The situation for Other Nuclei.

For other nuclei, the situation is much worse. Carbon has a resonant frequency range of 15000 Hz at typical values of Bo. Furthermore, equations (4) and (5) imply that not all nuclei are equally sensitive to the NMR experiment. Sensitivity is in fact proportional to g3, and since gc = 6.73 x 107 rad T-1s-1, this makes carbon about 62 times less sensitive than protons. Since its spin active nucleus (13C) is only 1% abundant, the overall receptivity (= sensitivity times isotopic abundance) is 6200 times less and the scan width is 25 times greater than protons. To obtain a good CW type carbon spectrum might take 600 x 25 x 6200 s = 2.95 years. For 15N, this becomes 150 years!
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Copyright (c) H. S. Rzepa and ICSTM Chemistry Department, 1994, 1995.