Laser induced fluorescence spectroscopy in the void region of a nanoparticle forming plasma
Résumé
Huge quantities of nanoparticles can strongly modify plasma properties [1, 2] by the trapping of free electrons at their surface [3]. This provokes an increase in the electron temperature [4, 5] and, in return, the entire chemistry is affected. Often plasma instabilities can be observed in nanodusty plasmas, some of them on time scales visible to the human eye [6, 7]. Because instabilities are a tempo-spatial phenomenon that can evolve on short time scales, adequate techniques to examine their nature are rare. In this study laser induced fluorescence [8] and absorption [9] spectroscopy were used to monitor the evolution of argon metastable atoms in a low pressure argon RF plasma. The growth of dense nanoparticle clouds is achieved from sputtering melamine-formaldehyde from the reactor walls and electrodes. The spectroscopic data are correlated with the pressure evolution and discharge current [10] in order to investigate the impact of localized effects, like void formation, on the global process parameters.
[1] A. M. Hinz et al., J. Phys. D: Appl. Phys. 48 (2015) 055203
[2] M. Mikikian et al., Pure Appl. Chem., 83 (2010) pp. 1273-7282
[3] T. Wegner et al., Appl. Phys. Lett. 108 (2016) 063108
[4] V. Masserau-Guilbaud et al., IEEE Transactions on Plasma Science 41 (2013) pp. 816
[5] A. A. Fridman et al., J. Appl. Phys. 79 (1996) 1303