Find in Library
Search millions of books, articles, and more
Indexed Open Access Databases
Investigation of adsorption and desorption behavior of small-volume cylinders and its relevance for atmospheric trace gas analysis
oleh: E. Satar, E. Satar, P. Nyfeler, P. Nyfeler, B. Bereiter, B. Bereiter, B. Bereiter, C. Pascale, B. Niederhauser, M. Leuenberger, M. Leuenberger
| Format: | Article |
|---|---|
| Diterbitkan: | Copernicus Publications 2020-01-01 |
Deskripsi
<p>Atmospheric trace gas measurements of greenhouse gases are critical in their precision and accuracy. In the past 5 years, atmospheric measurement and gas metrology communities have turned their attention to possible surface effects due to pressure and temperature variations during a standard cylinder's lifetime. This study concentrates on this issue by introducing newly built small-volume aluminum and steel cylinders which enable the investigation of trace gases and their affinity for adsorption and desorption on various surfaces over a set of temperature and pressure ranges. The presented experiments are designed to test the filling pressure dependencies up to 30 bar and temperature dependencies from <span class="inline-formula">−10</span> <span class="inline-formula"><sup>∘</sup></span>C up to 180 <span class="inline-formula"><sup>∘</sup></span>C for these prototype cylinders. We present measurements of <span class="inline-formula">CO<sub>2</sub></span>, <span class="inline-formula">CH<sub>4</sub></span>, CO and <span class="inline-formula">H<sub>2</sub>O</span> using a cavity ring-down spectroscopy analyzer under these conditions. Moreover, we investigated <span class="inline-formula">CO<sub>2</sub></span> amount fractions using a novel quantum cascade laser spectrometer system enabling measurements at pressures as a low as 5 mbar. This extensive dataset revealed that for absolute pressures down to 150 mbar the enhancement in the amount fraction of <span class="inline-formula">CO<sub>2</sub></span> relative to its initial value (at 1200 mbar absolute) is limited to 0.12 <span class="inline-formula">µ</span>mol mol<span class="inline-formula"><sup>−1</sup></span> for the prototype aluminum cylinder. Up to 80 <span class="inline-formula"><sup>∘</sup></span>C, the aluminum cylinder showed superior results and less response to varying temperature compared to the steel cylinder. For <span class="inline-formula">CO<sub>2</sub></span>, these changes were insignificant at 80 <span class="inline-formula"><sup>∘</sup></span>C for the aluminum cylinder, whereas a 0.11 <span class="inline-formula">µ</span>mol mol<span class="inline-formula"><sup>−1</sup></span> enhancement for the steel cylinder was observed. High-temperature experiments showed that for both cylinders irreversible temperature effects occur especially above 130 <span class="inline-formula"><sup>∘</sup></span>C.</p>