Three-dimensional orientation measurements of symmetric single chromophores using polarization microscopy
Article Abstract:
Band edge emission in CdSe nanocrystals (NCs) at 10 K goes through a 'dark axis' transition, making it possible to estimate both the in-plane and out-of-plane angles for each NC. The highly parallel and flexible detection of far-field polarization microscopy can thus be used to determine the 3D orientation of each NC within the sample. It has been found that NCs do not rotate during spectral shifts, indicating that the local field changes over time. There is potential for using single NCs at chemically and biologically relevant temperatures to assess orientation and conformation shifts in systems such as polymers.
Publication Name: Nature
Subject: Zoology and wildlife conservation
ISSN: 0028-0836
Year: 1999
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Modulation of cadmium uptake in phytoplankton by seawater CO2 concentration
Article Abstract:
Incubation experiments have shown that the variations in biological uptake of cadmium (Cd) in waters off California are controlled by the carbon dioxide partial pressure and by zinc. This effect is consistent with the observed regulation of Cd-carbonic anhydrase (CA) in culture. It also supports the view that Cd uptake in surface sea water is caused by its utilization in Cd-CA in phytoplankton. It appears that a region acting as a large atmospheric carbon dioxide sink exports Cd-rich organic matter, driving the surface water dissolved Cd/phosphorus ratio below the upwelled deep water ratio.
Publication Name: Nature
Subject: Zoology and wildlife conservation
ISSN: 0028-0836
Year: 1999
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Fluorescence intermittency in single cadmium selenide nanocrystals
Article Abstract:
The continuous excitation of single fluorescing cadmium selenide nanocrystals leads to intermittent on and off of the light emission at a gap of about 0.5 sec. The photoionization of the nanocrystal leads to the sudden turning off of the fluorescence. The effect of photoionization is due to the long neutralization process that follows photoionization. The intensity of the excitation determines the average on time of the light emission, although it fails to influence the average off time.
Publication Name: Nature
Subject: Zoology and wildlife conservation
ISSN: 0028-0836
Year: 1996
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