Ultrabroadband Midinfrared Pump-Probe Spectroscopy Using Chirped-Pulse Up-conversion in Gases

Ultrafast dynamics in molecules, nanostructures, and interfaces are commonly studied using pump-probe spectroscopy. The bandwidth for this approach has been limited to about 1000 cm⁻¹ in the midinfrared region. The authors develop an upconversion technique for femtosecond-scale detection, and demonstrate an ultrabroadband pump-probe system with a spectral range of 200---5000 cm⁻¹. Their system dramatically improves access to the energy regions of interest for investigating the relaxation of optically excited systems as diverse as proteins, liquid water, semiconductors, and topological insulators.