Time-resolved spectroscopy for 5s′ ⁴ D _7/2 state transitions undergoing electron–ion recombination in femtosecond laser-produced copper plasma

Abstract

In the femtosecond laser-produced Cu-plasma, the transient transition dynamics that the excited state 5s 4 D 7/2 via electron-ion recombination transfers to 4p 4 F 0 9/2 (465.11 nm, Λ 1 line) and 4p 4 D 0 7/2 (529.25 nm, Λ 2 line) states are investigated by using the time-resolved spectroscopy. The occupation number and relevant lifetime of the excited state 5s 4 D 7/2 , the temporal evolutions of spectral intensities for Λ 1 line and Λ 2 line emissions are demonstrated to be in direct proportion to the employed laser intensity, which reveals the transient features of transition dynamics clearly differing from that resulted in the traditional collision excitation. Furthermore, some unique characteristics for Λ 1 and Λ 2 transitions stemming from electron-ion recombination are examined in detail.