doi:10.1016/j.saa.2005.07.048 
Copyright © 2005 Elsevier B.V. All rights reserved.
Vibrational assignment, integrated intensities of liquid toluene-d8 from 4000 to 450 cm−1 at 25 °C
C. Dale Keefe
, 
and Jennifer L. MacDonald
Department of Physical and Applied Sciences, Cape Breton University, Sydney, NS, Canada B1Y 6L2
Received 27 June 2005;
revised 27 June 2005;
accepted 21 July 2005.
Available online 28 December 2005.
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Abstract
The curvefit and vibrational assignment of toluene-d8 are presented as well as previous assignments. A total of 172 peaks are required to fit the experimental imaginary molar polarizability spectrum with CDHO bands. The R2-value is 0.9998 which indicates a near perfect fit. The area under the fitted spectrum is 0.3% larger than the area under the experimental spectrum. The integrated intensities of toluene-d8 are compared with those of toluene, benzene and several halogen substituted benzenes using the F-sum rule.
Keywords: Vibrational assignment; Curvefit; Toluene-d8; Integrated intensities; Liquid
Fig. 1. The fitted and the experimental imaginary molar polarizability spectra of liquid toluene-d8 at 25 °C from 4000 to 450 cm−1. The upper spectra in each box are the experimental and fitted spectra multiplied by 10.
Fig. 2. The Raman spectrum of toluene-d8 at room temperature between 4000 and 100 cm−1.
Table 1.
Observed features in the imaginary molar polarizability and Raman spectra of liquid toluene-d8, the parameters of the bands used to fit the imaginary molar polarizability spectra, and the assignment of the features
a The unit is cm
−1. VS indicates very strong, S strong, M medium, W weak, VW very weak, Sh shoulder, and Br broad.
b The numbers in parentheses are the relative intensities of the peaks.
c The unit is cm
−1. NF indicates the feature was not fit.
d The unit is cm mol
−1. Divide by 1 × 10
5 to convert to the usual unit of km mol
−1.
e Herzberg's notation is used to label the vibrations. The assignments are limited to fundamentals, first overtones and active binary combinations (sum and difference). WV indicates the band is assigned to water vapour in the spectrometer.
Table 2.
Integrated intensities for fundamentals of liquid toluene-d8; with and without the intensities of the combination bands included
a NO, not observed.
b NM, not measured, NF, not fit (see text for details).
c The values in this column are the uncertainties due to the neighbouring combinations and overtones, expressed as a percentage of the intensity without the combinations.
d ν3 and
ν22 are assigned to the same band. In this table, all the intensity is assigned to
ν22 as was done for toluene
[5].
e ν26 and
ν32 are assigned to the same band. In this table, all the intensity is assigned to
ν26.
Table 3.
Integrated intensities, transition moments and dipole moment derivatives of toluene and toluene-d8
NO, not observed.
a The unit is cm
−1.
b The unit is km mol
−1.
c The unit is debye, D, where 1 D = 3.336 × 10
−30 Cm = 0.0208
e nm = 0.208
e Å, where
e is the elementary charge.
d The unit is D Å
−1 u−1/2 = 10 D nm
−1 u−1/2 = 8.186 × 10
−7 C kg
−1 = 0.208
e u−1/2.
Table 4.
F-sums for fundamental vibrations of various monosubstituted benzenes
a ν7 and
ν27 are both assigned to 1155 cm
−1, making it impossible to separate the integrated intensity. The ranges given are for when the intensity is assigned completely to one vibration. The actual value will be somewhere in between but is impossible to determine from the current measurements.
b For C
6H
6 and C
6D
6, the values listed are for the A
u vibrations.
c For C
6H
6 and C
6D
6, the values listed are for the E
1u vibrations.
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