Diagnostics of nitrogen plasma by trace rare-gas–optical emission spectroscopy

Abstract

Trace rare-gas–optical emission spectroscopy is carried out to characterize the nitrogen plasma as a function of discharge parameters. The functional dependence of N2(CΠu3) and N2+(BΣu+2) excited states is monitored by measuring the emission intensities of the bandheads of second positive and first negative systems. The excited-state population density of N atoms and N2 molecules, extracted from their optical emission, is related to the ground-state population density after normalizing the changes for excitation cross section and electron energy distribution function by optical actinometry. The electron temperature is determined from the plasma-induced optical emission of trace rare gas by the line-to-line method. The obtained data may help us to adjust the optimum discharge conditions for the production of active species, which are considered to be important for the desired treatment of the samples.

Operation modes of the helium dielectric barrier discharge for soft ionization

“…In contrast to helium-based discharges, the N 2 + 391 nm emission cannot be initiated in pure nitrogen DBD plasmas at atmospheric air [23,26]. In helium-based DBD discharges the N 2 + (B 2 Σ u + ) state could be in principle populated either due to electron impact or due to energy transfer in collisions with highly excited helium species.…”

Langmuir probe characterization of nitrogen plasma for surface nitriding of AISI-4140 steel

“…Detailed information regarding electron number density, electron temperature, and electron energy distribution function (EEDF) are often used to understand physical processes in the plasma such as particle collision processes, plasma reactions, and plasma surface interactions. Therefore, accurate and reliable information about plasma parameters is critical to understand the complex plasma behavior and to optimize plasma conditions for surface modification or related processing applications (Qayyum et al, 2006a, b Various diagnostic techniques are employed for the determination of electron temperature and density, such as plasma spectroscopy (Griem, 1964;Qayyum et al, 2005b), Langmuir probe (Head and Wharton, 1965;Huddlestone and Leonard, 1965), laser interferometry, and Thomson scattering (Hieftje, 1992;Van de Sanden et al, 1992). Langmuir probe is one of the simplest and reliable techniques for obtaining information about the plasma.…”

Silicon Nitride Encapsulated Silicon Nanocrystals for Lithium Ion Batteries

“…Emission lines observed over the range of 300–490 nm are related to the second positive band system of N 2 , which is the radiative transition system from the third excited state ( C ) to the second excited state ( B ), . In a pure N 2 plasma, the state, which is ∼11 eV above the ground state, is populated predominantly via direct electron impact excitation of ground state ( X ), . In Figure b and c, the first negative band system of is also observed over the range of 320–450 nm, which overlaps with the second positive system of N 2 .…”