Bulletin of the American Physical Society
55th Annual Meeting of the APS Division of Atomic, Molecular and Optical Physics
Monday–Friday, June 3–7, 2024; Fort Worth, Texas
Session J08: Photon Induced Processes
2:00 PM–3:48 PM,
Wednesday, June 5, 2024
Room: 203B
Chair: Robert Lucchese, Lawrence Berkeley National Laboratory
Abstract: J08.00001 : Dissociation dynamics in the 3-body breakups of methanol upon valence photo double ionization*
2:00 PM–2:12 PM
Presenter:
Sarvesh Kumar
(Lawrence Berkeley National Laboratory)
Authors:
Sarvesh Kumar
(Lawrence Berkeley National Laboratory)
Moniruzzaman Shaikh
(Lawrence Berkeley National Laboratory)
Wael Iskander
(Lawrence Berkeley National Laboratory)
Richard Thurston
(Lawrence Berkeley National Laboratory)
Muhammad A Fareed
(Lawrence Berkeley National Laboratory)
Ryan Enoki
(Department of Physics, University of Nevada)
Chandan Bagdia
(J.R. Macdonald Laboratory, Physics, Kansas State University)
Naoki Iwamoto
(J.R. Macdonald Laboratory, Physics, Kansas State University)
Travis Severt
(J.R. Macdonald Laboratory, Physics, Kansas State University)
Joshua B Williams
(Department of Physics, University of Nevada)
Itzik Ben-Itzhak
(J.R. Macdonald Laboratory, Physics, Kansas State University)
D. S Slaughter
(Lawrence Berkeley National Laboratory)
Thorsten Weber
(Lawrence Berkeley National Laboratory)
Collaboration:
Authors Thank DOE national facility LBNL - ALS (Advanced Light Source) for 2- Bunch mode photon beam. ALS operators and Beamline scientists for support during the beamtime.
1Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA-94720, USA
2Department of Physics, University of Nevada, Reno, NV-89557, USA
3J.R. Macdonald Laboratory, Department of Physics, Kansas State University, Manhattan, NS-66506, USA
We investigated the valence photo double ionization (54eV) of single methanol molecules, which represent the simplest hydrocarbon with a hydroxyl and methyl group, hence can be considered methyl substituted water, using the COLTRIMS (COLd Target Recoil Ion Momentum Spectroscopy) technique. We were able to detect the momenta of two ejected electrons and nascent photo-fragments in coincidence. We focused on two competing 3-body fragmentation channels resulting in
(a) CH3OD+ hv (54 eV) -> (CH3OD)*2+ + 2e- -> CH2+ + OD+ + H + 2e-
(b) CH3OD+ hv (54 eV) ->(CH3OD)*2+ + 2e- -> CH2+ + OD + H+ + 2e-
Electron transfer has been reported to contribute to the photodissociation via spin orbit coupling (SOC) [1] , which we recently found to contribute to the photo dissociation of deuterated water molecules. We derived the electronic energy sharing, the electron-ion energy sharing, as well as the fragment pair momentum sharing distributions.
From these observables we concluded that both reactions are initiated on the same manifold of dication states, but that channel (a) is almost solely driven by direct double ionization and results in an instant 3-body breakup. On the other hand, reaction channel (b) shows a contribution from both, direct double ionization and autoionization, which mainly initiates a sequential breakup into with a subsequent electron transfer from the hydroxyl group to the proton.
From Momentum sharing maps it is clearly visible that for reaction (a) H/OD+ are highly correlated and are dominant in comparison to reaction (b)
Investigations of the relative fragment emission angles and recoil frame photoelectron angular distributions as well as a native frame analysis are underway to further track down the role of SOC in the charge transfer process.
References:
[1] W. Iskander et.al. J. Chem. Phys. 159, 094301 (2023).
*This research is supported by Department of Energy under Contract No. DEAC02-05CH11231 (LBNL) and No. DE-FG02-86ER13491 (KSU) as well as the National Sciences Foundation under Award No. NSF-1807017 and NSF-2208017 (UNR).
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