Good video for understanding the splitting patterns! Regarding the origin and understanding of the J-coupling, there is a property of nuclear spins in NMR that you don't seem to be aware of and it is the fact that both 1H nuclear spin states are almost equally populated inside a sample. As you said, there are 2 possible orientations of a 1H nuclear spin with respect to the external magnetic field, with different energy levels: ↑ and ↓. The population difference between these two states inside a sample is defined by Boltzmann's law: N↓/N↑ = exp(-E/kT), with E = h γ B the difference between the two energy levels. From this law, one can calculate that the population difference is actually very small, even inside a strong external magnetic field (
Aware of since I took a graduate course in NMR, but for this level I try to keep it simple enough that not too many important details get glossed over. Relying on boltzmann distributions to describe spin populations seems a bit optimistic for a sophomore level organic course. but thanks for your feedback
Thank you for the great video! Your comments help to understand that I am not the only one who is confused with some information, like why would some of the spins point against the applied magnetic field
Glad it was helpful! I worked with Brad Chmelka at the University of California, Santa Barbara, who's work revolves around NMR and even taking his class it was clear that even he didn't fully understand the technique. Working with his students, they were pretty sure that no one really understands how NMR works.
A quarter of quarters would be four peaks each split into 4 peaks - so 16 total peaks - whereas a septet would be just 7. When it splits that much you'll generally see people write "multiplet" because, while it's truly a quartet of quartets, in practice each peak would only be 4-8% of a single proton signal (so less than 1% of the signal of two methyl groups creating it), so unless your signal-to-noise (S/N) is incredible, it'll just be a bunch of bumps against the baseline.
![เบิ้ล ปทุมราช - สาวสอง ( มีมี่ของอ้าย ) ft. ตาต้า,ต้องเต [OFFICIAL MV]](http://i.ytimg.com/vi/mqlMjnP08XI/mqdefault.jpg)
I love how the underlying logic behind why all this occurs is basically 'voodoo sorcerey' ha ha. Very thoroughly-explained video though, thanks!
thanks, I appreciate it
i was looking for something to understand the shouldering affect, and it seems that the quartet of quartet idea just established that, thanks so much.
Thanks, I really appreciate that
Good video for understanding the splitting patterns!
Regarding the origin and understanding of the J-coupling, there is a property of nuclear spins in NMR that you don't seem to be aware of and it is the fact that both 1H nuclear spin states are almost equally populated inside a sample.
As you said, there are 2 possible orientations of a 1H nuclear spin with respect to the external magnetic field, with different energy levels: ↑ and ↓. The population difference between these two states inside a sample is defined by Boltzmann's law: N↓/N↑ = exp(-E/kT), with E = h γ B the difference between the two energy levels. From this law, one can calculate that the population difference is actually very small, even inside a strong external magnetic field (
Aware of since I took a graduate course in NMR, but for this level I try to keep it simple enough that not too many important details get glossed over. Relying on boltzmann distributions to describe spin populations seems a bit optimistic for a sophomore level organic course. but thanks for your feedback
Thank you for the great video!
Your comments help to understand that I am not the only one who is confused with some information, like why would some of the spins point against the applied magnetic field
Glad it was helpful! I worked with Brad Chmelka at the University of California, Santa Barbara, who's work revolves around NMR and even taking his class it was clear that even he didn't fully understand the technique. Working with his students, they were pretty sure that no one really understands how NMR works.
2:52
No it is not unlikely, the proportion of spin up vs spin down atoms in a given sample is only something like 50.1%
Thanks alot for this video. I do appreciate
So "quartett of quartetts" for the CH2 in Propane, wouldnt that in the spectra then just look like a Septett ?
A quarter of quarters would be four peaks each split into 4 peaks - so 16 total peaks - whereas a septet would be just 7. When it splits that much you'll generally see people write "multiplet" because, while it's truly a quartet of quartets, in practice each peak would only be 4-8% of a single proton signal (so less than 1% of the signal of two methyl groups creating it), so unless your signal-to-noise (S/N) is incredible, it'll just be a bunch of bumps against the baseline.