Microsecond-resolved XAFS of the triplet excited state of Pt2(P2O5H2)4(4-)
Little is known about the excited-state structures of most inorganic compounds. Time-resolved resonance Raman and time-resolved infrared spectroscopies can provide only indirect structural information for short-lived excited species in solution at room temperature. Time-resolved X-ray diffraction has the potential to give more direct information, but no excited-state structures have yet been reported; picosecond gas-phase electron diffraction has been proposed recently, but not yet demonstrated. Here we report a technique that combines the X-ray absorption fine-structure (XAFS) method with rapid-flow laser spectroscopy to measure structural changes in a solution-phase excited-state transition-metal complex with microsecond resolution. We find that the triplet excited state of Pt2(P2O5H2)4(4-), with a lifetime of about 4 microseconds, undergoes a contraction in the Pt-Pt distance of 0.52 +/- 0.13 A relative to the ground state. We anticipate that time-resolved XAFS will have broad applications in chemistry and biology.
Department of Applied Physics, Cornell University, Ithaca, New York 14853.
D J
DJ
Thiel
P
P
Liviņs
E A
EA
Stern
A
A
Lewis
D015502:Absorptiometry, Photon / Q000379:methods; D011756:Diphosphates / Q000737:chemistry*; D008958:Models, Molecular; D008968:Molecular Conformation; D010984:Platinum / Q000737:chemistry*; D017671:Platinum Compounds
D011756:Diphosphates; D017671:Platinum Compounds; D010984:Platinum; C080017:tetrakis(pyrophosphito)diplatinate(II)