小型飞行时间质谱装置的构建

飞行时间质谱仪（TOF MS）在准确度、分辨率、灵敏度、质量上限、分析速度等方面具有优势，在生命科学等领域发挥着重要作用。目前商用飞行时间质谱仪已经比较成熟，但仪器尺寸普遍较大，且价格昂贵，维护困难；而小型仪器则面临分辨率较低等问题。提高小型飞行时间质谱仪的分辨率，降低购置成本和维护成本，对于飞行时间质谱仪的大范围推广有着重要意义。本工作构建了一套分辨率较高的小型飞行时间质谱装置，包括真空系统、离子源、锥孔、引出加速及偏转模块、离子反射镜模块、探测器模块、电路系统等。该仪器主体尺寸较小（0.5 m×0.5 m×0.7 m），飞行管长度仅0.25 m。由于采用了模块化设计思路，各个模块之间独立封装，仪器的维护、升级工作简单易行。该仪器的关键模块采用创新设计，使得在m/z 2 000处分辨率可达4 200。

Design of a Compact Type Time-of-Flight Mass Spectrometer

Mass spectrometer(MS) is one of the most important analytical instruments in the fields of life science, environmental science, geological survey and clinical diagnosis, etc. Since its birth in 1946 and its combination with matrix-assisted laser desorption/ionization(MALDI) source in the late 1980 s, time-of-flight(TOF) mass analyzer has gradually played an increasingly important role in the MS instruments. Thanks to its advantages in mass accuracy, resolution, sensitivity, mass range, analysis speed, TOF have been widely used in microbial identification, clinical diagnosis, proteomics, and some other fields. The performance such as resolution of modern commercial TOF-MS is getting higher and higher. However, the expensive-price, large-in-size, difficult-to-maintain of TOF-MS confined it in the laboratory and made it difficult to broadly applicate in industrial and medical fields. In this work, a compact type time-of-flight mass spectrometer was developed to study the preparation and detection of nanoscale metal clusters. It mainly included a vacuum system, an ion source, a skimmer, an extraction/acceleration and deflection module, an ion mirror, a detector, a circuit system, and the like. Two turbo pumps provided vacuum of 5×10-5 Pa. The laser ablation ion source could output stable ion beams for a long time, which was beneficial to the development of the TOF. The ions deflection module and the position/angle-tunable detector extended the mass range of the instrument. Skimmers with different diameters were designed to meet the demand for resolution and signal intensity. The time-of-flight mass analyzer could be taken out of the cavity as a whole, which was beneficial to the maintenance and upgrade of the instrument. Metal-coated ceramic was used as the electrodes of the ion mirror. Compared with conventional 304 stainless steel electrodes, the metal-coated ceramic achieves a high flatness in a thinner plate, which facilitates the resolution improvement and the instrument miniaturization. The size of the instrument is small, the length, width and height are 0.5, 0.5 and 0.7 m, respectively, and the flight tube length is only 0.25 m. The modules were packaged independently according to our modular design, and the maintenance and upgrade of the instrument were easy. Several innovative designs allow the instrument resolution to reach 4 200 at m/z 2 000, m/z 50-5 000, and signal intensity is in the range of 1 to 1 000 mV.