Auger spectroscopy of simple gaseous molecules

Measuring Auger spectra of simple gaseous molecule

Overview of surface studies on high energy materials at Mound

Since 1975 Mound has been examining the surface structure of high energy materials and the interaction of these materials with various metal containers. The high energy materials that have been studied include: the pyrotechnic TiH/sub x//KClO/sub 4/, the Al/Cu/sub 2/O machinable thermite, the PETN, HMX and RDX explosives, and two plastic bonded explosives (PBX). Aluminum and alloys of Fe, Ni and Cr have been used as the containment materials. Two aims in this research are: (1) the elucidation of the mechanism of pyrotechnic ignition and (2) the compatibility of high energy materials with their surroundings. New information has been generated by coupling Auger electron spectroscopy (AES) and x-ray photoelectron spectroscopy (XPS) with thermal data. In particular, AES and XPS studies on the pyrotechnic materials and on thermites have shown the mechanism of ignition to be nearly independent of the type of oxidizer present but directly related to surface chemistry of the fuels. In studies on the two PBX's, PBX-9407 and LX-16, it was concluded that the Exon coating on 9407 was complete and greater than or equal to 100A; whereas in LX-16, the coating was < 100A or even incomplete. AES and scanning Auger have been used to characterize the surface composition and oxide thickness for an iron-nickel alloy and showed the thicker oxides to have the least propensity for atmospheric hydrocarbon adsorption. Data are presented and illustrations made which highlight this new approach to studying ignition and compatibility of high energy materials. Finally, the salient features of the X-SAM-800 purchased by Mound are discussed in light of future studies on high energy materials

Quantitative Nondestructive Density Determinations of Very Low-Density Carbon Foams

Carbon foams have been manufactured at EG&G Mound Applied Technologies through the use of a salt replica process [1,2] that has been modified by a Mound propriety process [3]. Applications of these foams have been described in an early publication [4]. In the basic process [1,2] of manufacturing the foams, salt is pressed into bars; the bars are then cured, infused with polymer and cured again. The salt is then removed by copious solvent rinsings and finally carbonized into very porous and light-weight, briquette-like material [2,5]. In this paper, the carbon density and the carbon distribution in various foams were determined either by bulk measurements of weight and volume or by x-ray computed tomography (CT)

Double strand breaks in DNA resulting from double-electron-emission events

A mechanism of double strand breaking (DSB) in DNA due to the action of two electrons is considered. These are the electrons produced in the vicinity of DNA molecules due to ionization of water molecules with a consecutive emission of two electrons, making such a mechanism possible. This effect qualitatively solves a puzzle of large yields of DSBs following irradiation of DNA molecules. The transport of secondary electrons, including the additional electrons, is studied in relation to the assessment of radiation damage due to incident ions. This work is a stage in the inclusion of Auger mechanism and like effects into the multiscale approach to ion-beam cancer therapy.Comment: 4 pages, 3 figure

MANIFESTATION OF ATOMlC DYNAMICS THROUGH THE AUGER EFFECT

Utilisant comme exemple le spectre Auger du néon, il est montré que le spectre Auger renferme des informations précises sur l'interaction du rayonnement, ou des particules, avec les électrons du cortège électronique et sur les mécanismes d'interaction électron-électron dans l'atome ionisé dans ses couches internes. On peut différencier les processus d'ionisation simple, d'ionisation double, d'ionisation-excitation, etc. Environ 90 lignes du spectre du néon sont classifiées d'après ces processus fondamentaux. Les énergies et les intensités relatives des lignes appartenant aux différents processus sont présentées et comparées avec la théorie et des résultats d'autres expériences. La dépendance du spectre au mode d'excitation est discutée.Using the neon Auger spectrum as an example, Auger spectra are shown to yield detailed information on the interaction of radiation or particles with atomic electrons and on the mechanics of electron-electron interaction of the innershell ionized atom. Processes such as simple ionization, simple excitation, double ionization, excitation-ionization, etc., can be distinguished and studied by way of Auger electron spectrometry. In accordance with the underlying physical processes we present a classification of the some 90 lines of the neon spectrum, obtained both by photon and electron excitation. Relative energies and intensities of the lines within the various categories are given, and compared with theory and data from different sources. Dependence of spectral intensities on excitation conditions is discussed

