J. Phys. IV France
Volume 125, June 2005
Page(s) 885 - 888

J. Phys. IV France 125 (2005) 885-888

DOI: 10.1051/jp4:2005125205

A photoacoustic spectrometer for trace gas detection

E.M. Telles1, 2, E. Bezerra1 and A. Scalabrin3

1  Unilaser Indústria e Comércio Ltda., 13087-602, Campinas, Brazil
2  Universidade Metodista de Piracicaba, UNIMEP, 13400-911, Piracicaba, Brazil
3  Universidade Estadual de Campinas, UNICAMP, 13083-970, Brazil

A high-resolution external laser photoacoustic spectrometer has been developed for trace gas detection with absorption transitions in coincidence with CO2 laser emission lines (9,2-10,9 $\mu$m: 920-1086 cm-1). The CO2 laser operates in 90 CW lines with power of up to 15 W. A PC-controlled step motor can tune the laser lines. The resonance frequency of first longitudinal mode of the photoacoustic cell is at 1600 Hz. The cell Q-factor and cell constant are measured close to 50 and 28 mVcmW-1, respectively. The spectrometer has been tested in preliminary studies to analyze the absorption transitions of ozone (O3). The ethylene (C2H4) from papaya fruit is also investigated using N2 as carrier gas at a constant flow rate.

© EDP Sciences 2005