Revisiting the structural and optical properties of <i>γ</i>-N<sub>2</sub>

Jinwei Yan; Hai-An Xu; Pu Wang; Lewis J. Conway; Wan Xu; Chuansheng Hu; Zeming Qi; Xiao-Di Liu; Eugene Gregoryanz

doi:10.1063/5.0315313

Volume 11 Issue 4

Jul. 2026

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Article Navigation > Matter and Radiation at Extremes > 2026 > 11(4): 047802

Jinwei Yan, Hai-An Xu, Pu Wang, Lewis J. Conway, Wan Xu, Chuansheng Hu, Zeming Qi, Xiao-Di Liu, Eugene Gregoryanz. Revisiting the structural and optical properties of γ-N2[J]. Matter and Radiation at Extremes, 2026, 11(4): 047802. doi: 10.1063/5.0315313

Citation:

Jinwei Yan, Hai-An Xu, Pu Wang, Lewis J. Conway, Wan Xu, Chuansheng Hu, Zeming Qi, Xiao-Di Liu, Eugene Gregoryanz. Revisiting the structural and optical properties of γ-N₂[J]. Matter and Radiation at Extremes, 2026, 11(4): 047802. doi: 10.1063/5.0315313

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Revisiting the structural and optical properties of γ-N₂

doi: 10.1063/5.0315313

Jinwei Yan^{1, 2, 3
,},
Hai-An Xu¹,
Pu Wang¹,
Lewis J. Conway^{4, 5
,},
Wan Xu^1
,,
Chuansheng Hu^6
,,
Zeming Qi^6
,,
Xiao-Di Liu^{1
,
,
,},
Eugene Gregoryanz^{1, 2, 3, 7
,
,
,}

1.
Key Laboratory of Materials Physics, Institute of Solid State Physics, HFIPS, Chinese Academy of Sciences, Hefei 230031, China
2.
Shanghai Key Laboratory MFree, Shanghai Advanced Research in Physical Sciences, Pudong, Shanghai 201203, China
3.
Centre for Science at Extreme Conditions and School of Physics and Astronomy, University of Edinburgh, Edinburgh, United Kingdom
4.
Department of Materials Science and Metallurgy, University of Cambridge, 27 Charles Babbage Road, Cambridge CB3 0FS, United Kingdom
5.
Advanced Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan
6.
National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei, Anhui 230029, China
7.
Center for High Pressure Science and Technology Advanced Research, Shanghai, China

More Information

Corresponding author: a)Authors to whom correspondence should be addressed: xiaodi@issp.ac.cn and e.gregoryanz@ed.ac.uk
Received Date: 2025-12-05
Accepted Date: 2026-03-12

Available Online: 2026-07-24

Publish Date: 2026-07-24

Abstract

Abstract

For decades, γ-N₂ has been known to exist at very low temperatures and pressures, located in a tiny area of the nitrogen phase diagram. Recently, it was shown that γ-N₂ occupies most of the P–T space usually associated with molecular phases such as δ, ɛ, and ζ, and that it plays a pivotal role in shaping nitrogen’s phase diagram. Using powder synchrotron X-ray diffraction, Raman and infrared spectroscopy, and density function theory calculations, we have investigated the structural and optical properties of γ-N₂ in a wide P–T range. The combined X-ray diffraction and infrared spectroscopy results unequivocally demonstrate that γ-N₂ adopts the monoclinic (P2₁/c space group) configuration with two N₂ molecules per unit cell. It appears that the γ-N₂ is structurally closely related to θ-N₂, leading to both phases having very similar Raman signatures. Additionally, the Raman spectroscopy reveals a vibrational mode intensity resonance effect in both phases, caused by a strong vibrational coupling between the isotopic ¹⁵N¹⁴N and ¹⁴N₂ vibrational excitations.

The authors have no conflicts to disclose.
Conflict of Interest
Author Contributions
Jinwei Yan: Data curation (equal). Hai-An Xu: Data curation (equal). Pu Wang: Data curation (equal). Lewis J. Conway: Data curation (equal). Wan Xu: Data curation (equal). Chuansheng Hu: Data curation (equal). Zeming Qi: Data curation (equal). Xiao-Di Liu: Data curation (equal); Investigation (equal); Resources (equal); Supervision (equal); Writing – review & editing (equal). Eugene Gregoryanz: Investigation (equal); Supervision (equal); Writing – original draft (equal); Writing – review & editing (equal).
The data that support the findings of this study are available within the article and from the corresponding authors upon reasonable request.

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References(32)

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