91影视

There are two atoms whose energies and average lifetime at each level are indicated.

Stimulated emission is a process by which an incoming photon of a certain frequency can interact with an electron atomic electron (or other exciting molecular structure), causing it to plummet.

For stimulated emission to take place, need a long-lived state above a short-lived state in both the atoms. In addition for the light emitted by A to cause stimulated emission of B, energy matching the transition is required. Now, using the figure, get the transition states in both cases. Now, for the case of energy per photon in only B, the energy difference is taken.

The above conditions given in the concept are fulfilled for the transition from the 6.9 eV state (lifetime 3 ms) to 3.9 eV state $\left(3\mathrm{渭蝉}\right)$in A and the transition from 10.8 eV state (lifetime 3 ms) to 7.8 eV state $\left(3\mathrm{渭蝉}\right)$in B considering the given figure.

Thus, the energy per photon of the stimulated emission of B is given by:

$$\begin{gathered} \mathrm{E}=\left(10.8-7.8\right)\mathrm{eV} \\ =3\mathrm{eV} \end{gathered}$$

Hence, the value of the energy per photon for emission of B is 3 eV.