962. Surface analysis with heavy ion induced Auger electrons

Classified abstracts 962-970 is determined by the spectral range to be investigated. A compact design out of one piece and large windows permit the use of the cell interchangeably among a variety of commercially available ir and uv-visible spectrophotometers. The design of the cell has been reported. In addition two specific applications of the cell to high vacuum and high pressures at elevated temperature (200°C) are described. (Germany) E Gallej and E Schadow, Rev Sci Insrrum, 45 (12), 1974, 1504-1506. 33 962. Surface analysis with heavy ion induced Auger electrons. (Germany) High energy heavy ion induced Auger electron spectroscopy is proposed as a new tool for surface analysis. First measurements are described. Applicability, sensitivity and the possibility of selective excitation of trace impurities are discussed and the method is compared with other techniques. K 0 Groeneveld and R Spohr, Vukuum-Terh, 23 (8), 1974, 226-229 (in German). 33 %3. A high-voltage telefocus electron gun with remote focussiag. (USA) A new design for a telefocus electron gun is presented. Features include a nearly constant minimum FWHM of 180 pm with team currents of l-400 PA at focal distances from + to 1) m. The gun is expecially designed to operate under adverse vacuum conditions with background pressures as high as 10e4 torr with accelerating potentials of 10 to 60 keV. In addition the gun can be remotely focused and positioned from outside the vacuum chamber in which the gun is used. H Schmoranzer et al, Rea Sci Instrum, 46 (l), 1975, 89-91. 33 964. A high energy (keV), large angular range, precision electron spectrometer for atomic and molecular targets. (USA) An electron impact spectrometer for operation in the keV incidentelectron energy range is described. The spectrometer operates between 20 and 60 keV incident-electron energy, utilizing both a low-resolution silicon surface barrier detector (5 keV FWHM), and a high-resolution (0.7 eV FWHM) MGllenstedt energy analyser over a 1.7 keV energy loss range. It features a large angular scan range (0 I B < l20”), high target gas throughput (i.e., 19,000 I/s for He and 13,000 l/s for Nz through a tube of 0.15 mm dia), and a wide range of incidentelectron beam currents (0.1400 PA) with a focused electron team size of less than 200 PFWHM over most of the current range. Careful measurements of the gas density profile of the target gas emanating from the nozzle are also reported. Results are presented for the Bethe surface of He and N2. The latter example is reported here for the first time. In addition, the observation of the angular dependence of the Lyman-Birge-Hopfield band in N, (dipole forbidden) is compared with the dependence of a neighbouring dipole allowed transition. H F Wellenstein et al, Rev Sci Znstrum, 46 (I), 1975, 92-97. 33 965. The application of transmission electron microscopy through the use of thin foils. (USA) Basic procedures of TEM are described, and the recent advances in the technique and in its application are reported. Among the most recent developments are: (i) high-voltage electron microscopy, which lessens the stringement requirement for producing foils as thin as 2000-500 8; and (ii) scanning transmission electron microscopy, which offers benefits over conventional TEM, e.g., an increase in penetrating powder by a factor of about 3, and a time-resolved image. The application of these techniques, as well as energy analysis, will become widespread as more instruments become available, enlarging further the number and types of problems capable of solution with TEM. D M Moon, J Vat Sci Technol, 11 (6), 1974, 1084-1086. 33 966. Secondary-ion mass analysis: Instrumentation, data interpretation and applications. (USA) The field of secondary-ion mass analysis is discussed starting with the historical events leading up to present-day instrumentation. The two principal types of instruments are described in some detail, as well as anticipated new developments. Problems in data interpretation and quantitative treatment of data are discussed as a background for the presentation of several examples of the technique’s usefulness. B F Phillips, J Vat Sci Technol, 11 (6), 1974, 1093-1099.

33 967. Higher zones of stability for the quadrupole mass filter. (USA) Matrix methods based on phase-space dynamics are used to examine the feasibility of operating a quadrupole mass filter using one of the higher zones of stability. Ion transmission efficiencies are calculated for various modes of operation. By using lower rf, performance may approach that of the conventional mass filter under certain conditions, but instrument apertures are generally somewhat smaller. (Canada) P H Dawson, J Vat Sci Technol, 11 (6), 1974, 1151-l 153. 34. HIGH ALTITUDE

AND SPACE TECHNOLOGY

34 968. Microwave double resonance study of collision induced population transfer between levels of interstellar methanol lines. (Canada) Collision induced transitions between rotational levels of methanol have been investigated by steady state microwave double resonance, in order to study collisional excitation mechanisms for methanol in the interstellar medium. Experiments are described on pure CH,OH and on dilute mixtures of CH,OH with excess He and HZ, for various four level systems of astrophysical interest. For pure CH,OH, the results are qualitatively consistent with dipolar selection rules, AJ = 0, * I and Ak = 0, * I, but certain aspects of the quantita. tive analysis are unexplained. For collisions of CH,OH with either He or HZ, the collisional transition rates decrease relatively slowly with IJ. In the collisions with He, parallel 1k = 0 collisional transitions occur about four times more frequently than perpendicular Ik = &l transitions, whereas in collisions with normal HZ, 6k = 0 transitions are approximately twice as frequent as lk =I iI transi. tions. R M Lees and S S Haque, Can J Phys, 52 (22), 1974, 225&2271. 34 969. Free-space propagation of h-radiance fluctuations and the fourth. order coherence function. (USA) In studies of propagation through random media, an equation was developed that governs the propagation of the fourth-order coherence function. Here, we use this equation, without the scattering term, to investigate the propagation of the fourth-order coherence function in free space. Irradiance fluctuations are studied as a special case for infinite and finite beams. For a finite beam, the normalized on-axis irradiance fluctuations that result from a weak phase screen reach a maximum value before decaying to zero as the propagation distance becomes very large. In agreement with earlier results, the infinite beam is found to approach a constant value. M JBeranand AM Whitman, JOpt Sot Am,64(12), 1974,1636-1640.

37. METALLURGY, CAL CHEMISTRY

INORGANIC

CHEMISTRY,

ANALYTI.

37 970. Cleavage surface energy of the ((111)) plane of strontium fluoride. (USA)

Due to its excellent optical transmission in the 2-6.pm wavelength region, SrF, is an attractive candidate window material for high. energy CO and chemical lasers. Fracture strength, an essential parameter used to evaluate window materials, is largely controlled by the specific surface energy of potential cleavage planes in brittle ionic crystals such as SrF2. This quantity has been measured previ. ously for the ((111)) plane of CaF, and BaF*, but not for SrF,. In order to obtain this information, a modification of the ObreimovGilman cleavage technique has been used to determine the specific surface energy of SrF, ((I 11)) under a variety of conditions and two methods of calculation of the experimental value have been examined and compared. The apparent surface energy of annealed SrF, decreases linearly with the logarithm of crosshead speed from 0.002 in./min to 2.0 in./min. This effect is attributable, at least qualitatively, to energy dissipation through dislocation multiplication by the m;ltiple cross glide mechanism in the region of the crack tip. While vacuum (10m6 torr) annealing at 800°C and variation in the direction of crack propagation are found to have a negligible effect on y, cleavage at 77 K or in the presence of a DMF/DMSO solu. tion leads to significant increases in y. These increases may be attributed, respectively, to crack blunting and energy dissipation by dislocation multiplication and step formation. P Kraatz and T Zoltai, J Appl Phys, 45 (ll), 1974, 4741-4750. 293