When high energetic electron beam , (i.e., cathode rays) strike the heavier metal, then X-ray are produced. Spectrum of X-ray are classified into two categories: (i) continous spectrum, and (ii) characteristic depends only on the potential difference across the electrode. But wavelength of characteristic spectrum depends on the atomic number `(z)`.
The production of characteristic X-ray is due to the

Options

A. continuous acceleration of incident electrons towards the nucleus
B. continuous ratardation of incident electrons towards the nucleus
C. electron transition between inner shells of the target atom
D. electron transition between outer shells of the target atom

Explanation

To answer the question regarding the production of characteristic X-rays when high-energy electron beams strike heavier metals, let's break down the explanation step by step.

### Step-by-Step Solution:

1. **Understanding X-ray Production**:
- When a high-energy electron beam (cathode rays) strikes a heavy metal target, X-rays are produced. This process involves the interaction of the electrons with the atoms of the metal.

2. **Types of X-ray Spectra**:
- The X-ray spectrum is classified into two categories:
- **Continuous Spectrum**: This spectrum is produced when electrons are decelerated upon interaction with the nucleus of the target atoms.
- **Characteristic Spectrum**: This spectrum arises from specific electron transitions within the atoms of the target material.

3. **Dependence on Potential Difference**:
- The characteristic spectrum depends on the potential difference applied across the electrodes. This potential difference determines the energy of the incoming electrons.

4. **Wavelength Dependence on Atomic Number**:
- The wavelength of the characteristic X-ray spectrum is dependent on the atomic number (Z) of the target material. Higher atomic numbers result in shorter wavelengths.

5. **Mechanism of Characteristic X-ray Production**:
- Characteristic X-rays are produced due to electron transitions between energy levels in the target atom.
- When the high-energy electrons collide with the target atoms, they can eject inner-shell electrons (core electrons) from the atom.
- This creates vacancies in the inner shells, and electrons from higher energy levels (outer shells) transition down to fill these vacancies.
- The energy difference between the two levels is emitted as X-ray photons, which corresponds to the characteristic X-ray spectrum.

6. **Conclusion**:
- Therefore, the production of characteristic X-rays is primarily due to the transition of electrons between the inner shells of the target atom after an inner-shell electron has been ejected.

### Final Answer:
The production of characteristic X-ray is due to the **electron transition between the inner shell of the target atom**.

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