Excited-state structure by time-resolved X-ray diffraction

• Published in: Acta crystallographica. Section A, Foundations of crystallography Foundations of crystallography, 2002-03, Vol.58 (2), p.133-137
• Main Authors: Kim, Christopher D., Pillet, Sebastien, Wu, Guang, Fullagar, Wilfred K., Coppens, Philip
• Format: Article
• Language: English
• Subjects: Condensed matter: structure, mechanical and thermal properties; Exact sciences and technology; excited-state structure; Inorganic compounds; Metal complexes; Physics; Single-crystal and powder diffraction; Structure of solids and liquids; crystallography; Structure of specific crystalline solids; time-resolved X-ray diffraction; X-ray diffraction and scattering
• ISSN: 0108-7673; 1600-5724
• DOI: 10.1107/S0108767301017986

X‐ray crystallography has traditionally been limited to the study of the ground‐state structure of molecules and solids. Recent technical advances are removing this limitation as demonstrated here by a time‐resolved stroboscopic study of the photo‐induced 50 µs lifetime excited triplet state of the [Pt2(pop)4]4− ion [pop = pyrophosphate, (H2P2O5)2−], performed at helium temperatures with synchrotron radiation. The shortening of the Pt—Pt bond by 0.28 (9) Å upon excitation is compatible with the proposed mechanism involving promotion of a Pt—Pt antibonding dσ* electron to a weakly bonding p orbital. The contraction is accompanied by a 3° molecular rotation. The time‐resolved diffraction technique described here is applicable to reversible light‐driven processes in the crystalline solid state.