K-Alpha Line
Definition
The characteristic X-ray emitted when an electron drops from the L-shell to fill a K-shell vacancy. Brightest line for most elements; the workhorse line in EDXRF.
- Origin
- Electron transition, L-shell to K-shell vacancy
- Property
- Brightest characteristic line for most elements
- Primary application
- Elemental identification by EDXRF
Common questions
Why is the K-alpha line preferred over other characteristic lines for identification?+
It is usually the most intense line for a given element, giving the best signal-to-noise ratio for detecting and quantifying trace elements in a sample.
What causes the K-shell vacancy that produces the K-alpha line?+
Bombarding the sample with X-rays or electrons ejects an inner K-shell electron, and an outer electron falling in to fill that vacancy releases the characteristic X-ray photon.
Related terms
- Anode Target
- The metal block (commonly Cu, Mo or Rh) that electrons strike inside an X-ray tube to produce the X-ray beam. Choice of...
- Bragg's Law
- nλ = 2d sin(θ). A monochromatic X-ray beam diffracted off the parallel lattice planes of a crystal produces constructive interference only at...
- Characteristic X-Rays
- Sharp emission lines produced when an inner-shell vacancy in an atom is filled by an outer electron. Their energies are element-specific (Moseley's...
- Continuous (Bremsstrahlung) Radiation
- Smooth background X-ray spectrum produced when high-energy electrons decelerate in the anode. Element-independent. The 'hump' under the characteristic lines.
- D-Spacing
- The perpendicular distance between adjacent parallel planes of atoms in a crystal lattice, measured in angstroms or nanometres. Each set of planes...
- EDXRF
- Energy-dispersive X-ray fluorescence. A solid-state detector resolves the entire emission spectrum at once by photon energy. Cheap, portable, faster.
- WDXRF
- Wavelength-dispersive X-ray fluorescence. An analyser crystal disperses fluorescence by wavelength (Bragg's law again). Slower, costlier, much higher resolution.