A METHOD OF CALIBRATION OF THE FORMIC-ACID MONOMER CONCENTRATION IN THE GAS-PHASE

Pyrolysis of t-butyl formate, (CH3)(3)C-O-CHO, has been carried out in a carrier gas stream of Ar or N-2 in a temperature range of 200-400 d egrees C. Between 200 and 300 degrees C, the pyrolysis yielded an equi molar mixture of HCOOH and (CH3)(2)C = CH2. The results have been used as a calibration method for determining the concentration of the gas- phase HCOOH monomer without interference from the formation of the for mic acid dimer. Using this technique, the gas-phase infrared absorptio n cross-section of HCOOH at 1105 cm(-1) (peak to valley) for the resol ution of 0.5 cm(-1) has been determined to be 6.76 x 10(-19) cm(2) mol ecule(-1).