INFRARED INTENSITIES OF LIQUIDS .13. ACCURATE OPTICAL-CONSTANTS AND MOLAR ABSORPTION-COEFFICIENTS BETWEEN 6500 AND 435 CM(-1) OF TOLUENE AT25-DEGREES-C, FROM SPECTRA RECORDED IN SEVERAL LABORATORIES
Je. Bertie et al., INFRARED INTENSITIES OF LIQUIDS .13. ACCURATE OPTICAL-CONSTANTS AND MOLAR ABSORPTION-COEFFICIENTS BETWEEN 6500 AND 435 CM(-1) OF TOLUENE AT25-DEGREES-C, FROM SPECTRA RECORDED IN SEVERAL LABORATORIES, Applied spectroscopy, 48(1), 1994, pp. 127-143
This paper presents accurate infrared absorption intensities of liquid
toluene at 25 degrees C. The accuracy is estimated from the agreement
between the intensities measured by different spectroscopists using t
he same instrument in the same laboratory and also by different spectr
oscopists in different laboratories using instruments made by differen
t manufacturers. The average agreement between integrated intensities
over specific wavennmber ranges is about +/-1.8%. The spectra from the
different laboratories have been averaged, unweighted, to give intens
ity spectra of toluene that are presented as the best available. The u
se of data from different instruments in different laboratories has in
cluded the influence of systematic instrumental errors, so that the pr
ecision of the intensity data presented should be a better approximati
on to its accuracy than would be the case from an extensive study by o
ne person on one instrument. The results obtained agree with the only
measurements that have been made against a primary standard, the estim
ated accuracy of which is about 6%. The results are presented as graph
s and tables of the molar absorption coefficient spectrum and the real
and imaginary refractive index spectra between 6500 and 435 cm(-1). T
he peak heights and the areas under the bands in the imaginary refract
ive index (i.e., absorption index) and molar absorption coefficient sp
ectra rue reported. The absorption index, k(($) over tilde nu), and mo
lar absorption coefficient, E(m)(($) over tilde nu), values are believ
ed to be accurate to an average +/-2.5% at the peaks of 39 strong, med
ium, and weak bands and +/-1.9% at the peaks of 51 very weak bands bel
ow 4100 cm(-1). Above 4100 cm(-1), 11 very weak bands have an average
accuracy of +/-1.3%. The baseline k(($) over tilde nu) values are accu
rate to between +/-3 and +/-10%. The areas under bands or band groups
in k(($) over tilde nu) and epsilon(m)(($) over tilde nu) spectra are
accurate to 2.4% on average, or 1.2% for strong, medium, and weak band
groups between 3150 and 775 cm(-1);with 0.002 < k(max) < 0.112. The r
eal refractive index, n(($) over tilde nu), values are believed to be
accurate to 0.2%.