Timeline for Radiofrequency transmitter in an NMR experiment: Is there an involvement of (electromagnetic) radio wave?
Current License: CC BY-SA 4.0
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| Apr 18 at 19:16 | history | edited | Karl | CC BY-SA 4.0 |
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| Sep 15, 2019 at 18:16 | history | edited | Karl | CC BY-SA 4.0 |
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| Sep 13, 2019 at 6:10 | history | edited | Karl | CC BY-SA 4.0 |
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| Sep 11, 2019 at 7:39 | comment | added | Karl | @M.Farooq The word "transmitter" is just jargon. Its a hf amplifier that could also be used to power a radio station. The actual probe circuit (coil+capacitors) is not part of the box labelled as transmitter. In between, there is usually a T junction with crossed diodes, where the "receiver" (the preamp, and mixer, ADC etc. behind it) are connected. | |
| Sep 11, 2019 at 6:44 | comment | added | Buck Thorn♦ | @M.Farooq I think I understand better what your question is about. I would say, of course there is an RF field in the probe. The question seems more to be, how does that field interact with the nuclei? I think this can but certainly need not be treated semi-classically (it could be treated in a fully QM way, but why would you), ie using a classical Hamiltonian to describe the field but QM to describe the nuclei. | |
| Sep 11, 2019 at 6:41 | comment | added | Buck Thorn♦ | @Karl Ok, thanks for freeing me of the shame of continuing to be confused :-) | |
| Sep 11, 2019 at 2:35 | comment | added | ACR | contd....So the same goes for our friend Karl. A good rule of thumb in chemical education is to avoid complicated jargon because then it reduces to a mere play of words or as others said becomes cryptic. Often, at a deeper level it doesn't mean anything. I wasn't interested in the $acquisition$ of FID signal. And a preparatory $\ce{B1}$ pulse $alone$ doesn't mean anything either. I am more interested in knowing what happens in the RF transmitter coil and does it emit radio waves or not. Apparently there is an emission of radio waves and after all why it is called a RF transmitter? | |
| Sep 11, 2019 at 2:24 | comment | added | ACR | Long time ago, a physicist had posed a question that a famous physicist had asked him: How will you convince an 11 year old about the size of the molecules in the air? He said nobody could provide a decent answer and he was curious to know our opinions. I suggested, what if we ask the child to look at the dust particles in the air near a sunny window. Since they are floating and constantly moving, chances are whatever is hitting those dust particles is invisible to us and must be smaller than the dust particles. The physicist said that it is a good start and the theme is correct... contd | |
| Sep 10, 2019 at 21:46 | history | edited | Karl | CC BY-SA 4.0 |
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| Sep 10, 2019 at 21:38 | history | edited | Karl | CC BY-SA 4.0 |
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| Sep 10, 2019 at 21:11 | history | edited | Karl | CC BY-SA 4.0 |
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| Sep 10, 2019 at 21:07 | comment | added | Karl | @BuckThorn On second thought, I think the statement is still true and to the point. Imagine putting a powerful dipole emitter inside the probe. Photons (EM radiation) coming out of it would not be absorbed by the probe coil, at least not strongly. Ergo, the probe also cannot produce much photons on its inside. | |
| Sep 10, 2019 at 20:27 | comment | added | Karl | @BuckThorn Ja. ;) It d be great if anyone could improve on that. The last sentence reads like a "stop bugging me you idiots, I havent understood that myself". | |
| Sep 10, 2019 at 20:19 | comment | added | Buck Thorn♦ | That last paragraph is incredibly cryptic. | |
| Sep 10, 2019 at 20:13 | history | edited | Karl | CC BY-SA 4.0 |
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| Sep 10, 2019 at 20:03 | history | edited | Karl | CC BY-SA 4.0 |
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| Sep 10, 2019 at 19:56 | comment | added | Karl | I might also add that the matter is somewhat more complicated in high field MRI with humans, where the sample dimensions reach a similar dimension than the wave lenght of photons with that energy level. | |
| Sep 10, 2019 at 19:51 | history | answered | Karl | CC BY-SA 4.0 |