  Correlated rotational alignment spectroscopy correlates observables of
ultrafast gas-phase spectroscopy with high-resolution, broad-band rotational
Raman spectra. This article reviews the measurement principle of CRASY,
existing implementations for mass-correlated measurements, and the potential
for future developments. New spectroscopic capabilities are discussed in
detail: Signals for individual sample components can be separated even in
highly heterogeneous samples. Isotopologue rotational spectra can be observed
at natural isotope abundance. Fragmentation channels are readily assigned in
molecular and cluster mass spectra. And finally, rotational Raman spectra can
be measured with sub-MHz resolution, an improvement of several
orders-of-magnitude as compared to preceding experiments.
