Research On Analysis And Testing Technology For TOF-SIMS

Time of Flight Secondary ion mass spectroscopy(TOF-SIMS) is a powerful surface analysis technique,and which was used in many fields. This topic comes from "National Major Scientific Instruments and Equipment Development Special Project TOF-SIMS Scientific Device dedicated to isotopic geochronology", which aims at developing time-of-flight secondary ion mass spectrometer applied in geochronology stable isotope analysis.At present,some instruments has been set up and need to be tested.In the process of testing,the data need to be processed.So the research on data processing algorithm and the development of data analysis software to meet the demand for data analysis in the process of instrument testing experiment, TOF-SIMS copper isotope analysis test the instrument, meet the needs of the project, TOF-SIMS analysis of rare earth elements do prophase preparatory work for the project application.First,the algorithm of data processing and analysis is studied,the data analysis software of TOF-SIMS is developed.According to the principle of TOF-SIMS,mass-to-charge ratio is calculating by curve-fitting method;The peak search method based on continuous wavelet transform is introduced into the TOF-SIMS. Based on the characteristics of TOF-SIMS peak shape,the wavelet transform coefficient formula of single spectral peak is calculated,according to the formula to calculate the parameters of the scale of the continuous wavelet transform,then the peak is searched based on continuous wavelet transform method,and this method are compared with the derivative method,the result show this method is better.The characteristics of spectral peak peak information are obtained by Gaussian fitting way.Compared the variety of some denoising methods,the wavelet transform threshold value method was selected. Then in the development of data analysis software, according to the requirements of researcher and business logic process,The MVC architecture is adopted. the software structure is divided into view、control and model.In the model, due to the data is the core of the model, so the model is divided into four modules: data processing、data analysis、document and data operation to facilitate maintenance and upgrade of the software,data as the core, the other modules only interact with the data module,the other modules are independent of each other.In view part, the data was display by mass spectrogram,and a variety of observing spectra tools were provided.In the control part through the event attributes of each control in the platform to realize response distribution function.Through the research of the data processing algorithm and the development of data analysis software, the requirements of the data needed to be analyzed was meet, tof-sims qualitative and quantitative analysis is realized.The developed TOF-SIMS spectrometer is used in the copper isotope analysis of the natural abundance of pure copper and bronze samples to test precision of the instrument.The instrument is debuged to the best state before experiment, the data analysis software is used to processing and analysis data in this paper.The result show that the error is 0.2% ~ 0.4%, the standard deviation is in the range of 0.018 ~ 0.029, the relative standard deviation is about 3% in the analysis of the copper isotope analysis.The conclusion is the accuracy in the copper isotope analysis is not very accuracy, the cause on the one hand is the cause of the performance of the instruments, such as poor repeat ability,on the other hand is the result of the isotope fractionation quality.In the end, in the process of experiment, the edge position and the center of isotope ratio difference phenomenon was studied throught the oxygen isotopes analysis by the double focusing magnetic deflection secondary ion mass spectrometry. The size of the measurement precision which effected by the edge effect is calculated in the experiments of the oxygen isotopes analysis. By using the SIMION simulation software simulation,we found that when the position of the sample in the sample target edge,the electric field distortion, thus cause the quality of the instruments fractionation, which explains the cause of the edge effect.TOF-SIMS is applied to the determination of rare earth element abundance by the time-of-flight secondary ion mass spectrometer, the results show that tof-sims instrument can detect all the trace rare earth elements at the same time. But the interaction of rare earth element isotope is larger, the instrument quality resolution is difficult to separate these isotopes, it need higher quality resolution test instrument.