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Differential scattering in the Ar(+)+N2 and He(+)+H2 systems was studied in detail at low keV energies and small scattering angle. Charge exchange processes were found to be important in these systems. It was demonstrated that the collision involves the entire molecule and that vibro-rotational and electronic excitation occur independently. Only selected electronic states of the molecules participate in the scattering. Ionization in Ar+Ar collisions was studied and was attributed to both single electron excitation processes and to the excitation of autoionizing states. Studies of low energy He(+)+He collisions have shown strong energy dependent oscillations in the polarization of light emitted from the 3d states of He. Coincidence measurements on electrons ejected from 25 keV Ar(+)+Ar collisions show the presence of fast and slow electrons. The slow electrons may be ejected after as well as before the fast Auger electrons. Coincidence measurements on the L2,3 M x-ray yield were made at energies from 16-30 keV in Ar(+)+Ar. Enhancement of the fluorescence yield above 20 keV is attributed to M shell excitation. Vacuum ultraviolet spectra in the range of 500-1100A were observed in 10-30 keV rare gas ion-atom collisions. The results suggest correlations between inner and outer shell excitations.

Source region EMP and close-in coupling calculations were performed in support of a source region EMP simulation experiment performed in the AURORA flash x-ray environment. Calculations were performed of the photon transport and electron transport to obtain the EMP drivers within an air-filled right circular cylinder. Maxwell's equations were solved by a finite difference technique to obtain the EMP fields and the current coupled to right circular cylindrical body within the cylindrical test chamber. (Author)

In order to evaluate some of the features of the electromagnetic response of space systems to pulsed, plane wave photon environments, it is necessary to understand the intensity, energy spectrum, and angular distribution of the electron emission current. For a realistic application, the electron emission spectrum and angular distribution can be found by convolving the incident photon spectrum with the electron yield as a function of photon energy. This electron yield, which expresses the number of electrons emitted from a surface per incident photon, can be expected to vary with angle of photon incidence and material composition as well as with photon energy. Soft x-rays contribute to electron emission primarily through photoelectric interactions and the electron yield for soft x-rays will be referred to here as the photoelectric yield. In this paper, a simple model of the photoelectric yield is proposed and predictions based upon the model are compared with published experimental data. Furthermore, simple expressions for the electron emission current for arbitrary incident photon fluxes are derived for the higher energy electron components.

A continuation of the experiment examining the sticking probability of energetic alkali ions on Ge is described. Results are given for the Ge(100)-Cs system in the zero coverage region. Experimental difficulties which forced discontinuation of the study are discussed. A study of the Ge(100)-Cs-O photosurface is described with particular emphasis on the structural changes associated with cathode formation. A stable negative electron affinity Si(100)-Cs-O photocathode was obtained and the optimum amount of Cs determined to be 1.3 monolayer. A work function value of approximately 0.6 eV was measured. Experimental results of an electron scattering experiment on Ge(100) are summarized. A full report is forthcoming. Auger spectra obtained from vacuum-cleaved alkali halide crystals are presented and some of the difficulties encountered are summarized. Preliminary evaluation of the use of Auger spectroscopy for the analysis of aqueous solutions is described. A description of a system for studying complex photocathodes is given. (Author)

Silicon (Si) and tungsten (W) single crystals were subjected to low-energy ion bombardment for the purpose of evaluating the effects of ion bombardment and post-anneals on surface structure. Bombardments were performed in a low-pressure d.c. plasma supported by a thermionic cathode. Low-energy electron diffraction (LEED) and Auger spectroscopy measurements were conducted to situ. The crystalline structure of Si surfaces was found to be very sensitive to Ar and Kr ion bombardment. Bombardment generally produced an amorphous surface layer. The threshold energy for producing surface damage Kr ions is around 5 eV. A major portion of the bombardment damage apparently anneals at normal discharge temperatures of 200 to 300 degrees C. The Auger spectrum of W exhibited a number of Auger peaks as expected from x-ray data., See also AD-824 974.

Pressure-vessel steels and weldments containing the residual elements copper and phosphorus show a marked tendency toward embrittlement after irradiation at 290C. Auger electron spectroscopy was used to analyze fracture surfaces of these materials to ascertain if segregation of copper and phosphorus during irradiation was responsible for the embrittlement. No evidence of segregation was found. An alternative mechanism is suggested in which the residual elements modify the defect microstructure, with attendant increases in yield strength and ductile-to-brittle transition temperature. (Author)

Microelectronic vacuum-integrated-circuit components were studied to determine the emission capability of a newly developed electron emitter which is necessary for vacuum-integrated-circuit operation, to determine the surface-potential variations in the cathode and grid structures, and to determine the effects of migration, transport, and diffusion. (Modified author abstract)

