Doppler-shifted optical absorption characterization of plume-lateral expansion in laser ablation of a cerium target

Miyabe, Masabumi   ; Oba, Masaki ; Iimura, Hideki  ; Akaoka, Katsuaki ; Maruyama, Yoichiro; Oba, Hironori  ; Tampo, Motonobu; Wakaida, Ikuo  

The temporal evolution of the ablation plume of cerium was investigated by absorption spectroscopy. Cerium oxide pellets were ablated in helium by 2nd harmonic radiation from a YAG laser. The lateral velocity of the plume was determined from the magnitude of the Doppler splitting of the absorption spectra. The velocities of neutral and ionized atoms were systematically investigated by varying several parameters. Temporal profiles of the transmittance signal were measured by detuning the probe laser frequency from the atomic resonant frequency in order to evaluate the temporal variation of the lateral velocity. On the basis of the drag force model, the slowing coefficients for atomic and ionic species in helium were evaluated along with the lateral velocity in a vacuum. This study may help in understanding the plume dynamics effect on deposited film properties as well as optimizing experimental conditions for ablation-based spectroscopic analysis.