Picosecond calorimetry: Time-resolved x-ray diffraction studies of liquid CH₂Cl₂

TY - JOUR

T1 - Picosecond calorimetry

T2 - Time-resolved x-ray diffraction studies of liquid CH2Cl2

AU - Georgiou, Panayiotis

AU - Vincent, Jonathan

AU - Andersson, Magnus

AU - Wöhri, Annemarie B.

AU - Gourdon, Pontus Emanuel

AU - Poulsen, Jens

AU - Davidsson, Jan

AU - Neutze, Richard

PY - 2006/6/21

Y1 - 2006/6/21

N2 - 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 μs. Multiphoton excitation was used to rapidly heat liquid C H2 Cl2 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 C H2 Cl2 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 C H2 Cl2, revealing the presence of a metastable state of multiphoton excited C H2 Cl2.

AB - 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 μs. Multiphoton excitation was used to rapidly heat liquid C H2 Cl2 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 C H2 Cl2 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 C H2 Cl2, revealing the presence of a metastable state of multiphoton excited C H2 Cl2.

U2 - 10.1063/1.2205365

DO - 10.1063/1.2205365

M3 - Journal article

C2 - 16821929

AN - SCOPUS:33745304378

SN - 0021-9606

VL - 124

JO - The Journal of Chemical Physics

JF - The Journal of Chemical Physics

IS - 23

M1 - 234507

ER -