Pressure broadening and shift rates for Ar (s-p) transitions observed in an Ar-He discharge

•Ar-He (s-p) pressure broadening and shift rates are measured in an RF discharge.•Temperature dependent broadening cross-sections agrees with Lindholm-Foley theory.•Helium induces a blue shift, while argon is red shifted.•An atmospheric pressure discharge would be sufficient for diode pumped rare gas laser.

The pressure broadening and shift rates have been measured for the 801.699 nm (s5→p8), 800.836 nm (s4→p6) and 795.036 nm (s3→p4) transitions in argon perturbed by 10-200 Torr of helium and argon at a temperature of 440±20K using a radio-frequency, capacitively coupled discharge. For a 10% Ar in He plasma the pressure broadening and shift rates were measured as 14.18±0.65 and 1.81±0.30MHz/Torr, 17.85±0.78 and 0.72±0.32MHz/Torr, and 16.59±1.22 and 2.94±0.48MHz/Torr for the 801.699 nm, 800.836 nm and 795.036  nm transitions, respectively. The influence of the slightly varying gas temperature on the broadening and shift rates is less than 1%. Stark broadening and shifting by electrons in the discharge are not measurable due to low electron densities and temperatures. Phase-changing collisional cross-sections in the literature decrease with temperature, in good agreement with the Lindholm-Foley T−0.2 trend based on the Lennard-Jones potential. Further investigation of the Ar⁎-Ar and Ar⁎-He interaction potentials is necessary to understand the behavior of the cross sections.