礦物材料現(xiàn)代測(cè)試技術(shù)3x熒光分析-在線瀏覽
2024-12-03 02:42本頁(yè)面
【正文】 5 EDSXRF (1) 第二部分 . X熒光成分分析 The second and more mon method for analyzing obsidian is EDSXRF. EDS－ XRF systems detect elements on the periodic table between atomic numbers 11 (Na) and 92 (U). Samples can be analyzed nondestructively with little or no sample preparation in minutes and in some cases seconds. Elements in concentrations from as low as a few parts per million to 100% may be analyzed in the same sample simultaneously. Accuracy of less than one percent relative error are attainable with parable reproducibility 武漢理工大學(xué)資環(huán)學(xué)院 管俊芳 27 5 EDSXRF (2) 第二部分 . X熒光成分分析 Analysis by EDSXRF, like WDSXRF involves use of ionizing radiation to excite the sample, followed by detection and measurement of Xrays leaving the sample that are characteristic of the elements in the sample. However, unlike the crystal (wavelength) XRF, EDSXRF spectrometer electronics digitize the signal produced by Xrays entering the lithium drifted detector, and send this information to the PC for display and analysis. The Na to U spectral data are in the 137 KeV range. 武漢理工大學(xué)資環(huán)學(xué)院 管俊芳 28 5 EDSXRF (3) 第二部分 . X熒光成分分析 武漢理工大學(xué)資環(huán)學(xué)院 管俊芳 29 5 EDSXRF (4) 第二部分 . X熒光成分分析 The high resolution lithium drifted silicon Xray detectors provide low detection limits, few spectral interferences, and accuracy over a wide range of concentrations. These detectors are able to separate the electron energy ing from the sample into elemental ponents, which in turn are translated into ratio, qualitative, or quantitative elemental data in spreadsheet or word processor formats. Additionally, the tube voltages on EDSXRF are quite low and the entire instrument is plugged into a standard wall socket. WDSXRF requires filtered voltage at 220 V. 武漢理工大學(xué)資環(huán)學(xué)院 管俊芳 30 5 EDSXRF (5) 第二部分 . X熒光成分分析 Advantages: (1) NONDESTRUCTIVE In the vast majority of cases, analyzed samples are not destroyed or changed by exposure to xrays. They can thus be saved for future reference or used for other types of testing that may be destructive. (2) MINIMAL PREPARATION Many samples can be examined with little or no pretreatment. Many of the alternative techniques require dissolution procedures that are both timeconsuming and costly in terms of the acids or other reagents required. 武漢理工
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