Journal ArticleDOI
Detection of ground‐state atomic hydrogen in a dc plasma using third‐harmonic generation
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TLDR
In this paper, a 3D laser beam focused through H2 or CH4/H2 plasmas induced THG at 121.5 nm, near the atomic hydrogen 2p 2PoJ→1s 2S 1/2 Lyman-α transition.Abstract:
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.read more
Citations
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Effects of focusing on third-order nonlinear processes in isotropic media. [laser beam interactions
TL;DR: In this paper, a theoretical analysis of the third-order nonlinear interactions of focused laser beams is performed for the processes of focusing as tightly as possible, and the optimum degree of wavevector mismatch as a function of tightness and location of focus is determined for each of the three processes.
Journal ArticleDOI
Validation of actinometry for estimating relative hydrogen atom densities and electron energy evolution in plasma assisted diamond deposition reactors
TL;DR: The validity of the actinometry method applied to H-atom mole fraction measurements has been analyzed in this paper, where the authors showed that the H atoms excited in the level of quantum number n=3 (level used for OES experiments) are produced directly from the ground electronic state during collisions with electrons.
Journal ArticleDOI
Spatially resolved atomic hydrogen concentrations and molecular hydrogen temperature profiles in the chemical-vapor deposition of diamond
TL;DR: In this article, a direct measurement of the spatially resolved atomic hydrogen concentration profiles during hot-filament-assisted chemical-vapor deposition (HFCVD) of diamond films is reported.
Journal ArticleDOI
Unravelling aspects of the gas phase chemistry involved in diamond chemical vapour deposition
Michael N. R. Ashfold,Paul W May,James R. Petherbridge,Keith N. Rosser,James A Smith,Yuri A. Mankelevich,Nikolay V. Suetin +6 more
TL;DR: In this article, the authors describe laser and mass spectroscopic methods, and related modelling studies, that have been used to unravel details of the gas phase chemistry involved in diamond chemical vapour deposition (CVD) using both H/C (i.e. hydrocarbon/H2) and CO2/CH4) gas mixtures, and comment on the relative advantages and limitations of the various approaches.
Journal ArticleDOI
A vibrational study of the adsorption and desorption of hydrogen on polycrystalline diamond
TL;DR: In this article, the adsorption and desorption of hydrogen from diamond films were studied in ultrahigh vacuum using high resolution electron energy loss spectroscopy as a probe of surface vibrations.
References
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Journal ArticleDOI
Optical emission spectroscopy of reactive plasmas: A method for correlating emission intensities to reactive particle density
J. W. Coburn,M. Chen +1 more
TL;DR: In this article, a small concentration of suitably chosen noble gas to a reactive plasma is shown to permit the determination of the functional dependence of reactive particle density on plasma parameters, and examples illustrating the simplicity of this method are presented using F atomic emission from plasma-etching discharges and a comparison is made to available data in the literature.
Journal ArticleDOI
Effects of focusing on third-order nonlinear processes in isotropic media
TL;DR: In this article, a theoretical analysis of the third-order nonlinear interactions of focused laser beams is performed for the processes of focusing as tightly as possible, and the optimum degree of wavevector mismatch as a function of tightness and location of focus is determined for each of the three processes.
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