Experimental investigation of the dependences of the collision broadening and shift of the emission line of a mercury laser on He and Ne pressures

An experimental investigation was made of the impact (collision) broadening and shift of a mercury laser emission line representing the 6p'³P⁰₂→7s³S₁ (λ= 1.53μ) transition as a function of helium and neon pressures. The boradening of the mercury line varied at a rate of 16 MHz/mm Hg with the helium pressure and at a rate of 10.5 MHz/mm Hg with the neon pressure. Direct measurements indicated that the line was shifted in the direction of the violet side of the spectrum. The rate of shift with the helium pressure was 1.8 MHz/mm Hg and that with the neon pressure was 1.2 MHz/mm Hg. A comparison of the Hg-He and Hg-Ne interactions indicated that in both cases this interaction was the same and was described by the Lennard–Jones potential. Simultaneous measurements of the broadening and shift gave the values of the phenomenological constants C₆ and C₁₂, whose orders of magnitude were in agreement with the impact (collision) theory. An estimate was obtained of the lifetime of the 6p'³P⁰₂ level, which was ~2x10^–7 sec.