The phrase "an inner shell" is correct and usable in written English.
It can be used to describe a layer or structure that is located inside another layer or structure, often in a metaphorical or literal sense.
Example: "The scientist discovered that the organism had an inner shell that provided additional protection against environmental threats."
Alternatives: "a core layer" or "an internal casing".
Many modern helmets have an outer plastic skin that protects them from scratches and day-to-day wear, and an inner shell of crushable foam, usually expanded polystyrene, designed to absorb impact.
Every element in the boron group has three electrons in its outermost shell (so-called valence electrons), and for each element there is a sharp jump in the amount of energy required to remove the fourth electron, reflecting the fact that this electron must be removed from an inner shell.
A W-Be gradient layer was successfully fabricated as an inner shell.
When the excited electron comes from an inner shell, the so-called Auger de-excitation processes are especially likely.
Physically, in addition to increasing total absorption, the photoelectric effect typically leads to the ejection of an inner shell electron from an atom.
XRF results from the excitation of an inner shell of an atom by the ejection of an electron from this inner shell.
The vacancy also can be created by absorption of X-ray radiation or by nuclear capture of an inner-shell electron as it approaches the nucleus.
For the experiment the researchers beamed X-rays at the sulfur, exciting an inner-shell, or core, electron so that it jumped to a higher energy level and left an empty "core hole" in its place.
In the process of electron capture, an inner-shell atomic electron is captured by the atomic nucleus, initiating the transformation of a nuclear proton into a neutron and lowering the atomic number by one unit (see radioactivity: Types of radioactivity).
By contrast, inelastic scattering occurs when energy is transferred from the incoming X-ray to the crystal, e.g., by exciting an inner-shell electron to a higher energy level.
In addition to experimental evidence, a theoretical analysis of the thermodynamics of a "Fenton type" reaction offers evidence for an inner-shell or bridged reaction mechanism [1].
