Optical and FTIR studies of CdSe quantum dots

CdSe colloidal nanocrystals (∼3.4 nm) with zinc blende structure were synthesized at low temperature and at different reaction time via inverse micelle technique. CdSe QDs FTIR spectra show the existence of cadmium selenide compound and long alkane chains solvents. The Cd-Se band stretching can be observed at ∼722 cm⁻¹. All other peaks are corresponding to the structural bond of oleic acid and paraffin oil with cadmium selenide QDs e.i ∼1377, 1463, 2853, 2924 and 2953 cm⁻¹. CH3 bending deformed behaviour can be observed at ∼1377 cm⁻¹ and CH2 bending band behaviour at ∼1463 cm⁻¹. Also the present of CH2 stretching at ∼2853, 2924 and 2953 cm⁻¹. The presence of peak at ∼1712 cm⁻¹ proof of capping of as-prepared CdSe QDs by oleic acid. Interestingly, there is no peak observed at ≫3000 cm⁻¹ compared to FTIR spectra of CdSe QDs prepared by TOP based route that confirmed the elimination of hydroxide and amine group from non-TOP based route CdSe QDs samples. From this study, it also can be observed that almost all existed peak in FTIR spectra shows slightly shifting behaviour toward larger wavenumber as the crystal size increases.