Time- and polarization-resolved optical spectroscopy of colloidal CdSe nanocrystal quantum dots in high magnetic fields |
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Authors: | Furis Madalina Hollingsworth Jennifer A Klimov Victor I Crooker Scott A |
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Institution: | National High Magnetic Field Laboratory and Chemistry Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA. |
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Abstract: | In an effort to elucidate the spin (rather than charge) degrees of freedom in colloidal semiconductor nanocrystal quantum dots, we report on a series of static and time-resolved photoluminescence measurements of colloidal CdSe quantum dots in ultrahigh magnetic fields up to 45 T. At low temperatures (1.5-40 K), the steady-state photoluminescence (PL) develops a high degree of circular polarization with applied magnetic field, indicating the presence of spin-polarized excitons. Time-resolved PL studies reveal a marked decrease in radiative exciton lifetime with increasing magnetic field and temperature. Except for an initial burst of unpolarized PL immediately following photoexcitation, high-field time-resolved PL measurements reveal a constant degree of circular polarization throughout the entire exciton lifetime, even in the presence of pronounced exciton transfer via F?rster energy transfer processes. |
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