Detection of ground‐state atomic hydrogen in a dc plasma using third‐harmonic generation

Autor:	L. S. Plano, H. R. Thorsheim, James E. Butler, F. G. Celii, J. M. Pinneo
Rok vydání:	1990
Předmět:	Hydrogen Chemistry General Physics and Astronomy chemistry.chemical_element Diamond Chemical vapor deposition Plasma engineering.material Atomic electron transition engineering High harmonic generation Plasma diagnostics Atomic physics Microwave
Zdroj:	Journal of Applied Physics. 68:3814-3817
ISSN:	1089-7550 0021-8979
DOI:	10.1063/1.346263
Popis:	Third‐harmonic generation (THG) was used to monitor ground‐state atomic hydrogen H(1s 2S1/2) in a dc plasma system. A 364.6 nm laser beam focused through H2 or CH4/H2 plasmas induced THG at 121.5 nm, near the atomic hydrogen 2p 2PoJ→1s 2S1/2 Lyman‐α transition. Both the intensity and frequency shift of the excitation spectra exhibited dependence on the plasma power. Absolute H atom concentration was estimated by comparing the frequency shift to that obtained in a calibrated microwave discharge flow system. The sensitivity was ∼4×1013 cm−3 (100 ppm). The measured atomic hydrogen densities were substantially less than in other diamond chemical vapor deposition methods and may explain the lower diamond deposition rates obtained with dc plasma systems of this type.
Databáze:	OpenAIRE
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