Picosecond calorimetry: Time-resolved x-ray diffraction studies of liquid CH2Cl2
2006 (English)In: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 124, no 23, 234507- p.Article in journal (Refereed) Published
Liquid phase time-resolved x-ray diffraction with 100 ps resolution has recently emerged as a powerful technique for probing the structural dynamics of transient photochemical species in solution. It is intrinsic to the method, however, that a structural signal is observed not only from the photochemical of interest but also from the embedding solvent matrix. To experimentally characterize the x-ray diffraction signal deriving from the solvent alone we performed time-resolved diffraction studies of a pure liquid sample over a time domain from -250 ps to 2.5 mu s. Multiphoton excitation was used to rapidly heat liquid CH2Cl2 using UV pulses of 100 fs duration. A significant x-ray diffraction signal is visible prior to the onset of thermal expansion, which characterizes a highly compressed superheated liquid. Liquid CH2Cl2 then expands as a shock wave propagates through the sample and the temporal dependence of this phenomenon is in good agreement with theory. An unexpectedly slow initial release of energy into the liquid as heat is observed from multiphoton excited CH2Cl2, revealing the presence of a metastable state of multiphoton excited CH2Cl2.
Place, publisher, year, edition, pages
2006. Vol. 124, no 23, 234507- p.
Computer and Information Science
IdentifiersURN: urn:nbn:se:kth:diva-75449DOI: 10.1063/1.2205365ISI: 000238436000032OAI: oai:DiVA.org:kth-75449DiVA: diva2:490493
QC 201202282012-02-052012-02-052012-02-28Bibliographically approved