Pressure-Driven Energy Band Gap Narrowing of λ-N_(2)  

作　　者：李月 刘静仪 吴彬彬 陶雨 耿延雷 王晓丽 雷力 Yue Li;Jingyi Liu;Binbin Wu;Yu Tao;Yanlei Geng;Xiaoli Wang;Li Lei(Institute of Atomic and Molecular Physics,Sichuan University,Chengdu 610065,China;School of Physics and Electronic Information,Yantai University,Yantai 264005,China)

机构地区：[1]Institute of Atomic and Molecular Physics,Sichuan University,Chengdu 610065,China [2]School of Physics and Electronic Information,Yantai University,Yantai 264005,China

出　　处：《Chinese Physics Letters》2024年第4期173-177,共5页中国物理快报（英文版）

基　　金：supported by the National Natural Science Foundation of China(Grant Nos.12374013,U2030107,and 11974154);the Fundamental Research Funds for the Central Universities(Grant No.2020SCUNL107);the Taishan Scholars Special Funding for Construction Projects。

摘　　要：Probing the energy band gap of solid nitrogen at high pressures is of importance for understanding pressuredriven changes in electronic structures and insulator-to-metal transitions under high pressure.The λ-N_(2) formed by cold compression is known to be the most stable one in all solid nitrogen phases observed so far.By optimizing the optical system,we successfully measured the high-pressure absorption spectra of λ-N_(2) covering the polymericnitrogen synthetic pressures(124 GPa-165 GPa).The measured optical band gap decreases with increasing pressure,from 2.23 eV at 124 GPa to 1.55 eV at 165 GPa,with a negative pressure coefficient of-18.4 meV/GPa,which is consistent with the result from our ab initio total-energy calculations(-22.6 meV/GPa).The extrapolative metallization pressure for theλ-N_(2) is around 288(18)GPa,which is close to the metallization pressure(280 GPa)for the η-N_(2) expected by previous absorption edge and direct electrical measurements.Our results provide a direct spectroscopic evidence for the pressure-driven band gap narrowing of solid nitrogen.

关 键 词：ABSORPTION TRANSITIONS SPECTROSCOPIC 

分 类 号：O469[理学—凝聚态物理]