TUTORIAL

TUTORIAL PROGRAM FID (Windows 95 Version) FID was written to help beginners understand the features of the pulse NMR experiment. For a given set of input parameters, which include frequencies, intensities, spin-lattice relaxation time T , and the 1spin-spin relaxation time, T , the program will display the impulse response, or free induction decay (FID). 2 The constructive and destructive interference of the individual frequencies (actually the rotating x,y magnetization vectors) can be clearly seen. You may specify the flip angle, the receiver gain, and the relaxation delay, and to further develop the simulation you may add random noise and then watch it disappear with repetitive pulses. Exponential noise reduction may be applied. In the jargon of the FTNMR experiment, this is called "line broadening." Somewhat the opposite manipulation, resolution enhancement via a Lorentz-Gauss or sine-bell transformation may also be performed. Another operation allowed is apodization. Finally, sampling rate and aliasing may be addressed. You choose the sampling frequency and the program marks the points on the FID where data are taken. In this way it is easy to see that sampling frequencies that are too low will lead to transformed spectra with erroneous frequencies. After observing the FID, the Fourier transform may be calculated and the frequency domain spectrum drawn. Examination of the transformed data shows clearly how noise, signal averaging, ...