What is the Physical Situation Described by this Unidentified Transition Rate?

[yeshuamo]

Homework Statement

I am identifying equations on the final exam equation sheet for my quantum II class. I've identified them all except this one, what I am guessing is a transition rate for some kind of emission or absorption of radiation case. Please help me identify the physical situation that this expression describes.

Homework Equations

This is the unidentified equation:
R_{i->f}=\frac{\pi}{2\hbar^2}\Big|\Big<\psi_f^o\Big|V\Big|\psi_f^o\Big>\Big|^2\delta(\omega_{fi}-\omega)

R\equiv\frac{dP}{dt}
, where P is the transition probability.

\omega_{fi} = \frac{E_f^o-E_i^o}{\hbar}
is the Bohr frequency for transition.

The Attempt at a Solution

I would integrate the transition rate over time to find the transition probability, but I don't think \omega depends on time.

How do I identify the physical situations that this transition rate describes?

 

[DrClaude]

That's pretty much Fermi's Golden Rule, provided one of the $\psi_f^0$ is actually $\psi_i^0$.