Hydrogen isotope analysis by quadrupole mass spectrometry

The analysis of isotopes of hydrogen (H, D, T) and helium (/sup 3/He, /sup 4/He) and selected impurities using a quadrupole mass spectrometer (QMS) has been investigated as a method of measuring the purity of tritium gas for injection into the Tokamak Fusion Test Reactor (TFTR). A QMS was used at low resolution, m/..delta..m < 150, for quantifying impurities from m/q = 2 to 44, and at medium resolution, m/..delta..m approx. 600, for determining concentrations of HD in /sup 3/He, and /sup 4/He in HT/D/sub 2/

EXCITATION ACCOMPANYING PHOTOIONIZATION IN ATOMS AND MOLECULES AND ITS RELATIONSHIP TO ELECTRON CORRELATION

Si on néglige la corrélation électronique, un seul électron est émis par l'effet photoélectrique. Mais l'expérience montre qu'il existe une grande probabilité pour l'excitation ou l'ionisation simultanée d'un second électron. Cette excitation additionnelle est expliquée par les corrélations électroniques : de façon implicite dans les calculs de shakeoff électronique, avec des fonction d'ondes d'un seul électron, ou de façon explicite par l'utilisation des fonctions d'ondes corrélées. Nous avons étudié les pics satellites dans les spectres photoélectroniques des couches internes et externes des gaz rares et de quelques molécules simples. Ces pics satellites sont interprétés à partir des transitions discrètes de l'atome simplement ionisé. Elles nous permettent de mieux comprendre l'excitation simultanée dans l'émission photoélectrique.If electron correlation is neglected, the photoelectric effect requires that only one electron be ejected from an atom. Experimentally, however, it is found in the photoionization process that there is a high probability for simultaneous excitation or ionization of a second electron in the same atom. This extra excitation can be explained by electron correlation : in some cases implicitly through the use of single-electron wave functions as in electron shake-off calculations, and in other cases through the use of wave functions that explicitly include correlation. We have utilized two recently constructed high resolution electron spectrometers to measure satellite lines in the photoelectron spectra of both the inner and valence shells of the rare gases and some simple gaseous molecules. These satellite lines are interpreted in terms of transitions to excited states of the singly charged ion, and are used to form a broader basis for the understanding of simultaneous excitation as the result of the photoelectron process

High strength glass-ceramic to metal seals

In many applications, ceramics are joined to other materials, especially metals. In such cases, interfacial strength is as important as the strength of each constituent material. Examples are presented for tailoring materials and processes to optimize the glass-ceramic-to-metal seal. Means for detecting defects, nondestructively, are also identified

A compatibility study of containment materials in FEFO, bis-(2-fluoro-2,2-dinitroethyl) formal

We report on a program to evaluate the compatibility of energetic fluids with candidate containment materials. The energetic fluids are constituents of various extrudable explosives developed by Lawrence Livermore National Laboratory. These paste-like explosives consist of explosive particulates (HMX, TATB for example) suspended in mixtures of energetic liquids and are designed to remain extrudable over a wide temperature range for many years. It is important to preclude or minimize interactions between the constituents of the paste and the containment materials since such interactions could result in decreased reliability or failure of the containment vessel as well as intrinsic changes in the flow or explosive characteristics of the paste. In this report we focus on one specific paste formulation: RX-52-AE (Transferable Insensitive Explosive, TIE), composed principally of the solid explosive TATB and the energetic liquid, FEFO. Compatibility between a number of organic and metallic materials with neat FEFO has been evaluated. The 300 series stainless steels, Al 6061-T6, and Monel 400 showed evidence of surface attack (oxidation or pitting). Polished gold coupons became discolored and XPS analysis revealed the formation gold cyanide. Platinum, iridium, titanium, tantalum and Ta-10% W showed little evidence of reaction. Among the organic materials, the per-fluorinated materials showed only slight interaction with the FEFO while the polyethylene, polyester and Aclar{reg_sign} materials were attacked by the liquid. These interactions were manifested in changes in color, net weight gain and mechanical properties. The changes were exaggerated by higher temperatures