原子能科学技术2026，Vol.60Issue(5)：1038-1046,9.DOI:10.7538/yzk.2025.youxian.0550
U2F10成键特性与红外光谱研究
Study on Bonding Characteristics and Infrared Spectra of U2F10
林剑锋 1靳强 2陈宗元 2索兵兵 3伊小伟 4郭治军 2李超凡 3党海军 5张伟超 6邹文利 3刘志超 4马越 4杨俊威 4张海涛4
作者信息
- 1. 兰州大学 核科学与技术学院,核生化灾害防护化学全国重点实验室,教育部稀有同位素前沿科学中心,甘肃 兰州 730000||西北核技术研究所 强脉冲辐射环境模拟与效应全国重点实验室,陕西 西安 710024
- 2. 兰州大学 核科学与技术学院,核生化灾害防护化学全国重点实验室,教育部稀有同位素前沿科学中心,甘肃 兰州 730000
- 3. 西北大学 现代物理研究所,陕西省理论物理前沿重点实验室,陕西 西安 710127
- 4. 西北核技术研究所 强脉冲辐射环境模拟与效应全国重点实验室,陕西 西安 710024
- 5. 中国科学院 地球环境研究所,西安加速器质谱中心,陕西 西安 710061
- 6. 西北核技术研究所 强脉冲辐射环境模拟与效应全国重点实验室,陕西 西安 710024||中国科学院 西北生态环境资源研究院 油气资源研究中心,甘肃 兰州 730000
- 折叠
摘要
Abstract
U2F10 is an important intermediate in molecular laser isotope separation(MLIS),where the polymerization of UF5 significantly affects the process efficiency.The molecular structure,bonding characteristics,and vibrational properties of U2F10 were systematically investigated by scalar relativistic density functional theory(DFT)calculations combined with low-temperature matrix-isolation infrared spectroscopy.Theoretical calculations were performed using the B3LYP-D3(BJ)method in Gaussian 16,with the ECP60MDF pseudopotential and def2-TZVP basis set adopted for uranium and fluorine,respectively.Considering the open-shell nature of U2F10,multiple spin states were optimized to determine the ground-state configuration,and wavefunction stability analyses were conducted for all optimized structures.Bonding characteristics were elucidated through wavefunction analyses including Mayer bond order,natural population analysis(NPA),electron localization function(ELF),and localized orbital locator(LOL).Experimentally,U2F10 was generated by pulsed Nd:YAG laser(1 064 nm)ablation of a uranium target in an F2/Ne gas mixture(0.05%-1.0%)and codeposited in a neon matrix at 3.2 K.A high-resolution Fourier transform infrared spectrometer was used to record the spectra of the sample before and after controlled annealing(5.0-10.0 K).Theoretical calculation results show that U2F10 adopts a D2h symmetric structure stabilized by two fluorine bridges(U-Fbri bond length of 2.296 Å)without direct U-U bonding.The terminal U-Fend bonds exhibit strong ionic character(bond order is 1.1;NPA charges:U=+2.94e,Fend ≈-0.58e),whereas the bridging U-Fbri bonds are weaker(bond order is 0.4)but crucial for dimer stability,with the bridging fluorine atoms accumulating higher electron density(NPA charge:Fbri=-0.66e).Thermodynamic analysis confirms that the dimerization of UF5 to form U2F10 is a highly exothermic process(ΔH=-39.5 kcal/mol at 4 K).Meanwhile,the stepwise fluorination of U2 by F2 exhibit very strong exothermicity(for example,the formation of U2F2 has ΔH=-274 kcal/mol).Four experimentally observed absorption bands at 630.2,614.4,581.1,and 554.1 cm-1 in neon matrix—exhibiting synchronous intensity changes during annealing and fluorination—were unambiguously assigned to U2F10 vibrations,aligning with theoretical modes with minor matrix shifts(ΔNe-calcd=4.6-7.8 cm-1).This study experimentally identifies the gaseous U2F10 for the first time,resolving its structure,ionic bonding characteristics,and spectral features,thereby filling the critical long-standing knowledge gap.The results establish a molecular-level understanding of the stability of the UF5 dimer and the reactivity of U2F10,providing key insights for optimizing the molecule laser isotope separation(MLIS)efficiency and the uranium conversion mechanisms for the nuclear fuel cycle.关键词
U2F10/成键特性/氟桥键/氖基质隔离/红外光谱Key words
U2F10/bonding characteristics/fluorine bridging bond/Ne matrix isolation/infrared spec-troscopy分类
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林剑锋,靳强,陈宗元,索兵兵,伊小伟,郭治军,李超凡,党海军,张伟超,邹文利,刘志超,马越,杨俊威,张海涛..U2F10成键特性与红外光谱研究[J].原子能科学技术,2026,60(5):1038-1046,9.
