An automated differential titration photocalorimeter (ADTPC) has been designed for investigating
photoinduced processes. This instrument provides means to record thermal and spectral (absorbance)
changes in a calorimetric cell. Metrological characteristics of the described ADTPC are detection limit,
0.001 J with a reproducibility of 0.0002 J or better; short-duration noise level, ±5 rel. units; long-duration
noise level, ±29 rel. units. ADTPC has been certified against the heats of mixing of solvents and the heat of
neutralization reaction between tris(hydroxymethyl)aminomethane and HCl. The photocalorimetric unit of
the device has additionally been certified against the heat of photolysis of K3[Fe(C2O4)3] and the heat of
isomerization of azobenzene in heptane. Within the claimed errors, the heats measured with ADTPC are in
agreement with the values recommended for the above systems.
