Correction to “Using FT-IR Spectroscopy to Measure Charge

Addition/Correction pubs.acs.org/JPCB

Correction to “Using FT-IR Spectroscopy to Measure Charge Organization in Ionic Liquids” Christopher M. Burba,* Jonathan Janzen, Eric D. Butson, and Gage L. Coltrain† J. Phys. Chem. B 2013, 117 (29), 8814−8820. DOI: 10.1021/jp403122x It has come to our attention that the equation describing the transverse optic-longitudinal optic (TO-LO) mode splitting is incorrectly written in our paper. The equation for TO-LO splitting was first derived by Decius1 and was written in terms of angular frequency, ω, with units of rad s−1. In later papers, however, Decius and co-workers2−5 favored the symbol ν in lieu of ω for the vibrational frequency (see especially refs 4 and 5). Unfortunately, we did not realize the author’s notation change from ω to ν was not accompanied by a change in units from rad s−1 to s−1. Therefore, our eq 1 should be written 2

( ),

as ωLO2 − ωTO2 = 4πN

∂μ ∂q

where ω is the angular

−1

frequency with units of rad s . This oversight introduced a systematic error of 2π in our dipole moment derivative and dipole moment derivative ratio calculations. Corrected values are provided in the following table: compound

|(∂μ/∂q)DCT| (cm3/2 s−1)

|(∂μ/∂q)KKT| (cm3/2 s−1)

dipole moment derivative ratio

[C2mim]CF3SO3 [C4mim]CF3SO3 [C6mim]CF3SO3 [C8mim]CF3SO3

100.34 94.18 93.31 96.26

172.3 170.0 174.7 177.0

0.582 0.554 0.534 0.544

In revising Figures 2 and 4, we also discovered that the y-axis of Figure 4A is incorrect. The corrected versions of both of these figures are provided below.

Figure 4. Correlations between (A) molar conductivity and (B) fluidity and the dipole moment derivative ratio (DMDR) of [Cnmim]CF3SO3 with n = 2, 4, and 6. The temperature is 30 °C.

measured through dipole moment derivative ratiosis not as low as originally reported. Furthermore, the molar conductivities and fluidities of the ionic liquids remain linearly correlated to the dipole moment derivative ratios. We apologize for these errors.

■ ■

AUTHOR INFORMATION

Notes †

Deceased.

Figure 2. Plot of the dipole moment derivative ratio of [Cnmim]CF3SO3 versus the number of carbon atoms composing the alkyl side chain on the imidazolium ring. The temperature is 30 °C for all of the samples.

Fortunately, these errors do not affect the central conclusions of our paper. The quantitative measurements of charge organization, which were derived from FT-IR spectroscopic measurements, still reveal a disorganized quasilattice structure for these ionic liquids. However, the degree of disorderas © XXXX American Chemical Society

REFERENCES

(1) Decius, J. C. Dipolar Coupling and Molecular Vibrations in Crystals. I. General Theory. J. Chem. Phys. 1968, 49, 1387. (2) Frech, R.; Decius, J. C. Dipolar Coupling and Molecular Vibrations in Crystals. II. Rhombohedral Lattices. J. Chem. Phys. 1969, 51, 1536. (3) Frech, R.; Decius, J. C. Dipolar Coupling and Molecular Vibrations in Crystals. III. Polarizabilities of Molecular Anions and the Internal Field in Some Rhombohedral Crystals. J. Chem. Phys. 1969, 51, 5315.

A

DOI: 10.1021/acs.jpcb.6b02693 J. Phys. Chem. B XXXX, XXX, XXX−XXX

The Journal of Physical Chemistry B

Addition/Correction

(4) Frech, R.; Decius, J. C. Dipolar Coupling and Molecular Vibrations in Crystals. IV. Frequency Shifts and Dipole Moment Derivatives. J. Chem. Phys. 1971, 54, 2374. (5) Carlson, R. E.; Decius, J. C. Dipolar Coupling and Molecular Vibrations in Crystals. V. Correlation of Microscopic and Macroscopic Theory. J. Chem. Phys. 1973, 68, 4919.

B

DOI: 10.1021/acs.jpcb.6b02693 J. Phys. Chem. B XXXX, XXX, XXX−XXX