Spatially-Resolved Spectroscopic Diagnostics of a Miniature RF Atmospheric Pressure Plasma Jet in Argon Open to Ambient Air

Sainct, Florent P.; Durocher‐Jean, Antoine; Gangwar, Reetesh Kumar; Gonzalez, Norma Yadira Mendoza; Coulombe, Sylvain; Stafford, L.

doi:10.3390/plasma3020005

Cited by 10 publications

(7 citation statements)

References 48 publications

(58 reference statements)

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“…A typical measurement along with the corresponding Voigt fit is presented in figure 2. Based on detailed line broadening analysis, the experimental conditions investigated herein lead to a T g value in the order of 2200 ± 200 K. This value agrees well with those reported by Durocher-Jean et al [42] for microwave plasma jets; however, it is considerably higher than the values commonly observed for low and mid-frequency plasma jets (T g ∼ 300-550 K [50,51]). Considering that the population of the Ar 1s state is sufficiently small within the range of experimental conditions employed herein (typically below 10 9 cm −3 [42]), the radiation trapping of Ar 2p-to-1s transitions was neglected [41].…”

Section: Experimental Setup and Diagnosticssupporting

confidence: 91%

Optical response of plasmonic silver nanoparticles after treatment by a warm microwave plasma jet

et al. 2023

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This work investigates the effect of plasma treatment on the morphology and composition of 15 x 15 mm2 silver nanoparticle (70–80 nm) thin films. The silver nanoparticles are deposited onto thermal silica (SiO2/Si) substrates by spin-coating, then they are treated by an open-to-air microwave argon plasma jet characterized by a neutral gas temperature of 2200 ± 200 K. Scanning electron microscopy analysis reveals that the number of isolated nanoparticles in the film sample decreases after exposure to multiple jet passes, and that polygonal structures with sharp corners and edges are produced. Similar structures with much rounder edges are obtained after conventional thermal annealing at temperatures up to 1300 K. Based on localized surface plasmon resonance (LSPR) analysis in the range of 350–800 nm, the main extinction band of silver nanoparticles experiences a redshift after treatment with the plasma jet or with thermal annealing. Moreover, both treatments induce surface oxidation of the nanoparticles, as evidenced by X-ray photoelectron spectroscopy. However, only the plasma-exposed samples exhibit a significant rise in the surface-enhanced Raman scattering (SERS) signal of oxidized silver at 960 cm-1. 29 × 29 µm2 mappings of hyperspectral Raman IMAging (RIMA) and multivariate curve resolution analysis by log-likelihood maximization demonstrate that the SERS signal is controlled by large-scale micrometer domains that exhibit sharp corners and edges.

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Section: Experimental Setup and Diagnosticssupporting

confidence: 91%

Optical response of plasmonic silver nanoparticles after treatment by a warm microwave plasma jet

et al. 2023

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“…For example, a judicious control of neutral gas heating in non-thermal plasmas at atmospheric pressure plays a critical role in plasma processing of heat-sensitive materials like polymers and human tissue [3][4][5], in fuel synthesis through plasma dissociation of complex molecules [6][7][8][9], and in plasma deposition of functional, nanostructured coatings [10][11][12]. Regrettably, acquiring T g while Sainct et al reported a decrease of T g from 400 K to 380 K along the outlet of an RF atmospheric-pressure argon plasma jet sustained with 40 W [15]. Rayleigh scattering is a well-established way of acquiring T g , relying on photons scattering on electrons bound to atoms or molecules [16].…”

Section: Introductionmentioning

confidence: 99%

On the rotational–translational equilibrium in non-thermal argon plasmas at atmospheric pressure

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Durocher‐Jean

Stafford

2021

Plasma Sources Sci. Technol.

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This work examines the rotational–translational equilibrium in non-thermal, argon-based plasmas at atmospheric pressure. In particular, rotational temperatures (T rot) and neutral gas temperatures (T g) are compared along the axis of plasma columns sustained by either radiofrequency (RF) or microwave (MW) electromagnetic fields. Water vapours or N2 admixtures are added to the high-purity argon plasmas to record the rotational temperatures from the emission spectra of either the OH(A2Σ + − X2Π i ) or the N2 +(B2Σ u + − X2Σ g + ) rovibrational systems. T g values are also deduced from the line broadening of selected Ar emission lines using an hyperfine spectrometer. In the MW Ar/H2O plasma, T g decreases from ∼2100 K close to the wave launcher to ∼1600 K near the end of the plasma column, while T rot is mostly constant in the 1500 K range. In presence of N2 admixtures instead of water vapours, T g is higher by about 300 K (from ∼2400 K to ∼1900 K), while T rot decreases from ∼3200 K to ∼2750 K along the plasma column. A discrepancy between T g and T rot is also observed in the much colder RF plasmas with T g ∼ 400 K and T rot ∼ 515 K. Such departure from the rotational–translational equilibrium in both plasmas is ascribed to the influence of electrons competing with neutrals to impose their own temperature on the distribution of rotational levels of both ground and excited states.

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“…However, it is not so easy to capture the effluent image if T gas is close to the room temperature (T room ). The employment of thermocouples for T gas measurements are also reported on the literature [33][34][35]. Nonetheless, this kind of device usually has metallic components in the sensor probe.…”

Section: Introductionmentioning

confidence: 93%

On the gas heating effect of helium atmospheric pressure plasma jet

2023

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Plasma medicine is an emerging research ﬁeld which has been driven by the development of plasma sources suitable to generate low temperature plasmas. In many cases, such devices can operate without a gas ﬂow, producing a plasma discharge from the ambient air. However, the most common case is the use of a working gas at a given ﬂow rate to produce a plasma jet. Helium (He) is one of the gases commonly used as the carrier gas to generate cold atmospheric pressure plasma jets (CAPPJs) due mainly to the easiness to ignite a gas discharge with it. However, in this work it was observed that most of the heating of a He CAPPJ can come just from the expansion of the He gas. This was found through measurements of gas temperature (Tgas), using ﬁber optic temperature (FOT) sensors, and thermal output, using both FOT and infrared imaging with the He ﬂow impinging on a copper (Cu) plate. Such ﬁndings were achieved through comparisons of Tgas and the temperature on the Cu (TCu) plate in the conditions with and without discharge ignition, as well as comparing Tgas in the free gas/jet mode with and without discharge ignition. It was veriﬁed that the Tgas values increased as the distance from the gas outlet was enlarged, especially at low He ﬂow rates, even without discharge ignition. Despite the temperature increase with distance, it is possible to produce plasma jets with temperatures lower than 40 °C at low He ﬂow rates.

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Spatially-Resolved Spectroscopic Diagnostics of a Miniature RF Atmospheric Pressure Plasma Jet in Argon Open to Ambient Air

Cited by 10 publications

References 48 publications

Optical response of plasmonic silver nanoparticles after treatment by a warm microwave plasma jet

Optical response of plasmonic silver nanoparticles after treatment by a warm microwave plasma jet

On the rotational–translational equilibrium in non-thermal argon plasmas at atmospheric pressure

On the gas heating effect of helium atmospheric pressure plasma jet

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