Emily A Kaplan edited section_Methods_textit_experimental_set__.tex  over 8 years ago

Commit id: 8dbc8ad6ae1d5661f6f75c621cdf94db5166dbb9

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techniques used to generate data \\}  Our setup consisted of a TeachSpin Earth's-Field NMR instrument, as well as two variable current inputs and an oscilloscope. The Earth's Field NMR instrument consisted of a solenoid, gradient coils, and Helmholtz coils, the magnetic field of which could all be varied separately. \textbf{(I will create and insert a more detailed figure of these)} A bottle of the substance for which we were performing NMR (in this case, water) was inserted into the center of the solenoid. The solenoid, with a coil constant of $15 \mu $15~\mu  T/Amp$, was used to apply a magnetic field to polarize the water. We could adjust the polarization time (time over which a field was applied) using the Earth's Field NMR instrument, and the magnetic field could be varied by using a variable current input. The field of the Helmholtz coils, which effectively artificially increased or decreased the Earth's magnetic field applied in the sample, was adjusted using a separate variable current input. The gradient coils changed the gradient of the magnetic field in the x, y, and z directions, but the gradient was not varied over the course of the experiment. A bandpass filter, part of the NMR instrument, was used to only let through the Larmor precession frequency and reduce and background noise such as 60 Hz fluctuations in the field due to current-carrying wires in the room. The oscilloscope, which was recording the variations in magnetization due to the Larmor precession, was triggered by the NMR instrument to start when the magnetic field from the solenoid stopped being applied. A simplified block diagram of the electronic setup for this is shown in Fig.~/ref{fig:block}.