INFRARED INTENSITIES OF LIQUIDS .18. ACCURATE OPTICAL-CONSTANTS AND MOLAR ABSORPTION-COEFFICIENTS BETWEEN 6500 AND 800 CM(-1) OF DICHLOROMETHANE AT 25-DEGREES-C, FROM SPECTRA RECORDED IN SEVERAL LABORATORIES
Je. Bertie et al., INFRARED INTENSITIES OF LIQUIDS .18. ACCURATE OPTICAL-CONSTANTS AND MOLAR ABSORPTION-COEFFICIENTS BETWEEN 6500 AND 800 CM(-1) OF DICHLOROMETHANE AT 25-DEGREES-C, FROM SPECTRA RECORDED IN SEVERAL LABORATORIES, Applied spectroscopy, 49(6), 1995, pp. 840-851
This is the last of four papers that present the detailed measurements
and results that led to the acceptance by the International Union of
Pure and Applied Chemistry of Secondary Infrared Absorption Intensity
Standards for liquids. In this paper accurate infrared absorption inte
nsities of liquid dichloromethane at 25 degrees C are presented. The a
ccuracy was estimated from the +/-1.5% average agreement of integrated
intensities over specific wavenumber ranges between spectra measured
by five spectroscopists in four laboratories. The use of data from dif
ferent instruments in different laboratories has significantly include
d the effect of systematic instrumental errors. The spectra from the d
ifferent spectroscopists have been averaged, unweighted, to give inten
sity spectra of dichloromethane that are presented as the best availab
le. The results obtained agree with the only measurements that have be
en made against a primary standard, the estimated accuracy of which is
about 5.5%. The spectra of the molar absorption coefficient and or th
e real and imaginary refractive indices are reported as tables and gra
phs between 6500 and 800 cm(-1). Also reported are the peak heights an
d the areas under band groups in the molar absorption coefficient and
imaginary refractive index spectra. The imaginary refractive index, k(
(v) over tilde), and molar absorption coefficient, E(m)((v) over tilde
), values are believed to be accurate to an average +/-2.3% over the 3
6 measured bands. The baseline k((v) over tilde) values are believed t
o be accurate to similar to 8% below 6000 cm(-1), similar to 1% below
4500 cm(-1), and similar to 25% above 6000 cm(-1), where the absorptio
n is extremely weak. The areas under band groups in the k((v) over til
de) and E(m)((v) over tilde) spectra are believed to be accurate to 1.
5% averaged over the 15 measured band groups and to 1.0% over the 10 b
and groups below 3600 cm(-1). The real refractive index, n((v) over ti
lde), values are believed to be accurate to 0.2%.