Optical Spectroscopy A Practical Approach Or Mukamel For Dummies Fixed: Principles Of Nonlinear
He is solving for all possible directions, but in 90% of experiments, you only care about the rephasing (echo) direction. Ignore the rest until you are a pro. Principle 4: Feynman Diagrams for the Practically Confused Mukamel loves double-sided Feynman diagrams. They look like spaghetti on mirrors. Here is how to fix them:
A laser pulse hits your molecule. The electric field pushes the electrons around. Your molecule gets a temporary dipole moment. This is called polarization (P) . He is solving for all possible directions, but
You are playing pool with light waves. The signal shoots off in a unique direction away from the laser beams. This is how you separate the tiny signal from the blinding laser light. They look like spaghetti on mirrors
Ignoring the rotating wave approximation (RWA). Fix: The RWA means you drop terms that oscillate at optical frequencies (they average to zero). Without RWA, you will cry. With RWA, you get simple exponentials. Your molecule gets a temporary dipole moment
When you poke with three beams (wavevectors ( k_1, k_2, k_3 )), the polarization emits light in specific directions. The most famous is the :
A diagram has two vertical lines (left = ket, right = bra). Time goes up. Arrows point toward the molecule (absorption) or away from it (emission).
But here is the dirty secret of experimentalists: