Macro view of NMR - Revision history

Milllo: /* Peak Splitting vs Transition Peak Splitting */

2020-06-19T22:10:13Z

Peak Splitting vs Transition Peak Splitting

Milllo: /* Peak Intensity vs Transition Intensity */

2020-06-19T22:08:35Z

Peak Intensity vs Transition Intensity

Milllo: /* Peak Splitting vs Transition Peak Splitting */

2020-06-19T22:03:50Z

Peak Splitting vs Transition Peak Splitting

Milllo: /* Sensitivity vs Transition Sensitivity */

2020-06-19T22:01:44Z

Sensitivity vs Transition Sensitivity

Milllo: /* Peak Intensity vs Transition Intensity */

2020-06-19T21:57:56Z

Peak Intensity vs Transition Intensity

Milllo: /* Radio Pulse Power vs Transition Pulse Power */

2020-06-19T21:55:35Z

Radio Pulse Power vs Transition Pulse Power

Milllo: /* Spectra vs Transition Spectra */

2020-05-06T11:12:08Z

Spectra vs Transition Spectra

Milllo: /* Spectra vs Transition Spectra */

2020-05-06T11:11:21Z

Spectra vs Transition Spectra

Milllo: /* Spectra vs Transition Spectra */

2020-05-06T11:10:30Z

Spectra vs Transition Spectra

Milllo: /* Peak Intensity vs Transition Intensity */

2020-04-30T21:39:22Z

Peak Intensity vs Transition Intensity

@@ Line 88: / Line 88: @@
 ==Peak Splitting vs [[Micro view of NMR#Peak Splitting|Transition Peak Splitting]]==
-The real weakness of net magnetization theory is its inability to explain peak splitting in coupled NMR spectra.
+The real weakness of net magnetization theory is its inability to explain peak splitting in coupled NMR spectra. The whole idea of 'net magnetization' is that it is a sum of the magnetic moments at each frequency, and there is just one sum! So how can there be peak splitting?
 ==Relaxation vs [[Micro view of NMR#Relaxation|Transition Relaxation]]==
 ==Related Topics==

@@ Line 81: / Line 81: @@
 F(ω) = (M<sub>0</sub>T<sub>2</sub>)/2*[(1/(1+(ω<sub>0</sub>-ω)<sup>2</sup>T<sub>2</sub><sup>2</sup>)) + i((ω<sub>0</sub>-ω)/(1+(ω<sub>0</sub>-ω)<sup>2</sup>T<sub>2</sub><sup>2</sup>))]
-In this equation there is no time component, so the result is a display of intensity vs frequency (ω). In addition, the only concentration term is M<sub>0</sub>, which represents the amount of magnetic moment for a particular group. As can be seen from the equation, the intensity of a peak is directly proportional to M<sub>0</sub> and hence the concentration of the group represented by the peak. This means that the ratios of peak sizes for ethanol will be 3 for the methyl, 2 for the CH<sub>2</sub> and 1 for the OH (30-20-10 in the spectrum of ethanol above).
+In this equation there is no time component, so the result is a display of intensity (=F(ω)) vs frequency (ω). In addition, the only concentration term is M<sub>0</sub>, which represents the amount of magnetic moment for a particular group. As can be seen from the equation, the intensity of a peak is directly proportional to M<sub>0</sub> and hence the concentration of the group represented by the peak. This means that the ratios of peak sizes for ethanol will be 3 for the methyl, 2 for the CH<sub>2</sub> and 1 for the OH (30-20-10 in the spectrum of ethanol above).
 ==Sensitivity vs [[Micro view of NMR#Sensitivity|Transition Sensitivity]]==

@@ Line 88: / Line 88: @@
 ==Peak Splitting vs [[Micro view of NMR#Peak Splitting|Transition Peak Splitting]]==
 ==Relaxation vs [[Micro view of NMR#Relaxation|Transition Relaxation]]==
 ==Related Topics==

