original N-procedure transforms the experimental spectrum Y(x) according to the
Y(x,p,Dx) = Y(x)
- p[Y(x + Dx) + Y(x - Dx)].
Here, Y is the
count rate (intensity), x is the number of current “channel” in the spectrum
(running from 1
p = 2 (-2 - d2 + (d4 + 5 d2
+ 4)1/2)/ d2, where
Dx and G (in channels) are the procedure parameters.
The values of procedure
and G are selected in order to obtain optimum resolution after the transformation
at an appropriate signal-to-noise ratio. In the principle, one gets the best
results, if the value of G is close to the experimental “half – width” G for the narrowest component in the initial
spectrum to be distinguished. The Dx value is close to
value of G/2 (or less) while the signal-to-nose ratio is
appropriate. The less is the Dx value, the better is the resolution, but the more we
lose in the signal-to-nose ratio.
As the result one gets a
derived N-spectrum with a better spectral resolution as it consists of narrower
lines, the line position and the relative absorption area of
every spectral component remaining unchanged.
The very broaden components and various absorption
distributions lose in their amplitudes much more in the N-spectrum, than narrow
spectroscopic lines. It permits to reduce their influence on the narrow
In general, the N-procedure improves the visual
spectral resolution up to about 2-3 times at the expense of signal-to-noise ratio.
The fitting results (for overlapping spectral components) are characterized by
lower global correlation factors, if the N-transformed spectrum is used.