Mass Spectrometry Analyses of Ions Generated by Atmospheric-Pressure Plasma Jets in Ambient Air

Abstract

For biological and medical applications of low-temperature atmospheric-pressure plasmas (APPs), gas-and liquid-phase chemical reactions caused by the plasmas determine the effectiveness of the APP-based treatments of biological systems. In this study, ions generated by helium-based low-frequency APP jets were identified by mass spectrometry. It is shown that, among all positive ions generated by plasma jets in ambient air, hydronium ions (H 3 O +) are the dominant ions that form water clusters. The stability of a hydronium ion with water molecules suggests that all positive ions generated by plasma jets would transfer their charges to hydronium ions if water molecules were abundant, such as in humid air or water. Similarly, it is shown that, among all negative ions generated by the plasma jets in ambient air, relatively few, such as OH-, HO 2

Production and correlation of reactive oxygen and nitrogen species in gas- and liquid-phase generated by helium plasma jets under different pulse widths

“…26,27 Additionally, there are HO 2 signals detected by mass spectrometry; it means that O 3 and O 2 ions may be converted to HO 2 ions inside of this system. 31 And the peak of negative ion at m/z ¼ 60 may be assigned to CO , would form water clusters stably. 26,27 For example, when the plasma jet is applied to a water surface, the density of water molecules is typically high near the water surface, and ion water clusters are formed.…”

“…OH combines with other OH for H 2 O 2 production in both the gas and liquid phases. [31][32][33][34] Second, it is known when water is exposed to He plasma jet, a series of complex chemical reactions (listed in Table I) þ ) produced in the gas phase react with H 2 O, producing many OH radicals as in a series of chemical reactions from (1) to (12). Meanwhile, a large number of hydronium ions (H 3 O þ ) are formed as well as heavier ion water clusters (H 3 O þ (H 2 O) n ).…”

“…The NO 2 and NO 3 are the dominant negative ions that transport into water when the water is exposed to He plasma jet. 31 On the other hand, the NO, NO 2 , and N 2 O 5 in gas phase are also capable of reaching the gas-liquid interface and transported into water to form the aqueous NO 2 and NO 3 though complex chemical reactions from (13) to (18) that the main pathway of creation is through dissociative electron attachment of O 2 and subsequent oxidization to form many of the negative ion species, as shown in the reaction from (19) to (21) in Table I. In general, although mass spectrometry is so sensitive that it can detect very small quantities of gaseous ions, the observation shows that the concentrations of RONS generated by the plasma in the gas phase or at the gas-liquid interface are sufficiently high that they can affect the chemical nature of water that was exposed to the plasma. 38 The mass spectrometry data obtained in our study show that all dominant ion species generated by the plasma jet system contain either oxygen or nitrogen (…”

“…Refs [26][27][28][29][30][31][32][33],. among all positive ions generated by plasma jets in ambient air, hydronium ions (H 3 O þ ) are the dominant ions which reproduce to form water clusters.…”

Humidity-independent conducting polyaniline films synthesized using advanced atmospheric pressure plasma polymerization with in-situ iodine doping

“…, and O þ (H 2 O), from the ambient air, 32 resulting in an Ardominant gas condition in the nucleation region shielding the plasma generation region. In addition, in the case of the in-situ I 2 doping with advanced APP polymerization, the color of the plasma was brighter in the nucleation region, indicating that the vaporized iodine participated in the polymerization process.…”