https://doi.org/10.1140/epjp/s13360-025-06196-1
Regular Article
The rotational relaxation of ro-vibrationally excited H2(1,11) in collision with N2
1
Xinjiang Key Laboratory of Solid State Physics and Devices, Xinjiang University, 830017, Urumqi, China
2
School of Physical Science and Technology, Xinjiang University, 830017, Urumqi, China
Received:
14
October
2024
Accepted:
6
March
2025
Published online:
29
March
2025
The collisional energy relaxation behavior of the H2(v = 1, J = 11) molecule in an H2-N2 mixture was investigated at 300 K using a coherent anti-Stokes Raman spectroscopy technique, focusing on its near-resonant rotation-vibration dynamics. The pressure of the H2-N2 mixture is maintained at 500 Torr, while the molar ratios of N2 molecules are, respectively, adjusted to 0.2, 0.4, 0.5, 0.6, and 0.7. The H2(1,11) molecule is selectively excited through a stimulated Raman pumping technique, and the time-resolved CARS signal is observed from the J ≤ 11 rotational level of H2 molecules following collisions with N2. The results indicate that the rotational relaxation of H2(1,11) molecule involves both the multi-quantum relaxation process triggered by H2-H2 collisions and the single-quantum relaxation process via H2-N2 collisions. The rate coefficient for self-relaxation of H2-H2 collisions is (1.35 ± 0.14) × 10–14 cm3s−1, whereas the relaxation rate coefficient for H2-N2 collisions is (2.77 ± 0.27) × 10–14 cm3s−1. As the molar ratio of N2 increases, the continuous single-quantum relaxation of H2(1,11) molecules with J = 11 → 9 → 7 gradually becomes more pronounced. The rotational temperature of H2 with various N2 molar ratios is determined by the relative populations of a rotational Boltzmann distribution. When the molar ratio of N2 is small, the rotation temperature decreases at a faster rate primarily due to the rapid multi-quantum relaxation resulting from near-resonant collisions between H2-H2.
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© The Author(s), under exclusive licence to Società Italiana di Fisica and Springer-Verlag GmbH Germany, part of Springer Nature 2025
Springer Nature or its licensor (e.g. a society or other partner) holds exclusive rights to this article under a publishing agreement with the author(s) or other rightsholder(s); author self-archiving of the accepted manuscript version of this article is solely governed by the terms of such publishing agreement and applicable law.
