Microabsorptiometry with heavy ions.
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| Other Authors: | , , |
| Format: | Thesis Book |
| Language: | English |
| Published: |
1983.
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| Subjects: | |
| Online Access: | Link to ProQuest Copy Link to OAKTrust copy |
| Abstract: | This study investigated the use of heavy ion (Z > 3) absorptiometry for the measurement of thickness/density variations in low density (1-2 g/cm('3)) materials on a microscopic scale ((LESSTHEQ) 10 (mu)m lateral resolution) to include measurements in a static as well as a scanning mode. Three ion beams were utilized for absorptiometry: 8 MeV ('16)O, 15.3 MeV ('40)Ar, and 39.8 MeV ('84)Kr. Samples measured were: ultramicrotomed epoxy sections ((rho) (TURN) 1.2) and C foils ((rho) (TURN) 1.82) prepared by vacuum evaporation. Energy loss measurements using the 8 MeV ('16)O beam were carried out with a surface barrier detector. With this detector, thickness variations as small as 150 (ANGSTROM) were resolved in epoxy samples ((rho) (TURN) 1.2). Heavier ions (Z > 10), should provide still better depth resolution, however, their increased sensitivity to electron density is overshadowed by deteriorating detector resolution. Consequently, energy loss measurements with the 15.3 MeV ('40)Ar and 39.8 MeV ('84)Kr beams were handled with the time-of-flight (TOF) technique. Thickness resolution of 120 (ANGSTROM) and 90 (ANGSTROM) was achieved on C foils ((rho) (TURN) 1.82) using the ('40)Ar beam and ('84)Kr beam, respectively. The second objective of this study was to apply absorptiometry on a microscopic scale (i.e., to combine depth resolution with high areal resolution) and develop a means of scanning the sample in precise uniform steps. Collimators were used to limit the area analyzed down to 1 (mu)m diameter. The sample was moved across the microbeam with motorized linear and rotary translators. Reproducible sample movement in steps as small as 525 (ANGSTROM) could be obtained with the rotary translator available. Uniform samples consisting of electron microscopy (EM) grids (500-1000 mesh) were scanned with lateral resolution down to (TURN) 1.1 (mu)m. Nonuniform samples made of latex spheres ((TURN) 16 (mu)m diameter) were scanned with (TURN) 1.5 (mu)m resolution.... |
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| Item Description: | "Major subject: Chemistry." Typescript (photocopy). Vita. |
| Physical Description: | xiii, 90 leaves : illustrations ; 29 cm |
| Bibliography: | Includes bibliographical references (leaves 87-89). |