Rezumat
CZU 543.51+53.08
The paper considers ionic composition of the plasma bunch of laser plasma at laser mass spectrometry, depending on the parameter of laser radiation. The diameter of the focal spot of the radiation is demonstrated to play a significant role in the formation of laser plasma. In particular, at a small diameter of the focal spot (d) singly and doubly charged ions dominate, while at d ≈ 0.4–0.6 mm, there are detected ions with a charge of 3, 4, and even 5. The correlation between the parameters of the radiation and ion composition makes it possible to predict the operational conditions of laser radiation, in which ions of a certain charge are recorded. It is suggested that the coefficient of relative sensitivity for trace elements should be calculated for small d, where the relative yield of singly and doubly charged ions is 90%.
Keywords: laser mass spectrometry, element discrimination, ionization and recombination of ions, ion formation in plasma, relative sensitivity factor (efficiency).