@@ Line 85: / Line 85: @@
 ==Sensitivity vs [[Micro view of NMR#Sensitivity|Transition Sensitivity]]==
-If a 90 degree pulse is used in an experiment, a more concentrated sample will give a stronger peak.
+Assuming that instrumental parameters are the same, a more concentrated sample will give a stronger peak.
 ==Peak Splitting vs [[Micro view of NMR#Peak Splitting|Transition Peak Splitting]]==

@@ Line 69: / Line 69: @@
 M<sub>y</sub> = M<sub>0</sub>e<sup>-(t/T<sub>2</sub>)</sup>cos[(ω<sub>0</sub>-ω)t]
-in these equations, as time t increases, the amplitudes of the sin/cos functions decrease because e<sup>-(t/T<sub>2</sub>)</sup> gets smaller as time gets larger. M<sub>0</sub>, T<sub>2</sub> and ω<sub>0</sub> are constants. There is an M<sub>x</sub> and M<sub>y</sub> for each ω in the experiment
+in these equations, as time t increases, the amplitudes of the sin/cos functions decrease because e<sup>-(t/T<sub>2</sub>)</sup> gets smaller as time gets larger. Note that M<sub>0</sub>, T<sub>2</sub> and ω<sub>0</sub> are constants. There is an M<sub>x</sub> and M<sub>y</sub> for each ω in the experiment
 [[file:mx_and_my.png|200px]]

@@ Line 56: / Line 56: @@
 For a 270 degree pulse, at the end of the pulse M<sub>0</sub> is along the -X axis, which puts it 180 degrees out of phase compared to the 90 degree pulse.
-For a 360 degree pulse, the detector is not turned on until the end of the pulse, so even though M<sub>0</sub> went all the way down to -Z and back up again, when the detector is turned on, M<sub>0</sub> is back to +Z again so there is nothing to relax and thus no signal.
+For a 360 degree pulse, remember that the detector is not turned on until the end of the pulse, so even though M<sub>0</sub> went all the way down to -Z and back up again, when the detector is turned on, M<sub>0</sub> is back to +Z again so there is nothing to relax and thus no signal.
 ==Saturation vs. [[Micro view of NMR#Saturation|Transition Saturation]]==

@@ Line 21: / Line 21: @@
 v<sub>0</sub>=<span style="font-family:symbol;">g</span>*B<sub>0</sub>
-Since this v<sub>0</sub> is a moving charge, this represents electromagnetic frequency and can interact with an external electromagnetic frequency according to the usual rules of [[Wave mechanics|wave mechanics]]. In short, if an external electromagnetic frequency of the same magnitude is applied to the sample, it can 'resonate' with the sample, depending on the phases of the two fields. Fortunately, the gyromagnetic ratios of components of a sample are dramatically different, so a transmitter/receiver pair can be set up to 'look' at just one of the many v<sub>0</sub> in a sample.
+Since this v<sub>0</sub> is a moving charge, this represents electromagnetic frequency and can interact with an external electromagnetic frequency. In short, if an external electromagnetic frequency of the same magnitude is applied to the sample, it can 'resonate' with the sample, depending on the phases of the two fields. Fortunately, the gyromagnetic ratios of components of a sample are dramatically different, so a transmitter/receiver pair can be set up to 'look' at just one of the many v<sub>0</sub> in a sample.
 Based on the [[Derivation of Larmor frequency equation|Larmor equation]], the only variable for a particular atomic component is the external field strength B<sub>0</sub>, but since there are magnetic fields all around a molecule of the sample, each atomic component will experience slightly different B, and thus have slightly different v. Thus the transmitter/receiver pair will see several resonances for each atomic component in a sample of a molecule such as ethanol and it is these resonances that are studied in NMR. In addition, the atoms in a molecule that are in the same magnetic environment will experience the same B and thus have the same v and give the same peak.