UBC Theses and Dissertations
Towards nuclear magnetic resonance cross-polarization of an organic monolayer from optically pumped indium phosphide Grinder, Matthew Orion
Transferring a very large nuclear polarization from an optically pumped semi-conductor to an organic overlayer is a potentially exciting solid state NMR technique. Large polarization of nuclei can be generated in ³¹P by irradiation of InP with circularly polarized light near the bandgap energy at low temperatures. This nuclear spin polarization should then be transferable to an organic overlayer, provided atoms in the layer are coupled to the surface ³¹P nuclear spins. In this way, it should be possible to observe the NMR signal from the layer, even though there are few nuclei in the organic layer. A probe was custom built for this purpose and its properties tested. The effects of laser irradiation on polarization were observed with several samples of differently doped InP. A monolayer of octadecanethiol (thiol) was bonded to the surface of InP, and XPS was used to check the surface coverage of the thiol and characterize the effects of various chemical etches. Observation of the thiol hydrogen atoms under optical pumping conditions was attempted, with no success.
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