In NMR measurements for low-ψ nuclei, baseline distortion due to acoustic ringing is a serious problem. Especially in the case of quadrupolar nuclei having broad linewidths, NMR signals and baseline distortion cannot be distinguished frequently. Such distortion, corresponding to the disturbance at the first several points of FID, can be corrected by Back Linear Prediction (BLP); BLP replaces distorted points by undistorted ones predicted using normal data (Fig. 1). Figure 2 shows the Fourier transformed spectra after BLP, demonstrating that baseline distortion is almost removed by replacing 3 points.
Fig.1 Distorted and BLP-corrected data points of FID in 103Rh NMR of RhCl3
Fig.2 Effects of BLP in 103Rh NMR spectra of RhCl3
※ The number of points used in BLP for each spectrum is 64.