Key words Escape factor, rf discharge in argon, metastable state, emission spectroscopy, TDLAS.Reabsorption of the emitted light in the plasma volume has recently been used for density measurements of the lower level of optical transition by interpretation of emission spectra employing the escape factor concept. Following this idea, we apply this method to a radio-frequency argon discharge. By revising the theoretical background, the impact of different assumptions on excited species spatial distributions is investigated. Comparing with 1s5 and 1s4 concentrations obtained with laser absorption spectroscopy, the range of applicability of those assumptions is analyzed at different discharge parameters.

Molecule and particle formation in a capacitively coupled radio-frequency discharge has been investigated. Formation of molecular ions has been investigated by means of plasma process monitoring employing energydispersive mass spectrometry. Particle growth has been studied by recording the intensity of the transmitted and scattered laser light signal from the particle cloud. An oscillation of the transmitted laser intensity was observed which is caused by periodic formation and expansion of a central void. This behavior can be explained by multigeneration dust cloud formation.