超声射流冷却CCl2自由基的激光诱导荧光激发谱

在497—517nm波长范围观测超声射流冷却CCl₂自由基的激光诱导荧光激发谱。得到CCl₂在?←X跃迁中(v₁,v₂,0)←(0,0,0)振动带清晰的K结构。对近80个子谱带作了归属。振动分析给出较精确的v＇₁和v＇₂振动频率和非谐性常数;从K结构的分析得出(A＇-B＇)和(A″-B″)的值,文献未曾报道过。 关键词：     

对氯苯腈的双色共振双光子电离和质量分辨阈值电离光谱

本文利用双色共振双光子电离和质量分辨阈值电离光谱技术,研究了对氯苯腈分子第一电子激发态S₁和离子基态D₀的振动特征,确定了对氯苯腈分子S₁←S₀电子跃迁的激发能为35818±2 cm^–1,精确的绝热电离能为76846±5 cm^–1.对氯苯腈分子³⁵Cl和³⁷Cl两种同位素有相同的激发能和电离能以及相似的振动特征.采用高精度密度泛函方法,计算了对氯苯腈分子在中性基态S₀、第一电子激发态S₁、离子基态D₀的结构参数和振动频率,分析了电子激发和电离过程中对氯苯腈分子结构和振动频率的变化,并对激发态和离子基态的振动光谱进行了归属,振动光谱上的活性振动大多数是苯环平面内的弯曲振动.通过比较对氯苯酚、对氯苯胺、对氯苯甲醚、对氯苯腈与苯酚、苯胺、苯甲醚、苯腈分子的跃迁能,分析了取代基Cl原子与苯环之间的相互作用及其对分子跃迁能的影响.     

一种精密的边限振荡器型NQR谱仪及其应用

本文介绍一种精密的场效应管边限振荡器型核四极矩共振(NQR)谱仪。工作频率范围14MHz~35MHz,分段连续可调。这种谱仪的灵敏度高、波形失真小。在室温下,多晶粉未状氯酸钾样品中³⁵Cl的NQR频率测量精度大约3×10^-6。重结晶样品中³⁵Cl的NQR谱一次微分信号信噪比S/N ≥ 150。用该谱仪对KClO3、NaClO3、NaCl样品进行测试,得到氯的同位素³⁵Cl和37Cl的四极耦合常数比(eQq₃5Cl/(eQq₃7Cl的实测值分别为1.2687363、1.2687306、1.2687361。在77K到393K温度区间测量了氯酸钾多晶粉未状样品中³⁵Cl的NQR共振频率和温度的关系,在冰水混合温度附近,温度每变化0.1K,NQR频率的变化是478Hz。     

变换参考系解二体问题

【题目】真空中质量分别为m₁和m₂的两个小球,只受万有引力作用,某个时刻两个小球相距l₀,小球1的速度为v₀,方向指向小球2,小球2的速度为v₀,速度方向垂直两球球心的连线,问若m₁=m₂=m₀,当速度v₀满足什么条件时,两小球的间距可以为无穷远?解法1:惯性参考系法（质心参考系）解题思路:寻找惯性参考系,分析两小球相对于惯性参考系的受力,确定两小球在惯性参考系的运动特点,直接运用牛顿运动定律或能量守恒求两小     

用可调谐二极管激光光谱仪观测3657—3708cm-1区域CO2高分辨振转光谱

用可调谐二极管激光光谱仪观测到3657—3708cm^-1区域内CO₂各种同位素分子的9个振转谱带。首次观测到¹²C¹⁶O¹⁷O的10011—00001谱带和¹²C¹⁶O¹⁸O的11111—01101谱带,对其余7个谱带则扩充了其观测振转线的数目。用最小二乘方拟合法计算了各谱带的光谱常数,发现CO₂分子常数表中¹²C¹⁶O¹⁷O的10011—00001谱带中心v的计算值比本实验观测值大0.287cm^-1,而¹²C¹⁶O¹⁸O的11111—01101谱带中心v₀的计算值则比本实验观测值小0.048cm^-1。 关键词：     

