| Autor: |
Varghese S; Catalan Institute of Nanoscience and Nanotechnology (ICN2), BIST & CSIC, Campus UAB, Bellaterra (Barcelona) 08193, Spain., Mehew JD; Catalan Institute of Nanoscience and Nanotechnology (ICN2), BIST & CSIC, Campus UAB, Bellaterra (Barcelona) 08193, Spain., Block A; Catalan Institute of Nanoscience and Nanotechnology (ICN2), BIST & CSIC, Campus UAB, Bellaterra (Barcelona) 08193, Spain., Reig DS; Catalan Institute of Nanoscience and Nanotechnology (ICN2), BIST & CSIC, Campus UAB, Bellaterra (Barcelona) 08193, Spain., Woźniak P; ICFO-Institut de Ciencies Fotoniques, The Barcelona Institute of Science and Technology, 08860 Castelldefels, Barcelona, Spain., Farris R; Catalan Institute of Nanoscience and Nanotechnology (ICN2), BIST & CSIC, Campus UAB, Bellaterra (Barcelona) 08193, Spain., Zanolli Z; Chemistry Department and ETSF, Debye Institute for Nanomaterials Science, Utrecht University, Utrecht, The Netherlands., Ordejón P; Catalan Institute of Nanoscience and Nanotechnology (ICN2), BIST & CSIC, Campus UAB, Bellaterra (Barcelona) 08193, Spain., Verstraete MJ; Nanomat, Q-Mat, CESAM, and European Theoretical Spectroscopy Facility, Université de Liège, B-4000 Liège, Belgium., van Hulst NF; ICFO-Institut de Ciencies Fotoniques, The Barcelona Institute of Science and Technology, 08860 Castelldefels, Barcelona, Spain., Tielrooij KJ; Catalan Institute of Nanoscience and Nanotechnology (ICN2), BIST & CSIC, Campus UAB, Bellaterra (Barcelona) 08193, Spain. |
| Abstrakt: |
Diffusion is one of the most ubiquitous transport phenomena in nature. Experimentally, it can be tracked by following point spreading in space and time. Here, we introduce a spatiotemporal pump-probe microscopy technique that exploits the residual spatial temperature profile obtained through the transient reflectivity when probe pulses arrive before pump pulses. This corresponds to an effective pump-probe time delay of 13 ns, determined by the repetition rate of our laser system (76 MHz). This pre-time-zero technique enables probing the diffusion of long-lived excitations created by previous pump pulses with nanometer accuracy and is particularly powerful for following in-plane heat diffusion in thin films. The particular advantage of this technique is that it enables quantifying thermal transport without requiring any material input parameters or strong heating. We demonstrate the direct determination of the thermal diffusivities of films with a thickness of around 15 nm, consisting of the layered materials MoSe 2 (0.18 cm 2 /s), WSe 2 (0.20 cm 2 /s), MoS 2 (0.35 cm 2 /s), and WS 2 (0.59 cm 2 /s). This technique paves the way for observing nanoscale thermal transport phenomena and tracking diffusion of a broad range of species. |
