Technique: Hole Burning Experiments |
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Dielectric (non-resonant) hole-burning modifies the dielectric relaxation behavior of a material by exposing it to a high sinusoidal electric field prior to recording the relaxation. Between this pump or burn process and probing the dieletric modulus, a waiting time can be varied in order to observe the persistance time of the modification [103]. |
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Schematic representation of a typical hole burning experiment. After a recovery time
required to restore equilibrium conditions, a large sine voltage (burn,
pump) is applied, a variable waiting time is included, and then the relaxation
is probed. The difference of the signals obtained with and without sine
voltage are analyzed as a function of burn frequency, burn voltage, and
waiting time. |
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Time dependent high electric fields dissipate energy in the material, resulting in an effect similar to heating. The interesting feature in these experiments is the spectrally selective character of the hole burning, which means that only time scales near the burn frequency are being modified while the other relaxation components remain unaffected. This possibility of modifying specific relaxation times is directly associated with dynamic heterogeneity in liquids and glasses [106]. Our hole-burning setup is designed to burn 'holes' into the dielectric function ε*(ω), but the effects are observed in terms of the modulus M(t) for times between 1 ms and 100 s. The difference of M(t) signals with and without burning display peaks whose position on the time scale depend on the burn frequency. Typical difference peak amplitudes are 3×10-3 relative to the original signal M(t) at time zero [91, 98, 112, 115, 135]. |
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Reference numbers refer to the list of publications |
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Experimental techniques:
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Selected projects:
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