EPR Spectra of Mn2+-Doped ZnS Quantum Dots

• Published in: Chemistry of materials Vol. 16; no. 5; pp. 915 - 918
• Main Authors: Gonzalez Beermann, Pedro A, McGarvey, Bruce R, Muralidharan, Subra, Sung, Raymond C. W
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 09-03-2004
• Subjects: Applied sciences; Chemistry; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Condensed matter: structure, mechanical and thermal properties; Exact sciences and technology; General and physical chemistry; Physicochemistry of polymers; Physics; Polymers; Inorganic compounds; Organic compounds
• ISSN: 0897-4756; 1520-5002
• DOI: 10.1021/cm030435w

Powder Mn2+ EPR spectra of 5-nm ZnS:Mn quantum dots have been analyzed in detail to account for all the observed fine spectral features. The same spectral features are observed in samples with low doping of Mn2+ (0.003−0.008%), showing 10 weak forbidden transitions between the six-line pattern of the M S = −1/2 to M S = 1/2 transition for the six M I values. Spectral simulations have been performed with the Simfonia program with parameters g xx = 2.0064, g yy = 2.0064, g zz = 2.0066, D = 37.4 × 10-4 cm-1, E = 12.5 × 10-4 cm-1, A xx = 63.9 × 10-4 cm-1, A yy = 64.0 × 10-4 cm-1, and A zz = 64.4 × 10-4 cm-1, suggesting a lower than T d site symmetry for the doped Mn2+ in the cubic ZnS structure. At higher doping concentration (15.9%), a single broad line is observed with isotropic g and A.