Student Project Abstracts 2005 - Pluto - University of Washington

EFFECTS OF SURFACE CHEMISTRY ON CADMIUM SELENIDE NANOCRYSTAL FLUORESCENCERESULTSFigures 1 and 2 show that addition of both ODT and BTquench the fluorescence of CdSe NCs. Figures 3 and 4 show thatat low concentrations (below ~0.01 M) of ODA and BA, the NPfluorescence is enhanced. This quenching can be fit with a singlecomponent Langmuir isotherm. Due to solubility issues, solutionswith ODA concentrations above ~0.12 M were not tested.Solutions with 0 M ligand concentrations are plotted as 1E-15 Mfor the log scale in figures below.Addition of degassed BA at low concentrations increasedthe QY, but quenching occurred at concentrations above 4E-3 M.Mixing BA and chloroform is exothermic, and the temperaturerise for BA concentrations above ~0.6 M is noticeable. Figure5 shows the blue-shift phenomena of the maximum absorbancepeak at high BA concentrations.Figure 4. Quantum yield vs. 1-butylamine concentration[M] for 4 nm diameter CdSe NCs in chloroform.Figure 1. Quantum yeild vs 1-octadecanethiol concentration[M] for 4 nm diameter CdSe NCs in chloroform. (Core vialsnot mixed so absolute initial quantum yeild has err or).Figure 5. The maximum absorbance peak vs 1-butylamine concentrations [M].Figure 2. Quantum yeild vs 1-butanethiol concentration [M]for 4 nm diameter CdSe NCs in chloroform. (Core vials notmixed so absolute initial quantum yeild has error).Figure 6. The quantum yield vs ODA concentration [M]with constant [ODT] = 1.2E-5 M present in solution.Figure 3. Quantum yeild vs 1-octadecylamine concentration[M] for 4 nm diameter CdSe NCs in chloroform.Figure 7. The quantum yield vs ODA concentration [M]with constant [ODT] = 6.2E-6 M present in solution.90 CMDITR Review of Undergraduate Research Vol. 2 No. 1 Summer 2005