Precision spectroscopy of non-thermal molecular plasmas using mid-infrared optical frequency comb Fourier transform spectroscopy

Fuente: arXiv
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Autores principales: Sadiek, Ibrahim, Puth, Alexander, Kowzan, Grzegorz, Nishiyama, Akiko, Klose, Sarah-Johanna, Röpcke, Jürgen, Lang, Norbert, Masłowski, Piotr, van Helden, Jean-Pierre H.
Formato: Preprint
Publicado: 2024
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author Sadiek, Ibrahim
Puth, Alexander
Kowzan, Grzegorz
Nishiyama, Akiko
Klose, Sarah-Johanna
Röpcke, Jürgen
Lang, Norbert
Masłowski, Piotr
van Helden, Jean-Pierre H.
author_facet Sadiek, Ibrahim
Puth, Alexander
Kowzan, Grzegorz
Nishiyama, Akiko
Klose, Sarah-Johanna
Röpcke, Jürgen
Lang, Norbert
Masłowski, Piotr
van Helden, Jean-Pierre H.
contents Non-thermal molecular plasmas play a crucial role in numerous industrial processes and hold significant potential for driving essential chemical transformations. Accurate information about the molecular composition of the plasmas and the distribution of populations among quantum states is essential for understanding and optimizing plasma processes. Here, we apply a mid-infrared frequency comb-based Fourier transform spectrometer to measure high-resolution spectra of plasmas containing hydrogen, nitrogen, and a carbon source in the 2800 - 3400 cm$^{-1}$ range. The spectrally broadband and high-resolution capabilities of this technique enable quantum-state-resolved spectroscopy of multiple plasma-generated species simultaneously, including CH$_4$, C$_2$H$_2$, C$_2$H$_6$, NH$_3$, and HCN, providing detailed information beyond the limitations of current methods. Using a line-by-line fitting approach, we analyzed 548 resolved transitions across five vibrational bands of plasma-generated HCN. The results indicate a significant non-thermal distribution of the populations among the quantum states, with distinct temperatures observed for lower and higher rotational quantum numbers, with a temperature difference of about 62 K. Broadband state-resolved-spectroscopy via comb-based methods provides unprecedented fundamental insights into the non-thermal nature of molecular plasmas - a detailed picture that has never been accomplished before for such complex non-thermal environment.
format Preprint
id arxiv_https___arxiv_org_abs_2403_15568
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Precision spectroscopy of non-thermal molecular plasmas using mid-infrared optical frequency comb Fourier transform spectroscopy
Sadiek, Ibrahim
Puth, Alexander
Kowzan, Grzegorz
Nishiyama, Akiko
Klose, Sarah-Johanna
Röpcke, Jürgen
Lang, Norbert
Masłowski, Piotr
van Helden, Jean-Pierre H.
Chemical Physics
Non-thermal molecular plasmas play a crucial role in numerous industrial processes and hold significant potential for driving essential chemical transformations. Accurate information about the molecular composition of the plasmas and the distribution of populations among quantum states is essential for understanding and optimizing plasma processes. Here, we apply a mid-infrared frequency comb-based Fourier transform spectrometer to measure high-resolution spectra of plasmas containing hydrogen, nitrogen, and a carbon source in the 2800 - 3400 cm$^{-1}$ range. The spectrally broadband and high-resolution capabilities of this technique enable quantum-state-resolved spectroscopy of multiple plasma-generated species simultaneously, including CH$_4$, C$_2$H$_2$, C$_2$H$_6$, NH$_3$, and HCN, providing detailed information beyond the limitations of current methods. Using a line-by-line fitting approach, we analyzed 548 resolved transitions across five vibrational bands of plasma-generated HCN. The results indicate a significant non-thermal distribution of the populations among the quantum states, with distinct temperatures observed for lower and higher rotational quantum numbers, with a temperature difference of about 62 K. Broadband state-resolved-spectroscopy via comb-based methods provides unprecedented fundamental insights into the non-thermal nature of molecular plasmas - a detailed picture that has never been accomplished before for such complex non-thermal environment.
title Precision spectroscopy of non-thermal molecular plasmas using mid-infrared optical frequency comb Fourier transform spectroscopy
topic Chemical Physics
url https://arxiv.org/abs/2403.15568