For every atomic nucleus, its total angular momentum is represented by the symbol I and called its nuclear spin. This spin is then determined by its quantum number, which is represented by the symbol S. Each nuclear spin is associated with a magnetic moment. When this moment is placed in an external magnetic field, these spin states differ in magnetic potential energy. If placed in a static magnetic field with a small amount of spin polarisation however, certain radio frequency signals can allow a transition between spin states, with some of the spins being placed in a higher energy state. When the signal is then switched off, the amount of radio frequency signal at the resonant frequency can then be measured. This is produced by the spins
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If a photon is emitted it is possible for an unpaired electron to leap from one energy level to the other. As we know the energy of a photon to be and the resonance condition to be , we get the equation which is the fundamental equation of electron spin resonance where we can find the microwave resonance frequency.
When electromagnetic energy in the microwave range is applied, the magnetic field corresponds to value of approximately 0.35 T which is needed to gain useful ESR spectra. Energies in the radio range would need a magnetic field of approximately 0.7 T for resonance.
Figure 2 gives us a glimpse of what ESR spectra should look like. On the first diagram we can the first derivative detection of absorption line on the bottom and the absorption is represented by the peaks above and proves that hyperfine interactions have occurred between energy …show more content…
This causes its resistance to increase. To ensure the beam current is kept at around 10mA and to extend the life of the tungsten filament for as long as possible, the cathode current is adjusted accordingly. If there is a higher cathode current, the filament will erode at a faster rate. At every 30 minutes, values for the parameters will be recorded to ensure N@C60 is being synthesised at an optimal rate. On average, it would take around 4 hours for the Tungsten filament to erode which would often happen at the end of a 2nd session of synthetisation, with each session lasting 2 hours. It is better to not bombard the filament with positive ions for longer as this would cause the filament to erode at an even faster
If a photon is emitted it is possible for an unpaired electron to leap from one energy level to the other. As we know the energy of a photon to be and the resonance condition to be , we get the equation which is the fundamental equation of electron spin resonance where we can find the microwave resonance frequency.
When electromagnetic energy in the microwave range is applied, the magnetic field corresponds to value of approximately 0.35 T which is needed to gain useful ESR spectra. Energies in the radio range would need a magnetic field of approximately 0.7 T for resonance.
Figure 2 gives us a glimpse of what ESR spectra should look like. On the first diagram we can the first derivative detection of absorption line on the bottom and the absorption is represented by the peaks above and proves that hyperfine interactions have occurred between energy …show more content…
This causes its resistance to increase. To ensure the beam current is kept at around 10mA and to extend the life of the tungsten filament for as long as possible, the cathode current is adjusted accordingly. If there is a higher cathode current, the filament will erode at a faster rate. At every 30 minutes, values for the parameters will be recorded to ensure N@C60 is being synthesised at an optimal rate. On average, it would take around 4 hours for the Tungsten filament to erode which would often happen at the end of a 2nd session of synthetisation, with each session lasting 2 hours. It is better to not bombard the filament with positive ions for longer as this would cause the filament to erode at an even faster