Ultrafast changes of molecular crystal structure induced by dipole solvation

• Published in: Physical review letters Vol. 98; no. 24; p. 248301
• Main Authors: Braun, M, Korff Schmising, C v, Kiel, M, Zhavoronkov, N, Dreyer, J, Bargheer, M, Elsaesser, T, Root, C, Schrader, T E, Gilch, P, Zinth, W, Woerner, M
• Format: Journal Article
• Language: English
• Published: United States 15-06-2007
• Subjects: CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; CRYSTAL STRUCTURE; Crystallization; DIFFUSE SCATTERING; DIPOLE MOMENTS; DIPOLES; Models, Chemical; Models, Molecular; MOLECULAR CRYSTALS; MOLECULAR STRUCTURE; Nitriles - chemistry; Solutions - chemistry; SOLVATION; X-RAY DIFFRACTION
• ISSN: 0031-9007; 1079-7114
• DOI: 10.1103/physrevlett.98.248301

Femtosecond photoexcitation of organic chromophores in a molecular crystal induces strong changes of the electronic dipole moment via intramolecular charge transfer as is evident from transient vibrational spectra. The structural response of the crystal to the dipole change is mapped directly for the first time by ultrafast x-ray diffraction or diffuse scattering. Changes of diffracted and transmitted x-ray intensity demonstrate an angular rearrangement of molecules around excited dipoles following the 10 ps kinetics of charge transfer and leaving lattice plane spacings unchanged. Transient x-ray scattering is governed by solvation, masking changes of the chromophore molecular structure.