A signal function S(t1, t2) is obtained from a plurality of coherence transfer pathways in a single acquisition by preparing a molecular system in a coherent non-equilibrium state, and alternately and sequentially detecting signals at individual sampling points, in t2, from the plurality of coherence transfer pathways by using gradient refocusing of a new pathway after signal detection at a sampling point in another pathway. A frequency domain spectrum S( omega 1, omega 2) is another pathway. A frequency domain spectrum S( omega 1, omega 2) is constructed by first Fourier transforming the time domain signals S(t1, t2) in the t2 dimension and producing real and imaginary components which modulate as sine and cosine signals in t1. The real ( omega 2) cosine (t1) components are combined with the imaginary ( omega 2)sine (t1) components to form a complex data set S(t1, omega 2) that is amplitude modulated in t1. The complex data set is then Fourier transformed in the t1 dimension to construct in frequency domain spectrum S( omega 1, omega 2) which contains construct in frequency domain spectrum S( omega 1, omega 2) which contains pure absorption lineshapes. <IMAGE>
Method and apparatus for obtaining pure-absorption two-dimensional lineshape data for multidimensional NMR spectroscopy using switched acquisition time gradients.