8 ITMP3 / 8éme conférence internationale de photoacoustique et photothermique
J. Phys. IV France 04 (1994) C7-491-C7-494
CO-laser photoacoustic spectroscopy on dimerization of fatty acid, moleculesR. Kästle and M.W. Sigrist
ETH Zurich, Institute of Quantum Electronics, 8093 Zurich, Switzerland
Absorption spectra of fatty-acid molecules with carbon number below five were recorded as a function of temperature and partial pressure in the 1560-1950 cm-l wavelength range using photoacoustic spectroscopy with a CO laser as radiation source. A special Helmholtz PA cell providing good temperature uniformity and stability was developed and used to study flowing gaseous mixtures at varying temperatures. Dimerization enthalpies ΔH for acetic (ΔH=60.8 +/- 3.5 kJ/mole), propionic (ΔH=62.4+/-4.0kJ/mole), acrylic (ΔH=61.0+/-3.5kJ/mole) and butyric (ΔH=58.7+/-1.0kJ/mole) acid agree well with values obtained by other methods.
© EDP Sciences 1994