International Journal of Thermophysics

, Volume 34, Issue 8, pp 1661–1665

\(\text{ CO}_{2}\) Laser-Based Pulsed Photoacoustic Ammonia Detection

  • Arturo Vallespi
  • Verónica Slezak
  • Alejandro Peuriot
  • Guillermo Santiago
Article

DOI: 10.1007/s10765-012-1354-2

Cite this article as:
Vallespi, A., Slezak, V., Peuriot, A. et al. Int J Thermophys (2013) 34: 1661. doi:10.1007/s10765-012-1354-2

Abstract

Detecting ammonia traces is relevant in health, manufacturing, and security areas, among others. As ammonia presents a strong absorption band (the \(\nu _{2}\) mode) around 10 \(\upmu \)m, some of the physical properties which may influence its detection by means of pulsed photoacoustic (PA) spectroscopy with a TEA \(\text{ CO}_{2}\) laser have been studied. The characteristics of the ammonia molecule and the laser intensity may result in a nonlinear dependence of the PA signal amplitude on the laser fluence. Ammonia absorption can be described as a simple two-level system with power broadening. As \(\text{ NH}_{3}\) is a polar molecule, it strongly undergoes adsorption phenomena in contact with different surfaces. Therefore, physical adsorption–desorption at the cell’s wall is studied. A theoretical model, based on Langmuir’s assumptions, fits well to the experimental results with stainless steel. Related to these studies, measurements led to the conclusion that, at the used fluenced values, dissociation by multiphotonic absorption at the 10P(32) laser line may be discarded. A calibration of the system was performed, and a detection limit around 190 ppb (at 224 \(\text{ mJ}\cdot \text{ cm}^{-2}\)) was achieved.

Keywords

Adsorption Ammonia Photoacoustics 

Copyright information

© Springer Science+Business Media New York 2012

Authors and Affiliations

  • Arturo Vallespi
    • 1
  • Verónica Slezak
    • 1
  • Alejandro Peuriot
    • 1
  • Guillermo Santiago
    • 2
  1. 1.CEILAP-UNIDEF-CITEDEF, Juan Bautista de La Salle 4397 (B1603ALO)Villa Martelli, Buenos AiresArgentina
  2. 2.Laboratorio Láser, Facultad de IngenieríaUniversidad de Buenos AiresBuenos AiresArgentina

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