Direct excitation by a surface sliding discharge is applied for the fi
rst time to an HF laser. The laser operates at atmospheric pressure wi
th a gas mixture of He/SF6/C3H8. Details are presented on the efficien
cy of energy transfer, the dependence of laser performance on input en
ergy deposition, circuit parameters and gas mixture. The F atom produc
tion rate is estimated from the linear dependence of the specific outp
ut energy on the electric charge passed through the discharge. Output
energies of 135 mJ were obtained at 1.2% efficiency from a small activ
e discharge of 10 cm(3) volume and 38 cm length. These values compare
favourably with the values reported for similar laser systems, while t
he maximum values of specific input and output energy extraction obtai
ned, of 1700 and 15 J/l respectively, are among the highest reported f
or non-chain-reaction type gas mixtures. These results demonstrate tha
t the sliding discharge, although simple in design, is an efficient sc
heme for developing gas discharge lasers.