Abstract
After a short presentation of the NMR fundements, three new methods of spin -lattice relaxation in liquids are reported. (1) The method consists of measuring the steady-state nuclear magnetization under strong off-resonance rf irradiation as a function of the angle {theta} between external field and effective field. For purely dipolar relaxation between homonuclear spins under isotropic Brownian molecular rotation, this variation yields the value of the local correlation time. A departure from the theoretical shape reveals the existence of complex motions or complex relaxation mechanisms. These results have been verified by experimental illustrations. Some numerical simulations have been performed for studying the effects of the distribution of chemical shift and for studying the coherence of the local correlation time concept. (2) The improvements of a modified ROESY experiment are discussed. The use of a time-modulated strong off-resonances rf irradiation permits to suppress totally the problems of the NOESY (suppression of cross-relaxation peaks for molecules where {omega}{tau}{sub c} {approx_equal} 1.1) and of the ROESY (HOHAHA transfer and angular dispersion due to the chemical shift distribution). The angle {theta} defined previously can be used as a constraint: either to obtain a ratio of the cross over direct dipolar relaxation rates independent on
More>>
Citation Formats
Desvaux, H.
Investigation of new NMR methods for structural and dynamic studies in the liquid state; Exploration de nouvelles methodes de R.M.N. pour les etudes structurales et dynamiques dans les liquides.
France: N. p.,
1993.
Web.
Desvaux, H.
Investigation of new NMR methods for structural and dynamic studies in the liquid state; Exploration de nouvelles methodes de R.M.N. pour les etudes structurales et dynamiques dans les liquides.
France.
Desvaux, H.
1993.
"Investigation of new NMR methods for structural and dynamic studies in the liquid state; Exploration de nouvelles methodes de R.M.N. pour les etudes structurales et dynamiques dans les liquides."
France.
@misc{etde_10154146,
title = {Investigation of new NMR methods for structural and dynamic studies in the liquid state; Exploration de nouvelles methodes de R.M.N. pour les etudes structurales et dynamiques dans les liquides}
author = {Desvaux, H}
abstractNote = {After a short presentation of the NMR fundements, three new methods of spin -lattice relaxation in liquids are reported. (1) The method consists of measuring the steady-state nuclear magnetization under strong off-resonance rf irradiation as a function of the angle {theta} between external field and effective field. For purely dipolar relaxation between homonuclear spins under isotropic Brownian molecular rotation, this variation yields the value of the local correlation time. A departure from the theoretical shape reveals the existence of complex motions or complex relaxation mechanisms. These results have been verified by experimental illustrations. Some numerical simulations have been performed for studying the effects of the distribution of chemical shift and for studying the coherence of the local correlation time concept. (2) The improvements of a modified ROESY experiment are discussed. The use of a time-modulated strong off-resonances rf irradiation permits to suppress totally the problems of the NOESY (suppression of cross-relaxation peaks for molecules where {omega}{tau}{sub c} {approx_equal} 1.1) and of the ROESY (HOHAHA transfer and angular dispersion due to the chemical shift distribution). The angle {theta} defined previously can be used as a constraint: either to obtain a ratio of the cross over direct dipolar relaxation rates independent on the correlation time value, or to observe the sole chemical exchange. (3) The difference of the relaxation rates of the coherences at zero and two quanta is always exactly the cross relaxation rates measured by the NOESY experiment. The experimental illustration is presented.}
place = {France}
year = {1993}
month = {Jan}
}
title = {Investigation of new NMR methods for structural and dynamic studies in the liquid state; Exploration de nouvelles methodes de R.M.N. pour les etudes structurales et dynamiques dans les liquides}
author = {Desvaux, H}
abstractNote = {After a short presentation of the NMR fundements, three new methods of spin -lattice relaxation in liquids are reported. (1) The method consists of measuring the steady-state nuclear magnetization under strong off-resonance rf irradiation as a function of the angle {theta} between external field and effective field. For purely dipolar relaxation between homonuclear spins under isotropic Brownian molecular rotation, this variation yields the value of the local correlation time. A departure from the theoretical shape reveals the existence of complex motions or complex relaxation mechanisms. These results have been verified by experimental illustrations. Some numerical simulations have been performed for studying the effects of the distribution of chemical shift and for studying the coherence of the local correlation time concept. (2) The improvements of a modified ROESY experiment are discussed. The use of a time-modulated strong off-resonances rf irradiation permits to suppress totally the problems of the NOESY (suppression of cross-relaxation peaks for molecules where {omega}{tau}{sub c} {approx_equal} 1.1) and of the ROESY (HOHAHA transfer and angular dispersion due to the chemical shift distribution). The angle {theta} defined previously can be used as a constraint: either to obtain a ratio of the cross over direct dipolar relaxation rates independent on the correlation time value, or to observe the sole chemical exchange. (3) The difference of the relaxation rates of the coherences at zero and two quanta is always exactly the cross relaxation rates measured by the NOESY experiment. The experimental illustration is presented.}
place = {France}
year = {1993}
month = {Jan}
}