Time-resolved photoelectron spectroscopy of a dinuclear Pt(II) complex: Tunneling autodetachment from both singlet and triplet excited states of a molecular dianion

Journal Article · Sun Feb 07 00:00:00 EST 2016 · Journal of Chemical Physics

DOI:https://doi.org/10.1063/1.4940795· OSTI ID:22493718

Winghart, Marc-Oliver; Unterreiner, Andreas-Neil ^[1]; Yang, Ji-Ping ^[1]; Vonderach, Matthias ^[2]; Huang, Dao-Ling; Wang, Lai-Sheng ^[3]; Kruppa, Sebastian; Riehn, Christoph ^[4]

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1. Institute of Physical Chemistry, Karlsruhe Institute of Technology, P.O. Box 6980, 76049 Karlsruhe (Germany)
2. Centre for Proteome Research, Institute of Integrative Biology, University of Liverpool, Liverpool L69 7ZB (United Kingdom)
3. Department of Chemistry, Brown University, Providence, Rhode Island 02912 (United States)
4. Fachbereich Chemie und Landesforschungszentrum OPTIMAS, Technische Universität Kaiserslautern, Erwin-Schrödinger-Str. 52–54, 67663 Kaiserslautern (Germany)

Time-resolved pump-probe photoelectron spectroscopy has been used to study the relaxation dynamics of gaseous [Pt{sub 2}(μ-P{sub 2}O{sub 5}H{sub 2}){sub 4} + 2H]{sup 2−} after population of its first singlet excited state by 388 nm femtosecond laser irradiation. In contrast to the fluorescence and phosphorescence observed in condensed phase, a significant fraction of the photoexcited isolated dianions decays by electron loss to form the corresponding monoanions. Our transient photoelectron data reveal an ultrafast decay of the initially excited singlet {sup 1}A{sub 2u} state and concomitant rise in population of the triplet {sup 3}A{sub 2u} state, via sub-picosecond intersystem crossing (ISC). We find that both of the electronically excited states are metastably bound behind a repulsive Coulomb barrier and can decay via delayed autodetachment to yield electrons with characteristic kinetic energies. While excited state tunneling detachment (ESETD) from the singlet {sup 1}A{sub 2u} state takes only a few picoseconds, ESETD from the triplet {sup 3}A{sub 2u} state is much slower and proceeds on a time scale of hundreds of nanoseconds. The ISC rate in the gas phase is significantly higher than in solution, which can be rationalized in terms of changes to the energy dissipation mechanism in the absence of solvent molecules. [Pt{sub 2}(μ-P{sub 2}O{sub 5}H{sub 2}){sub 4} + 2H]{sup 2−} is the first example of a photoexcited multianion for which ESETD has been observed following ISC.

• OSTI ID: 22493718
• Journal Information: Journal of Chemical Physics, Vol. 144, Issue 5; Other Information: (c) 2016 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA); ISSN 0021-9606
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
COULOMB FIELD
ELECTRON LOSS
ELECTRONS
ENERGY LOSSES
EXCITED STATES
FLUORESCENCE
KINETIC ENERGY
LASER RADIATION
MOLECULES
PHOSPHORESCENCE
PHOTOELECTRON SPECTROSCOPY
PLATINUM COMPLEXES
RELAXATION
SOLVENTS
TIME RESOLUTION
TRANSIENTS
TRIPLETS
TUNNEL EFFECT
YIELDS