کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
1616270 | 1516372 | 2012 | 7 صفحه PDF | دانلود رایگان |

Far-infrared reflectivity spectra, in spectral region 50–600 cm−1 and temperature region 80–300 K, of CdS and Cd1−xMnxS nanocrystals embedded in hexametaphosphate, are presented. The analysis of the far-infrared experimental reflectivity spectrum was made by the fitting procedure. The Maxwell–Garnet effective medium theory is used for modeling an effective dielectric function as well as to separate respond from nanoparticles.To analyze spectra in CdS ωTO(≈238 cm−1) to ωLO(≈305 cm−1) spectral region, quantized dipolar modes in a spherical isotropic material quantum dot (QD) are considered in the framework of a continuum model. As to the mechanical boundary conditions rigid sphere is concerned. Experimental far-infrared reflectivity spectra of our samples are in general agreement with the predictions of this model.Experimentally registered and through fitting procedure located features for CdS nanoparticles in spectral region below CdS ωTO at: ≈102 cm−1, ≈135 cm−1, ≈170 cm−1 and ≈210 cm−1 are associated to defect induced modes, especially to defects located near the surface of CdS QD. In region over CdS ωLO, modes are identified as multiphonons. In Cd1−xMnxS QD spectra new reflectivity peaks are at: ≈85 cm−1, ≈110 cm−1 and ≈180 cm−1 in spectral region below CdS ωTO, ≈270 cm−1 inside CdS ωTO–ωLO spectral region and ≈356 cm−1 and ≈376 cm−1 in region over CdS ωLO. First two registered modes are associated to both mass and force constant defects at the surface, and rest four modes are consequence of MnS phases present in the sample.
► FIR spectra of CdS and Cd1−xMnxS nanocrystals in matrix are presented.
► Effective dielectric function modeling by Maxwell–Garnet effective medium theory.
► Quantized dipolar modes in a spherical isotropic material quantum dot are analyzed.
► Intensive modes associated to defects near the surface are registered.
► MnS phases are registered in the sample.
Journal: Journal of Alloys and Compounds - Volume 521, 25 April 2012, Pages 134–140