300 attosecond response of acetylene in two-photon ionization/dissociation processes

By performing delay scans of two replicas of a few-pulse attosecond pulse train (APT), we investigated two-photon ionization/dissociation processes of C 2 H 2 . The correlation time of the C + yield is determined to be 300 as, which is, to the best of our knowledge, the shortest correlation time ever obtained in the delay-scan measurement of two APTs. We also extracted the contribution of the resonant excitation from the ground state to a specific excited state of C 2 H 2 + leading to C–C bond breaking by performing Fourier analyses of the yield and angular distribution of the C H + fragment ions, which are also generated within 300 as.