CONVERSION ELECTRON MOSSBAUER SPECTROSCOPIC STUDY ON THE SURFACE-LAYERS OF IRON PLATES EXPOSED TO THE AMBIENT ATMOSPHERE

Conversion electron Mossbauer spectroscopy and X-ray diffractiometry have been applied to the analysis of thin iron plates exposed to the ambient atmosphere in three districts of the metropolitan area from two days to four weeks. The conversion electron Mossbauer spectra of the iron plates obtained from a suburban area along a main road gave paramagnetic doublets ascribable to iron rust with a relative intensity of 20 and more than 80% for two- and six-day exposure, respectively. The X-ray diffraction patterns of the iron plates obtained at the central and suburban areas showed broad peaks ascribable only to gamma-FeOOH. On the other hand, the conversion electron Mossbauer spectra of these samples comprised two sets of doublets, suggesting that some amorphous iron compounds that were undetected by X-ray diffraction were formed on the surface in addition to gamma-FeOOH. These results indicate that conversion electron Mossbauer spectroscopy can be a useful technique for monitoring the atmospheric environment through the analysis of surface products on iron plates with a shorter exposure period.