BUNSEKI KAGAKU Vol. 34 (1985) Fig. 1 Diagram of anti-stokes delayed fluorescence (ASDF) by the mixed triplet mechanism (the numbered transitions refer to the equations)

BUNSEKI KAGAKU Vol. 34 (1985) Fig. 2 Absorption (A), fluorescence (B), and phosphorescence (77 K) (C) spectra of phenanthrene in ethanol (uncorrected) Fig. 3 Jablonski diagram of ASDF by the mixed triplet systems

Table 2 ASDF properties for proflavine systems and eosin systems

BUNSEKI KAGAKU Vol. 34 (1985) Fig. 4 Comparison between proflavine system and eosin system Fig. 5 ASDF spectra of proflavine mixed system (A) and analytical curve of perylene (B) at 20 Ž (uncorrected) Fig. 6 ASDF spectra of proflavine mixed system (A) and analytical curves of triphenylene and phenanthrene (B) at 25 Ž (uncorrected)

Fig. 7 ASDF spectra of eosin mixed system (A) and analytical curves of perylene and triphenylene (B) at 25 Ž (uncorrected) Fig. 8 ASDF spectra of eosin mixed system (A) and analytical curves of triphenylene and naphthalene (B) at 25 Ž (uncorrected)

BUNSEKI KAGAKU Vol. 34 (1985) prompt fluorescence of acceptor [A] and originates from the excited singlet state S1, but a much longer lifetime and a emission wavelength shorter than that of the exciting light. This paper describes the ASDF [D] in ethanol solution. The spectra of absorption, 1) C. A. Parker, C. G. Hatchard : Proc. Chem. Soc., 1962, 386. 2) C. A. Parker, C. G. Hatchard, T. A. Joyce : Analyst (London), 90, 1 (1965). 3) H. Lund, J. Bjerrum Ber., 64, 210 (1931) ; H. Lund : J. Am. Chem. Soc., 74, 3188 (1952). 4) E. J. Bowen : Trans Faraday Soc., 50, 97 (1954). 5) C. A. Parker, C. G. Hatchard, T. A. Joyce : Nature, 27, 1282 (1955). 6) C. A. Parker : "Photoluminescence of Solutions", p. 315 (1968), (Elsevier, New York, Amsterdam). 7) C. A. Parker, W. T. Rees : Analyst (London), 85, 587 (1960). Anti-Stokes delayed fluorometric analysis of polycyclic aromatic hydrocarbons using proflavine and/or eosin as donor. Tadao YAMAGUCHI, Keizo HIRAKI, Kiyotoshi MORISHIGE, Tsunenobu SHIGE- MATSU, and Yasuharu NISHIKAWA (Faculty of Science and Technology, Kinki University, 3-4-1, Kowakae, Higashiosaka-shi, Osaka 577) The phenomenon of anti-stokes delayed fluorescence (ASDF) is now being exploited to produce analytical techniques of great specificity and selectivity without prior separation. It has the same wavelength as properties for the mixed system of some aromatic hydrocarbons as acceptor-proflavine and/or eosin as donor fluorescence and low temperature phosphorescence (LTP) at 77 K were measured. Singlet and triplet energy levels were deduced from the values of these spectral data. From the experimental results, the fol- lowing mechanism was proposed to explain ASDF phenomenon : (2): 3D {A plet-to-singlet energy transfer can occur provided that the triplet level of the acceptor [3A] lies close to [3D 3A:low transfer efficiency (LTE) type] or below [3D>3A : high transfer efficiency (HTE) type] that of the donor [3D]. In theoretically, if the acceptor triplet lies well above that of the donor, energy trans- fer to an appreciable extent is impossible [3D<3A : no transfer efficiency (NTE) type]. However, the process of the mixed triplet interaction can give rise to the excited singlet of the acceptor molecules when the sum of the triplet energy is greater than the excited singlet energy of the acceptor. Accordingly, NTE type-mixed system can also shows ASDF emission, although the encounter efficiency and emission efficiency are very low. On the basis of these ASDF properties, the following analytical methods of some aromatic hydrocarbons in ethanol solution were designed. (1) : Proflavine [D] (Ex. 465 nm)-perylene (ASDF : 438 nm), phenanthrene (349,366 nm), anthracene (400 nm) [A] mixed system. (2) : Proflavine [D] (Ex. 465 nm)- anthracene (400 nm), phenanthrene (349, 366 nm), triphenylene (354, 364 nm) [A] mixed system. (3) : Eosin [D] (Ex. 533 nm)-perylene (438, 466 nm), an- thracene (400 nm), triphenylene (354, 364 nm) [A] mixed system. (4) : Eosin [D] (Ex. 533 nm)-anthra- cene (400 nm), phenanthrene (349, 366 nm), naphthalene (324 nm) [A] mixed system. (5) : Eosin [D] (Ex. 533 nm)-anthracene (400 nm), triphenylene (354, 372 nm), naphthalene (324 nm) [A] mixed system. By using this method, 10-8 mol dm -3 of perylene and anthracene [HTE type] could be determined. In the case of LTE type and/or NTE type mixed system, 10-6 mol dm-3 of aromatic hydrocarbons such as naphthalene, phenanthrene, and triphenylene could be determined without interferences from each others. (Received May 27, 1985) Keyword phrases anti-stokes delayed fluorometric analysis of polycyclic aromatic hydrocarbons ; energy transfer from proflavine and/or eosin as donor to polycyclic aromatic hydrocarbons as acceptor.