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Alisha Vira added A_bottle_of_the_substance__.tex
over 8 years ago
Commit id: 3370ac886d242d36cfba44fe7ed42b30d8100bb1
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A bottle of the substance on which NMR was being performed, which was $H_{2}O$ in our experiment, could be inserted into the center of the solenoid (as shown in Fig.(\textbf{whatever})). The parts of the apparatus which were key to performing the NMR are the solenoid, Helmholtz coils, and gradient coils, the magnetic field of which could all be varied separately, as well as a bandpass filter, all of which are discussed below.
The solenoid, with a coil constant of 15mT/A, was used to apply a magnetic field to polarize the water. The magnetic field of the solenoid could be varied used 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 this experiment.
A bandpass filter, part of the NMR instrument, was used to only let through frequencies around 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.
In order to obtain the data, an oscilloscope recorded the variations in magnetization due to the Larmor precession. In this experiment, the oscilloscope measured the amplitude of the decaying signal, expressed as a voltage, which corresponded to the magnetization of the sample. The oscilloscope was also used to measure the Larmor precession frequency, which was measured over ten cycles.
To summarize the different electronics used, a simplified block diagram of the electronic setup for this is shown in Fig.~/ref{fig:block}.
