Vacuum Ultraviolet Excited State Dynamics of the Smallest Ketone: Acetone

• Published in: The journal of physical chemistry letters Vol. 12; no. 35; pp. 8541 - 8547
• Main Authors: Forbes, Ruaridh, Neville, Simon P, Larsen, Martin A. B, Röder, Anja, Boguslavskiy, Andrey E, Lausten, Rune, Schuurman, Michael S, Stolow, Albert
• Format: Journal Article
• Language: English
• Published: American Chemical Society 09-09-2021
• Subjects: Physical Insights into Light Interacting with Matter
• ISSN: 1948-7185; 1948-7185
• DOI: 10.1021/acs.jpclett.1c02612

We combined tunable vacuum-ultraviolet time-resolved photoelectron spectroscopy (VUV-TRPES) with high-level quantum dynamics simulations to disentangle multistate Rydberg-valence dynamics in acetone. A femtosecond 8.09 eV pump pulse was tuned to the sharp origin of the A1(n3d yz ) band. The ensuing dynamics were tracked with a femtosecond 6.18 eV probe pulse, permitting TRPES of multiple excited Rydberg and valence states. Quantum dynamics simulations reveal coherent multistate Rydberg-valence dynamics, precluding simple kinetic modeling of the TRPES spectrum. Unambiguous assignment of all involved Rydberg states was enabled via the simulation of their photoelectron spectra. The A1(ππ*) state, although strongly participating, is likely undetectable with probe photon energies ≤8 eV and a key intermediate, the A2(nπ*) state, is detected here for the first time. Our dynamics modeling rationalizes the temporal behavior of all photoelectron transients, allowing us to propose a mechanism for VUV-excited dynamics in acetone which confers a key role to the A2(nπ*) state.