New photocalorimetric references for UV excitation

A set of calorimetric references for excitation at λ = 266 nm in acetonitrile solutions is proposed. Theophylline and several purinic compounds (purine, 6-methylpurine, 6-methoxypurine, 6-chloropurine, and 6-aminopurine) were investigated using pulsed laser optoacoustic spectroscopy with resolution times between 150 ns and 1 μs and compared with 2-hydroxybenzophenone. At room temperature, all these compounds show no fluorescence, good stability and no photochemical processes as photodegradation or multiphotonic effects below fluences of 1000 J/m 2 .