EUV-driven femtosecond dynamics in ethylene

We studied ion fragment yields from EUV-pump NIR-probe experiments performed on ethylene molecules (C₂H₄). Through study of the ion yields as a function of pump-probe delay we resolve molecular dynamics on the excited electronic states of the ion. The breakup channel yielding CH⁺ and CH⁺₃ indicated photo-isomerization to the ethylidene configuration (HC-CH₃)⁺ on an ultrafast timescale. This configuration is predicted to be a transient configuration for electronic relaxation. We observed this channel, and found that it takes the excited cation (C₂H⁺₄)* 50±25 fs to reach the ethylidene configuration. The transient ion yield of C ₂H²⁺₄ at zero delay (in combination with independent synchrotron experiments) indicates other ultra-fast dynamics in short-lived intermediate states are present.