  We study single silicon vacancy (SiV) centres in chemical vapour deposition
(CVD) nanodiamonds on iridium as well as an ensemble of SiV centres in a high
quality, low stress CVD diamond film by using temperature dependent
luminescence spectroscopy in the temperature range 5-295 K. We investigate in
detail the temperature dependent fine structure of the zero-phonon-line (ZPL)
of the SiV centres. The ZPL transition is affected by inhomogeneous as well as
temperature dependent homogeneous broadening and blue shifts by about 20 cm-1
upon cooling from room temperature to 5 K. We employ excitation power dependent
g(2) measurements to explore the temperature dependent internal population
dynamics of single SiV centres and infer almost temperature independent
dynamics.
