Abstract:
This thesis presents work undertaken using Synchrotron and Laboratory based
techniques in parallel on the Chemical State and Luminescence Imaging of Natural
and Synthetic Diamond. X-ray absorption spectroscopy (XAS) techniques have
revealed information on the chemical structure and bonding within brown and
variegated type Ia, IIa, CVD and high-pressure, high-temperature (HPHT) treated
diamonds.
XAS, Raman, X-ray Excited Optical Luminescence (XEOL) and Photoluminescence
(PL) are some of the techniques that have been applied to characterise and investigate
the cause of the brown colouration.
The XAS measurements have been undertaken in imaging mode with the capabilities
of correlating the luminescence image with the brown regions in partial luminescence
yield (PLY) and total luminescence yield (TLY). OD-XAS spectrums have been
obtained at non-brown and brown regions and have revealed a higher concentration of
sp2-bonded carbon present at the brown sites. Raman spectroscopy utilized in imaging
mode also supports this discovery.
