Scanning Microscopy


The Standards Committee of the Society for Luminescence Microscopy and Spectroscopy (SLMS) circulated doped zircon crystals as a standard for comparison of cathodoluminescence (CL) emission spectra obtained at different laboratories. Eleven laboratories have submitted spectra acquired from this standard. The crystals are synthetic zircons doped with 1.4 wt.% of Dy2O3

The participating laboratories used a variety of CL instrumentation including cold cathode optical micro-scope attachments, hot cathode optical microscope attachments, and EMPA/SEM-based systems. Two laboratories provided both uncorrected and corrected spectra. All other spectra are uncorrected. A variety of different spectrometers/spectrographs and detector systems were used. Photomultiplier tubes (PMTs), photo diode arrays, intensified photo diode arrays, and charge coupled devices (CCDs) are represented among the final results. The laboratories with apparently the best resolving power reported 8 peaks in the multiplet at 485 nm. The spectra submitted by some laboratories showed only a single peak at this position.

The wavelength scale calibrations were compared by noting the wavelength of the most intense peak in the 485 multiplet. This varied from 476.3 nm to 489 nm among the eleven laboratories. The systems have different overall transmission and detection functions: a combination of the influence of the transmission of the viewing window (typically leaded-glass), the microscope, the fiber optics coupling (if used), the response of the grating and spectrometer/spectrograph, and the detector response.

As an initial test of this variation, the ratio of the peak maximum intensity at 575 nm to that at 485 nm was compared. This ratio varied from 0.6 to 3.93 among the eleven laboratories.

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