Levich Institute Seminar Announcement, 03/18/2008

Tuesday, 03/18/2008 2:00 PM Steinman Hall, Room #312 (Chemical Engineering Conference Room) Professor Carlos Meriles City College of CUNY Physics Department "A New Approach to Magnetic Resonance at the Microscale: Dipolar Field Microscopy"

ABSTRACT

Nuclear Magnetic Resonance is unique in allowing the generation of images with various kinds of contrast, and therefore images with different information content. Unfortunately, NMR lacks the sensitivity essential to high-resolution screening, in part due to the low nuclear spin polarization present in most samples but, most importantly, because of the relatively low signal-to-noise detection ratio inherent to Faraday induction. In this talk I will introduce an alternative approach to high-sensitivity detection of Nuclear Magnetic Resonance (NMR) in organic matrices. The proposed approach-which we will refer to as Dipolar Field Microscopy or DFM-exploits the long-range dipolar interaction created between the sample and a neighboring hyperpolarized semiconductor tip serving as a detection center. I will show that, with a convenient protocol of radio-frequency (rf) pulses, it is possible to determine the local magnetization of the sample by inspecting the nuclear polarization of the semiconductor tip. This strategy will prove advantageous because ultra-sensitive detection methods specific to semiconductors have been developed in the recent past. In this context, I will briefly report on our work using Time Resolved Faraday Rotation to optically probe nuclear spin alignment in hyperpolarized GaAs; I will also describe some of the infrastructure we have completed aimed at the use of this methodology as an approach to DFM.

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