Examination of a C-Black by Various FT-IR Spectroscopic Methods

Carbon-black prepared by combustion of hexane has been studied by Fourier-transformed infrared spectroscopy, with the use of transmission, attenuated total reflectance, diffuse reflectance, and photoacoustic detection methods. When compared, the results indicate the presence of oxidative functional groups on the carbon-black lattice. The results obtained by photoacoustic detection differ substantially from those obtained by the other methods. The explanation offered is that the photoacoustic method produces a spectrum which is defined only by the optical characteristics of the interferometer head. A ratio of the photoacoustic spectrum to the standard TGS detector single beam spectrum results in the observation of the spectroscopic sensitivity profile of the TGS detector. For these low acoustic modulation frequencies, carbon-black is observed to display no surface functionality by FT-IR-PAS detection. This distinguishes FT-IR-PAS as an analytical tool for this particular chemical system.