Pump-probe spectroscopy is a technique used to study the dynamics of materials at very short time scales, typically in the femtosecond range. It involves two laser pulses: the first pulse, called the "pump," excites the sample, while the second pulse, the "probe," measures the changes in the sample after a controlled delay. This allows researchers to observe how materials respond to excitation over time. By analyzing the data collected from the probe pulse, scientists can gain insights into various processes, such as chemical reactions, electron dynamics, and energy transfer in molecular systems. This technique is valuable in fields like chemistry, physics, and materials science.