The UV-VIS absorption cross sections of the α-dicarbonyl compounds:: Pyruvic acid, biacetyl and glyoxal

The UV-VIS absorption cross sections of the alpha -dicarbonyl compounds, pyruvic acid and biacetyl (both at 298 K) and of glyoxal (at 295 K), were measured using a diode array detector. In general, the current data for biacetyl and glyoxal are in good agreement with earlier determinations. In the latter case, small deviations from Beer-Lambert law were observed even at pure compound's pressures below 1 Torr. This behavior was not detected in glyoxal-air mixtures at pressures up to 700 Torr. Comparison of the room temperature absorption spectrum of pyruvic acid, determined for the first time in this work, with data obtained at higher temperature reveals that at the lower temperature this spectrum is considerably shifted to the UV. (C) 2001 Published by Elsevier Science B.V.