Wade L. Fite

Reflection and Dissociation of H2 on Tungsten

Through the use of modulated atomic beam techniques, the reflection and dissociation of H2 at a tungsten surface above 2500°K has been studied. Two experimental configurations were employed. In the first configuration, a collimated beam of molecular hydrogen was directed at the tungsten surface, and the angular distribution of particles evaporating from the surface was examined mass spectrometrically. In the second configuration, the tungsten test surface was located in the first of three differentially pumped vacuum chambers. H2 was admitted into this chamber, thereby providing an isotropic source of incident particles. Particles evaporating from the surface were collimated and examined mass spectrometrically in the third chamber. From these experiments it is observed that at high temperatures the angular distribution of atomic hydrogen evaporating from the target surface obeys the cosine law. However, the angular distribution of reflected H2 displays a shift toward the specular ray. Above 2500°K the sti...

Associative ionization in U + O and U + O2 collisions

Collisions between thermal energy uranium atoms and oxygen atoms and molecules have been studied in four experiments. A triple crossed beam experiment has determined that the ratio of effective cross sections for the associative ionization processes U + O → UO+ + e and U + O2 → UO2 + e is 97±20. An experiment measuring the number of ions formed per unit length by uranium atoms passing through O2 has determined that the absolute cross section for U + O2 → UO2+ + e is 1.68±0.27 × 10−17 cm2. A total attenuation experiment indicates that the total reaction cross section between U and O2 is 1.78±0.45×10−15 cm2, implying that over 99% of the reactions lead to the neutral products UO+O while less then 1% give associative ionization. A modulated beam mass spectrometry experiment, employing phase spectrometry, indicates that the activation energy for U + O2 → UO2+ + e is extremely small if existent at all. Two Appendices treat the relations between effective cross sections as measured in various experiments to tru...

Charge Transfer between Atomic Hydrogen and N+ and O+

The cross sections for charge transfer in collisions between atomic hydrogen and singly charged atomic ions of nitrogen and oxygen have been measured within the energy range from 400 to 10 000 ev, using modulated‐beam techniques. The results are compared with recent calculations.

High-resolution residual gas analysis (HRRGA)

Analysis of residual gases in a typical oil-diffusion pumped and LN2-trapped vacuum system in the 10−7 Torr range under high resolution (greater than 3000) has yielded a number of surprise. It is found, among other things, that the mass 28 peak is a triplet with CO+ dominating both the N2+ and C2H4+ components. Mass 16 is primarily O+ but the remainder of the triplet is primarily NH2+ rather than CH4+ as commonly believed. Mass 44 is primarily CO2+ but two other ions are also present. Alkanes (e.g., C7H15+) and what are believed to be polystyrene fragments are major components near mass 100. Examination of a mercury-pumped vacuum system was made for comparison with the oil-pumped system, and a comparison of the results at several mass peaks is presented.

Associative ionization of uranium and thorium in collisions with ozone

Associative ionization channels in the U and Th with O3 systems are observed in a crossed beams apparatus with positive and negative ion mass spectrometric detection, and cross sections for open channels are measured. Electron impact ionization is used to measure beam intensities. The ozone beam is modulated, and phase spectrometry is used to demonstrate ozone beam purity. Measured cross sections (labeled by charge products) are 2×10−16(UO+2,e),2×10−16(UO+,e), 2×10−19(ThO+3,e),1×10−17(ThO+2,e), 4×10−16(ThO+,e),1×10−18(ThO+,O−2), and 2×10−18(ThO+2,O−) cm2 multiplied by the ratio of the cross sections for the production of O+2 by electron impact ionization of O3 and O2, and in the case of thorium, also multiplied by the ratio of thorium and uranium electron impact ionization cross sections.