Data for spin quantum beats in pump push spectroscopy

Spin quantum beats prove the quantum nature of reactions involving radical
pairs, the key species of spin chemistry. However, such quantum beats
remain hidden to transient-absorption-based optical observation because
the spin hardly affects the radical pairs’ absorption properties. We
succeeded in demonstrating such quantum beats in the photo-induced charge
separated state (CSS) of an electron-donor-acceptor dyad by using two
laser pulses, one for pumping the sample, and another one, with variable
delay, for further exciting the CSS to a higher electronic state, wherein
ultrafast recombination to distinct, optically detectable products of
singlet or triplet multiplicity occurs. This represents a spin quantum
measurement of the spin state of the CSS at the time instant of the second
(push) pulse.