Shedding light on the structure of a photoinduced transient excimer by time-resolved diffraction

• Published in: Physical review letters 2005-05, Vol.94 (19), p.193003.1-193003.4, Article 193003
• Main Authors: VORONTSOV, Ivan I, KOVALEVSKY, Andrey Yu, CHEN, Yu-Sheng, GRABER, Tim, GEMBICKY, Milan, NOVOZHILOVA, Irina V, OMARY, Mohammad A, COPPENS, Philip
• Format: Article
• Language: English
• Subjects: Atomic and molecular physics; Exact sciences and technology; Fluorescence and phosphorescence spectra; Fluorescence and phosphorescence; radiationless transitions, quenching (intersystem crossing, internal conversion); General molecular conformation and symmetry; stereochemistry; Molecular properties and interactions with photons; Multiphoton ionization and excitation to highly excited states (e.g., rydberg states); Multiphoton ionization and excitation to highly excited states (eg, Rydberg states); Photon interactions with molecules; Physics; Properties of molecules and molecular ions
• ISSN: 0031-9007; 1079-7114
• DOI: 10.1103/physrevlett.94.193003

Time-resolved single-crystal diffraction performed with synchrotron radiation shows that the 53(1) micros phosphorescent state, generated in the crystalline phase of trimeric {[3,5-(CF3)(2)Pyrazolate]Cu}(3) molecules by exposure to 355 nm of light at 17 K, is due to the formation of an excimer rather than the shortening of the intramolecular Cu...Cu distances within the trimeric units, or the formation of a continuous chain of interacting molecules. One of the intermolecular Cu...Cu distances contracts by 0.56 Angstroms from 4.018(1) to 3.46(1) Angstroms;, whereas the interplanar spacing of the trimers is reduced by 0.65 Angstroms; from 3.952(1) to 3.33(1) Angstroms. Density-functional theory calculations support the formation of a Cu...Cu bond through the intermetallic transfer of a Cu 3d electron to a molecular orbital with a large 4p contribution on the reacting Cu atoms.