Ultrafast phenomena is a research area in physics and chemistry that focuses on studying processes that occur on extremely short timescales, typically on the order of femtoseconds (10^-15 seconds) to picoseconds (10^-12 seconds). These processes often involve the rapid transfer of energy, relaxation of excited states, and dynamics of molecular and electronic structures. The study of ultrafast phenomena is important in understanding fundamental processes in fields such as materials science, chemical reactions, and biological systems. Techniques such as pump-probe spectroscopy, femtosecond laser spectroscopy, and time-resolved X-ray crystallography are commonly used in this area of research.