Theoretical Analysis of Frequency-domain "single-shot" (FDSS) ultrafast spectroscopy

"Single-shot" ultrafast spectroscopy based on the frequency encoding of transient absorbance kinetics using chirped probe pulses is analyzed theoretically. FDSS has an advantage over pump-probe spectroscopy in a situation where the "noise" is dominated by amplitude variations of the signal. Unlike "single-shot" techniques based on spatial encoding of the kinetics, no a priori knowledge of the excitation profile of the pump is needed. FDSS spectroscopy can be used for many types of samples, liquid or solid, including those comparable in thickness to the wavelength of the probe light. Another advantage is that due to the interference of quasimonochromatic components of the chirped probe pulse, an oscillation pattern near the origin of the FDSS kinetics emerges. This interference pattern is unique and can be used to determine the complex dielectric function of the photogenerated species.