In-Air Micro-PIXE Mapping with Chemical Contrast

Area of Science:

• Materials Science
• Analytical Chemistry
• Spectroscopy

Background:

• Chemically specific X-ray fluorescence imaging typically relies on synchrotron facilities and X-ray absorption.
• Existing methods are limited in accessibility and scope for detailed chemical analysis.

Purpose of the Study:

• To demonstrate a novel micro-PIXE spectroscopy method for 2D chemical state mapping.
• To analyze sulfur and phosphorus in inhomogeneous samples with high resolution.

Main Methods:

• Utilized a parallel-beam wavelength-dispersive tender X-ray emission spectrometer with polycapillary X-ray optics and a flat crystal analyzer.
• Recorded chemically sensitive Kβ X-ray emission to differentiate chemical states.
• Employed the ratio of intensities at specific X-ray emission energies as a spectral signature.

Main Results:

• Achieved 2D chemical state mapping of sulfur and phosphorus in model samples.
• Demonstrated pronounced chemical contrast by maximizing fluorescence signals.
• Obtained pure chemical state maps with high lateral resolution using a focused proton beam.

Conclusions:

• The developed micro-PIXE approach provides a powerful tool for chemical state analysis.
• This method enhances chemical contrast and lateral resolution in elemental mapping.
• The technique is adaptable to other micro X-ray fluorescence imaging methods beyond micro-PIXE.