. 2019 Jun 10;9(31):18042–18049. doi: 10.1039/c9ra02584g

Mulliken symbols and frequencies of zone-centered optical phonon modes of Bi₂O₂S. Raman or IR activity of each mode is also indicated by “Raman” and “IR”. The A_u mode is neither Raman nor IR active. The unit of the phonon frequency is cm⁻¹.

Symmetry	Bi₂O₂S	Activity	Symmetry	Bi₂O₂S	Activity
B_2g	9.5	Raman	B_3u	218.8	IR
A_g	13.9	Raman	A_g	285.2	Raman
A_u	53.7		B_3u	286.3	IR
B_2u	54.9	IR	B_2g	287.7	Raman
B_3u	60.7	IR	B_1u	288.5	IR
B_1u	64.9	IR	B_3u	364.4	IR
B_3g	65.2	Raman	A_g	367.8	Raman
B_1g	67.9	Raman	B_2u	404.2	IR
B_2u	75.7	IR	A_u	448.9
B_1g	83.0	Raman	B_1g	450.6	Raman
A_u	113.1		B_3g	452.4	Raman
B_2u	113.4	IR	B_2u	457.5	IR
B_3u	144.7	IR	B_1g	519.1	Raman
A_g	170.6	Raman

Mulliken symbols and frequencies of zone-centered optical phonon modes of Bi2O2S. Raman or IR activity of each mode is also indicated by “Raman” and “IR”. The Au mode is neither Raman nor IR active. The unit of the phonon frequency is cm−1.