Exclusive correlation spectroscopy (ECOSY) is an
NMR
Nuclear magnetic resonance (NMR) is a physical phenomenon in which nuclei in a strong constant magnetic field are perturbed by a weak oscillating magnetic field (in the near field) and respond by producing an electromagnetic signal with a ...
correlation
In statistics, correlation or dependence is any statistical relationship, whether causal or not, between two random variables or bivariate data. Although in the broadest sense, "correlation" may indicate any type of association, in statisti ...
experiment introduced by O. W. Sørensen, Christian Griesinger,
Richard R. Ernst and coworkers for the accurate measurement of small
J-coupling
In nuclear chemistry and nuclear physics, ''J''-couplings (also called spin-spin coupling or indirect dipole–dipole coupling) are mediated through chemical bonds connecting two spins. It is an indirect interaction between two nuclear spins that ...
s.
The idea behind the experiment is to measure an unresolved coupling with the help of a larger coupling which is resolved in a dimension orthogonal to the small coupling. Three active nuclei are needed (SXI spin system) and the pulse sequence must be able to transfer magnetization from I to S without changing the spin state of X, otherwise the ECOSY pattern will vanish.
References
* C. Griesinger and R. R. Ernst (1987). Frequency offset effects and their elimination in NMR rotating-frame cross-relaxation spectroscopy. J. Magn. Reson. 75, 261–271.
* C. Griesinger, O. W. Sørensen and R. R. Ernst (1985). Two-dimensional correlation of connected NMR transitions. J. Am. Chem. Soc. 107, 6394–6396.
* C. Griesinger, O. W. Sørensen and R. R. Ernst (1986). Correlation of connected transitions by two-dimensional NMR-spectroscopy. J. Chem. Phys. 85, 6837–6852.
* C. Griesinger, O. W. Sørensen and R. R. Ernst (1987). Practical aspects of the E.COSY technique. Measurement of scalar spin-spin coupling constants in peptides. J. Magn. Reson. 75, 474–492.
Nuclear magnetic resonance experiments