Population distribution of metastable states of neodymium atoms produced by electron beam heating

Shibata, Takemasa; Ogura, Koichi

The metastable states' population of neodymium atoms produced by electron beam heating was measured with the laser induced fluorescence method. The atomic excitation temperature derived from the metastable state distribution decreased to about 1500K with increasing deposition rate. This atomic excitation temperature is about three times higher than that of gadolinium atoms produced by electron beam heating. Near the evaporation surface the collisional relaxation of neodymium and gadolinium atoms occurs through inelastic collisions between fine structures. The gadolinium and neodymium atoms have ten valence electrons of 4f5d6s and six valence electrons of 4f6s, respectively. The orbital radius of 5d electron is relatively larger than that of 4f electron. Low collisional relaxation of neodymium is considered to be due to small orbital radius of 4f electron and no existence of 5d electron.