TY - JOUR KW - Laser ablation KW - Crater KW - Electron number density KW - Plasma temperature KW - Laser induced plasma spectroscopy AU - Haichen Liu AU - Xianglei Mao AU - Jong-Hyun Yoo AU - Richard E Russo AB -

The electron number density and temperature during the early phase (<300 ns) of laser-induced plasmas from silicon using a 266-nm, 3-ns Nd:YAG laser were deduced via spectroscopic methods. These parameters were measured as a function of delay time vs. irradiance in the range of 2–80 GW/cm2, and compared with crater volume measurements. A dramatic change in plasma characteristics (electron number density, temperature, and degree of ionization) as well as a sharp increase of mass removal was observed when the irradiance was increased beyond a threshold of 20 GW/cm2. Possible mechanisms such as inverse bremsstrahlung and self-regulation were used to describe these data in the low irradiance region. Laser self-focusing and critical temperature are discussed to explain the dramatic changes after the irradiance reaches the threshold.

AD -

Univ Calif Berkeley, Lawrence Berkeley Lab, Berkeley, CA 94720 USA Chinese Acad Sci, Guangzhou Inst Geochem, Canton 510640, Peoples R China

BT - Spectrochimica Acta Part B: Atomic Spectroscopy C2 - LBNL-43861 DA - 11/1999 DO - 10.1016/S0584-8547(99)00092-0 IS - 11 LA - eng N2 -

The electron number density and temperature during the early phase (<300 ns) of laser-induced plasmas from silicon using a 266-nm, 3-ns Nd:YAG laser were deduced via spectroscopic methods. These parameters were measured as a function of delay time vs. irradiance in the range of 2–80 GW/cm2, and compared with crater volume measurements. A dramatic change in plasma characteristics (electron number density, temperature, and degree of ionization) as well as a sharp increase of mass removal was observed when the irradiance was increased beyond a threshold of 20 GW/cm2. Possible mechanisms such as inverse bremsstrahlung and self-regulation were used to describe these data in the low irradiance region. Laser self-focusing and critical temperature are discussed to explain the dramatic changes after the irradiance reaches the threshold.

PY - 1999 SP - 1607 EP - 1624 T2 - Spectrochimica Acta Part B: Atomic Spectroscopy TI - Early phase laser induced plasma diagnostics and mass removal during single-pulse laser ablation of silicon VL - 54 ER -