Pressure broadening and shift rates for Ar (s–p) transitions observed in an Ar–He discharge. (August 2016)

• Record Type: Journal Article
• Authors: Eshel, Ben; Rice, Christopher A.; Perram, Glen P.
• Is Part Of: Journal of quantitative spectroscopy & radiative transfer. Volume 179(2016)
• Page Start: 40
• Page End: 50
• Publication Date: 2016-08
• Subjects: Laser -- Spectroscopy -- Plasma -- Radio-frequency discharges -- Argon -- Helium; Spectrum analysis -- Periodicals; Radiation -- Periodicals; Analyse spectrale -- Périodiques; Rayonnement -- Périodiques; Radiation; Spectrum analysis; Periodicals; 543.0858
• DOI: 10.1016/j.jqsrt.2016.03.006
• Languages: English
• ISSNs: 0022-4073

Abstract

Abstract: The pressure broadening and shift rates have been measured for the 801.699 nm ( s 5 → p 8 ), 800.836 nm ( s 4 → p 6 ) and 795.036 nm ( s 3 → p 4 ) transitions in argon perturbed by 10–200 Torr of helium and argon at a temperature of 440 ± 20 K 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 ± 0.30 MHz / Torr, 17.85 ± 0.78 and 0.72 ± 0.32 MHz / Torr, and 16.59 ± 1.22 and 2.94 ± 0.48 MHz / 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. Abstract : Highlights: 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.