Gaussian multiplication, resolution enhancement

Gaussian multiplication (Ernst, 1966 Marco and Wuethrich, 1976) has been used widely for resolution enhancement without significant loss of sensitivity in ID NMR spectra. There are two parameters altered by the... 

Heteronuclear-shift-correlation spectra, which are usually presented in the absolute-value mode, normally contain long dispersive tails that are suppressed by applying a Gaussian or sine-bell function in the F domain. In the El dimension, the choice of a weighting function is less critical. If a better signal-to-noise ratio is wanted, then an exponential broadening multiplication may be employed. If better resolution is needed, then a resolution-enhancing function can be used. 

Answer Gaussian multiplication has been applied to the FID to improve the resolution. The line broadening (LB) was set to -1.0 Hz and the Gaussian maximum (GB) to 0.1. The resulting spectra have distorted lineshapes and intensities. If we attempt to enhance the resolution still further using a GB of 0.15 and an LB of -2.0 Hz, the spectrum becomes almost unrecognizable, as shown below. These parameters must be optimized for each spectrum, or even each signal. 

Matched filter The multiplication of the free induction decay with a sensitivity enhancement function that matches exactly the decay of the raw signal. This results in enhancement of resolution, but broadens the Lorentzian line by a factor of 2 and a Gaussian line by a factor of 2.5. 

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