Experimental Study of Non-Exponential Relaxation Processes in Random Organic Solids

Ranko Richert, A. Elschner, H. Bassler

Research output: Contribution to journalArticle

27 Citations (Scopus)

Abstract

We compare experimental results on (i) thermally induced merocyanine → spiropyran transformation of a dye molecule substitutionally doped into a polymer (PMMA) matrix; (ii) growth of a photophysical hole burnt into the inhomogeneously broadened S1 ← S0 0–0 absorption band of tetracenedoped into a MTHF ḡlass at low temperature; (iii) diffusion-controlled trapping of a triplet excitationin a benzophenone glass. A common feature is the time-dependence of the observed, i.e. averaged event rate. While in each case a stretched exponential {exp[–(t/to)α]} provides a reasonably good fit to experimental data if restricted to a limited time domain, analysis of the short time behavior i dicates its failure for modelling the cases (i) and (ii). Instead, it isshown thatin these cases the concept of uncoupled parallel relaxations whose rate controlling parameter, an a tivation energy of atunnelling matrix element, is subject to a Gaussian distribution provides an appropriate description. Comparison with results of case (iii) demonstrates the possibility of distinguishing between parallel and serial relaxation mechanisms if experimental data span a sufficiently large time interval.

Original languageEnglish (US)
Pages (from-to)63-75
Number of pages13
JournalZeitschrift fur Physikalische Chemie
Volume149
Issue number1
DOIs
StatePublished - 1986
Externally publishedYes

Fingerprint

organic solids
Time domain analysis
Gaussian distribution
Relaxation processes
Polymethyl Methacrylate
Polymer matrix
Absorption spectra
Coloring Agents
Glass
time domain analysis
Molecules
matrices
normal density functions
time dependence
dyes
trapping
intervals
absorption spectra
Temperature
glass

Keywords

  • Disorder
  • Hole burning
  • Photochemistry
  • Spectroscopy

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry

Cite this

Experimental Study of Non-Exponential Relaxation Processes in Random Organic Solids. / Richert, Ranko; Elschner, A.; Bassler, H.

In: Zeitschrift fur Physikalische Chemie, Vol. 149, No. 1, 1986, p. 63-75.

Research output: Contribution to journalArticle

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AB - We compare experimental results on (i) thermally induced merocyanine → spiropyran transformation of a dye molecule substitutionally doped into a polymer (PMMA) matrix; (ii) growth of a photophysical hole burnt into the inhomogeneously broadened S1 ← S0 0–0 absorption band of tetracenedoped into a MTHF ḡlass at low temperature; (iii) diffusion-controlled trapping of a triplet excitationin a benzophenone glass. A common feature is the time-dependence of the observed, i.e. averaged event rate. While in each case a stretched exponential {exp[–(t/to)α]} provides a reasonably good fit to experimental data if restricted to a limited time domain, analysis of the short time behavior i dicates its failure for modelling the cases (i) and (ii). Instead, it isshown thatin these cases the concept of uncoupled parallel relaxations whose rate controlling parameter, an a tivation energy of atunnelling matrix element, is subject to a Gaussian distribution provides an appropriate description. Comparison with results of case (iii) demonstrates the possibility of distinguishing between parallel and serial relaxation mechanisms if experimental data span a sufficiently large time interval.

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