Spectrally resolved lithium isotope quantification through high-resolution spatial heterodyne spectrometry.

Area of Science:

• Analytical Chemistry
• Spectroscopy
• Materials Science

Background:

• Lithium isotope ratio determination is crucial for geochemistry and battery diagnostics.
• Mass spectrometry is the standard but is expensive and not portable.
• Optical emission spectroscopy offers an alternative but often lacks spectral resolution.

Purpose of the Study:

• To develop a high-resolution optical method for lithium isotope quantification.
• To overcome the limitations of traditional optical spectroscopy for isotope analysis.
• To provide a compact and potentially field-deployable alternative to mass spectrometry.

Main Methods:

• Utilized a custom-built spatial heterodyne spectrometer (SHS).
• Employed a reduced-pressure glow discharge source.
• Implemented deconvolution-based spectral lineshape recovery and bootstrapping-based error propagation.

Main Results:

• Achieved a resolving power of 189,000, enabling baseline resolution of lithium d-line emissions.
• Reached a detection limit of 30 pmol with a standard industrial camera.
• Demonstrated robust isotope ratio calibration and determined relative transition probabilities.

Conclusions:

• Spatial heterodyne spectroscopy is viable for high-specificity, high-resolution lithium isotope analysis.
• The SHS approach is compact, potentially field-deployable, and adaptable to other elements.
• This work paves the way for accessible, calibration-free optical isotopic analyses.