  We present frequency-matched strobo-spectroscopy (FMSS) of charge migration
(CM) in bromobutadiyne, simulated with time-dependent density-functional
theory. CM+FMSS is a pump-probe scheme that uses a frequency-matched
HHG-driving laser as an independent probe step following the creation of a
localized hole on the bromine atom that induces CM dynamics. We show that the
delay-dependent harmonic yield tracks the phase of the CM dynamics through its
sensitivity to the amount of electron density on the bromine end of the
molecule. FMSS takes advantage of the intrinsic attosecond time resolution of
the HHG process, in which different harmonics are emitted at different times
and thus probe different locations of the electron hole. Finally, we show that
the CM-induced modulation of the HHG signal is dominated by the recombination
step of the HHG process, with negligible contribution from the ionization step.
