Around x-ray, notice strange energy concentration (7)

I believe the answer is:

exciton

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'energy concentration' is the definition.
The definition suggests a singular noun which matches the answer.

'around x-ray notice strange' is the wordplay.
'around' indicates putting letters inside.
'x-ray' becomes 'x' (phonetic alphabet: alpha, bravo, charlie etc.).
'strange' indicates an anagram.
'notice' is an anagram of 'eciton'.
'x' put into 'eciton' is 'EXCITON'.

Can you help me to learn more?

(Another definition for exciton that I've seen is " feature of some crystals".)

I've seen this clue in The Times.

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