Prosiectau Ffiseg ar gyfer myfyrwyr bl.3 a bl.4

Disgrifiad prosiect

Measuring strain and colour in diamonds

(supervisor: Rachel Cross)

Nature of project: experimental, data analysis

Available to students on full-time physics degree schemes only.

Project description and methodology

The colour of natural and synthetic diamonds is determined by optically-active defects in the crystal lattice. These defects can also affect the mechanical and electrical properties and such centres in diamond are currently one of the most promising candidates as qubits in quantum computers. In this project, coloured diamonds will be studied using two optical methods: Raman spectroscopy and photoluminescence. Raman spectroscopy can be used to measure local strain and chemical composition while luminescence reveals the energy and location of light-emitting centres.

Both techniques will be applied to the study of visibly-different diamond samples and the successful completion of the project will require the collection and analysis of the measured spectra. Features in the spectra will be identified and compared with the scientific literature, enabling correlations between the properties measured by the two methods to be investigated.

A successful project will develop beyond the above in one/some of the following directions:
Both optical methods can be developed to provide spatially-resolved information, for example for diamonds that show lateral variations in light absorption and reflection. There is scope to develop instrumentation, software control and analysis to provide spatially-resolved spectroscopy and imaging.

The project can also develop a theoretical theme, with data analysis and modelling of existing research data to compare to literature.

When considering where to take your project, please bear in mind the time available. It is preferable to do fewer things well than to try many and not get conclusive results on any of them. However, sometimes it is useful to have a couple of strands of investigation in parallel to work on in case delays occur.

Additional scope or challenge if taken as a Year-4 project: An additional challenge for a year 4 project is to study the effect of sample treatments such as high temperature annealing on the internal structure and light emission.

Please speak to Rachel Cross if you consider doing this project.

Initial literature for students:

  1. Ferraro, J.R., Nakamoto, K., Brown, C.W., 2003. Introductory Raman Spectroscopy, Direct. doi:10.1002/jrs.1407
  2. Perkowitz, S., 2012. Optical Characterization of Semiconductors: Infrared, Raman, and Photoluminescence Spectroscopy. doi:10.1016/B978-0-12-550770-7.50013-8
  3. Fox, M., 2007. Optical Properties of Solids.
  4. Erasmus, R.M., Comins, J.D., Fish, M.L., 2000. Raman and photoluminescence spectra of indented cubic boron nitride and polycrystalline cubic boron nitride. Diamond and Related Materials 9, 600–604. doi:10.1016/S0925-9635(00)00241-7

Novelty, degree of difficulty and amount of assistance required

The project involves the use of research spectrometers and imaging systems and will require data analysis in curve fitting and image processing.

Project milestones and deliverables (including timescale)

milestoneto be completed by
Outline of optical methodsend of October
Setting up of optical systemsChristmas
Initial measurements on standard samplesend of February
Measurement of complex samples and data processingEaster

Students taking this project will have to submit a full risk assessment form