Department of Physics (Fredericton)

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Laser spectroscopy of holmium fluoride
Laser spectroscopy of holmium fluoride
by Anna Kristoffersen, Laser spectroscopy has greatly increased the knowledge of the molecular electronic structure and bonding mechanisms over the past years. Although many molecules have been studied, the lanthanide diatomics have been largely neglected. The ground state of the A-X and B-X systems of Holmium monofluoride (HoF) have already been studied, but very little is known about the excited states. In this project the preliminary results of a global analysis of the vibrational bands of the A-X and B-X systems ofHoF will be presented. The predictions of the electronic configuration are based upon the Ligand Field theory. It is hoped that this study will contribute to the understanding of the electronic configuration of the ground state and the A and B states of HoF., 4 unnumbered pages before the first numbered page Appendix numbered A1- D15
Laser spectroscopy of ytterbium fluoride
Laser spectroscopy of ytterbium fluoride
by Tracy E. Clarke, Appendix has irregular pagination.
Laser-induced breakdown spectroscopy of meteorites
Laser-induced breakdown spectroscopy of meteorites
by Alex Adair, Meteoroids are a direct, earth-based means of studying extraterrestrial materials, which can provide information on the Earth’s atmospheric dynamics, on the origins of the solar system, and on the properties of other planetary systems. The properties of a meteoroid can be determined by analyzing the light that is produced when it burns up during atmospheric entry. To simulate these effects in a laboratory setting, we used intense laser light to break down the surface structure of a meteorite sample. We used a technique known as laser-induced breakdown spectroscopy (LIBS) to analyze the elemental composition of the sample. We also studied relationships between environmental pressure and the dimensions of the resulting light-producing plasma halo. Our results confirmed the existence of many expected elements in the meteorite and also demonstrated an increase in the size of the plasma halo as the environmental pressure was decreased, Appendix numbered A0-A24, B0-B4
Lidar investigations of the stratospheric aerosol layer
Lidar investigations of the stratospheric aerosol layer
John Gerald Cormier, The stratosphere has been probed using the LIDAR (fight detection and ranging) technique for the purpose of detecting the stratospheric aerosol layer, and determining typical aerosol parameters. Analysis of this data has required writing several FORTRAN programs to manipulate the raw data and invert the signal return to obtain the aerosol backscattering coefficient. Additionally, the signal depolarization has been recorded for all of the nights that measurements were made. A theoretical treatment of the two main scattering processes will be given. The development of the LIDAR equation and the method of inversion are presented, as well as a detailed error analysis of the results. The nature and origin of the stratospheric aerosol layer, as well as its effects on the global climate, will also be presented
Magnetic resonance imaging of compact bone
Magnetic resonance imaging of compact bone
by Jonathan S. Dysart, Magnetic Resonance Imaging in clinical applications has traditionally been used for visualization of soft tissues and semi-fluid materials. The need for a method to image solids, namely bone, has prompted research in this area. The UNB MRI Centre has developed a method of imaging called SPRITE, Single Point Ramped Imaging with T1 Enhancement, that has proven successful in imaging solid like materials such as concrete and plastics (polymers). In this thesis the SPRITE technique has been applied to image bone, a composite material with magnetic resonance characteristics similar to that of polymers. The thesis examines compact bone in the form of ex vivo bovine long bones (femur or humerus) both with and without intact bone marrow. The studies in this thesis further exemplify the power of SPRITE by implementing inversion recovery sequences with SPRITE which are capable of zeroing the marrow signal. The potential significance of this research will be in clinical evaluation of bone for disorders such as osteoporosis. A fast, non-invasive method of examining the detailed structure of bone may save health care billions of dollars through early diagnostics and clinical evaluation of these disorders.
Magnetic resonance imaging of flowing gas
Magnetic resonance imaging of flowing gas
by Andrew Coristine, Gas phase MRI is of great contemporary interest in current NMR/MRI literature. Traditional imaging techniques are particularly susceptible to induced flow artifacts. Using Single Point Ramped Imaging with T1 Enhancement (SPRITE), sulfur hexalfuoride is imaged at flow rates approaching l 2m/s. The experiments are conducted in the presence of a motion-sensitive magnetic field gradient that introduces signal attenuation as a function of encoding times and flow, through induced phase cancellation. Additional variables are also examined as of method of observing flow patterns. These techniques are examined through the study of non-steady gas pipe flow within a 3.5cm diameter tube containing a half square-cylinder obstruction.
