Isotopically resolved hydrogen analysis in polymers by laser‐induced

breakdown spectroscopy

O. Urbán^1,2, D.J. Palásti^1,2, Á. Bélteki^1,2, M. Aladi², M.Á. Kedves², J. Kámán², M. Veres², G. Galbács^1,2*

¹ Department of Molecular and Analytical Chemistry, University of Szeged, Hungary; ² Nanoplasmonic Laser

Fusion Research Laboratory (NAPLIFE), HUN‐REN Wigner Research Centre for Physics, Hungary

^*galbx@chem.u‐szeged.hu

Hydrogen isotope analysis is relevant for a number of scientific and industrial reasons. For example,

deuterium is used as a tracer to reveal chemical reaction mechanisms and deuterium annealing is

employed by the semiconductor industry to increase the lifetime of microelectronic chips. Hydrogen

isotopes are also important in fusion research as these species are either fuels or byproducts of

nuclear reactions [1]. In these analytical applications, laser‐induced breakdown spectroscopy (LIBS)

has a good potential, considering that it is trace sensitive, fast and can be applied even remotely.

However, isotopically resolved quantitative LIBS hydrogen analysis is challenging, partly because the

experimental conditions need to be carefully optimized, and also because the measurement requires

reliable calibration samples. Our research aimed at preparing suitable calibration standards for such

purposes in the form of synthetic polymers with a controlled and covalently bound deuterium content

as well as constructing a suitable LIBS measurement system for this analysis. We also use deuterated

and nanoparticle‐doped polymers as laser targets in nanoplasmonics ignited fusion; the composition

of these targets also require monitoring [2].

We constructed and optimized a nanosecond‐pulse LIBS setup, centered around a compact, modular

vacuum chamber. Our system is able to work at both 1064 nm and 532 nm wavelengths, uses co‐axial

light collection optics and can be operated at pressures as low as 1 Pa. Detection is done by fiber

optics coupled spectrometers: either a high resolution echelle or an in house built spatial heterodyne

spectrometer. The best spectral resolution we can achieve near the Hα line is 20 pm (Figure 1). Several

polymer samples of different compositions (PS, UDMA‐MMA, etc.) with varying deuteration levels (0

100%, validated by H‐NMR and Raman spectroscopy) and added colorants to improve light absorption

at the laser wavelength were prepared in the form of flat discs [3]. Good linearity calibration curves

were recorded and a detection limit of 0.1 m/m% for D was obtained. This work was supported by

NKFIH (Hungary) under projects K 146733, 2022‐NL‐2.1.1.‐2022‐00002, as well within an industrial

cooperation funded by Infineon Technologies Austria AG in the course of IPCEI Microelectronics.

References

[1] N. Kroó, M. Aladi, M. Kedves, B. Ráczkevi, A. Kumari, P. Rácz, M. Veres, et al.; Sci. Reports, 2024, 14, 1828.

[2] T. S. Biró, N. Kroó, L. P. Csernai, M. Veres, M. Aladi, I. Papp, M.Á. Kedves, et al.; Universe, 2023, 9, 233.  

[3] D.J. Palásti, O. Urbán, F.A. Casian‐Plaza, J. Kámán, I. Rigó, et al.; Polymer Testing, 2024, 139, 108565.