Picosecond spectroscopy fluids

Kenney-Wallace GA, Jonah CD. (1982) Picosecond spectroscopy and solvation clusters. The dynamics of localizing electrons in polar fluids. J Phys Chem 86 2572-2586. 

Deactivation of 2-naphthylamine singlet state by pyridines in enhanced by dipole moment and the ability to form hydrogen bonds. Picosecond laser spectroscopy shows charge transfer from the excited amine. The fluorescence of 2-iV,A -dimethylaminopyridine induced by p-nitroaniline is also caused by exciplex formation. The latter enhances triplet population of p-nitroaniline. The quenching of the fluoresence of carbazole and some derivatives by trichloroacetic acid and related compounds in fluid solutions has been studied by Johnson.A charge-transfer interaction is involved and the basicity of carbazole and derivatives determined. Charge transfer is also involved by quenching of carbazole by halocarbons. The A -isopropylcarbazole-dimethylterephthalate exciplex has been observed in PMMA films.Photoinduced electron-transfer in the p-phenylenediamine-paraquat complex yields the paraquat cation. ... 

Fig. 2. Spectroscopy of electrons in fluids. Ensemble shows absorption maxima and coefficients in n-alcohols at picosecond (A ) and nanosecond (A) times, diols (B), amines (C), ethers (D), alkanes ( ), and color center (F). The absorption (F ) and stimulated (Fg) emission in KBr color center laser are also shown.

In fluid solvents at room temperature, spectral relaxation is usually comjdete prior to emission and occurs within abont 10 ps. This process is too rapid to be resolved with the usual instrumentation for TD or FD fluorescence. However, advances in laser technology and methods for ultrafast spectroscopy have resulted in an increasing interest in picosecond and femtosecond solvent dynaaiics. Becmise of the rapid timescale, the data on solvent dynamics are usually obtained using flurvescence upconversion. Hiis method is described in Section 4.7.C. lypical data are... 

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