448 research outputs found
Photo induced ionization dynamics of the nitrogen vacancy defect in diamond investigated by single shot charge state detection
The nitrogen-vacancy centre (NV) has drawn much attention for over a decade,
yet detailed knowledge of the photophysics needs to be established. Under
typical conditions, the NV can have two stable charge states, negative (NV-) or
neutral (NV0), with photo induced interconversion of these two states. Here, we
present detailed studies of the ionization dynamics of single NV centres in
bulk diamond at room temperature during illumination in dependence of the
excitation wavelength and power. We apply a recent method which allows us to
directly measure the charge state of a single NV centre, and observe its
temporal evolution. Results of this work are the steady state NV- population,
which was found to be always < 75% for 450 to 610 nm excitation wavelength, the
relative absorption cross-section of NV- for 540 to 610 nm, and the energy of
the NV- ground state of 2.6 eV below the conduction band. These results will
help to further understand the photo-physics of the NV centre.Comment: 9 pages, 7 figure
Fluorescent nanodiamonds for FRET-based monitoring of a single biological nanomotor FoF1-ATP synthase
Color centers in diamond nanocrystals are a new class of fluorescence markers
that attract significant interest due to matchless brightness, photostability
and biochemical inertness. Fluorescing diamond nanocrystals containing defects
can be used as markers replacing conventional organic dye molecules, quantum
dots or autofluorescent proteins. They can be applied for tracking and
ultrahigh-resolution localization of the single markers. In addition the spin
properties of diamond defects can be utilized for novel magneto-optical imaging
(MOI) with nanometer resolution. We develop this technique to unravel the
details of the rotary motions and the elastic energy storage mechanism of a
single biological nanomotor FoF1-ATP synthase. FoF1-ATP synthase is the enzyme
that provides the 'chemical energy currency' adenosine triphosphate, ATP, for
living cells. The formation of ATP is accomplished by a stepwise internal
rotation of subunits within the enzyme. Previously subunit rotation has been
monitored by single-molecule fluorescence resonance energy transfer (FRET) and
was limited by the photostability of the fluorophores. Fluorescent nanodiamonds
advance these FRET measurements to long time scales.Comment: 10 pages, 4 figure
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