The Structure of Photoexcited Platinum Pop Measured with Microsecond Resolved XAFS

Abstract

We report a µsec resolved XAFS measurement of the excited triplet electronic state 3A2u (dσ* pσ) of Pt2(P2O5H2)4 4- in solution employing a new technique. The measurement utilizes a vertical flow of 10 m/s produced by a small nozzle, similiar to that of a dye laser. A line focused laser excites the molecules in the flow while a 10 µm vertically confined line of x-ray radiation probes the flow downstream of the laser. We find that the phosphor planes of the molecule in the excited state each move inward along the Pt-Pt axis by 0.26(08) Å, relative to its the center. Also, the platinum phosphorous bonds contract 0.050(11) Å. The optical transition promotes an electron from an anti-bonding orbital to a bonding orbital, and the observations indicate that this occupied bonding orbital strongly increases the overall structural bonding forces of the molecule.