Je. Bertie et al., COMPACT TABLE FOR THE PUBLICATION OF INFRARED-SPECTRA THAT ARE QUANTITATIVE ON BOTH INTENSITY AND WAVE-NUMBER AXES, Applied spectroscopy, 47(12), 1993, pp. 1989-2001
A Compact Table format is presented for the publication of infrared sp
ectra that are quantitative on both intensity and wavenumber axes. The
format is illustrated with a molar absorption coefficient spectrum, E
(m)(nu) vs. nu, and with infrared real and imaginary refractive index
spectra, n(nu) vs. nu and k(nu) vs. nu, respectively. The algorithm co
nsists of two steps: first, the number of spectral points is reduced b
y using larger wavenumber spacings than appear in the original spectru
m; second, the resulting spectral points are presented in a compressed
table format. The Compact Table is about one tenth the size required
for the original spectrum to be presented in a conventional XY table.
The essential criterion for increasing the wavenumber spacing is that
it must be possible to recover the original spectrum by interpolation
to an accuracy better than that of the original spectrum. Nearly all t
he recovered imaginary refractive index and molar absorption coefficie
nt values are within 1% of the original values, and for each quantity
the average of the magnitudes of the accuracies of recovery is 0.2%. T
he real refractive index spectrum is most accurately recovered by Kram
ers-Kronig transformation of the recovered imaginary refractive index
spectrum. Nearly all the recovered real refractive index values are wi
thin 0.02% of the original values, and the average of the magnitudes o
f the accuracies of recovery is 0.005%. The real and imaginary infrare
d dielectric constant spectra, epsilon'(nu) vs. nu and epsilon''(nu) v
s. nu, can be calculated from the recovered data with an accuracy in e
psilon' that is about one half of that of the real refractive index an
d an accuracy in epsilon'' that is approximately that of the imaginary
refractive index. The detailed method is outlined and is applied to i
nfrared intensities of chlorobenzene. Computer programs are presented
for the construction of the Compact Table and for the recovery of the
full spectrum from the tabulated information.