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Depth profiling of sterically-stabilised polystyrene nanoparticles using laser ablation/ionisation mass spectrometric
Albert Pegus1, David Kirkwood, Dean B Cairns
1Department of Chemistry, University of Sussex, Falmer, Brighton, UK.
Physical Chemistry Chemical Physics : PCCP
|June 18, 2005
Summary
Laser ablation mass spectrometry enables nanoparticle depth profiling. Varying laser wavelength, not power, controls analysis depth, distinguishing surface from core material in polystyrene nanoparticles.
Area of Science:
- Analytical Chemistry
- Materials Science
- Spectroscopy
Background:
- Nanoparticle characterization is crucial for various applications.
- Laser ablation coupled with mass spectrometry offers a sensitive analytical technique.
- Understanding surface and core composition of nanoparticles requires advanced methods.
Purpose of the Study:
- To investigate the depth profiling capabilities of laser ablation mass spectrometry for polystyrene nanoparticles.
- To determine the influence of laser wavelength and power on the analysis of nanoparticle composition.
- To correlate experimental observations with existing laser ablation models.
Main Methods:
- Introduction of polystyrene nanoparticles (129 nm mean diameter) using an aerodynamic lens.
- Laser ablation at wavelengths of 266, 355, and 523 nm.
- Mass spectrometric detection of ion intensity.
- Analysis of poly(ethylene glycol) surface coating (approx. 5 nm depth).
Main Results:
- Depth profiling was achieved by altering laser wavelength.
- Changing laser power at a fixed wavelength had minimal effect on observed ions.
- 523 nm wavelength primarily ablated surface-bound poly(ethylene glycol).
- 266 nm wavelength predominantly ablated polystyrene core ions.
Conclusions:
- Laser wavelength is a key parameter for controlling ablation depth in nanoparticles.
- The study validates wavelength-dependent depth profiling for heterogeneous nanoparticles.
- Observed phenomena align with established laser ablation mechanisms.