Non-Sequential Spectral Acquisitions and Data Reconstruction to Remove Time-Dependent Effects from X-Ray Spectra.

X-ray spectroscopy techniques may require prolonged exposure of a sample to an electron beam to generate X-rays. With typical spectroscopic methods the measured signal is acquired while varying the independent parameter in a systematic way, for example, stepping a photon detector in a series of energy steps from one end of the range of interest to the other incrementally or varying the energy of the incoming excitation incrementally. This can be a time-consuming process when signal strength is low, and if the sample is affected by prolonged beam exposure it could potentially change the shape and position of the obtained X-ray spectrum.

Diversity in early crustal evolution: 4100 Ma zircons in the Cathaysia Block of southern China.

Zircons are crucial to understanding the first 500 Myr of crustal evolution of Earth. Very few zircons of this age (>4050 Ma) have been found other than from a ~300 km diameter domain of the Yilgarn Craton, Western Australia. Here we report SIMS U-Pb and O isotope ratios and trace element analyses for two ~4100 Ma detrital zircons from a Paleozoic quartzite at the Longquan area of the Cathaysia Block.

Low-voltage electron-probe microanalysis of Fe-Si compounds using soft X-rays.

Conventional electron-probe microanalysis has an X-ray analytical spatial resolution on the order of 1-4 μm width/depth. Many of the naturally occurring Fe-Si compounds analyzed in this study are smaller than 1 μm in size, requiring the use of lower accelerating potentials and nonstandard X-ray lines for analysis. Problems with the use of low-energy X-ray lines (soft X-rays) of iron for quantitative analyses are discussed and a review is given of the alternative X-ray lines that may be used for iron at or below 5 keV (i.