The report discusses a completed study of the adsorption and decomposition of CO on a Pt(111) surface by Auger electron spectrometric (AES) and electron-induced desorption (EID) techniques. CO was found to adsorb on the clean surface by first-order Langmuirian kinetics. Adsorbed carbon produced by electron-induced decomposition of adsorbed CO poisoned the adsorption process. The kinetics of this process have been determined from AES and EID studies. A continuing study of gas adsorption on Fe(110) is also discussed. The experimental techniques being used, plan of attack and results to date are presented. (Modified author abstract)

The mechanical behavior of polycrystalline nickel specimens that were deformed in tension and cathodically charged with hydrogen simultaneously was investigated with particular emphasis on the fracture of such electrodes. This procedure leads to very definite if, however, weak serrated yielding and also markedly reduces the elongation at fracture compared to polycrystals unexposed to hydrogen. Moreover, in contrast to hydrogenated nickel monocrystals which neck down to give a chisel-edge fracture typical of ductile metals, hydrogenated polycrystal fractures are brittle and intergranular. The embrittlement of nickel by hydrogen is shown by means of Auger electron spectroscopy to be associated with the segregation of hydrogen recombination poisons to the grain boundaries. (Author Modified Abstract)

The report concerns a trip associated with research accomplished to date on the project entitled 'Structure of Highly Stripped Nitrogen, Oxygen, Fluorine, Chlorine, and Argon Ions.' Specifically, attendance and presentations at the International Seminar on Ion-Atom Collisions and the 8th International Conference on the Physics of Electronic and Atomic Collisions are described. (Modified author abstract), Report on Structure of Highly Stripped Nitrogen, Oxygen, Fluorine, Chlorine, and Argon Ions.

Translational energy spectroscopy has been previously employed by Wilson and co-workers and Diesen et al. to study energy and angular distributions of photodissociation processes in the visible and the near ultraviolet. Pulsed lasers have been used as light sources and photofragments have been detected by mass spectroscopy.

Papers which resulted from the research are: 'Cone Formation on Metal Targets during Sputtering'; 'Alloy Sputtering Studies with in situ Auger Electron Spectroscopy'; 'Auger Electron Spectroscopy Studies of Sputter Deposition and Sputter Removal of Mo from Various Metal Surfaces'; 'Escape Length of Auger Electrons'; and 'Purple Plague and Au-Al Diffusion Studies with Auger Electron Spectroscopy'. (Modified author abstract), See also report dated May 71, AD-724 960.

A scanning Auger microscope was constructed at the Air Force Avionics Laboratory to permit surface analysis of solid state devices. The instrument was operated in a scanning electron microscope mode for initial tests and calibration. Electron gun operation was verified by measuring a beam current of 0.8 microampere. Electron beam diameter was determined to be approximately 20 microns by observing the resolution of the display. A cylindrical mirror analyzer was installed on the electron gun assembly and synchronous detection techniques were used to record Auger spectra. An apparent inability to record Auger peaks was localized to the analyzer. Wiring diagrams and operating instructions were formulated for the use of future operators of the apparatus. (Author)

The use of atomic and molecular scattering in an ultrahigh vacuum chamber is described. The studies also include LEED, Auger electron spectra, flash desorption, and gravimetric studies of adsorption, surface structure, and reactivity. The interactions of H2, D2, He, Ne, Ar, Kr, Xe, N2, N2O, CH4, O2, and C2H4 have been examined on Pt(111), W(110), Ag(111), W(100), graphite, and diamond surfaces. (Author)

Work on metal/metal interfaces is reported. Calculations of reflection coefficient for McRae multiple scattering LEED Theory are presented for s-wave case. Kambe's Theory is briefly discussed. A decomposition technique using a Dupont curve resolver is discussed using experimental curves of Nb(110) and of Mo(100). Development of apparatus is outlined. Experimental work presented in detail covers LEED/Auger studies of Al on Mo(110) and Nb(110). Less detailed analysis of other work include Al shell casings, a turbine blade, and fractured samples of D6AC and Ti-6-6-2 alloys. (Author)

The average surface free energies of chromium, molybdenum, and tungsten have been measured at 0.6 to 0.8 of the absolute melting temperature by multiphase equilibrations with liquid tin or silver in tantalum-gettered argon. With grain boundary groove angles measured by interferometry and stylus profile tracing, the respective values were found. (Author)

The work concerned atomic collisions of the type X(+) + Y yields X(+m) = Y(+n) + (m+n-1)e at keV energies (T(o)) and large scattering angles. Of interest are the inelastic energy (Q) distributions, and average ionization probabilities P(mn) for the many combinations for the collision partners investigated. The systems studied were the Ar(+)- Ar, Ne(+,++,o)- Ne, N(+)- Ar, and Ar(+)- Kr cases. The neon case was studied at 200 keV to test Lichten's prediction that the fast electron ejection intensities should be in the ratio of 0:1:2 for incident neutrals, singly charged ions and doubly charged ions respectively. The Ar(+)- Ar case was recently studied to show that the inner shell vacancy leading to Auger electron emissions can be caused by promotion of an electron to a bound state of the ion. The N(+)- Ar and Ar(+)- Kr cases were studied in great detail in order to see if one could, for example, predict Ar(+)- Kr result on the basis of previous Ar(+)- Kr and Kr(+)- Kr data. A statistical model similar to that of Everhart and Kessel has been developed for these cases. (Author), Continuation of Grant AF-AFOSR-805-65.

