Variations

Key Features

Low sample volume: < 10 mL

Sensitive analysis: < 1 picomole

Moderate path length: e.g., 5 m

Compact size

Incredibly simple and robust alignment

Various wavelength ranges, including the entire mid-infrared range

Components

Hollow core fiber with reflective inner coating

Wedged optical windows (range of materials)

Swagelok style gas fittings

Compatible with 30 mm cage mount systems

Mounting holes for integration onto an optical bench or in a custom housing

Alignment

The relatively large fiber diameter (ID = 0.2-1.5 mm) and single pass configuration enables obtaining ‘first light” with minimal effort. In some cases, you can collimate your beam and mount your laser on one end and simply put your detector at the other end.

Versatile Systems

Gas cells kits can utilize a wide range of Guiding’s hollow core fiber optic waveguides. Options include different sample volumes, path lengths, and wavelength ranges.

Case Study: Measuring NO Gas Using a Gas Cell

I. Test Instrument Connection and Procedures

Procedures:

1. Install the 5.26 um laser and set it to collimated output.

2. Connect the other end of the 5-meter gas cell to the MCT detector.

3. Connect the detector and oscilloscope using a BNC-to-SMA cable.

Turn on the laser, adjust the current and temperature, and observe the second harmonic absorption spectrum of NO molecules on the oscilloscope.

II. Test Results and Analysis/Verification:

By adjusting the laser current and temperature, we scanned the laser wavelength across the absorption peak of NO molecules at around 5260 nm, and measured the second harmonic absorption spectrum as shown in the figure below.

To verify that the absorption is from NO molecules, we queried the HITRAN database for the following parameters.

We can see that the absorption peaks in the database perfectly match the peaks we measured on the oscilloscope. This verifies that the absorption spectrum shown on the oscilloscope is indeed the absorption of NO molecules.

FTIR Gas Cell

It is also a great solution for FTIR analysis. Standard configurations have excellent transmission from λ= 3 -12 µm (additional wavelength ranges available) with low sample volume requirements (V < 10 mL).

Species Concentration

2,3 Butanedione: 99.7 ppm

Acetaldehyde: 230.2 ppm

Acetone: 130.8 ppm

Methane: 259.3 ppm

Water: -38.8 ppm

Sulfur dioxide: 2.5 ppm

Trace Gas Analysis

Versions of our hollow fiber gas cells have been used for a range of trace gas applications.Typical concentration sensitivities are in the 100 ppb range. Considering the small sample volume, this can equate to picomole level sensitivity.

Isotope Analysis

Stable isotope analysis such as the ratio of `13C/12C, provide additional information for a range of applications from greenhouse gas attribution to plant microbe interactions. Laser spectroscopy is an excellent means to perform isotope analysis due to unambiguous absorption features from different isotopologues; however, reduced pressure (P ~ 0.01 to 0.1 Atm) is often needed to effectively separate the features by “narrowing” their widths. The Omega is designed to be operated at such pressures and due to small sample volume, can be operated with relatively small pumps.

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