The presence of long-lived spin states in organic solids with rapid molecular motions.
For organic solids with sufficiently mobile molecular segments, the application of a long and weak pulse (gammaB1/2pi approximately Hz) can yield inverted sharp peaks with linewidths of approximately 100 Hz in the 1H NMR spectra, and the use of multi-frequency weak pulses can excite multiple inverted sharp peaks. For these compounds, the normal 1H free induction decay (FID) of a static sample contains a slowly decaying part, which can be detected by acquisition delay up to about 2 ms. The presence of highly mobile molecular segments can also be identified by using a "dipolar filter."
Fung
B M
BM
Department of Chemistry and Biochemistry, University of Oklahoma, Norman, OK 73019-3051, USA. bmfung@ou.edu
Ermakov
Vladimir L
VL
D004578:Electron Spin Resonance Spectroscopy; D006801:Humans; D006859:Hydrogen; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D008280:Magnetics; D008968:Molecular Conformation; D009930:Organic Chemicals / Q000737:chemistry*; D013997:Time Factors
D009930:Organic Chemicals; D006859:Hydrogen