Experiments on cone formation in sputtering of multicomponent materials were continued. Auger electron spectroscopy of insulator surfaces poses no particular problems when one operates with the primary beam energy in regimes where the secondary electron coefficient is larger than unity. The main part of the work concerns in situ Auger electron spectroscopy studies of sputter deposition and sputter removal of Mo from various metal surfaces. The sputtering yield of Mo atoms from Cu, Au, Al expecially at low ion energies is much lower than that of Mo from Mo 200 eV Ar ions remove Mo atoms from an Al surface with a yield which is only 1/1000 of the bulk Mo yield. Mo monolayer islands protect the underlying Cu, Au, Al from being sputtered and this is responsible for the formation of cones. A significant conclusion is that the use of low energy ion bombardment for layer removal and determination of composition profiles may often lead to erroneous results. (Author)

An electron spectrometer of the LEED-Auger type was installed n the authors' laboratory. The principle of operation, the significance of the measurements and possible applications are described. The capabilities of the technique are demonstrated by studying the clean and gas-covered silicon (111) surface. The results suggest that the spectrometer is a sensitive and versatile instrument for the analysis of surface composition, structure and properties. (Author)

A theoretical model for scattering of ions and neutrals in the hyperthermal energy range from perfect crystal surfaces was developed. Using an approximate model for ion recombination rate through Auger-neutralization, an ion beam is converted into a neutral beam with a distribution of velocities modified by the ion image attraction prior to its neutralization. A model was then constructed for the scattering of hyperthermal molecules from a surface of a perfect semi-infinite lattice composed of uncoupled harmonic oscillators. A pairwise gas-solid Morse potential was assumed. It was concluded that some overall features of ion recombination rates could be determined by comparing scattered flux distributions of a hyperthermal neutral beam and an identical ion beam. (Author), Also available from Massachusetts Inst. of Tech., Cambridge. Fluid Dynamics Lab. as Rept. T70-2.

For collision of an ion with a metal surface, with reference to aerodynamic applications, the report examines the general problem of the physical mechanisms of the accompanying processes and the specific problem of the charge states of the gas particle and surface. The semi-empiric Hagstrum theory is discussed with correction of its internal contradictions. It is considered firmly established that ion neutralization by given metallic surfaces corresponds to the mechanism of Auger neutralization. The theory discussed permits calculation of aerodynamic values with good accuracy. It is found that practically all positive ions that collide with a pure metallic surface are neutralized. Secondary electrons must be taken into account in calculation of the charge state. A considerable part of the energy of ion neutralization and the energy of strongly excited atoms is converted to thermal energy, which can exceed ion kinetic energy at a velocity of about 8 km/sec. (Author), Unedited rough draft trans. of Aerodinamika Razreshennykh Gazov (USSR) n3 p110-123 1967.

Results are given of (1) a study of the cone formation which arises at the surface of a high sputtering yield target such as Cu when it is seeded during sputtering with another material such as Mo, and (2) the analysis of composition changes at the surface of multicomponent targets under ion bombardment and of sputter deposited films by means of in situ auger electron analysis. (Author)

Research effort was concentrated to employ high resolution lithium drifted germanium detectors in an effort to obtain high precision measurements of atomic fluorescence yields. This portion of the research was accomplished successfully. Other efforts to investigate ways of using Auger electron spectroscopy to enhance knowledge of atomic fluorescence yields were not achieved. The report describes the research techniques used in the two areas. (Author)

A theory of the ejection of electrons from atomically clean metals by slow ions of the noble gases arising from Auger transitions is presented. Scattering matrix elements are evaluated from first principles and the secondary ejected electron energy distribution and total yield are found. The approach used in the solution of this problem is that of the quantum theory of scattering. This approach eliminates determining transition matrix elements per unit time as a function of the distance of the ion from the metal surface, and will allow the direct calculation of the secondary electron energy distribution, total yield, spatial distribution, position of most probable neutralization, and depth of origination of Auger electrons. The formal solution is applied to the situation of He(+) ions of low energy incident on atomically clean tungsten. Normal incidence is treated although the theory is not restricted to this case. Typical theoretical curves are presented and compared with the experimental results of others. A discussion of such effects as energy broadening, effective ionization energy, uncertainty principle effects, inelastic electron scattering, and density of electron states in metals is included. (Author)

A soft x-ray appearance potential spectrometer (SXAPS) has been assembled, tested, and used to record spectra of selected materials for the purpose of studying the feasibility of routine elemental and chemical characterization of surfaces. These initial results demonstrate capabilities of SXAPS as a surface analysis tool and provide guidelines for the development of a more sensitive detection system for the technique. Characteristics of the SXAP spectrometer and criteria for the development of a detection system with an improved dynamic range of sensitivity are presented. (Author)