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72 G a s , C h e m i c a l , a n d F r e e - E l e c t r o n L a s e r s Chemical Lasers 73

3.5 Other Chemical Laser Concepts

3.5.1 DF-CO Transfer Devices
2
DF-CO transfer devices are another chemical alternative associated
2
with DF devices. A DF laser can relatively easily be converted to
CO lasing on the 10.6-µm transition by the addition of CO to the
2
2
conventional devices and appropriate changes to resonator optics.
This conversion is possible because of a relatively efficient near-
resonant vibrational energy transfer between the two molecules via
the reaction:

DF(v) + CO (000) → DF(v – 1) + CO (001) (3.33)
2 2
Both CW flowing and pulsed devices have been demonstrated using
this approach.

Other Hydrogen Halide Devices
It is also possible to construct other halogen halide chemical lasers.
However, bond energies are such that there is not a simple analog to
HF and DF cold reaction devices. Instead, one must also rely on the
hot reaction; in practice, this forces one to rely primarily on chain
reaction type devices. Table 3.4 summarizes the pertinent bond
energies. Note that the H bond is stronger than either the HBr or
2
HCl bonds but weaker than the HF bond. However, it is still the
case that cycling chain reactions are exothermal for both bromine
and chlorine systems. In addition, HI in place of H has been used
2
to produce HCl lasers, though these have never been scaled as
favorably as HF and DF devices. 5

Molecule kJ/mol
F 2 156.9
Cl 242.6
2
Br 193.9
2
H 2 436.0
HF 568.6
HBr 365.7
HCl 431.6
HI 298.7
Table 3.4 Bond
Energies 18