NCI-I激光系统的基础性质研究与金属镍吸附氢同位素的量子力学计算

【作者】 刘幼成；

【导师】 朱正和；

【作者基本信息】 四川大学 ， 原子与分子物理， 2003， 博士

【摘要】 激光具有极其广泛的用途，吸引了许多科学家的注意。作为定向激光武器的O₂-Ⅰ红外激光系统（COIL）成为研究热点。在O2-Ⅰ系统中，O₂（α ¹Δ_g）使低能级的Ⅰ(²P_3/2)共振激发为Ⅰ^*(²P_1/2)，而Ⅰ^*(³P_1/2在1个光子hv作用下，一方面使Ⅰ^*(²P_1/2)转变为Ⅰ(²p_3/2)，另一方面产生2个光子hv激光，发射激光波长为13150（?），即7604.5cm^-1。在O₂-Ⅰ红外激光系统中的O₂（a ¹Δ_g）生成与供应中，由于有H₂O蒸气介入，使得O₂（a ¹Δ_g）作COIL能量共振转移的介质存在一定的缺陷。为此设想拟用O₂的等电子分子NCl来替代O₂，作为共振能量转移的介质。本文围绕此命题，利用原子分子反应静力学（AMRS）原理、量子力学ab initio计算和势能函数多体展式方法研究了N₂/N₂⁺/N₂^-体系、NX（X=F，Cl，Br）体系、N₂X/NX₂体系（X=F，Cl，Br）以及N₃⁺/N₃^-/N₃体系的电子状态、离解极限、势能函数、结构与性能间的关系。讨论了N₃Cl分子稳定构型以及NX（a ¹Δ）（X=F，Cl，Br）替代O₂（a ¹Δ_g）的可行性与能量共振转移的充要条件。 通过ab iniito计算优化计算并应用AMRS理论确定了N₂^-/N₂⁺/N₂、N₃^-/N₃⁺/N₃、NX/N₂X/NX₂（X=F，Cl，Br）、NiY（Y=H，D，T）、N₃Cl等分子的可能结构与电子状态。计算首次得到了f轨道对第一周期化合物NF影响不大，对第二、第三周期元素的分子NCl，NBr的基态、激发态的平衡几何Re一律最优，甚至精确约10倍，对ω_e的计算亦是最优。说明了f轨道对高周期元素分子的成键是有贡献的，f轨道亦是极其重要的极化函数。 根据原子分子反应静力学（ARMS）理论，确定了前述分子的离解极限，在此基础上，用正向法，通过ab iniito计算得到了双原子分子（离子）N₂/N₂⁺/N₂^-；NX（X=F，Cl，Br）基态³∑^-，激发态a ¹Δ与b¹∑⁺分子的Murrell-Sorbie分析势能函数。利用实验光谱常数反向导出了前述分子的M-S势函数。应用MCSCF/6-311++g^**（3df）方法重点计算了a ¹Δ态NX分子（X=F，Cl，Br），得到了NX（a ¹Δ）分子结构与分析势能系列函数，并与光谱常数确定的分子结构与分析势能函数进行了比较。 应用ab initio计算了N₂X与NX₂（X=F，Cl，Br）、N₃⁺/N₃^-/N₃分子、N₃Cl分四川大学博士学位论文子的分子可能结构与力常数、离解能。将导出势能函数的多体展开方法推广到了土1价的叠氮三原子分子离子;首次导出了NZX入从、N犷入多入3分析势能函数，并作出了等值势能图，以此为基础，详细分析了这些分子的形成过程与离解过程，为利用这些势能函数，研究动力学特性提供了一些信息。首次得到了 N Ol“Jl-四 /N3CI分子的稳定构型为qv型‘Al态，其可能结构为Cl一N、 \ 通过计算讨论了在COIL激光器中，源能量介质用NX（a‘△）替代02（a‘△g）的可能性。研究表明，NF（a‘△）不能作为激光介质，而NCI（a‘△）和NBr（al△）却可以作为激光介质。首次提出实现使I（2P3甩）一I‘（“P:二）能量共振转移的充分条件为:由N3X（‘Al）光解或热解生成NX（a‘△）必须满足AMRS原理要求，即分子电子状态构造的群论原理、微观过程的可逆性原理、传递性原理和最优能量过程原理;必要条件为:①△E放出)△E吸收，即NX激光介质激发态辐射能量△E放出==此（Nx，a‘△—3艺一）必须不小于屺啾=E[I’，（“Pl二）一（x，（“P3二））」=7603 .5 cm一‘。②速率保证。研究表明x二Cl，Br满足上述要求。 在全面考察已报道双原子分子光谱常数的有关分子Murren一Sorbie分析势能函数，发现有近20个M一S分析势须在a值上取复根实部作选择，这给构造精确的双原子分析势带来较大误差，在四阶力常数上f;偏差较大，如FCI分子不仅因a取复根实部导致在远离R。处出现二次极小，而且在近O处出现极大，这与双原子分子物理意义不符。首次提出了应用4一PG函数作为弥补M一S势al值取复根实部的不足。应用4一PG函数还可以用来描述同一分子具有不同态的分析势函数，如BeD分子。 基于不少双原子分子在稳定激发态系列中存在。。已知，而R。未知现象，结合NX（a‘△）替代氧碘激光a‘△g的可能性研究需要确定的Ncl、NBr分子Re，在对近60个双原子分子光谱数据的系统研究，首次提出了叭R忿=C模型。以NX（x=F，Cl，Br）为例，NX（a‘△）Re模型计算结果与B3LYP/6一311++g”（3df）基水平上的计算结果也十分吻合。充分说明该模型具有十分高的通用性与可靠性。 利用原子分子反应静力学（AMRS）与群论，确定了NIH，NID和NIT的基电子状态为“习+。应用基函数6一3n++g”和组态相关CI与QclsD方法，计 ·11·四川大学博士学位论文算了氢同位素分子及其综化合物的微观性，热力学量E，C、与S。首次提出量子力学方法计算多相化学反应处理更多还原

