The data used in the first two notebooks (Visualizing 1D data and Visualizing 2D data) was very kindly provided by Hélène Seiler, from the Kambhampati Group (McGill University, Montreal, Canada).
Her PhD work is in ultrafast optical spectroscopy. Below is a picture of her experimental setup. Such a spectrometer is used to study nanocrystals in solution.
In the experiment, a light pulse creates a coherence between two electronic states. A second light pulse is used to excite electrons in the sample under study. These are the pump pulses. A probe pulse detects the changes induced by the pumps. If the emission energy can be higher than the excitation energy, it means that lower-energy states are coupled to higher-energy states.