Talk:Phy5646

Question: A monoatomic atom undergo spontaneous emission. It changes from an excited state $|e\rangle$ with $l=0$ to an intermediate state $|i\rangle$ with $l=1$ emitting a photon with wave vector $\mathbf {k}$ , and then to the ground state $|g\rangle$ with $l=0$ emitting a photon with wave vector $\mathbf {k'}$ . Find the probability that the angle between the two wavevectors to be $\phi$ .