Lifetimes and oscillator strength trends for the 4s2ndD2series of Ga i

Theoretical transition probabilities for kf-nd and mp-nd transitions in Ga(k=4–6, Ga i (k=4–6, m=4–7, and n=4–8) are reported together with lifetimes for the first five members of the 4$s^2$nd ${}_{}{}^2{}_{}{}^{}D$ series. Mixing with 4s4$p^2$ ${}_{}{}^2{}_{}{}^{}D$ is found to be very important. The sensitivity of the nd ${}_{}{}^2{}_{}{}^{}D$ lifetimes to the position of this perturber is discussed, together with the oscillator strength trend for the transitions from the nd ${}_{}{}^2{}_{}{}^{}D$ series, n=4–11, to the ground state. The calculated lifetimes are in good agreement with recent laser experiments.