Alex Clarke

PhD Project title: The extraction and study of presolar silicon carbide (SiC) grains

PhD supervisors: Professor Ian Lyon and Dr Torsten Henkel

Contact email address:  alex.clarke-2@manchester.ac.uk

 

Project Description

Presolar grains are micron-sized dust grains which condensed from the gases surrounding dying stars. They are identified by their highly anomalous isotope ratios (relative to solar compositions) which vary by several orders of magnitude, and are only explained by stellar nucleosynthesis. Detailed study of these grains can provide an insight into the astrophysical environment in which they formed, as well as any alteration processes they have been subjected to over their history.

Presolar silicon carbide (SiC) grains are the best studied, with over 17,000 individual grains having been analysed. However, nearly all of these grains were separated from their host meteorite with the use of harsh acids, which have been shown to damage grain surfaces. This damage can include removing or altering grain coatings, or material implanted from the interstellar medium. In order to eliminate this damage, the grains can either be measured in-situ, or ‘gently separated’ without the use of acids.

My research focuses on analysing presolar SiC grains extracted using different methods. Gently separated, in-situ and acid residue grains are all comprehensively analysed, in order to determine any elemental or isotopic heterogeneity within the grain, as well as to assess the effects of each extraction method. A Cameca NanoSIMS 50L is used to determine high precision isotope ratios of C, N and Si, whilst a Time-of-Flight Secondary Ion Mass Spectrometer (TOF-SIMS) is used to measure the full elemental and isotopic composition of each grain.

 

Publication List

Conference Abstracts:

Clarke A., Lyon I. C. and Henkel T. (2016). Towards a comprehensive analysis of presolar SiC grains: A comparison of in-situ, acid residue and gently separated grains. 79th Annual Meeting of the Meteoritical Society, Berlin, Germany. Abstract #6432 (page 64).

Lyon I. C., Clarke A., Henkel T., Moore K. L. and McMahon G (2016). Very high spatial resolution isotope and elemental imaging of pre-solar SiC grains: Topographic and imaging artefacts that may lead to apparent, but spurious, heterogeneity within grains. 79th Annual Meeting of the Meteoritical Society, Berlin, Germany. Abstract #6464 (page 288).

Clarke A., Lyon I. C. and Henkel T. (2016). A comprehensive analysis of presolar SiC grains using NanoSIMS and TOF-SIMS. From Stars and Planet Formation to Early Life (page 54), Vilnius, Lithuaniua.

Clarke A., Lyon I. C. and Henkel T. (2015). Combined TOF-SIMS and NanoSIMS analysis of gently separated presolar SiC grains. SEAES Postgraduate Research Conference, Manchester, UK.

Clarke A., Lyon I. C. and Henkel T. (2015). Combined TOF-SIMS and NanoSIMS analysis of gently separated presolar SiC grains. Meteorites and Solar System Formation Workshop, NHM, London, UK.

Clarke A., Lyon I. C. and Henkel T. (2015). Combined TOF-SIMS and NanoSIMS analysis of gently separated presolar SiC grains. 5th NanoSIMS International Workshop, Manchester, UK.

Lyon I. C., Clarke A. and Henkel T. (2015). High spatial resolution isotope ratio imaging and 3D reconstruction of presolar SiC grains. 78th Annual Meeting of the Meteoritical Society, Berkeley, USA. Abstract #5297 (page A230).

Clarke A., Lyon I. C. and Henkel T. (2015).  Combined TOF-SIMS and NanoSIMS analysis of gently separated presolar SiC grains. 78th Annual Meeting of the Meteoritical Society, Berkeley, USA. Abstract #5321 (page A89).

Clarke A.,Lyon I. C and Henkel T. (2015). Analysis of presolar silicon carbide grains using TOF-SIMS and NanoSIMS. UK Planetary Forum 12th Early Career Planetary Scientists’ Meeting, Kent, UK.

Clarke A., Lyon I. C. and Henkel T. (2014). The extraction and study of presolar SiC grains. SEAES Postgraduate Research Conference, Manchester, UK.

Clarke A., Lyon I. C. and Henkel T. (2014). The extraction and study of presolar SiC grains. BRIDGCE Meeting, Keele, UK.

 

Other Information

  • Co-Chair of the UK Planetary Forum
  • Involved in outreach with the Earth & Solar System group at The University of Manchester, including contributing to the blog and twitter accounts.
  • Teaching assistant for four undergraduate courses at The University of Manchester (‘Introduction to Earth’, ‘Planet Earth’, ‘Properties of Minerals’ and ‘British Stratigraphy & Geological Maps’).
  • Online CV
▲ Up to the top