Rami Arieli: "The Laser Adventure" Chapter 6.1.9 Chemical Laser, page 1a
The Material in a Chemical Laser
Most chemical lasers are based on Hydrogen halides.

HF
The most well known member of this family is Hydrogen Fluoride (HF).
The emitted radiation is in the Infra-Red (IR), with a few lines in the spectrum range: 2.6 - 3.0 [mm].
DF
When Hydrogen is replaced by its heavier isotope - Deuterium, another member of the family: Deuterium Fluoride (DF) is created and emits in the spectrum range: 3.5 - 4.2 [mm].

Other halides such as Hydrogen Chloride (HCl) and Hydrogen Bromide (HBr) have demonstrated lasing in the lab, but are not common.

Because Fluorine and Hydrogen are very reactive gasses:

Hydrocarbons are used as a Hydrogen source, and

Fluorine compounds such as SF6 or NF3 are used as a source for Fluorine.

 Fluorine extraction is done by electrical discharge which separates the SF6 molecule into Fluorine and Sulfur.

In commercial chemical lasers, Oxygen is added to the reaction chamber, to react with the Sulfur to create SO2 molecules.

Helium gas is added as a dilution gas, and sometimes other gasses as well.

The total pressure inside a chemical laser is low (a few torr).