I studied the effect of wall collisions on the electron paramagnetic resonance (EPR) of gas phase alkali metal atoms (87Rb). Two types of walls were studied: antirelaxation-coated walls and RbH-coated walls. I measured the dwell times of spin polarized Rb atoms on the two most common antirelaxation coatings, octadecyltrichlorosilane (OTS)- and paraffin. I found that at a cell temperature of 72 C the dwell times for OTS- and paraffin-coated walls are 0.9 ± 0.1 μs and 1.8 ± 0.2 μs, respectively. The implication of these dwell times, which are much longer than what was previously reported in the literature, is discussed in connection with the relaxing property of these coatings. In cells coated with RbH salt I made the first observation of the EPR frequency shift of the gas phase 87Rb atoms. Due to collisions with the RbH salt, which was nuclear spin polarized by spin exchange with optically pumped Rb vapor. The measured EPR frequency shifts are of the order of several hundred Hz in a millimeter-sized cell. By measuring the dependence of the EPR frequency shifts on cell length and by comparing the EPR frequency shifts in RbH-coated cells with those in OTS-coated cells, I provided convincing evidence that the observed EPR frequency shifts are due to collisions with RbH-coated walls, and not due to gas phase processes. The EPR frequency shift is due to the Fermi contact interaction between the s-electron of the adsorbed 87Rb atom and the polarized nucleus on the salt surface. The measured EPR frequency shifts allowed me to calculate the ensemble-averaged phase shift experienced by the Rb atom while adsorbed on the walls. Under our experimental condition this is about 70 mrad. My experiment opens up the possibility of studying surface NMR using gas phase EPR. The phase shift is proportional to the surface nuclear polarization, thus provides an interesting method for measuring the surface nuclear polarization using gas phase EPR. My observation will alert the high precision miniature atomic magnetometry community that collisions with cell walls may cause a systematic error and line broadening in the magnetic resonance frequency.
Subject (authority = RUETD)
Topic
Physics, Applied
RelatedItem (type = host)
TitleInfo
Title
Rutgers University Electronic Theses and Dissertations
Identifier (type = RULIB)
ETD
Identifier
ETD_5628
PhysicalDescription
Form (authority = gmd)
electronic resource
InternetMediaType
application/pdf
InternetMediaType
text/xml
Extent
viii, 103 p. : ill.
Note (type = degree)
Ph.D.
Note (type = bibliography)
Includes bibliographical references
Note (type = vita)
Includes vita
Note (type = statement of responsibility)
by Emily Joy Ulanski
Subject (authority = ETD-LCSH)
Topic
Rubidium
Subject (authority = ETD-LCSH)
Topic
Magnetic resonance
RelatedItem (type = host)
TitleInfo
Title
Graduate School - Newark Electronic Theses and Dissertations
Identifier (type = local)
rucore10002600001
Location
PhysicalLocation (authority = marcorg); (displayLabel = Rutgers, The State University of New Jersey)
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