Effect of dark states on the fluorescence of carbon nanodots
العنوان: | Effect of dark states on the fluorescence of carbon nanodots |
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المؤلفون: | D. K. Nelson, A. N. Starukhin, D. A. Kurdyukov, Valery G. Golubev, D. A. Eurov |
المصدر: | Physical Chemistry Chemical Physics. 20:29045-29050 |
بيانات النشر: | Royal Society of Chemistry (RSC), 2018. |
سنة النشر: | 2018 |
مصطلحات موضوعية: | Materials science, General Physics and Astronomy, 02 engineering and technology, Liquid nitrogen, 010402 general chemistry, 021001 nanoscience & nanotechnology, 01 natural sciences, Fluorescence, Molecular physics, 0104 chemical sciences, Intersystem crossing, Singlet state, Physical and Theoretical Chemistry, Triplet state, 0210 nano-technology, Phosphorescence, Saturation (chemistry), Excitation |
الوصف: | The nonlinear fluorescence properties of colloidal carbon dot solutions in glycerol were investigated at T = 298 K and 77 K. It was first found that the fluorescence intensity depended sublinearly on optical excitation intensity even at moderate excitation levels. With increasing excitation, the fluorescence signal shows a trend toward saturation, the latter being most pronounced at liquid nitrogen temperature. The relation between the fluorescence intensity and the excitation density was shown to be well approximated by the hyperbola equation. The behavior of the fluorescence intensity was theoretically described by a 3-level model that involves the singlet fluorescent state S1 and optically "dark" triplet state T1 of a carbon dot. The triplet states are almost inactive optically and manifest themselves in a very weak phosphorescence of the carbon dots that is several orders weaker than the fluorescence of the dots. The lifetimes of the triplet state were measured to be 0.75 ms at room temperature and 0.25 s at T = 77 K. Within the model used, the intersystem crossing (S1 → T1) lifetime in the carbon dots was estimated to be τIST ∼ 10-5 s at T = 77 K and τIST ∼ 10-6 s at T = 298 K. |
تدمد: | 1463-9084 1463-9076 |
DOI: | 10.1039/c8cp05034a |
URL الوصول: | https://explore.openaire.eu/search/publication?articleId=doi_dedup___::1397c178c40ac04cb3bfabc8f4aada85 https://doi.org/10.1039/c8cp05034a |
Rights: | CLOSED |
رقم الانضمام: | edsair.doi.dedup.....1397c178c40ac04cb3bfabc8f4aada85 |
قاعدة البيانات: | OpenAIRE |
تدمد: | 14639084 14639076 |
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DOI: | 10.1039/c8cp05034a |