Abstract
Adsorption of dynamically diluted ammonia at
part-per-billion to low part-per-million concentrations
in dry nitrogen was studied with treated and non-treated
stainless steel and polymer test tubes. The treatments
included electropolishing and two types of coatings based
on amorphous silicon. Cavity ring-down spectroscopy with
an external cavity diode laser operating in the
near-infrared wavelength range was used to monitor the
adsorption process in real time in continuous-flow
conditions to obtain quantitative assessment of the
adsorptive properties of the studied surfaces. The
investigated polymers were all less adsorptive than any
of the treated or non-treated stainless steel surfaces.
Some of the commercial coatings reduced the adsorption
loss of stainless steel by a factor of ten or more.
Polyvinylidene fluoride was found to be superior (less
adsorption) to the four other studied polymer coatings.
The number of adsorbed ammonia molecules per surface area
obtained at different ammonia gas phase concentrations
was modeled with Langmuir and Freundlich isotherms. The
time behavior of the adsorption–desorption process
occurring in the time scale of seconds and minutes was
simulated with a simple kinetic model.
| Original language | English |
|---|---|
| Pages (from-to) | 185-196 |
| Journal | Applied Physics B: Lasers and Optics |
| Volume | 115 |
| Issue number | 2 |
| DOIs | |
| Publication status | Published - 2014 |
| MoE publication type | A1 Journal article-refereed |
Keywords
- physical chemistry
- laser technology
- quantum optics
- polymers
- coatings
- adsorption