Transition Probabilities for the5s′[12]1−3pTransitions of Ne I

Abstract

Transition probabilities for nine allowed transitions between the $5s^{\prime }{\left[\frac{1}{2}\right]}_1$ and $3p$ states of neon have been measured in side light emission from a discharge tube placed inside a He-Ne-laser radiation field. The laser was tunable at nine visible lines belonging to the $5s^{\prime }{\left[\frac{1}{2}\right]}_1-3p$ array. The gas mixture and the discharge current were adjusted so as to obtain a transparent plasma at the respective laser wavelength. Such a plasma is characterized by an absence of both resonance absorption and stimulated emission, creating a condition that $\frac{N_1}{N_2}=\frac{g_1}{g_2}$ between the upper- and the lower-energy levels of the laser transition. This condition immediately enables the intensity ratio of two transitions arising from two different energy levels to be reduced to the ratio of the transition probabilities. The relative $A$ values were put into an absolute scale using Bennett and Kindlmann's lifetime data on $3p$ levels. Nine independent measurements were made through the use of nine laser transitions. Excellent agreement was seen between these independent measurements. The estimated error in the relative measurements is 2%, and the best value of the absolute $A_{632.8}$ was found to be (0.339 ± 0.014) × ${10}^7$ ${\mathrm{s}}^{-1\mathrm{}}$ When compared with the data of Hansch et al. and Bychkova et al., who employed a similar method but only one laser transition at 632.8 nm, significant disagreement is seen. It was found that the self-absorption of $3p-3s$ lines is as large as 20%. Argon was added to reduce this effect to a negligible level. There is strong evidence that this effect was disregarded in other measurements, thereby resulting in the large disagreement with our data.