Compact ambient pressure pyroelectric ion source for mass spectrometry

Area of Science:

• Analytical Chemistry
• Materials Science

Background:

• Conventional ionization sources often require high vacuum or complex setups.
• There is a need for robust, low-power ionization sources for challenging analytical applications.

Purpose of the Study:

• To develop and implement a compact, low-power pyroelectric ionization source for ambient pressure operation.
• To investigate the ion formation mechanisms and applicability of the source for mass spectrometry.

Main Methods:

• Utilized z-cut lithium niobate or lithium tantalate crystals with resistive heaters.
• Thermally cycled crystals over a narrow temperature range (30 K) to induce pyroelectric effects.
• Coupled the source to an ion trap mass spectrometer for analysis of various organic compounds.

Main Results:

• Successfully generated both positive and negative ions alternately through thermal cycling.
• Observed singly deprotonated species and clusters for hexafluoro-2-propanol and benzoic acid.
• Observed singly protonated species for triethylamine and triphenylamine.
• Ion formation primarily resulted from electrical discharges (dielectric breakdown) on the crystal surface.
• The source demonstrated robustness, with performance largely unaffected by crystal face contamination.

Conclusions:

• The developed pyroelectric ionization source is a compact, low-power, and robust alternative for mass spectrometry.
• Its ability to operate at ambient pressure and tolerate contamination makes it suitable for harsh environments and unattended operation.