Atmos Gas Cells


The standard long pathlength gas cell range is now the new Atmos™ series of metal-bodied fixed-pathlength gas cells.

They have been optimised using the latest optical modelling tools to give maximum signal-to-noise.

Wide pathlength range (2.5 to 20m) and vacuum to 125 psi operation.

Up to 200 °C with heating jacket and Ni-coated aluminium body.

Gold mirrors (protected) and Viton or Kalrez 'O' ring seals.

CaF2 or ZnSe windows, purgeable transfer optics box and leverlock series baseplate mounting.

Optional features include: vacuum / gas inlet & outlet taps, pressure gauge, desiccant storage caps and purge bellows.

Pathlength (m)2.55.01020
Base pathlength (mm)104139250455
Number of passes24364044
Volume (L)0.270.632.123.68

The Atmos™ range of cells are heatable to 200 °C with the addition of a heating jacket and temperature controller.

Why Atmos™?

  • Optimized optical path for unmatched signal-to-noise
  • Low cell volume for fast gas exchange
  • Ni-coated Al cell bodies for improved thermal transfer from heating jackets. Also holds higher gas pressure than glass.
  • Inert stainless-steel mirror substrates and avoidance of glues to prevent outgassing
  • 125 psi (8.6 bar) maximum cell pressure
  • Retrofittable heating jacket option for up to 200 °C

Which pathlength should I choose?

The absorbance of a gas depends on the distance travelled by the IR light beam through the gas sample. The relationship between absorbance, A, concentration, C, and pathlength, L, is given by Beer’s Law:

A = -log10 (I/I0) = a.C.L

Atmospheric concentrations of gases are usually expressed in C.L units of ppm.m – the number of molecules that would be encountered by the infrared beam across a 1.0 m path.

A gas at 0.1 ppm atmospheric concentration will absorb as much IR light over a pathlength of 100 m as would the same gas at 1 ppm over 10 meters or at 10 ppm over 1 meter.

Accordingly, the pathlength of cell should be chosen to give absorbance values within the spectrometer’s linear range for a given concentration. The following table may be taken as a guide:


Gas nameformulav (cm-1)ppm.mabsorbance
Carbon dioxideCO223601000.4
Carbon monoxideCO21701000.04
C2 to C6 n-alkanes29601000.1
Nitrogen dioxideNO216301000.15
Nitric oxideNO19001000.015
Sulfur dioxideSO213701000.09
Hydrogen sulfideH2S130010000.002
Hydrogen chlorideHCl29401000.04
Vinyl chlorideCH2CHCl950, 9001000.06
TolueneC6H5CH3730, 6901000.1
Carbonyl sulfideCOS20701000.4
Nitrous oxideN2O22351000.15
Sulfur hexafluorideSF6950100.4


Contact us

If you have any questions or require further information, please do not hesitate to email us at [email protected], call us on +44 (0)113 286 4536 or submit a contact form.