JMSSJ On-line

JMSSJ On-line, Vol. 50 (2002) No. 2, pp. 72-74

Secondary Ions Produced by 400 eV He⁺ Ions on N₂ and O₂ Thin Films at 8 K		>> Full Text PDF >> References
*Makoto WATANABE,^a) Tetsuya SATO,^b) Kenzo HIRAOKA,^b) and Kunihiko MORI^a)** ^a)Graduate School of Engineering, Yamanashi University (4-3-11 Takeda, Kofu 400-8511, Japan) ^b)Clean Energy Research Center, Yamanashi University (4-3-11 Takeda, Kofu 400-8511, Japan)*

Secondary ions produced by 400 eV He⁺ ion impact on N₂ and O₂ thin films deposited on a silicon substrate at 8 K were measured as a function of film thickness using a reflectron-type time-of-flight mass spectrometer. While the major ions observed were N_n⁺ with n up to 4 for N₂ film, larger cluster ions of O_n⁺ (n up to 10) were observed. The secondary ion intensities for N₂ and O₂ reached the plateau with film thickness of about 20 and 400 monolayers, respectively. The observed marked difference in the film-thickness dependence between N₂ and O₂ films is discussed on the viewpoint of relaxation of electronic energy deposited in the solid films by the incident 400 eV He⁺ ions.

Key words: TOF/SIMS, van der Waals solid, Ion impact, Neutral cluster