Abstract
Abstract Laser flux dependences of multiphoton ionization (MPI) of benzene and benzene-d6 were measured both in gaseous phase and in molecular beam with ArF (193 nm) and KrF (248 nm) excimer lasers. Several different behaviors were observed at 193 nm in comparison with the MPI at 248 nm : An unexpected enhancement of the MPI efficiency at high laser power involving three-photon ionization process, an unusually small ratio of (C4D4+• + C4D3+ + C4D2+•)/C3D3+ (1—2) compared with the ratio expected from the breakdown diagram (3—5) and a very large isotope effect on the relative intensity of C4H4+•/C4D4+• (0.65). To interpret these phenomena, we propose a new MPI and fragmentation scheme at 193 nm involving two-photon ionization of benzene via the intermediate triplet state(s), possibly T1 and/or T2, and one-photon ionization of C3H3 (C3D3) radical formed via two-photon dissociation of benzene. The observed laser flux dependences of MPI efficiency and intensities of several major ions were analyzed with the rate equation model derived from the proposed scheme. As a result, more than 80% of the observed C3D3+ ions were found to be produced from the C3D3 radical. The analyses also suggest the existence of at least two isomeric species for the C3D3 (C3H3) radical and the C4D4+• (C4H4+•) ions, respectively.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
