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HL: Fachverband Halbleiterphysik

HL 23: Ultra-fast phenomena

HL 23.1: Vortrag

Dienstag, 17. März 2020, 09:30–09:45, POT 112

Atomic disorder in electroninc materials revealed by decoherence — •Samuel Palato¹, Hélène Seiler¹, Patanjali Kambhampati², Parmeet Nijjar³, and Oleg Prezhdo³ — ¹Frits-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, 14169 Berlin — ²Department of Chemistry, McGill University, 801 rue Sherbrooke O., Montréal, Qc, Canada H3A 0B8 — ³Department of Chemistry, University of Southern California, Los Angeles, California 90089

Disorder in electronic materials is a challenge for both experimental studies and theoretical description. Coherent dynamics provide a sensitive spectroscopic probe of electronic disorder. We exploit recent advances in multidimensional spectroscopy to study coherent dynamics in the model system of CdSe nanocrystal quantum dot (QD). Coherence mapping in both amplitude and phase reveals the nature of the coherent dynamics as vibrational or electronic. According to the standard model for the electronic structure of semiconductor QDs, decoherence is dominated by inhomogeneity in the sizes of the nanocrystals. Predictons from this model are inconsistent with the observation. Instead, we show decoherence arises naturally when accounting for the individual atoms by performing ab initio molecular dynamics of a single QD. Accounting for atomic positions results in a complicated electronic manifold. This atomistic disorder is intrinsic to the QD, and is expected to be a general phenomenon in nanostructures.