Energy trapping processes in aromatic crystals

Wolf, Hans Christoph

doi:10.1351/pac197127030439

Cited by 22 publications

(2 citation statements)

References 14 publications

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“…Acenaphthene was reported to emit light on periodic deformation, but the emission was erratic as a function of time rather than periodic, clearly indicating random small fracture events; moreover, its triboluminescence is quenched under 2-propanol and hexane 35 and thus must be dependent on a gas discharge. Only doped salts have been shown to generate triboluminescence by deformation alone: their defects migrate and excite luminescent centers. ,,− A similar mechanism in many organics would be consistent with the observed mobility and trapping of excitons in aromatics by impurities or other defects. − Such a mechanism would not be expected to correlate with crystal symmetry as is usually the case. We are convinced that at least an elastic deformation always occurs and is necessary for piezoelectric polarization but that deformation alone is not the source of the electronic excitation in triboluminescence except in the doped salts.…”

Section: Discussionmentioning

confidence: 93%

“…2,13,82-85 A similar mechanism in many organics would be consistent with the observed mobility and trapping of excitons in aromatics by impurities or other defects. [86][87][88] Such a mechanism would not be expected to correlate with crystal symmetry as is usually the case. We are convinced that at least an elastic deformation always occurs and is necessary for piezoelectric polarization but that deformation alone is not the source of the electronic excitation in triboluminescence except in the doped salts.…”

Section: Discussionmentioning

confidence: 99%

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Crystal Structure and Triboluminescence 2. 9-Anthracenecarboxylic Acid and Its Esters

et al. 1997

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Triboluminescence activity is usually assumed to be a consequence of crystal dissymmetry; however, the multitude of reports of centrosymmetric triboluminescent materials cast doubt on that assumption. We examine here the connection between triboluminescence and crystal symmetry without prejudice, by synthesizing 12 esters of 9-anthracenecarboxylic acid and correlating their triboluminescence activity and that of the acid with crystal structure, purity, and photoluminescence. In this series, a noncentrosymmetric crystal structure is necessary but not sufficient for triboluminescence in relatively pure materials; impurities are necessary for triboluminescence activity in all centrosymmetric and one noncentrosymmetric materials. Crystallization motif and other structure factors were only weakly correlated with triboluminescence. The results provide evidence in support of a charge separation and recombination mechanism for the excitation of the triboluminescence.Supporting Information Available: For 3-4 and 6-12, complete lists of atomic coordinates, bond lengths, bond angles, and anisotropic displacement coefficients (52 pages); for 2-4 and 6-12, correlation of crystal cell parameters with stacking motif (1 page); and observed and calculated structure factors (46 pages). Ordering information is given on the current masthead page. CM960438R

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Section: Discussionmentioning

confidence: 93%

Section: Discussionmentioning

confidence: 99%

Crystal Structure and Triboluminescence 2. 9-Anthracenecarboxylic Acid and Its Esters

et al. 1997

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Effets des pièges sur la fusion triplet–triplet dans les cristaux de naphtalètne

Bonno

Laporte

Rousset

1982

Physica Status Solidi (b)

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L'étude de 300 à 77 K des fluorescences retardées de polycristaux de naphtalène purs ou dopés à l'anthracène permet de préciser l'effet de l'introduction dans le cristal de petites quantités de cette impureté. Lorsque la température décroǐt, l'intensité des fluorescences retardées varie de façons très différentes pour le cristal pur et les cristaux mixtes. Ces comportements sont interprétés à partir de la présence d'un piège pour l'exciton triplet (ΔE = 1575 cm−1, τ = 3,6 × 10−2 s) liè à l'introduction de l'anthracène au sein du cristal. La concentration de ce piège varie comme celle de l'impureté.

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