Dresden 2014 – wissenschaftliches Programm

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 37: Poster Session 2

CPP 37.9: Poster

Mittwoch, 2. April 2014, 15:00–19:00, P3

Relaxation Processes Interpreted as Low-Pass Filters — •Lothar Kador — University of Bayreuth, Institute of Physics and BIMF, 95440 Bayreuth

Many systems in physics perform relaxation processes upon external stimulation. Examples are glasses investigated with dielectric spectroscopy and fluorescing or phosphorescing chromophore molecules after absorbing appropriate optical frequencies. When the stimulation is modulated, relaxing systems behave like electronic low-pass filters: Low modulation frequencies are transmitted without attenuation, signals of high frequencies are integrated and experience a phase shift. If the relaxation is single-exponentially, there is full equivalence to a simple RC low pass; more complicated relaxation laws correspond to low-pass filters of higher order. Measurements of the relaxation behavior in the frequency domain and the corresponding filtering behavior are interpreted in terms of the Cole-Cole or polar plot. Special situations arise, when the system responds non-linearly to the external stimulation.