SPECPR Users’ Manual                                                   Page 8-f9.1

F9:  Band Removal (Reflection Method)                     Alias: band[rem]
This absorption band removal routine
takes one half of an absorption band and reflects
it about the band minimum then, divides a given reflection
spectrum by the calculated band.
The routine will request:

"Type in the file id and file # to be processed, e to include
errors, followed by l or r for left- or right-side of band to be
reflected.  type e or x to exit."
The "l" or "r" refers to left- or right-side of the band minimum when the
spectrum is stored in increasing wavelength from left to right.
It refers to the side of the band that you want to be reflected to
the other side.
Next you will be instructed to:

"enter outer limits of band (2 values), estimated half height
point on side to be reflected followed by h, a, n (channel,
wavelength, inverse wavelength), and wavelength file id and number.
type e or x to exit."
The two outer limits are on either side of the band minimum.  The
first limit tells where to stop the reflection process, the second
tells where to stop looking for the band minimum.  The program
types "WORKING" and is doing the following:

• correlating the given band limits to channels in the wavelength
  file, default is that the limits are given in terms of channels.

• searching for the band minimum by looking for a datum that is
  smaller than the three values on either side of it, between the
  limits of the ½ height and the second outer band limit.

• puts values of one side of band into the position symmetrically
  opposite to it relative to the band minimum.

• divides spectrum by reflected band.

• scales the errors by a factor of (the residual ÷ the original
  spectrum).

• calculates title and history.

WARNING:
This is a primitive means of removing a band.  It was used in the
1970’s but does not take into account the nonlinear nature of
reflection spectra.  The results for reflectance spectroscopy are
not quantitative.

Original author: Lucy Mcfadden