The infrared spectrum of synthetic akaganeite, beta-FeOOH

Fourier-transform infrared spectra of a synthetic akaganeite, beta-FeOOH, w ere acquired in transmittance, attenuated total reflectance (ATR) and diffu se reflectance. The transmittance spectra showed a distinct dependence on t he mode of sample preparation: measurements taken on pellets prepared by pr essing the sample with alkali halides (KBr or CsI) displayed bands at 1096, 1050, and 698 cm(-1) that were not observed in spectra of the neat materia l and must therefore be considered artifacts. Variations in the sampling en vironment (e.g., water and/or organic volatiles) were also observed to exer t a noticeable influence on the development of the IR spectra. Infrared bands due to akaganeite were found at 3480 + 3390 (doublet), 1630, 850 + 820 (doublet), 650, 490, and similar to 420 cm(-1). Diffuse reflecta nce spectra dominated by volume scattering (loose), diffuse reflectance spe ctra comprised of both volume and surface scattering (compacted), ATR spect ra (surface only), and transmittance spectra (absorbance only, inverse of A TR) showed compatible trends for the akaganeite features both above and bel ow similar to 1000 cm(-1). This indicates that the multiple akaganeite meas urements are consistent and confirms the band assignments.