This study investigates the spectroscopy and dynamics of the hydrated electron at the water/air interface using time-resolved electronic sum-frequency generation (SFG) spectroscopy. The research focuses on the electronic spectrum and dynamics of the hydrated electron following photo-oxidation of the phenoxide anion. The spectral maximum of the hydrated electron at the interface matches that of bulk hydrated electrons, indicating that the electron's orbital density resides predominantly in the aqueous phase. However, the chemistry at the interface differs from that in bulk water, with the hydrated electron diffusing into the bulk and leaving the phenoxyl radical at the surface. The results resolve long-standing questions about the hydrated electron at the water/air interface and highlight its potential role in interfacial chemistry. The hydrated electron, e⁻(aq), is a fundamental species in radiation chemistry and has been studied extensively in solution. However, its behavior at the water/air interface remains less understood. The study uses SFG spectroscopy to measure the electronic spectrum and dynamics of the hydrated electron at the interface. The results show that the hydrated electron at the interface has a similar spectrum to bulk hydrated electrons, but its dynamics differ, with the electron diffusing into the bulk and leaving the phenoxyl radical at the surface. The study also shows that the hydrated electron at the interface is fully solvated, with only a small fraction of its electron density exposed to the vapor phase. This challenges previous interpretations suggesting a partially hydrated electron with most of its density protruding into the vapor phase. The study also explores the dynamics of the hydrated electron at the interface, showing that it diffuses into the bulk, which makes it insensitive to the second-order non-linear spectroscopic probe. The results suggest that the dynamics of the hydrated electron at the interface are different from those in the bulk, with the electron diffusing into the bulk and leaving the phenoxyl radical at the surface. The study also highlights the importance of the water/air interface in interfacial chemistry and suggests that the ultrafast radical separation dynamics may be common at many aqueous interfaces. The findings have implications for understanding chemical reactivity at the water/air interface and in atmospheric chemistry.This study investigates the spectroscopy and dynamics of the hydrated electron at the water/air interface using time-resolved electronic sum-frequency generation (SFG) spectroscopy. The research focuses on the electronic spectrum and dynamics of the hydrated electron following photo-oxidation of the phenoxide anion. The spectral maximum of the hydrated electron at the interface matches that of bulk hydrated electrons, indicating that the electron's orbital density resides predominantly in the aqueous phase. However, the chemistry at the interface differs from that in bulk water, with the hydrated electron diffusing into the bulk and leaving the phenoxyl radical at the surface. The results resolve long-standing questions about the hydrated electron at the water/air interface and highlight its potential role in interfacial chemistry. The hydrated electron, e⁻(aq), is a fundamental species in radiation chemistry and has been studied extensively in solution. However, its behavior at the water/air interface remains less understood. The study uses SFG spectroscopy to measure the electronic spectrum and dynamics of the hydrated electron at the interface. The results show that the hydrated electron at the interface has a similar spectrum to bulk hydrated electrons, but its dynamics differ, with the electron diffusing into the bulk and leaving the phenoxyl radical at the surface. The study also shows that the hydrated electron at the interface is fully solvated, with only a small fraction of its electron density exposed to the vapor phase. This challenges previous interpretations suggesting a partially hydrated electron with most of its density protruding into the vapor phase. The study also explores the dynamics of the hydrated electron at the interface, showing that it diffuses into the bulk, which makes it insensitive to the second-order non-linear spectroscopic probe. The results suggest that the dynamics of the hydrated electron at the interface are different from those in the bulk, with the electron diffusing into the bulk and leaving the phenoxyl radical at the surface. The study also highlights the importance of the water/air interface in interfacial chemistry and suggests that the ultrafast radical separation dynamics may be common at many aqueous interfaces. The findings have implications for understanding chemical reactivity at the water/air interface and in atmospheric chemistry.