′�?, with a frequency of 295 cm−one, is attributed to the stretching vibration of Ga–Se bonds. The two-phonon absorption of the 295 cm−one phonon corresponds into the crystal IR absorption edge, rather then the residual absorption peak. Density purposeful principle computations clearly show which the residual absorption with the BGSe https://baga4s7-crystal19730.nizarblog.com/32920731/the-best-side-of-baga4se7-crystal