Principles Of Nonlinear Optical Spectroscopy A Practical Approach Or Mukamel For Dummies Fixed Today

A diagram has two vertical lines (left = ket, right = bra). Time goes up. Arrows point toward the molecule (absorption) or away from it (emission).

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. A diagram has two vertical lines (left = ket, right = bra)

But here is the dirty secret of experimentalists: Ignoring the rotating wave approximation (RWA)

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: With RWA, you get simple exponentials

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) .

Confusing ( T_1 ) (population lifetime) and ( T_2 ) (dephasing time). Fix: ( T_2 ) = ( 1/( \textlinewidth ) ). ( T_1 ) = how long excited state lives. Always ( T_2 \le 2T_1 ). If your ( T_2 ) is shorter than ( 2T_1 ), you have pure dephasing.

That new light is your signal .