Abstract:

To satisfy the requirements for a high-field asymmetric waveform ion mobility spectrometer (FAIMS), a novel ambient direct current corona discharge chemical ion source is put forward. It consists of an inner line electrode, an outer cylinder electrode, and a traction electrode. The inner and outer electrode radii are 0.08 and 2 mm, respectively. There are four slots in the cylinder electrode for injection of samples and traction of ions. The mass spectrumexperiment results show that chemicals, such as acetone, ethanol, aniline, N,N-dimethyl formamide, dimethyl methylphosphonate (DMMP), ethyl acetate, formic acid, acetic acid, and phenol, can be ionized well. Electrometer experiments show that the ion source can produce a stable ion current. By analysis of the mass spectra, we found that the main ions were same at different time indicating that the ion source is stable. The ion source was fabricated on a silicon substrate by inductively coupled plasma (ICP) etching, which demonstrates that the structure is compatible with micro-electro-mechanical systems (MEMS) technics. The ion source is small, has a simple structure, is non-radiative, stable etc. It satisfies the requirements for FAIMS and can also be used in an ambient mass spectrometer (MS), micro MS, and  ion mobility spectrometer (IMS).

Key words: Mass spectrum, Ambient, FAIMS, Corona discharge, Ion source, MEMS