Existence of life in the cosmos, interesting results from Electron Probe Microanalysis

Scientists all around the world have found some interesting results while analyzing meteors and comet remains on the ground. Electron Probe Microanalysis provides some detailed data on the chemistry of the remains.

Electron Probe Microanalysis (EPMA) basically works by bombarding a sample with a focused electron beam (typical energy = 5-30 keV) and collecting the X-ray photons thereby induced and emitted by the various atomic species in the sample. Because the wavelengths of these X-rays are characteristic of the emitting species, the sample composition can be easily identified by recording WDS spectra (Wavelength Dispersive Spectroscopy). WDS spectrometers are based on Bragg's law and use various moveable, shaped mono-crystals to reflect the X-rays in the direction of the detectors (mostly gas-filled proportional counters).

EPMA is a fully qualitative and quantitative method of non-destructive analysis at the surface of materials, with sensitivity at the level of ppm. Routine quantification to 1% reproducibility is obtained over several days. It is the one of the most precise and accurate micro-analysis techniques available.

Source: India Daily, Technology Team,
Dec. 7, 2005