8th International Topical Meeting on Photoacoustic and Photothermal Phenomena
8 ITMP³ / 8éme conférence internationale de photoacoustique et photothermique

J. Phys. IV France 04 (1994) C7-487-C7-490
DOI: 10.1051/jp4:19947114

New approach in determining absorption coefficients of strongly absorbing liquids : optothermal studies on sunflower oil, oleic acid (and its chloroform solutions) at 3.39 microns

D. Bicanic¹, M. Chirtoc², I. Chirtoc², B. van Veldhuizen³, J.P. Favier¹, P. Helander⁴, J. Harryvan⁵, J. Cozijnsen⁶ and M. Lubbers<sup>7

1</sup>  Laser Photoacoustic Laboratory, Department of Agricultural Engineering and Physics, Agricultural University, Bomenweg 4, 6703 HD Wageningen, The Netherlands
²  Institute for Isotopes and Molecular Technology, P.O. Box 700, 3400 Cluj-Napoca, Romania
³  Department of Organic Chemistry, Agricultural University, Dreyenplein 8, 6703 HB Wageningen, The Netherlands
⁴  AB Varilab, Fullerstavägen 32, 14144 Huddinge, Sweden
⁵  Department of Human Nutrition, Biotechnion, Agricultural University, Bomenweg 2, 6703 HD Wageningen, The Netherlands
⁶  Department of Food Science, Agricultural University, Biotechnion, Bomenweg 2, 6703 HD Wageningen, The Netherlands
⁷  Department of Soil Science and Geology, Agricultural University, Duivendaal 10, 6701 AR Wageningen, The Netherlands

Abstract
Large values (nearly 3000 cm^-1) of absorption coefficients β (unaccessible by conventional spectrometric methods), were measured for pure monounsaturated oleic acid (C18 : l) at 3.39 µm (C-H stretch vibration) using He-Ne laser in combination with a novel, compact optothermal sensor. Failure (except in a low concentration range) of C-H stretch vibration to follow Lambert-Beer's law was observed for solutions of C18 : 1 in chloroform. At 3.39 µm minimum detectable concentration of C18 : 1 in chloroform is 0.35 %.

© EDP Sciences 1994