Selective polarization inversion of protons in rotating solids.
The selective inversion of lines under phase modulated Lee-Goldburg (PMLG) decoupling in MAS proton spectroscopy is demonstrated. Short pulses inserted between consecutive PMLG irradiation intervals selectively invert the polarization of an on-resonance line while sustaining a high resolution proton evolution. The pulse scheme is combined with windowed-PMLG detection to obtain a one-dimensional high resolution spectrum with one of the proton lines inverted. Initial preparation of the protons in selectively inverted states can be used to follow the flow of polarization during spin diffusion. Examples of proton-proton spin exchange in alanine and histidine are demonstrated. Selective inversion is also used in conjunction with proton carbon LG-cross-polarization to achieve carbon spectra with lines characterized by different polarization states.
Goobes
Gil
G
Department of Chemical Physics, Weizmann Institute of Science, Rehovot 76100, Israel.
Vinogradov
Elena
E
Vega
Shimon
S
D000409:Alanine / Q000737:chemistry*; D006639:Histidine / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D011522:Protons
D011522:Protons; D006639:Histidine; D000409:Alanine