| Popis: |
We study unknown features obtained from Raman spectra of protective rusts consisting of Fe3O4 discovered in the investigation of concrete buildings on Hashima Island in Nagasaki, Japan, a World Heritage site. The Raman shift shows not only the A1g peak of Fe3O4 but also a previously unknown peak at a higher wavenumber, i.e., at 700 to 800 cm− 1 or higher. Here, we investigate the characteristics of the unknown peak and indicate that the peak intensity becomes stronger than that of the original A1g as the incident light intensity is increased. This phenomenon has never been noted in Raman spectroscopy. Therefore, we consider the physical meaning of the phenomenon. As a result, we are able to explain this phenomenon by adding a hypothesis to Albrecht's vibronic theory. We also see that the results obtained in this study can be considered applicable not only to protective rust but also to other materials. |
