Temperature dependent single molecule rotational dynamics in PMA

Adhikari, Subhasis; Selmke, Markus; Cichos, Frank

doi:10.1039/c0cp01959c

Cited by 36 publications

(67 citation statements)

References 45 publications

(65 reference statements)

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“…65,66 It has found use in interpreting neutron scattering experiments, 67,68 Kerr-effect spectroscopy in liquids, 69 studies of glass-forming liquids, 70 dielectric relaxation, [71][72][73][74][75] luminescence spectroscopy, 76,77 linear dichroism correlation spectroscopy, 78 lipid bilayer dynamics, 79 NMR spinlattice relaxation in a random Heisenberg chain, 80 light scattering, 74,75 ion conductivity measurements, 81 NMR studies of ion conduction, 82,83 photobleaching relaxation, 84 and various forms of structural relaxation. 85,86 It is not straightforward to relate the parameters R* and β to the dynamics.…”

Section: B Stretched-exponential Nmr Relaxation: R * and βmentioning

confidence: 99%

Methyl group rotation, 1H spin-lattice relaxation in an organic solid, and the analysis of nonexponential relaxation

Beckmann

Schneider

2012

The Journal of Chemical Physics

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We report 1 H spin-lattice relaxation measurements in polycrystalline 4,4 -dimethoxybiphenyl at temperatures between 80 and 300 K at NMR frequencies of ω 0 /2π = 8.50, 22.5, and 53.0 MHz. The data are interpreted in terms of the simplest possible Bloch-Wangsness-Redfield methyl group hopping model. Different solid states are observed at low temperatures. The 1 H spin-lattice relaxation is nonexponential at higher temperatures where a stretched-exponential function fits the data very well, but this approach is phenomenological and not amenable to theoretical interpretation. (We provide a brief literature review of the stretched-exponential function.) The Bloch-Wangsness-Redfield model applies only to the relaxation rate that characterizes the initial 1 H magnetization decay in a high-temperature nonexponential 1 H spin-lattice relaxation measurement. A detailed procedure for determining this initial relaxation rate is described since large systematic errors can result if this is not done carefully.

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Section: B Stretched-exponential Nmr Relaxation: R * and βmentioning

confidence: 99%

Methyl group rotation, 1H spin-lattice relaxation in an organic solid, and the analysis of nonexponential relaxation

Beckmann

Schneider

2012

The Journal of Chemical Physics

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“…While such experiments have shown potential in probing dynamic heterogeneity in glassforming systems including molecular (9-13) and polymeric glass formers (14)(15)(16)(17)(18), limitations related to characteristics of the single-molecule fluorescent probes have substantially hindered these experiments and interpretation thereof (8,19).…”

mentioning

confidence: 99%

Ideal probe single-molecule experiments reveal the intrinsic dynamic heterogeneity of a supercooled liquid

Paeng

Park

Hoang

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

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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, singlemolecule 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.espite decades of intensive study, a full theory of the glass transition is lacking; so too is a full understanding of the causal relationships between the unusual phenomena displayed by glass-forming liquids in the supercooled regime and the glass transition. One such phenomenon is the onset of nonexponential relaxations in the supercooled regime. Consistent with such relaxations, a variety of experiments have suggested the presence of dynamic heterogeneity, where-over a given time-molecular mobility in a given region may differ by orders of magnitude from that in another region, potentially just nanometers away (1, 2). While some experiments have sought to quantify the size of these regions, others have sought to quantify their persistence in time, as supercooled liquids are assumed to be ergodic, requiring that over long times, all dynamic environments are sampled (3-5). Precise description of dynamic heterogeneity in glass formers remains challenging due to the ensemble, subensemble, and/or time averaging inherent in most experimental techniques. However, such description remains of significant interest given the poorly understood causal relationship between dynamic heterogeneity and the glass transition as well as the need for experimental observations that may distinguish between various theories of the glass transition (6, 7).Typically, putative dynamic heterogeneity has been recognized in experiments through the shape of the ensemble relaxation, which is well described by a stretched exponential (exp[−(t/τ fit ) β ]) where the deviation of β below 1 describes the degree of stretching and has been interpreted as a barometer of dynamic heterogeneity. Multiple scenarios are consistent with an ensemble stretched exponential relaxation, and two limiting cases can be straightforwardly described: The ensemble stretched exponential emerges from (i) a superposition of exponentials with different relaxation times or (ii) identical stretched exponentials with the same relaxation time. The former limit describes a system with variation of time scales distributed in space but not time, while the latter represents the opposite extreme. The former case describes a system that is not ergodic over times acce...

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“…As it was shown before, single molecules in polymer matrices can rotate at temperatures higher than T g . This corresponds to our observations of DAE switching kinetics.…”

Section: Resultsmentioning

confidence: 99%

Fluorescent Diarylethene Photoswitches—A Universal Tool for Super‐Resolution Microscopy in Nanostructured Materials

Nevskyi

Sysoiev

Dreier

et al. 2018

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Super-resolution fluorescence microscopy allows for unprecedented in situ visualization of biological structures, but its application to materials science has so far been comparatively limited. One of the main reasons is the lack of powerful dyes that allow for labeling and photoswitching in materials science systems. In this study it is shown that appropriate substitution of diarylethenes bearing a fluorescent closed and dark open form paves the way for imaging nanostructured materials with three of the most popular super-resolution fluorescence microscopy methods that are based on different concepts to achieve imaging beyond the diffraction limit of light. The key to obtain optimal resolution lies in a proper control over the photochemistry of the photoswitches and its adaption to the system to be imaged. It is hoped that the present work will provide researchers with a guide to choose the best photoswitch derivative for super-resolution microscopy in materials science, just like the correct choice of a Swiss Army Knife's tool is essential to fulfill a given task.

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Temperature dependent single molecule rotational dynamics in PMA

Cited by 36 publications

References 45 publications

Methyl group rotation, 1H spin-lattice relaxation in an organic solid, and the analysis of nonexponential relaxation

Methyl group rotation, 1H spin-lattice relaxation in an organic solid, and the analysis of nonexponential relaxation

Ideal probe single-molecule experiments reveal the intrinsic dynamic heterogeneity of a supercooled liquid

Fluorescent Diarylethene Photoswitches—A Universal Tool for Super‐Resolution Microscopy in Nanostructured Materials

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