so , i was characterizing the coating of nano particles. since i have easy access to ATR i thought lets get the data using ATR(solid sample), however when i compared it with FTIR(in liquid) the peaks and data were different. could anybody help what is the difference between ATR(SOLID) and FTIR(LIQUID).
ATR mode is Attenuated Total Reflection of Infra red spectra. In this mode of FTIR, the bond at near the surface are highlighted i.e. detected as the reflected IR are 'Fourier Transform'. In general, FTIR is recorded in Transmission mode i.e. transmitted IR is 'Fourier Transform', which contain the signature of all the bond throughout the bulk. So, there is huge scope of different peak position even intensity for a non 'ideal homogeneous material'.
When interpreting ATR-FTIR spectra where quantitative results are important, note that non-corrected ATR spectra have much stronger absorbance bands at longer wavelengths (smaller wave numbers) than at shorter wavelengths (larger wave numbers) compared to normal FTIR transmittance spectra. The reason being that the penetration depth is dependent on (in addition to refractive indices of sample and ATR crystal, and angle of incident radiation) the radiation wavelength, and increases with increasing wavelength (decreasing wave number). Various details about the ATR-FTIR technique may be found in the following article (which may be requested through Research Gate): B. P. Jelle, T.-N. Nilsen, P. J. Hovde and A. Gustavsen, ”Accelerated Climate Aging of Building Materials and their Characterization by Fourier Transform Infrared Radiation Analysis”, Journal of Building Physics, 36, 99-112, 2012.
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