The performance of quantitative low-temperature fluorometry by the technique of matrix Isolation Is reported. Matrix-isolated samples of polycyclic aromatic hydrocarbons (PAH) are prepared by mixing the PAH vapors effusing from a Knudsen cell with a large excess of nitrogen gas; the gaseous mixture Is then deposited onto an optical window at ~15 K. Detection limits for PAH in nitrogen matrices are on the order of 11 g. Quantitative working curves for PAH are linear over five decades or more in concentration. Linear working curves can readily be obtained for Individual PAH In mixtures of Isomeric compounds. The use of matrix-isolation fluorometry for identification and quantitation of PAH in complex samples derived from coal liquids Is demonstrated.

The matrix isolation (MI) Fourier transform Infrared and

1769boundary and depend on its structure (we neglect any proton transfer in the interior of the micelles having low dielectric constant, since ten units lowering of it than water was observed to lower the complexation significantly under the present experimental conditions*). The ASo values given in Table I varied in the order SDS < water < T X 100 < (CTAB + TX 100) < (SDS + T X 100) < CTAB < PEG. The environment for the reaction was then most ordered in SDS, much less in CTAB, and the least in PEG.The free energy changes for the individual additives followed the order PEG < T X 100 < water < SDS < CTAB. Appearance of PEG and CTAB at the two extreme ends and that of SDS just before CTAB advocated the significant roles of charge and other specific effeds1i4 than the water structure. The effects of micellar charge, the environmental dielectric, changed pK, water structure, and the partition of the species between the micelle and the bulk would all work in conjunction, whose dissection at present would not be meaningful.In conclusion we make a statement that inspite of accepting the error related possibility of a linear enthalpy-entropy correlation,21 we observed such a nice extrathermodynamic compensation for the present proton transfer process in the presence and absence of different additives including the hydroxylic nonaqueous solvents reported earlier.4 Publication costs assisted by the National Science Foundation and the Nectric Power Research InstituteQuasilinear "Shpol'skii" fluorescence spectra of polycyclic aromatic hydrocarbons can be observed by matrix isolation, employing an n-alkane as the matrix, if the vapor-deposited sample is annealed at elevated temperature (ca. 140 K) prior to observation of the spectrum at low temperature (16 K). Quasilinear spectra obtained by matrix isolation compare closely to those obtained by conventional frozen-solution techniques in Shpol'skii matrices. Temperature variations of vapor-deposited samples after deposition but before spectral measurements reveal the presence of matrix "memory effects".

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