Impact of NH Emission on Determining the Rotational Temperature From the Second Positive System of N2

R.O. Houben; T.P.W. Salden; R.A.H. Engeln; B. Macco; W.M.M. Kessels; J. Held

doi:10.1002/ppap.70190

Impact of NH Emission on Determining the Rotational Temperature From the Second Positive System of N2

Research output: Contribution to journal › Article › Academic › peer-review

13 Downloads (Pure)

Abstract

The gas temperature is a key parameter in low‐temperature plasmas, strongly influencing plasma chemistry and energy balance. It is commonly determined from the second positive system (SPS) ofN2 , particularly the(0, 0) band at 337 nm, assuming rotational–translational equilibrium. However, trace impurities can induce NH (A–X) emission that overlaps with this band and distorts temperature evaluation. We analyze optical emission from an atmospheric‐pressureN2 dielectric barrier discharge and a low‐pressure radiofrequency plasma. Small amounts of water vapor lead to NH formation, despite the absence of other hydrogen‐related markers in the DBD. Neglecting NH contributions causes significant errors in rotational temperatures. Simultaneous fitting ofN2 SPS (v= 0 ) and NH emission mitigates this effect and improves consistency.

Original language	English
Article number	e70190
Number of pages	8
Journal	Plasma Processes and Polymers
Volume	23
Issue number	5
DOIs	https://doi.org/10.1002/ppap.70190
Publication status	Published - May 2026

Funding

The authors acknowledge Caspar van Bommel and Janneke Zeebregts for technical assistance and Gunnar Nelson and Uwe Kortshagen from the University of Minnesota Twin Cities for enabling the measurements on the low‐pressure RF reactor. This research is performed at Eindhoven University of Technology, carried out by SolarLab, part of SolarNL, a national research, innovation, and industrial development program funded by the Netherlands National Growth Fund.

Keywords

gas temperature
optical emission spectroscopy
plasma diagnostics
rotational temperature

Access to Document

10.1002/ppap.70190

pdfFinal published version, 1.05 MBLicence: CC BY

Cite this

@article{df41f443dfe54e2b918a270b72ab67cb,

title = "Impact of NH Emission on Determining the Rotational Temperature From the Second Positive System of N2",

abstract = "The gas temperature is a key parameter in low‐temperature plasmas, strongly influencing plasma chemistry and energy balance. It is commonly determined from the second positive system (SPS) ofN2 , particularly the(0, 0) band at 337 nm, assuming rotational–translational equilibrium. However, trace impurities can induce NH (A–X) emission that overlaps with this band and distorts temperature evaluation. We analyze optical emission from an atmospheric‐pressureN2 dielectric barrier discharge and a low‐pressure radiofrequency plasma. Small amounts of water vapor lead to NH formation, despite the absence of other hydrogen‐related markers in the DBD. Neglecting NH contributions causes significant errors in rotational temperatures. Simultaneous fitting ofN2 SPS (v= 0 ) and NH emission mitigates this effect and improves consistency.",

keywords = "gas temperature, optical emission spectroscopy, plasma diagnostics, rotational temperature",

author = "R.O. Houben and T.P.W. Salden and R.A.H. Engeln and B. Macco and W.M.M. Kessels and J. Held",

year = "2026",

month = may,

doi = "10.1002/ppap.70190",

language = "English",

volume = "23",

journal = "Plasma Processes and Polymers",

issn = "1612-8850",

publisher = "Wiley-VCH Verlag",

number = "5",

}

TY - JOUR

T1 - Impact of NH Emission on Determining the Rotational Temperature From the Second Positive System of N2

AU - Houben, R.O.

AU - Salden, T.P.W.

AU - Engeln, R.A.H.

AU - Macco, B.

AU - Kessels, W.M.M.

AU - Held, J.

PY - 2026/5

Y1 - 2026/5

N2 - The gas temperature is a key parameter in low‐temperature plasmas, strongly influencing plasma chemistry and energy balance. It is commonly determined from the second positive system (SPS) ofN2 , particularly the(0, 0) band at 337 nm, assuming rotational–translational equilibrium. However, trace impurities can induce NH (A–X) emission that overlaps with this band and distorts temperature evaluation. We analyze optical emission from an atmospheric‐pressureN2 dielectric barrier discharge and a low‐pressure radiofrequency plasma. Small amounts of water vapor lead to NH formation, despite the absence of other hydrogen‐related markers in the DBD. Neglecting NH contributions causes significant errors in rotational temperatures. Simultaneous fitting ofN2 SPS (v= 0 ) and NH emission mitigates this effect and improves consistency.

AB - The gas temperature is a key parameter in low‐temperature plasmas, strongly influencing plasma chemistry and energy balance. It is commonly determined from the second positive system (SPS) ofN2 , particularly the(0, 0) band at 337 nm, assuming rotational–translational equilibrium. However, trace impurities can induce NH (A–X) emission that overlaps with this band and distorts temperature evaluation. We analyze optical emission from an atmospheric‐pressureN2 dielectric barrier discharge and a low‐pressure radiofrequency plasma. Small amounts of water vapor lead to NH formation, despite the absence of other hydrogen‐related markers in the DBD. Neglecting NH contributions causes significant errors in rotational temperatures. Simultaneous fitting ofN2 SPS (v= 0 ) and NH emission mitigates this effect and improves consistency.

KW - gas temperature

KW - optical emission spectroscopy

KW - plasma diagnostics

KW - rotational temperature

UR - https://www.scopus.com/pages/publications/105040611348

U2 - 10.1002/ppap.70190

DO - 10.1002/ppap.70190

M3 - Article

SN - 1612-8850

VL - 23

JO - Plasma Processes and Polymers

JF - Plasma Processes and Polymers

IS - 5

M1 - e70190

ER -

Impact of NH Emission on Determining the Rotational Temperature From the Second Positive System of N2

Abstract

Funding

Keywords

Access to Document

Other files and links

Fingerprint

Cite this