一种用于高场非对称波形离子迁移谱系统的新型敞开式化学离子源

Novel Chemical Ion Source for a High-Field Asymmetric Waveform I Mobility Spectrometer Used under Ambient Conditions

根据高场非对称波形离子迁移谱(FAIMS)系统的要求,本文提出了一种新型敞开式直流电晕放电化学离子源.该离子源主要由内线电极、外筒电极和牵引电极组成,内、外电极半径分别是0.08、2mm.筒壁电极上开有对称的4个槽,用于通入样品和牵引离子.质谱实验结果表明,该离子源能够在敞开环境下很好地离子化丙酮、乙醇、苯胺、N,N-二甲基甲酰胺、甲基磷酸二甲酯(DMMP)、乙酸乙酯、甲酸、乙酸、苯酚等正、负电性物质.静电计测试实验结果说明该离子源能够稳定地产生离子电流.通过分析不同时刻的谱图发现,在不同时间点上产生的主要离子相同,具有很好的稳定性.利用感应耦合等离子体(ICP)工艺在硅片上加工了该离子源,从而验证了该结构可以由微机电系统(MEMS)加工技术实现.该离子源具有体积小、结构简单、无辐射、工作稳定等特点,不仅可以满足FAIMS系统的要求,还可用于敞开式质谱、微型质谱仪、离子迁移谱(IMS)等仪器.

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 spectrum experiment 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）.