Cd_1-xMn_xS Nanoparticles: Far-Infrared Phonon Spectroscopy

Phonon spectra of Cd1-xMnxS (x = 0; 0.01; 0.05; 0.1; 0.15; 0.3) nanoparticles (d ~ 4.5 nm) have been investigated by far-infrared reflection (FIR) (spectral range 40 - 600 cm-1, temperature range 80 – 300 K) and Raman spectroscopy (100 – 700 cm-1, 300 K). Cd1-xMnxS nanoparticles have been synthesized by using aqueous solution precipitation. We obtained interesting features in FIR spectra: there are expected modes of bulk CdS (240 cm-1, 300 cm-1), new modes connected with nano-size of CdS (130 cm-1, 170 cm-1) and additional mode at 120 cm-1 in Cd1-xMnxS nanoparticles which can be assigned to the presence of Mn. The position of obtained modes is discussed in the frame of the linear chain model with both mass and force constant defects. Raman spectroscopy gives us only the mode at 300 cm-1 and its second harmonic.