How is a spectrum obtained in NMR spectroscopy?


A. Low-frequency radio waves bombard the atom and cause nuclei in a low spin state to move to a higher spin state.
B. High-frequency ultraviolet rays bombard the atom and cause nuclei in a high spin state to move to a lower spin state.
D. Low-frequency ultraviolet rays bombard the atom and cause nuclei in a low spin state to move to a higher spin state.

Is the answer b

I think the answer is A, but I am not sure. I believe that Low frequency radio waves are used, which eliminates answer choices B and D, which should be answer choice C. I have used NMR is performing research, but I never had to know the type of frequency used nor did I care to know.

Good question.

just took the quiz, the answer was A :)

I think B and D are eliminated because of the "ultraviolet rays" part of the answer. The nuclei are irradiated by VHF or UFH RADIO frequency as per this site. High and low are relative terms but I think of UHF and VHF as high. Here's the site. And I don't see answer choice c.

http://en.wikipedia.org/wiki/Nuclear_magnetic_resonance

That last part of my sentence should have said, "D should be answer choice C."

No, the answer is not B. In NMR spectroscopy, a spectrum is obtained by using low-frequency radio waves to bombard the sample.

Here's how it works:

1. First, a sample containing nuclei with a spin property (such as hydrogen or carbon) is placed in a strong magnetic field.

2. The nuclei in the sample align themselves with the magnetic field along two energy states, often called spin-up and spin-down.

3. Radiofrequency pulses are then applied to the sample at specific frequencies that match the energy difference between the two spin states.

4. This causes the nuclei to absorb energy and transition from the lower energy state to the higher energy state (spin-flip).

5. After the radiofrequency pulse is turned off, the nuclei return to their original alignment by releasing the absorbed energy as electromagnetic radiation.

6. The emitted radiation is detected by a receiver coil and converted into an NMR spectrum.

The spectrum obtained provides information about the chemical environment and chemical bonding of the nuclei in the sample, which can be used for structural determination and identification of compounds.