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Impact ionisation spectra from hypervelocity impacts using aliphatic poly(methyl methacrylate) microparticle
Mark J Burchell1, Steven P Armes
1Centre for Astrophysics and Planetary Science, School of Physical Sciences, Ingram Building, University of Kent, Canterbury CT2 7NH, UK. m.j.burchell@kent.ac.uk
Rapid Communications in Mass Spectrometry : RCM
|January 25, 2011
Summary
Poly(methyl methacrylate) (PMMA) microparticles were accelerated to hypervelocities and impacted a target, generating impact ionization spectra. These spectra, dominated by PMMA fragments, differ from polystyrene and mimic aliphatic micrometeorites.
Area of Science:
- Materials Science
- Analytical Chemistry
- Planetary Science
Background:
- Hypervelocity impacts of microparticles generate characteristic ionization spectra.
- Poly(methyl methacrylate) (PMMA) is an aliphatic polymer with known chemical fragility.
- Polystyrene (PS) microparticles have been previously studied for impact ionization.
Purpose of the Study:
- To investigate the impact ionization spectra of poly(methyl methacrylate) (PMMA) microparticles.
- To compare the fragmentation patterns of PMMA with polystyrene (PS) under hypervelocity impact.
- To assess the suitability of PMMA microparticles as synthetic analogs for aliphatic carbonaceous micrometeorites.
Main Methods:
- Spherical PMMA microparticles (724 nm diameter) coated with polypyrrole were electrostatically accelerated to 4-8 km/s.
- Microparticles impacted a rhodium target, generating cations via impact ionization.
- Time-of-flight mass spectrometry was used to analyze the generated ions.
Main Results:
- PMMA microparticles produced distinct impact ionization spectra with strong signals at m/z 41, 65, and 115.
- These major signals correspond to known PMMA fragment ions.
- PMMA microparticles generated low-mass fragment ions more readily at lower impact speeds compared to PS microparticles.
Conclusions:
- The impact ionization spectra of PMMA are significantly different from those of PS.
- The observed fragmentation patterns of PMMA correlate with its greater chemical and thermal fragility.
- PMMA microparticles serve as valuable synthetic analogs for studying aliphatic carbonaceous micrometeorites.
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