Magnetic resonance imaging of radiation dose distribution: a proposed dosimeter
Magnetic resonance imaging of radiation dose distribution: a proposed dosimeter
by Maria L. Kilfoil, Paramagnetic metal ions have recently been proposed as NMR contrast agents for use in radiation dosimetry. Most work in this area has concentrated on altering T1 by changing the electronic structure, and thus the electron spin relaxation time, τ1e, of the paramagnetic metal under the action of radiation. An alternative approach will be discussed, that of incorporating the metal ion into a polymer formed under the action of radiation; this increases its rotational correlation time, τR, which also decreases T1. In a water-based gel matrix, formation of the polymer provides a contrast mechanism which is spatially-resolved and constitutes a suitable radiation dosimeter. Several gel/metal ion combinations have been studied in order to characterize the process; one such combination involves the use of nickel as the paramagnetic ion. Attaching it to an acrylic monomer, in a 30% acrylamide solution, changed T1 by a factor of four when polymerization was induced. A field-dependence study of the gel/metal ion combinations has also been conducted.
Magnetic resonance imaging of soils and plant roots
Magnetic resonance imaging of soils and plant roots
by Howlan Mullally, Magnetic Resonance Imaging, or MRI, has been proposed as a tomographic tool in the study of soil dynamics and soil structure because it is a non-destructive way to view internal structure in opaque materials such as soils. A natural extension of this application of MRI is the study of plant root dynamics such as growth and water uptake from a surrounding soil. Traditionally, MRI has been used to study fluid samples, or fluid saturated samples, most notably the human body. There are severe drawbacks to studying solid or solid-like materials with MRI, especially heterogeneous materials such as soils, mainly arising from the rapid loss of signal from such samples. Using a technique developed at UNB called SPRITE, an acronym for "Single-Point Ramped Imaging with T1-Enhancement", these drawbacks can be circumvented, and images of rigid and semi-rigid samples, such as concrete and compact bone, can be acquired. This thesis presents results from tests done on soil and plant root samples which, using the SPRITE method, have been imaged to study soil water migration (drying) and water uptake by roots in soils.
Methanol absorption of 9.4P (16) CO2 laser radiation
Methanol absorption of 9.4P (16) CO2 laser radiation
by Brian A. Oliver, A laser-microwave double resonance experiment was performed, in an attempt to confirm a suggested CH30H (methanol) submillimeter laser optical pumping mechanism. Failure to make the confirmation lead to an investigation of the methanol absorption of the P(16) line of the 9.4 micron band of the CO2 molecule. Results indicate that the suggested assignment is very likely wrong. Consideration is given to identifying an alternative pumping mechanism.
Microwave double resonance spectroscopy of methanol
Microwave double resonance spectroscopy of methanol
by Franco Di Diodato, Thesis is handwritten.
Microwave double resonance study of collision induced population transfer of rotational energy in OCS
Microwave double resonance study of collision induced population transfer of rotational energy in OCS
by Edwin Ghahramani, The technique of microwave double resonance was applied to investigate collision induced transitions between rotational levels of OCS in the ground vibrational state, with the M sublevels separated by a Stark field. The (1+2)p-(2+3)s' (1+2)p-(3+4)s and (2+3)p-(1+2)s systems have been studied for pure OCS and its mixture with excess He. For four level systems having dipolar connections (AJ = 1; LlM = 0, ±1; parity ±++) be.tween pump and signal levels, it is found for OCS that the dipole-type• AJ = 1 transitions always dominate the collisional transfer, but for the OCS-He mixture that AJ = 2 quadrupole-type transitions are dominant. The fractional intensity changes AI/I for almost all the four level transitions were in good agreement with the theoretical results.
Microwave spectrometer - computer interface
Microwave spectrometer - computer interface
by Ian T. Lawson, The purpose of this research project was to create an interface between a microwave spectrometer and an IEEE 488 Bus. Initially the microwave spectrometer was controlled by both an Apple II and a Macintosh LC computer, which was inconvenient. The software package LabVIEW 2 was supposed to us to integrate the present system on the Macintosh LC, but LabVIEW 2 was incompatible with the IEEE 488 Bus. Then an RS-232 interface was used to connect the TN-1505 signal analyzer to the computer's modem port, thus allowing LabVIEW 2 to control the signal analyzer, and collect and store data for future manipulation.

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