The nitrogen-vacancy (N-V⁻) colour centre in diamond has potential applications
in quantum information processing and single photon generation. It
is currently the only known defect in a solid detected at a single site level
that has a non-zero spin in the electronic ground state. For the proposed
applications it is desirable to have a good understanding of the electronic
structure and photodynamics of the centre, however this is currently not the
case. Various models have been proposed to explain the fluorescence characteristics
observed in single site experiments. The challenge has been to
also account for the properties of the centre well-known from observations of
the fluorescence from large ensembles of N-V⁻ in diamond. Firstly, that a
non-Boltzmann population distribution between the. ground state spin levels
is induced by optical excitation. Secondly, that the fluorescence intensity
exhibits a strong dependence on the spin orientation. The models proposed
to date either cannot account for these properties, or do so only by invoking
optical processes that are arbitrary or, in some cases, not physical.
In this thesis an alternative model is presented. The derivation of the
model, from group theoretical considerations, does not form part of this
thesis. This thesis is concerned primarily with a series of independent measurements
to determine the transition rates which govern the photodynamics
of the centre. When these transition rates are known, there will be no free
parameters in the model and the N-V⁻ emission can be simulated for an
arbitrary optical field by solving the classical rate equations. To conclude
the first part of this thesis, a two-pulse optical excitation is considered and
the results of experiment are compared to the predictions of the model.
The latter part of t his thesis is concerned with optically detecting single
N-V⁻ centres. A confocal microscope system, to enable single site detection,
was developed as part of this work. The photon statistics from a single N-V⁻ centre
is compared to the statistics predicted by the model. The implications
for the modelling of individual N-V⁻ photon statistics are discussed