Chemical State and Luminescence Imaging of Natural and Synthetic Diamond

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.