Ultrafast Laser Spectroscopy

Ultrafast Laser Spectroscopy

Ultra-fast laser spectroscopy is the study of molecules on extremely short time scales (nanoseconds to femtoseconds) after their excitation with a pulsed laser. This method is used extensively to examine the energy states and electron dynamics of any molecule whose reaction to light is of interest. Many different procedures have been developed; some common methods are: ultra-fast transient absorption (TA); time-correlated single photon counting (TCSPC); and time-resolved photo-electron spectroscopy (TRPES). All methods must take into consideration the quantum-mechanical nature of absorption and fluorescence, specifically that individual molecules, even in pure samples, will not emit their photons simultaneously even though they are excited simultaneously, and the rate of decay between the two states is related to the difference in energy between them (see Atomic spectral lines for more information).