Wavelength-dependent amplitude of Teflon Raman lines

Raman and other spectroscopy systems operating in the deep ultraviolet (DUV) spectral region below 250 nm lack scattering standards. Such standards are particularly important for experiments that use multiwavelength excitation and/or when results are compared across different experiment platforms. Teflon has been used as an external standard in the visible and near-IR spectral regions and has been suggested for use in the ultraviolet (UV). Comparison of the relative amplitudes of prominent Teflon Raman lines indicates a significant effect on line ratios when the excitation wavelength is below 250 nm. This dependence on excitation wavelength has been commented on previously and attributed to pre-resonance effects, but no detailed examination had been undertaken to date. We present the results of a study of Teflon Raman line ratios obtained from closely spaced excitation wavelengths in the DUV from 210 to 320 nm. The 731 cm−1 line is identified as well suited for a standard. Electronic transition energies associated with resonance of principal Teflon Raman lines are obtained. Copyright © 2010 John Wiley & Sons, Ltd.