Accurate measurements of the bond dissociation energies of^(14)N_(2),^(14N)^(15)N and^(15)N_(2)  

作　　者：Liya Lu Pan Jiang Hong Gao 

机构地区：[1]Beijing National Laboratory for Molecular Sciences(BNLMS),Institute of Chemistry,Chinese Academy of Sciences,Beijing 100190,China [2]University of Chinese Academy of Sciences,Beijing 100049,China

出　　处：《Fundamental Research》2025年第1期151-157,共7页自然科学基础研究(英文版)

基　　金：supported by the National Natural Science Foundation of China(21973100,22103090);the Program for Young Outstanding Scientists of Institute of Chemistry,Chinese Academy of Science(ICCAS);Beijing National Laboratory for Molecular Sciences(BNLMS);Hong Gao is also supported by the K.C.Wong Education Foundation;Pan Jiang is supported by the China Postdoctoral Science Foundation(2020TQ0324).

摘　　要：Accurate determinations of bond dissociation energies(BDEs)and the corresponding enthalpies of formation derived from them are of fundamental importance,while on the other hand also very challenging in chemistry.In this study,we demonstrate a direct experimental scheme for measuring the BDEs of^(14)N_(2),^(14N)^(15)N and^(15)N_(2)to an accuracy of a few wavenumbers.The high-resolution quantum-state-selected velocity-mapped ion images for several rotational levels with accurately known spectroscopic term energies slightly above the dissociation limit N(^(2)D_(5/2,3/2))+N(^(2)D_(5/2,3/2))were obtained for each of the dinitrogen isotopologue molecules.A linear fit between squares of the radii of the quantum-state-selected images and the spectroscopic term energies gives out an accurate measurement of the threshold D0 for dissociating into the channel N(^(2)D_(5/2,3/2))+N(^(2)D_(5/2,3/2)).The BDEs of^(4)N_(2),^(14N)^(15)N and^(15)N_(2)into the lowest channel N(4S)+N(4S)are independently determined to be 78,688±3,78,705±4 and 78,728±4 cm^(−1),respectively.These independently determined BDEs are found to give a consistent value of De after considering the zero-point energies for each of the isotopologues,implying the reliability of the present measurement.Comparisons with several previous measurements and theoretical calculations are discussed.The experimental scheme demonstrated in this study should be generally applicable for precisely determining the BDEs of many other diatomic molecules.

关 键 词：N_(2) Bond dissociation energy PHOTODISSOCIATION Vacuum ultraviolet Velocity-mapped imaging 

分 类 号：O57[理学—粒子物理与原子核物理]