Measurement of pressure shift and broadening for Ar and Kr 4s[3/2]2 → 4p[5/2]3 transition in rare gases using diode-laser spectroscopy

Kinetics of Metastable Argon Optical Excitation and Gain in Ar/He Microplasmas

“…The good stability of the laser wavelength setting is demonstrated by the mole fraction variations at constant pressure in Figure . The measured blue-shifts in He are roughly 4 to 6 MHz/Torr, , roughly matching the 2 GHz line width of the Ti:S laser over this range of pressure variation. The blue-shift effect may contribute to the slight reduction in optically pumped gain observed at 500 Torr.…”

“…The 1s 5 → 2p 9 absorption line is well-known to be blue-shifted with increasing pressure by collisions with He. 19,37,38 During the pressure variation experiments, the wavelength of the 1s 5 → 2p 9 pump laser was held constant, peaked up on the transition at 300 Torr. The good stability of the laser wavelength setting is demonstrated by the mole fraction variations at constant pressure in Figure 6.…”

“…The apparent red-shift in the peak transition frequency with increasing pressure is probably an artifact of the collisional blue-shift of the absorption line with respect to the fixed wavelength of the pump laser. The 1s 5 → 2p 9 absorption line is well-known to be blue-shifted with increasing pressure by collisions with He. ,, During the pressure variation experiments, the wavelength of the 1s 5 → 2p 9 pump laser was held constant, peaked up on the transition at 300 Torr. The good stability of the laser wavelength setting is demonstrated by the mole fraction variations at constant pressure in Figure .…”

Pressure broadening of 772.376 and 772.421 nm argon lines and kinetics of argon metastable atoms

“…Moreover, often in thermal plasmas the gas temperature was not homogeneous and well defined 29,28,32 , introducing extra uncertainty on measured coefficients. But after the event of the spectrally narrow band tunable diode lasers and their use in absorption spectroscopy (TDLAS) technique, the correction of the apparatus function width was no more needed and the pressure induced widths and shifts of many argon lines ending on the four lowest excited states of argon (two metastable Ar*(1s3) and Ar*(1s5) and two resonant Ar*(1s2) and Ar*(1s4) 33 ), which are always highly populated in argon plasmas, have been measured by several groups 34,35,36,37,38,39,40 41 . However, none of the above cited publications provided the pressure broadening coefficients of the 772.38 nm (1s5-2p7) and 772.42 nm (1s3-2p2) lines, which are studied in this work.…”