title: Fast and simultaneous measurement of longitudinal and transverse NMR relaxation times in a single continuous wave free precession experiment.
abstract: The purpose of this communication is to describe a method for rapid and simultaneous determination of longitudinal (T1) and transversel (T2) relaxation times, based on a single continuous wave free precession (CWFP) experiment which employs RF pulses with a pi/2 flip angle. We analyze several examples, involving nuclei such as 1H, 31P, and 19F, where good agreement with T1 and T2 measurements obtained by traditional methods is apparent. We also compare with the more time-consuming steady-state free precession (SSFP) method of Kronenbitter and Schwenk where several experiments are needed to determine the optimum flip angle. The role of an inhomogeneous magnetic field on the observed decays and its effect upon the accuracy of relaxation times obtained by these methods is examined by comparing numerical simulations with experimental data. Possible sources of error and conditions to minimize its effects are described.
authors.affiliation: Universidade de São Paulo, Instituto de Química de São Carlos, Avenida Trabalhador São-Carlense 400, São Carlos, SP 13560-590, Brazil.
authors.forename: Tiago
authors.initials: T
authors.lastname: Venâncio
authors.forename: Mario
authors.initials: M
authors.lastname: Engelsberg
authors.forename: Rodrigo B V
authors.initials: RB
authors.lastname: Azeredo
authors.forename: Neif E R
authors.initials: NE
authors.lastname: Alem
authors.forename: Luiz A
authors.initials: LA
authors.lastname: Colnago
mesh_terms: D046911:Macromolecular Substances; D008962:Models, Theoretical; D019906:Nuclear Magnetic Resonance, Biomolecular / Q000379:methods*; D010756:Phosphoric Acids / Q000032:analysis; D013997:Time Factors
chemical_list: D046911:Macromolecular Substances; D010756:Phosphoric Acids; C030242:phosphoric acid