Since lower atomic number elements have fewer filled shells, they have fewer X-ray peaks. Carbon for example, has only one peak, a K alpha X-ray at 282 eV. Conversely, the higher atomic numbered elements have more number of X-ray peaks.
While some of the high atomic numbered X-rays can be over 50 KeV, a spectral range of 0-20 KeV can detect all the elements from boron to uranium.
Essentially, each element has characteristic X-ray line(s) that allow a sample's elemental composition to be identified by a nondestructive technique.
Since the X-rays are formed by the electron beam interaction with the sample surface, what ever area of the sample being imaged is analyzed. This allows the SEM to perform elemental analysis in very selected areas as small as 1/2 a micron in size. The X-rays are emitted from a depth equivalent to how deep the secondary electrons are formed. Depending on the sample density and accelerating voltage of the incident beam, this is usually from 1/2 to 2 microns in depth.
Detectibility limits can be as low as 0.2% for the higher atomic number elements.
EDX analysis can also quantify the elements it detects. A quantitative analysis can be performed by a standards or standardless analysis.
Since lower atomic number elements have fewer filled shells, they have fewer X-ray peaks. Carbon for example, has only one peak, a K alpha X-ray at 282 eV. Conversely, the higher atomic numbered elements have more number of X-ray peaks.While some of the high atomic numbered X-rays can be over 50 KeV, a spectral range of 0-20 KeV can detect all the elements from boron to uranium.Essentially, each element has characteristic X-ray line(s) that allow a sample's elemental composition to be identified by a nondestructive technique.Since the X-rays are formed by the electron beam interaction with the sample surface, what ever area of the sample being imaged is analyzed. This allows the SEM to perform elemental analysis in very selected areas as small as 1/2 a micron in size. The X-rays are emitted from a depth equivalent to how deep the secondary electrons are formed. Depending on the sample density and accelerating voltage of the incident beam, this is usually from 1/2 to 2 microns in depth.Detectibility limits can be as low as 0.2% for the higher atomic number elements.EDX analysis can also quantify the elements it detects. A quantitative analysis can be performed by a standards or standardless analysis.
การแปล กรุณารอสักครู่..