Department of Mechanical Engineering, Carnegie Mellon University, 5000 Forbes Ave., Pittsburgh, Pennsylvania 15213, United States.
Center for Nanoscale Materials, Argonne National Laboratory, 9700 S Cass Ave., Lemont, Illinois 60439, United States.
Nano Lett. 2023 May 10;23(9):3687-3693. doi: 10.1021/acs.nanolett.2c04627. Epub 2023 Apr 24.
Infrared-pump, electronic-probe (IPEP) spectroscopy is used to measure heat flow into and out of CdSe nanocrystals suspended in an organic solvent, where the surface ligands are initially excited with an infrared pump pulse. Subsequently, the heat is transferred from the excited ligands to the nanocrystals and in parallel to the solvent. Parallel heat transfer in opposite directions uniquely enables us to differentiate the thermal conductances at the nanocrystal/ligand and ligand/solvent interfaces. Using a novel solution to the heat diffusion equation, we fit the IPEP data to find that the nanocrystal/ligand conductances range from 88 to 135 MW m K and are approximately 1 order of magnitude higher than the ligand/solvent conductances, which range from 7 to 26 MW m K. Transient nonequilibrium molecular dynamics (MD) simulations of nanocrystal suspensions agree with IPEP data and show that ligands bound to the nanocrystal by bidentate bonds have more than twice the per-ligand conductance as those bound by monodentate bonds.
红外泵浦、电子探针（IPEP）光谱用于测量悬浮在有机溶剂中的 CdSe 纳米晶体的热流进出情况，其中表面配体最初通过红外泵浦脉冲激发。随后，热量从激发的配体传递到纳米晶体，并与溶剂平行传递。相反方向的平行热传递使我们能够独特地区分纳米晶/配体和配体/溶剂界面的热导。通过对热扩散方程的一种新解法，我们拟合 IPEP 数据发现，纳米晶/配体的电导范围在 88 到 135 MW m K 之间，大约比配体/溶剂的电导高 1 个数量级，后者的范围在 7 到 26 MW m K 之间。纳米晶体悬浮液的非平衡分子动力学（MD）模拟与 IPEP 数据一致，并表明通过双齿键结合到纳米晶体上的配体的每个配体电导是通过单齿键结合的配体的两倍多。
