Yude Li

Size-Resolved Source Apportionment of Aerosol Particles with a Confocal Micro X-Ray Fluorescence Spectrometer

A laboratory confocal micro X-ray fluorescence (micro-XRF) spectrometer based on a polycapillary focusing X-ray lens (PFXRL) in the excitation channel and a polycapillary parallel X-ray lens (PPXRL) in the detection channel was used to carry out the size-resolved source apportionment of aerosol particles. The PPXRL in the detection channel both increased the collection angle of the detector and improved the signal-to-noise ratio of the X-ray spectrum. When this confocal micro-XRF spectrometer was used to carry out the quantitative XRF analysis of single aerosol particles with smaller size than that of the overlapping foci of the PFXRL and the PPXRL, the sensitivity was corrected by using a Gaussian function. The size-resolved “fingerprint database” for the air pollution sources was established based on the quantitative XRF results for single aerosol particles. The size-resolved aerosol particles on hazy-foggy days in Beijing were apportioned.

Application of polycapillary X-ray optics in residual stress measurement

A polycapillary X-ray optics is developed and used in a micro-area XRD residual stress measurement. The results are compared with the traditional pinhole method. Both diffraction intensity and peak height obtained from the application of this polycapillary are enhanced by dozens of times than that from the pinhole method. The experimental results exhibit the advantage of this polycapillary optics in the micro-area residual stress measurement with higher detectable signal and more accuracy.

Application of a polycapillary x-ray optics in high pressure XAFS

A polycapillary x-ray optics is developed for high pressure x-ray absorption fine structure spectroscopy (XAFS). Profiting from a large gain of power density and enlarged divergence of x-ray beams transmitted through the polycapillary, the range of x-ray energies accessible for the measurements is expanded considerably. A contrastive experiment with and without this polycapillary was carried out at the Beijing Synchrotron Radiation Facility (BSRF) high pressure XAFS station (1W1B). The disturbing diffraction peaks from the diamond layer were basically eliminated.

Application of a new-structure polycapillary x-ray optics in high pressure XAFS

New-structure polycapillary x-ray optics for high pressure x-ray absorption fine structure (XAFS) absorption spectroscopy using the diamond anvil cells (DAC) method are applied in synchrotron radiation analysis. The optics are composed of a solid glass fiber in the center and surrounded by a hollow glass capillary array. They can restrain the higher harmonic of incident synchrotron radiation and obtain smooth and clear XAFS spectra. At the biological macromolecule station in the Beijing Synchrotron Radiation Facility (BSRF), a method of aligning these optics was developed and the transmission efficiency for both fundamental and higher harmonic waves investigated. The XAFS spectra of topological insulator material of Bi2Se3 were obtained by combining the optics.