In He-Ne laser, metastable state exists in

Options

A. He
B. Ne
C. Both (1) & (2)
D. Neither He nor Ne

Answer

To answer the question about the existence of the metastable state in a Helium-Neon (He-Ne) laser, we can break down the explanation into clear steps:

### Step-by-Step Solution:

1. **Understanding the He-Ne Laser**:
- The He-Ne laser operates on the principle of light amplification by stimulated emission of radiation. It involves two types of gases: helium (He) and neon (Ne).

2. **Role of Helium and Neon**:
- In the He-Ne laser, helium atoms are used to excite the neon atoms. When an electric discharge occurs, helium atoms absorb energy and become excited.

3. **Metastable State**:
- The term "metastable state" refers to a state where an atom remains in an excited state for a longer duration than typical excited states. In the case of the He-Ne laser, some of the excited neon atoms reach a metastable state.

4. **Duration of Metastable State**:
- The metastable state in the He-Ne laser lasts for about \(10^{-8}\) seconds. This is significantly longer than the typical excited state, allowing for stimulated emission to occur.

5. **Emission of Radiation**:
- After staying in the metastable state for a brief period, the neon atoms will return to a lower energy state, emitting photons (light) in the process. The wavelength of the emitted light corresponds to the energy difference between the excited and lower energy states.

6. **Conclusion**:
- Therefore, in the He-Ne laser, the metastable state exists in the neon atoms, which are excited by the energy transferred from the helium atoms.

### Final Answer:
In the He-Ne laser, the metastable state exists in the neon atoms (option B is correct).

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