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Fluorescence yields and molecular orientation of thin organic films: Vapor-Deposited Oligothiophenes α3T–α8T (1995)

Oelkrug, D. ; Egelhaaf, H. -J. ; Worrall, D. R. ; [et al.]

Springer

Journal of fluorescence 5 (1995), S. 165-170

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ISSN: 1573-4994

Keywords: Thin organic films ; vapor-deposited oligothiophenes ; quantum yields

Source: Springer Online Journal Archives 1860-2000

Topics: Physics

Notes: Abstract The fluorescence quantum yields of vapor-deposited (VD) films of α-oligothiophenes,nT, with ring numbers ofn=3–8 and layer thicknesses ofd=3–50 nm were determined at room temperature andT=77 K and compared to the yields of dilute solutions and small (5T)x clusters. The yields of highly oriented ultrathin films are of the order of ΦF=5*10−5-1*10−4. The yields increase strongly with the layer thickness and also upon cooling, but do not reach the values in dilute solution. The main nonradiative deactivation step S1 → T1 in solution was quantified by1O2 production, the yields of which systematically decrease withn from ΦF (3T) to 0.36 (6T), in contrast to the fluorescence yields, which increase from ΦF=0.01 (2T) to 0.40 (6T). In films or clusters the S1 → T1 deactivation step must be a very unimportant side reaction: neither1O2 nor any signal of triplet-triplet absorption could be positively identified.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF00727534

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Über geordnete Perowskite mit Kationenfehlstellen. XI. Das System Ba2Gd2/3□1/3U1-xWxO6 (1982)

Wischert, W. ; Oelkrug, D. ; Schittenhelm, H.-J. ; [et al.]

Weinheim : Wiley-Blackwell

Zeitschrift für anorganische Chemie 495 (1982), S. 219-231

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ISSN: 0044-2313

Keywords: Chemistry ; Inorganic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Description / Table of Contents: On Ordered Perovskites with Cationic Vacancies. XI. System Ba2Gd2/3□1/3U1-xWxO6The cation deficient polymorphic perovskites Ba2Gd2/3□1/3UO6 and Ba2Gd2/3□1/3WO6 form a continuous series of mixed crystals, which crystallize over a wide range (x = 0.1 up to 0.99) in a cubic 1:1 ordered perovskite lattice. According to the investigations of the vibrational spectra, the diffuse reflectance spectra, and the photoluminescence - opposite to isostructural perovskites without vacancies - different species of UO6 and WO6 octahedra are present. Numerous differences in properties - e. g. an orange emission colour in comparison with a green one by absence of vacancies - are based upon that.

Notes: Die beiden fehlstellenhaltigen, polymorphen Perowskite Ba2Gd2/3□1/3UO6 und Ba2Gd2/3□1/3WO6 bilden eine lückenlose Reihe von Mischkristallen, die in einem weiten Bereich (x = 0,1 bis 0,99) in einem kubischen 1:1 geordneten Perowskitgitter kristallisieren. Wie die Untersuchung der Schwingungsspektren, der diffusen Reflexionsspektren und der Photolumineszenz zeigen, liegen - im Gegensatz zu isostrukturellen fehlstellenfreien Perowskiten - mehrere Sorten an UO6- und WO6-Oktaedern vor. Hierauf sind zahlreiche Eigenschaftsunterschiede - z. B. eine orangefarbene Emission im Unterschied zu einer grünen bei Abwesenheit von Fehlstellen - zurückzuführen.

Additional Material: 4 Ill.