Raman study of gaseous bubble inclusions in bismuth gernanate and bismuth germanium silicon oxide single crystals

摘要

Gaseous bubble inclusions in bismuth germanate (BGO) and bismuth germanium silicon oxide (BGSO) crystals were studied by means of Raman spectroscopy at room temperature. Their Raman spectra in the range from 60 to 70 cm~(-1) showed three peaks for the rotational Raman modes of O_2 and N_2. Vibrational Raman modes of O_2 and N_2 were also recorded for BGO and BGSO crystals. It was found that all the rotational and vibrational modes were blue shifted from those of free molecules due to the hydrostatic pressure in the bubbles. Internal pressure in the bubbles was estimated from the rotational and vibrational Raman mode frequencies. O_2 gas pressure in the bubble was estimated as 140 GPa, and N_2 gas pressure, as 31 GPa. The pressure coefficient of the vibrational mode frequency of O_2 (0.368 cm~(-1)/GPa for O_2 vibrational mode of 1580 cm~(-1)) and N_2 (0.322 cm~(-1)/GPa for N_2 vibrational mode of 2331 cm~(-1)) was also obtained from the blue shift and the calculated bubble pressure.