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

Molecules are constantly bumped by solvent molecules. This causes random fluctuations in their energy levels.

Mukamel simplifies this by treating the density matrix like a single vector and the Hamiltonian like a "superoperator" (the Liouvillian). Molecules are constantly bumped by solvent molecules

Hits the sample after a delay. It converts the coherence into a population (either in the ground state or excited state). The system is now left to evolve, vibrate, or transfer energy during the "Population time" ( Molecules are constantly bumped by solvent molecules

The "fixed" approach—the practical approach—reduces to three commandments: Molecules are constantly bumped by solvent molecules