Analysis of RF heating and sample stability in aligned static solid-state NMR spectroscopy.
Sample instability during solid-state NMR experiments frequently arises due to RF heating in aligned samples of hydrated lipid bilayers. A new, simple approach for estimating sample temperature is used to show that, at 9.4 T, sample heating depends mostly on (1)H decoupling power rather than on (15)N irradiation in PISEMA experiments. Such heating for different sample preparations, including lipid composition, salt concentration and hydration level was assessed and the hydration level was found to be the primary parameter correlated with sample heating. The contribution to RF heating from the dielectric loss appears to be dominant under our experimental conditions. The heat generated by a single scan was approximately calculated from the Q values of the probe, to be a 1.7 degrees C elevation per single pulse sequence iteration under typical sample conditions. The steady-state sample temperature during PISEMA experiments can be estimated based on the method presented here, which correlates the loss factor with the temperature rise induced by the RF heating of the sample.
Department of Chemistry and Biochemistry, Florida State University, Tallahassee, 32310, USA.
Conggang
C
Li
Yiming
Y
Mo
Jun
J
Hu
Eduard
E
Chekmenev
Changlin
C
Tian
Fei Philip
FP
Gao
Riqiang
R
Fu
Peter
P
Gor'kov
William
W
Brey
Timothy A
TA
Cross
D006358:Hot Temperature; D008051:Lipid Bilayers / Q000737:chemistry*; D019906:Nuclear Magnetic Resonance, Biomolecular / Q000379:methods*; D010713:Phosphatidylcholines / Q000737:chemistry; D010715:Phosphatidylglycerols / Q000737:chemistry; D011846:Radio Waves; D012965:Sodium Chloride; D013696:Temperature
D008051:Lipid Bilayers; D010713:Phosphatidylcholines; D010715:Phosphatidylglycerols; D012965:Sodium Chloride; C051388:1,2-dioleoyl-sn-glycero-3-phosphoglycerol; C017251:1,2-oleoylphosphatidylcholine