Non-toxic, water-soluble photocalorimetric reference compounds for UV and visible excitation

A set of non-toxic, water-soluble photocalorimetric reference compounds has been characterized. These compounds are brilliant blue G, brilliant black BN, new coccine, indigo carmine, and tartratine. Neutral aqueous solutions of all compounds are photochemically stable under UV-visible excitation (la mbda > 300 nm). None of these dyes are fluorescent or show optical transien ts detectable by laser flash photolysis on the nano- to microsecond time sc ale. The relationship between the amplitude of the photoacoustic signal and the laser fluence is linear up to at least 350 J/m(2). The fraction of abs orbed energy delivered to the medium as heat within the integration time of the instrument (alpha) is equal to 1 for all of the samples, within the ex perimental error let (+/- 0.05), With the exception of tartrazine, no photo induced structural volume changes were detected for any of the dyes. (C) 19 99 Elsevier Science B.V. All rights reserved.