Separation of net polarization and multiplet effect in coupled spin systems by two-dimensional CIDNP

Abstract

Net polarization and multiplet CIDNP effects can be measured independently by a 2D NMR method. By a 90° rf pulse the multiplet effect is transformed into a mixture of multiple-quantum coherences, which evolve during the t 1 period of a 2D experiment and which can be detected by a second 90° rf pulse. After Fourier transformation, net and multiplet effects occur at different ω 1 frequencies. The method has been applied to the photoreaction of flavin I with N-acetyl tyrosine and p-methoxyphenol.