Effect of molybdenum foil width on small mass spectrometer experiment
The influence of molybdenum foil width on the experiment was analyzed by analyzing the structure, working principle, sensitivity and measuring range of the magnetic deflection mass spectrometer. The optimum width of molybdenum strip is 0.60-1.00mm.
Mass spectrometer is an experimental instrument which uses the moving law of charged particles in electromagnetic field to separate according to the mass to load ratio, so as to detect the components and contents of the material. Mass spectrometry is a map arranged according to the mass to load ratio m/q of the substance. The early development of mass spectrometry is based on the determination of atomic mass and the search for isotopes, component analysis and component separation. The current mass spectrometer has been used in many fields, such as nuclear science, organic chemistry, biology, medicine, pharmacology and geology. The small-scale mass spectrometer is a dynamic analysis instrument which uses magnetic field to separate the material according to the mass to load ratio. The surface ionization particle source is suitable for the analysis and measurement of solid samples with low ionization energy.
The ion source used in mini mass spectrometer is surface ionization ion source, which is composed of molybdenum foil and ion extraction hole (exit slot). When the temperature of molybdenum strip is high enough, the sample will decompose and emit into space in the form of atoms, which will be surrounded by a certain concentration of atoms on the metal surface. The electrons impinging on the hot metal surface may ionize and form a certain concentration of atoms, ions and electrons near the metal surface. If a negative voltage V (i.e. accelerating voltage) is applied to the ion extraction orifice plate, the positive ions can enter the analysis area through the outlet hole. In order to improve the efficiency of ion extraction, two deflection electrodes are placed on both sides of the metal strip, and different negative voltages are applied respectively. Ions can be converged through the outlet hole and a larger ion current can be obtained.
