title: Radiation damping on cryoprobes.
abstract: Radiation damping on 600 and 800 MHz cryoprobes was investigated. The phase angle β between a vector 90° phase shifted to the precessing magnetization and the rf field induced in the coil was found to depend markedly on whether an FID was being acquired or not. The magnitude of the radiation damping field was sufficiently strong to restore 95% of the equilibrium water magnetization of a 90% H2O sample in a 5 mm sample tube within about 5 ms following a 165° pulse. This can be exploited in water flip-back versions of NOESY and TOCSY experiments of proteins, but care must be taken to limit the effect of the radiation damping field from the water on the Ha protons. Long water-selective pulses can be applied only following corrections. We developed a program for correcting pulse shapes if β is non-zero. The WATERGATE scheme is shown to be insensitive to imperfections introduced by radiation damping.
authors.affiliation: Research School of Chemistry, Australian National University, Canberra, ACT 0200, Australia.
authors.forename: Dmitry
authors.initials: D
authors.lastname: Shishmarev
authors.forename: Gottfried
authors.initials: G
authors.lastname: Otting
mesh_terms: D019840:2-Propanol / Q000737:chemistry; D000465:Algorithms; D002247:Carbon Isotopes; D003080:Cold Temperature; D004121:Dimethyl Sulfoxide / Q000737:chemistry; D004574:Electromagnetic Fields; D007202:Indicators and Reagents; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D011522:Protons; D011846:Radio Waves; D015203:Reproducibility of Results; D014867:Water / Q000737:chemistry
chemical_list: D002247:Carbon Isotopes; D007202:Indicators and Reagents; D011522:Protons; D014867:Water; D019840:2-Propanol; D004121:Dimethyl Sulfoxide