【Abstract】 Metastable atoms & diatomic molecules have long been recognized for their importance as energy carries in Lasemedia by many sciensits’ . For example, in the hear-in-frared COIL Chemical Laser System the O2( a 1A) metastable pumps the I* (2P1/2)→I(2P3/2) (asing transition at 1.315fzm(7604. 5 cm-1) through the resonant energy transfer reaction between O2(a 1Δ) & ground state I(2P3/2).In the first part of the paper, using the general principle of Atomic & Molecular Reaction States (AMRS) , quantum mechanics ab initio method & Many-body Expansion Method (MEM) of Analytic potential energy function, we have studied the electronic states, dissociation limits, analftic potential energy function & relationship between structure & properties of N2/N2+/N2~ %NX(X = F,Cl,BrKN2X/ NX2( X= F.Cl.Br) & N3* /N3~ /N3 systems etc. Study of the posibilities which O2 (a ’Δg) is replaced by NX(a *A) in the near-in-frared COIL chemical laser system (O2 - I system) , & study of the resonant energy transfer conditions which above process happend excist.The resonant energy transfer conditions as follows:(1) necessary conditions: AEOUiput^-AEabsorp. where AEoutpul means: the energy ; AEabsorp means the energy of I (2 P1/2 →2 P3/2 ) ,the Oalue ofAEabsorp is 7603.5cm-1.(ii) Ample conditions: AMRS rules exsist. in the resonant energy transfer process. The comfortable result of aboure process has been obtained is that X maybe Cl & Br in NX(a’A) series.The some structure & electronic states of N2- /N2+ /N2, N3~ /N3+ /N3 .. NX/ N2X/NX2(X=F,Cl,BrKNiY(Y = H,D,T) molecules (ioms) have been obtained by employing ab initio calculation (i.e. CISD% MCSCFNB3LYP etc) & AMRS theory. The present paper has first calculated the excited states b 1+ ,a 1Δ & ground states X 3S ~ for molecules NX(X =F,Cl,Br) using the density functional theory (DFT) Becke 3LYP. In comparison between the calculated results with forbitals basis set 6 - 311 + + G ** (3df) & that the polarization function f orbitals significantly contribute to improve in bond lengths Re & vibration frepuencies we for NCI & NBr, but not for NF. Therefore the f orbitals not only play some subtle aspects in bonding for lanthanides & achnidesi but also for the elements lighter than lanthanum.We have induced the dissociation limits of above molecules by using AMRS, further, obtained their potential curves by ab initio method, and induced their ana-lyxc potential energy function in virhce of Murrell-Sorbie function. The calculation spectroscopic data are in agreement with experimental data. We have also importantly obtained the struture of NX(a !A,X = F,Cl,Br) molecules by CIS/6-311 + + g**(3df) MCSF/6-311+ +g**(3df), B3LYP/6 - 311 + +g" method, & induced some M - S potential parameters.The present paper proposes an empirical formula eRae = C, which is different with published paper, in which a is constantly as 2.The force constants & dissociation energyies of N2X & NX2(X = F,Cl,Br) % N3+ /N3" /N3 & N3C1 molecules have been culculated by B3LYP/6 - 311 + + g** (3df) method. Applying MEM to oue charged three-atom-molecule. In the first-time we have, induced their analytic potential energy functions, plotted their potential energy surfaces, disscussed the form & dissociation of these molecules, given some information about their preparation & application. In first ticne stability structure of N3C1 which btained in first time is C^v thpe group & *Aj state. Itsstructure is as follows: The electronic ground states of NiH, HiD & NiT is derived to be 2 S + based on AMRS, then, energy E, heat capacity at constant volume Cv & entropy S of these molecules have been calculated using QCISD/6 - 311G** method. Considering the characteristics of different motion types, the electronic & vibrational energy or entropy of molecule are assumed to be the corresponding values of their solid states. Then, it is easy to calculated ΔH°,ΔS°,ΔG° & epuilibrium pressure & ex-amine the isotopic effect. The present method is somehow applicable to theoretical更多还原