Systematic Comparison between Half and Full Dielectric Barrier Discharges Based on the Low Temperature Plasma Probe (LTP) and Dielectric Barrier Discharge for Soft Ionization (DBDI) Configurations

Abstract

Dielectric barrier discharge (DBD)-based analytical applications have experienced rapid development in recent years. DBD designs and parameters and the application they are used for can vary considerably. This leads to a diverse field with many apparently unique systems that are all based on the same physical principle. The most significant changes among DBDs used for chemical analysis are in how the discharge electrodes are separated from the ignited discharge gas. While the official definition of a DBD states that at least one electrode has to be covered by a dielectric to be considered a DBD, configurations with both electrodes covered by dielectric layers can also be realized. The electrode surface plays a major role in several plasma-related technical fields, surface treatment or sputtering processes, for example, and has hence been studied in great detail. Analytical DBDs are often operated at low power and atmospheric pressure, making a direct transfer of insight and know-how gained from the aforementioned well-studied fields complicated. This work focuses on comparing two DBD configurations: the low temperature plasma probe (LTP) and the dielectric barrier discharge for soft ionization (DBDI). The LTP is representative of a DBD with one covered electrode and the DBDI of a design in which both electrodes are covered. These two configurations are well suited for a systematic comparison due to their similar geometric designs based on a dielectric capillary.

Development of an inverse low‐temperature plasma ionization source for liquid chromatography/mass spectrometry

“…The second electrode is located outside the dielectric and is connected to the high‐voltage potential. In contrast, arrangements where the voltage is applied to the inner electrode and the ground to the outer electrode 9 are called inverse LTP (iLTP). In addition, plasma is also generated by an electrode set to a high voltage within a dielectric without a second metal electrode, which is called FμTP (flexible‐microtube plasma) 10 .…”

Flexible Microtube Plasma (FμTP) as an Embedded Ionization Source for a Microchip Mass Spectrometer Interface

“…Soft ionization sources for mass spectrometry (MS) or ion mobility spectrometry (IMS) that are easy to handle and reliable are in high demand . In addition to atmospheric pressure chemical ionization (APCI), dielectric barrier discharges (DBDs) have become a suitable ionization source for several types of applications. − In addition to having soft ionization capabilities, these discharges can also be used for atomic absorption spectroscopy (AAS) and optical emission spectroscopy (OES) when modified. − Thus, DBDs are highly versatile. Detailed studies have increased knowledge about fundamental discharge mechanisms in noble gas discharges at atmospheric pressure, which have led to further improvements in the use of these discharges. , Flexible microtube plasma (FμTP), being a small, easy, and safe-to-handle discharge, is the result of this optimization.…”

“…The covered ring electrode is in contact with high-voltage (HV). Differences in ionization efficiencies in mass spectra were observed when the pin electrode was at ground or floating potential . Thus, we constructed a plan for a modified bias-voltage LTP or inverse-voltage LTP (iLTP) design.…”

“…4,6,10,26,27 To ensure comparability, the LTP used here has the same small dimensions as the DBDI design. 2,28,29 Furthermore, the LTP is based on a half dielectric barrier discharge design, meaning that only one electrode is covered with a dielectric layer and the other is in direct contact with the partially ionized discharge gas. The covered ring electrode is in contact with highvoltage (HV).…”

“…Differences in ionization efficiencies in mass spectra were observed when the pin electrode was at ground or floating potential. 2 Thus, we constructed a plan for a modified bias-voltage LTP or inverse-voltage LTP (iLTP) design. In the iLTP case, the high-voltage powering the discharge is applied to the pin electrode, which is in direct contact with the plasma, and not to the electrode that is covered with the dielectric layer.…”