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Ultraviolet 363.8-nm Raman Spectroscopic System for in Situ Measurements at High Temperatures

Volume 51, Number 8 (Aug. 1997) Page 1224-1228

Yashima, Masatomo; Kakihana, Masato; Shimidzu, Ryosuke; Fujimori, Hirotaka; Yoshimura, Masahiro

A new ultraviolet (UV) Raman spectroscopic system to measure the Raman scattering from materials at high temperatures up to 1500 C has been designed. This system is based on a CW (continuouswave) ultraviolet argon-ion laser (363.8 nm), a spatial filter, a single monochromator coupled to a double-grating rejection filter, and a two-dimensional charge-coupled device (CCD) detector. The plasma lines from the laser are almost completely rejected by a PellinBroca prism combined with apertures. In situ Raman measurements for a zirconia (ZrO2) specimen at various high temperatures have been performed by using the UV excitation as well as the conventional visible 488.0-nm excitation for comparison. In the case of visible excitation, thermal emission obstructs the observation of the Raman scattering from zirconia even at 900 C; it becomes rapidly pronounced between 900 and 1100 C, and finally it is impossible to observe Raman spectra at temperatures higher than 1200 C. In sharp contrast to the visible excitation, the UV excitation provides good-quality Raman spectra with practically flat backgrounds for the Raman signal of tetragonal zirconia in the spectral region of 20-1100 cm -1 even at 1500 C, and it enables clear observation of the monoclinic-tetragonal phase transformation of zirconia occurring between 1100 and 1200 C.