Raman scattering investigation of the zinc cadmium tetrathiocyanate singlecrystals

The crystal growth, space group and Raman spectra of the zinc cadmium tetra thiocyanate (ZCTC) single crystal are introduced. The experiments show that the characteristic lattice vibrational modes of ZCTC crystal arises mainly from the internal vibrations of the SCN, ZnN4, and CdS4 groups. These mode s are assigned as upsilon (1) (160 cm(-1), a doubly degenerate CdS4 bending vibration), upsilon (2) (230 cm(-1), a doubly degenerate ZnN4 bending vibr ation), upsilon (3) (449 cm(-1), an NCS symmetrical bending vibration), ups ilon (4) (474 cm(-1), an NCS asymmetrical bending vibration), upsilon (5) ( 794 cm(-1), a CS stretching vibration), and upsilon (6) (2179 cm(-1), a CN stretching vibration), respectively. The three-dimensional network structur e of ZCTC crystal is identified, and the high nonlinearity of the crystal i s mainly attributed to the conjugated charge-transfer bridges(-Cd-S=C=N-Zn- ) that connect all the distorted tetrahedron ZnN4 and CdS4 together. (C) 20 01 Elsevier Science B.V. All rights reserved.