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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