Single crystal raman spectroscopy of cerussite

Abstract

Raman and infrared active modes of cerussite were assigned according to their symmetry species and compared to other aragonite group minerals. Small satellite bands at 823 and 1031 cm-1 on the low-wavenumber side of the fundamental vibrations ν2 and ν1, respectively, have been assigned to the isotopic substitutions of 13C and 18O. The Raman active ν1 and ν2 carbonate modes are observed at 1051 and 835 cm-1. The absence of the B2g component of the ν1 and ν2 vibrations has been explained by the small coupling between the Ag and B2g modes. The Raman active ν3 carbonate anti-symmetric stretching mode is observed at 1361(Ag), 1376 (B1g), 1419 (B3g), and 1477 (B2g) cm-1, while the corresponding infrared active bands are observed at 1396, 1432, and 1456 cm-1. The Raman active ν4 carbonate bending mode is observed at 673 (Ag), 668 (B2g), 681 (B1g), and 694 (B2g) cm-1. The corresponding infrared bands are observed at 670, 679, and 698 cm-1. In both ν3 and ν4 the factor group splitting between the B1g and B3g modes is 1 to 3 times smaller than the separation of the Ag and B2g modes. Raman active lattice vibrations are detected at 120 (B3g), 132 (Ag), 148 (B1g), 152(B2g), 174 (B2g), 179 (B1g), 213 (Ag), 226 (B3g), and 243 cm-1 (B2g). Corresponding infrared active bands are detected at 573, 543, 573, 423, 375, 290, 205, 165, 146, and 134 cm-1. Raman bands at 949, 966, 989, 1000, and 1104 cm-1 and at 922, 946, 967, 988, 996, and 1007 cm-1 in the infrared spectra are assigned to combination and overtone bands. Raman bands at 1676 (Ag), 1689 (Ag), 1730 (B3g), and 1740 (B1g) cm-1 are ascribed to combination modes of ν1 + ν4 with bands at 2052 and 2092 cm-1 assigned to 2ν1. Corresponding infrared bands are observed at 1729 and 1740 cm-1 (ν1 + ν3). Bands at 2359, 2409, 2471, and 2521 cm-1 are ascribed to ν1 + ν3, with broad bands at 1246 and 1323 cm-1 assigned to 2ν4 modes.