Simultaneous temporally and spectrally resolved Raman coherences with single-shot fs/ns rotational CARS

A novel technique for studies of the dynamics of molecular coherences has been developed. The concept is based on prompt excitation using broadband femtosecond (fs) laser pulses, whereupon a narrowband nanosecond (ns) laser pulse probes the fast dynamics of the coherences. Detection of the spectrally dispersed coherent signal using a streak camera allows simultaneous spectrally and temporally resolved studies of all excited coherences in a single-shot acquisition. Here we demonstrate the high capacity and versatility of this hybrid fs/ns coherent anti-Stokes Raman scattering (CARS) technique through some illustrative examples, all single-shot measurements, namely time-resolved studies of rotational Raman coherences in nitrogen and air, dynamics of Stark effect on rotational lines, and beating phenomena originating from close-lying rotational lines.