Structural and Thermal Characterisation of Nanofilms by Time-Resolved X-ray Scattering

Abstract

High time resolution in scattering analysis of thin films allows for determination of thermal conductivity by transient pump-probe detection of dissipation of laser-induced heating, TDXTS. We describe an approach that analyses the picosecond-resolved lattice parameter reaction of a gold transducer layer on pulsed laser heating to determine the thermal conductivity of layered structures below the transducer. A detailed modeling of the cooling kinetics by a Laplace-domain approach allows for discerning effects of conductivity and thermal interface resistance as well as basic depth information. The thermal expansion of the clamped gold film can be calibrated to absolute temperature change and effects of plastic deformation are discriminated. The method is demonstrated on two extreme examples of phononic barriers, isotopically modulated silicon multilayers with very small acoustic impedance mismatch and silicon-molybdenum multilayers, which show a high resistivity.

Low Efficiency of Laser Heating of Gold Particles at the Plasmon Resonance: An X-ray Calorimetry Study

“…This could indeed be the case for very small particles approaching the quantum size limit. Large particles nevertheless have earlier been investigated to show bulk-like behavior in thermal expansion and fluence-dependent lattice change . While both thermal lattice expansion and latent heat are not precisely linear in temperature, the combined caloric effect on lattice expansion is only deviating by a few percent from linearity.…”

In situstructural kinetics of picosecond laser-induced heating and fragmentation of colloidal gold spheres

“…Melting point depression is only expected to amount for about 10 K, 63 while the (initial) lattice expansion of gold nanoparticles is found not to deviate strongly from the bulk value. 64 It should be noted that an onset of melting removes the hottest particles from observation such that the apparent temperature is lower than the full ensemble average. This can explain the reduction of the slope above 80 J m À2 .…”

Transient heating of Pd nanoparticles studied by x-ray diffraction with time of arrival photon detection

“…In the case of the study of supported nanoparticles, using a laser pump-x-ray probe scheme allows the probe of inter-atomic distances and with that addresses directly the elastic properties of the material. 4 …”