title: Ideal probe single-molecule experiments reveal the intrinsic dynamic heterogeneity of a supercooled liquid.
abstract: The concept of dynamic heterogeneity and the picture of the supercooled liquid as a mosaic of environments with distinct dynamics that interchange in time have been invoked to explain the nonexponential relaxations measured in these systems. The spatial extent and temporal persistence of these regions of distinct dynamics have remained challenging to identify. Here, single-molecule fluorescence measurements using a probe similar in size and mobility to the host o-terphenyl unambiguously reveal exponential relaxations distributed in time and space and directly demonstrate ergodicity of the system down to the glass transition temperature. In the temperature range probed, at least 200 times the structural relaxation time of the host is required to recover ensemble-averaged relaxation at every spatial region in the system.
authors.affiliation: Department of Chemistry, Columbia University, New York, NY 10027; and Department of Chemistry, Sungkyunkwan University, Suwon 440-746, Republic of Korea.
authors.forename: Keewook
authors.initials: K
authors.lastname: Paeng
authors.affiliation: Department of Chemistry, Columbia University, New York, NY 10027; and.
authors.forename: Heungman
authors.initials: H
authors.lastname: Park
authors.affiliation: Department of Chemistry, Columbia University, New York, NY 10027; and.
authors.forename: Dat Tien
authors.initials: DT
authors.lastname: Hoang
authors.affiliation: Department of Chemistry, Columbia University, New York, NY 10027; and kaufman@chem.columbia.edu.
authors.forename: Laura J
authors.initials: LJ
authors.lastname: Kaufman
keywords: dynamic heterogeneity; ergodicity; fluorescence; single molecule; supercooled liquid
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