The semiconductor compound CuIn5S8 has the same cubic spinel structure as CdIn2S4 11, 21. The formula of this compound can be written as [Cu1121n1,2] [In2]oS4 which is obtained by the substitution of the two-valent cation of cadmium in CdIn2S4 by the single-valent cation of copper and the three-valent cation of indium. Thus, in CuIn5S8 crystal 115 part of indium atoms has a tetrahedral ( t ) coordination, and 4/5th of indium atoms has an octahedral (0) coordination.CuIn5S8 crystallizes in the space synlmetry group Oh (Fd3m). 42 normal modes in the center of the Brillouin zone may be presented as irreducible representations of the point group Oh:Here, the A + E + 3F modes are active in Raman spectra, while 4Flu modes are IR-active.The IR reflection spectra of CuIn5S8 crystal in the frequency range of 60 to 500 cm-' have been studied previously 131. The frequencies of four Flu optical modes have been determined.The unpolarized Raman spectra of the CuIn5S8 compound are investigated in the present note.The crystals studied were grown by the modified Bridgman method. The Raman spectra were excited by the Ar' laser with h = 514.5 nm. The spectra were registed in the back scattering geometry in the frequency range from 50 to 500 cm-' with the use of an automatic multichannel spectrometer. The measurements were carried out at room temperature.

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