Temporal afterglow between two pulses of repetitively pulsed argon-acetylene plasma: measuring electron and negatively charged species densities

Abstract

The temporal afterglow between two pulses of a repetitively pulsed radio-frequency driven low-pressure argon-acetylene plasma is experimentally explored using laser-induced photodetachment combined with microwave cavity resonance spectroscopy. The densities of electrons and negatively charged species, i.e., anions and dust particles, are measured temporally resolved until 1.9 s in the temporal plasma afterglow. Two different plasma-on times are adjusted to investigate the dynamics of anions and dust particles in the afterglow phase. The measurements show that while electrons decay rapidly within the first few milliseconds of the afterglow phase, the negatively charged species reside much longer in the plasma after the plasma is switched off. The electron density decay is measured to be faster for a longer plasma-on time. This effect is attributed to an enhanced recombination rate due to a higher dust particle density and/or size. The density of negatively charged species decays within two different timescales. The first 20 milliseconds of the afterglow is marked with a rapid decay in the negatively charged species density, in contrast with their slow density decay in the second time scale. Moreover, a residual of the negatively charged species densities is detected as long as 1.9 s after extinguishing the plasma.

Layer-by-layer structured nanocomposite deposits from plasma-synthesized organosilicon nanoparticles and organosilicon nanoparticles decorated with Ag nanoparticles by taking advantage of cyclic nanoparticle formation in Ar/HMDSO reactive plasmas

“…For each generation, it follows the same, previously identified, steps in the plasma: (i) formation of primary clusters after electron attachment to the precursor fragments, (ii) nucleation, (iii) coagulation and (iv) radical sticking on the surface of already formed NPs in order to achieve critical size that allows them to escape the plasma due to gravity and ion drag forces (Watanabe, 2006;Berndt et al, 2009;Dap et al, 2010;Despax et al, 2012;Despax et al, 2016;Garofano et al, 2019a). In addition, for NP synthesis in hydrocarbon-containing plasmas the presence of acetylene is required (Bouchoule and Boufendi, 1993;Berndt et al, 2009;Kovačević et al, 2009;Dap et al, 2010;Despax et al, 2012;Despax et al, 2016;Hasani et al, 2023). Unlike the case of continuous injection of the precursor into the plasma, where the formation of a maximum of two generations of NPs is observed, a pulsed injection of the precursor leads to a long-lasting formation of successive generations of NPs, as demonstrated in Ar/HMDSO plasmas (Despax et al, 2012;Despax et al, 2016;Garofano et al, 2019a).…”

Plasma properties and discharging of dust particles in an Ar/C2H2 plasma afterglow

“…For the formation of carbonaceous dust particles, gas discharges containing acetylene, methane or ethylene are usually used [3][4][5][6][7][8][9][10][11]. To control the dust particle growth, these plasmas have been intensively investigated by experimental measurements [3][4][5][6][7][8][9][10][11][12][13][14] and computer simulations [15][16][17][18][19][20]. Many experimental * Author to whom any correspondence should be addressed.…”

“…The densities of electrons in Ar/C 2 H 2 afterglow plasmas were measured in [11,13], while the densities of metastable argon atoms were measured in [11,12]. It was found that the lifetimes of argon metastable atoms in an Ar/C 2 H 2 afterglow plasma are strongly influenced by their quenching by acetylene [12].…”