as a function of primary ion energy in the range from 200 to 2500 eV have been measured for He+, Ne+, and Ar+ scattering from a variety of solid surfaces. The energy dependence of the yield curves contains information about the electronic states of surface atoms which complements normal ISS data. In addition, changes in the surface-atom chemical environment can be manifested as changes in the yield curve. A preliminary classification of yield curve shapes is proposed based on two considerations. First, does the target atom have an electronic state with a binding energy within approximately k IO eV of the bombarding species’ first ionization potential? Second, if the first criterion is satisfied, what are the orbital symmetries of this electronic state and the vacant ionic state? T W Rusch and R L Erickson, J Vuc Sri Techno/, 13 (I ) 1976 374-377. 36 1961. AES compositional profiles of mobile ions in the surface region of glass. (USA) Measurements have been made of the AES Na signal decay from a soda-lime silicate glass at both room temperature and liquid-nitrogen temperature and for various exciting electron-beam currents. Assuming a “residence” time which varies with temperature and beam current, all decay curves have been found to fit a single expression. Using a low temperature technique, “compositional profiles” have been measured on soda-lime silicate glasses which have reacted with water vapor. A discussion is included concerning the factors involved in the detailed interpretation of these AES, ion-milling profiles. C C Pantano et al, J Vuc Sci Technol, 13 (I), 1976, 414-418. 36 1962. Hydrogen and helium implantation in vitreous silica. The effects of 150-300-keV He+ and H+ implantation in vitreous silica have been examined by optical absorption spectroscopy, optical and scanning electron microscopy, gas reemission measurements, and microtopography. No surface blistering or exfoliation was observed at any implant temperature (6200” to -8OO”C), at Ruences in excess of lOi ions cm-2. The amount of compaction of the implanted layer was determined for high-fluence ion implantation and compared with existing data. Optical absorption studies show evidence for beam-assisted chemisorption, defect formation, and, with hydrogen implantation, the formation of large (~IOz2 cm-‘) concentrations of hydroxyl. Experimental results are correlated with gas diffusivity and solubility. Implications for fusion reactor applications are discussed. P L Mattern et al, J Vuc Sci Technol, 13 (I), 430-436. 36 1963. Surface analysis using complementary electronic and chemical measurements. (USA) Surface electronic properties using scanning low energy electron probe- (SLEEP) techniques have been studied in conjunction with surface chemical properties using Auger electron spectroscopy (AES). Some examples of SLEEP measurements such as scanning TV surface work function and secondary emission displays, work function and surface field distributions using sampling techniques, and determination of thin film dielectric constant and resistivity will
be described. Observed correlation between the variation function from SLEEP and changes in surface chemical using AES will be shown for some electronic applications. of SLEEP as a means for determining surface changes other techniques such as AES will also be discussed. G A Haas, J Vat Sci Technol, 13 (I), 1976, 479486.
of work properties The use caused by
36 1964. Versatile surface spectroscopy sample manipulator. (USA) This paper describes a UHV sample manipulator of nonmagnetic construction with six degrees of motion freedom and sample heating up to I200 K for use in uv photoemission, Auger, and related spectroscopies. The sample head, with continuously adjustable 0 and Z axis rotation can be used easily inside a retarding potential sphere for photoemission studies. The manipulator can be mounted in any orientation. It provides f3.2-mm linear motion in the X and Y directions, I l.4-cm linear motion in the Z direction, 360” rotation about the Z axis, and I lo” rotation about the 0 axis located 2.54 cm behind the sample surface. Several detent positions provide a set of rotational positions about an axis 4, 2.54 cm behind the 0 axis and perpendicular to both the 8 and Z axes. This motion (combined with appropriate linear motions) allows location of the sample in any one of a number of separate experimental ports-five in our case. Translational and rotational motions of the sample are available in each of the separate experimental areas. A liquid-nitrogen cooling attachment can be added with some loss of motion freedom but which yields a continuous thermal range from 80 to 1200 K. C J Russo and R Kaplow, J Vuc Sci Technol, 13 (I), 1976 487-489. 36 1965. Composition of binary alloys by simultaneous SIMS and ARS measurements. (USA) Simultaneous AES and SIMS measurements gave identical depth profiles for a thin Ni film on Cu. For a thin Al, Ti, or Ag film on Si, however, corresponding pairs of profiles obtained by AES and SIMS were different. To further study these discrepancies, binary alloy films of different composition ratios were then prepared by vacuum deposition from two evaporation sources. Alloy compositions measured by AES and SIMS showed a linear relationship for the Ni-Cu system; however, they deviated from the linear relationship for the Ti-Si system in the Ti-rich range. By use of composition dependent parameters in Shroeer’s model, the SIMS data could be partially explained for the Ti-Si system. The nonlinear relationship appeared to be caused by changes in the most probable ion energy, the shape of ion energy distribution curve, the work function, and the sputtering yield. (Japan) T Narusawa et al, J Vuc Sci Technol, 13 (I ), 1976, 5 14-5 I 8. 36 1966. Integral Auger spectra via tailored modulation techniques. (USA) A review of the properties of presently utilized display modes for broad-energy-range Auger electron spectra (from deflection-type analyzers) suggests that an N(E) presentation, stripped of its most troublesome backgrounds, would be an excellent mode in many respects. The general features of the instrument response function and the modulation waveform required to achieve such a result in real time are developed and applied to the spectra of several typical specimens. In addition to the practical advantage that the maximum possible sensitivity and resolution are simultaneously available from the analyzer employed, this approach also encourages modest realtime spectrum deconvolution to actually reduce the finite broadening associated with that analyzer. D J Poeker et al, .I Vuc Sci Technol, 13 (I ), 1976, 507-5 I I.
37. INORGANIC DISTILLATION
CHEMISTRY,
ANALYTICAL
CHEMISTRY,
37 1967. Adsorption and desorption of water on Au by the quarkrystaloscillator method. (USA) Initial water adsorption and de-sorption isotherms (Type II) are reported for Au-coated quartzcrystal substrates at temperatures of 15.5”, 23”, 30”, and 39” using a quartz-crystal oscillator with an ultimate sensitivity of -IO-* g/cm’. Hysteresis between adsorption and desorption is most probably related to Au porosity and thermal 361