C. Gooijer et al. / Spectrochimica Acta Part A 54 (1998) 1443–1449
1449
that are incompatible with the crystalline (n-
Acknowledgements
alkane) host matrix. In a simplified explanation
part of them occupy positional sites in the solid
matrix exhibiting quasi-lines, while the other part
are isolated molecules present in intercrystalline
amorphous positions, thus giving rise to broad
bands. The ratio of both fractions is strongly
influenced by the matrix choice. A well known
example of a type B molecule is acenaphthene,
whose Sphol’skii spectra have been thoroughly
studied [17]. Thus under the assumption that CPP
Gerard J. Stroomberg (Institute of Environmen-
tal Studies, Vrije Universiteit, Amsterdam, The
Netherlands) for carrying out reversed-phase chro-
matography and financial support from the Basque
Government (Beca para Formacion de Investi-
gadores (M.S.)) are gratefully acknowledged.
References
(
1) behaves as a type B molecule, the results
[
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rate, fraction 2 does not contain any ‘regular’ type
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[
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Hence, the lines observed at 378.0 and 379.6
nm in Fig. 2(C) have to be ascribed to CPP (1)
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(
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2
represent 0–0 transitions from two sites. This is in
accordance with the type B character of CPP (1).
In comparison with the fluorescence spectra
recorded for fractions 1 and 3 the line intensities
are weak, despite the fact that CPP (1) strongly
dominates (Fig. 1(A)). These results are not to-
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8
9.
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[
1
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yield (FF 0.003) for S -fluorescence reported [9].
2
Finally, the observation that the 378.0 and 379.6
nm lines are rather sharp is in agreement with
literature data. Because of the relatively long
emission lifetime ~ ꢀ3 ns [9], spectral lifetime
broadening effects, which are usually important
for emission from higher excited states, are negli-
gible for CPP (1).
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(
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[
[
In summary, our results substantiate the previ-
ously reported data concerning the occurrence of
anomalous S -state emission in the case of CPP
2
[17] J.W. Hofstraat, I.L. Freriks, M.E.J. de Vreeze, C. Gooi-
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(
1) [9].
.