Raman and infrared spectra were recorded for the ionic liquids
[CH3N(C4H8)Bu]+[(F3CSO2)2N]-, [Et3NH]+[(octyl)PO2H]-, [Bu4N]+[(hexyl)PO2H]-,
and [Bu4P]+[(octyl)2PO2]- and was compared to spectra calculated by Gaussian 03
using the density functional theory method B3LYP. The experimental and calculated
spectra were found to be very similar, indicating that no underlying anomalous effects
were perturbing the vibrational modes. The peaks of the experimental and calculated
Raman and infrared spectra were found to be broad and intertwined, because of the
close proximity of numerous vibrational bands.
The differential and absolute scattering cross sections of selected bands of the ionic
liquids were determined using a method of comparing the area of the ionic liquid’s
peak to standards of known cross section (cyclohexane, carbon tetrachloride, benzene,
dichloromethane, and acetonitrile). Differential and absolute cross sections were
determined experimentally at wavelengths 416 nm, 487 nm, 514 nm, 532 nm and 633
nm. A-term plots were constructed with these results to obtain the coupling constant
and the effective excited state energy. These parameters allowed the calculation of the
differential and absolute scattering cross sections at any wavelength.
This project is the first in a series of investigations to determine the electron transfer
rate of ionic liquids and determine their suitability as materials in new devices.