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Explain the existence of sharply defined K, and B, characteristic X-rays. |
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Answer» Solution :X-rays are produced when fast ELECTRONS IMPINGE on a metal target. Some of these electrons interact with the nuclei of the target atoms and are decelerated to different degrees. The loss in their kinetic energies CHARACTERISTIC X-rays. that is CONVERTED to X-rays give rise to the continuous X-ray spectrum. When the incident electrons have sufficient energy, some of them knock out tightly-bound inner-shell electrons of the target atoms. Then, an electron from an outer shell or a free electron from outside the atom occupies the energy state of the knocked out electron. The energy difference appears as an X-ray photon. Such photons have discrete energies characteristic of the target metal atom and give rise to the characteristic X-rays. When a K-shell (n =1) electron is knocked out, the transition of an L-shell electron (n=2) to that n=1 state results in the `K_(ALPHA)` line, while the transition of an M-shell electron (n=3) to the n =1 state gives rise to the `K_(p)` line, and so on. |
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