多参考组态相互作用方法研究BS+离子的势能曲线和光谱性质

利用量子化学从头计算方法MRCI+Q在AVQZ级别上对BS⁺离子进行了研究. 通过计算得到了与BS⁺离解极限B⁺（¹S_g）+S（³P_g）和B⁺（¹S_g）+S（¹D）对应的5个Λ-S态,确认了BS⁺离子的基态为X³∏电子态,而第一激发态¹∑⁺的激发能T_e仅仅为564.53 cm^-1. 首次纳入的旋轨耦合效应（SOC）使得BS⁺的5个Λ-S态分裂成为9个Ω态,原有的两个离解极限分裂为B⁺（¹S₀）+S（³P₂）,B⁺（¹S₀）+S（³P₁）,B⁺（¹S₀）+（³P₁）以及B⁺（¹S₀）+S（¹D₂）. 在考虑自旋轨道耦合效应之后,Ω态的基态为X2态. 通过势能曲线（PECs）可以发现所得到的Λ-S态和Ω态均为束缚态,利用LEVEL8.0程序拟合得到了对应电子态的光谱常数,这些结果可以为实验和理论方面进一步研究BS⁺的光谱性质提供准确的电子结构信息. 关键词： 势能曲线 光谱参数 多参考组态相互作用方法 Q)')" href="#">Davidson修正(+Q)     

一维 Frenkel-Kontorova(FK)模型原子链的相变研究

文章基于一维Frenkel-Kontorova模型,研究了边界原子的初始速度对原子链运动状态的影响,数值模拟结果表明:当v1时,原子处于"振荡区",当v₁2时,原子处于"混沌区",当v>v₂时,原子处于 "均匀区". 同时我们发现临界速度v₁和v₂随原子数目和垫底势高度的变化而变化. 关键词： Frenkel-Kontorova(FK)模型 相变     

电子关联与硼原子四个共壳P态的定性特征

研究了硼的²Ｐ⁰₁（基态），²Ｐ⁰₂，²Ｐ^e₁和⁴Ｐ^e₁４个Ｎ＝２共壳Ｐ态结构的定性特征，表明了电子关联对自旋极性的依赖，显示了各量子态对取向（相对于总角动量Ｌ）的偏爱，研究了它们的几何结构和内部运动模式，侧重探讨了量子力学对称性对微观系统的决定性效应。 关键词：     

Si中S0对、Se0对和Te0对的电子结构

利用紧束缚近似下的格林函数方法,讨论了Si中(S⁰)₂,(Se⁰)₂及(Te⁰)₂基态的能级和波函数。分析了几种不同的观点。(S⁰)₂,(Se⁰)₂及(Te⁰)₂均在禁带中引入一个对称性的A_1g能级和一个反对称性的A_2u能级,二者都是填满的。现有实验观测到的是较高的A_1g能级。从理论上指出了对称性的A_1g能级反而高于反对称性的能级的原因。而Si中(Se₂)⁺的g因子测量值和(S₂)⁺,(Se₂)⁺的ESR实验结果也支持本文的观点。 关键词：     

79BrF和81BrF基态X1∑+光谱性质同位素效应对结构性质的影响

采用原子分子静力学的基本原理分析了BrF基态X¹∑⁺的离解极限,采用Herzberg同位素理论分析了BrF基态X¹∑⁺光谱数据的同位素效应,并以此为基础,分析了光谱数据的同住素效应对振动能级和分子势能函数（Murrell-Sorbie势即MS势）的影响.结果表明,⁷⁹BrF和⁸¹BrF基态X¹∑⁺的光谱数据的同住素效应是一种弱效应,与Herzberg同住素理论符合得很好,低振动能态的能级对理论预计的偏离很小,高阶力常数f₄和高阶展开系数a₃与实验结果有较大偏差,但由于a₃本身比a₁和a₂小很多,结果对势能函数整体影响不大.     

Rotational analysis of the B2Σ+ → X2Σ+ system of the aluminum monoxide radical,AlO

Twenty-five bands of the B²Σ → X²Σ system of AlO with 0 ≤ v′ ≤ 9 and 0 ≤ v″ ≤ 6 have been photographed at high resolution. The measured positions of the assigned lines of each band have been fitted by least-squares to obtain estimates of the constants (B′, D′, B″, D″), the band origin, and Δγ_v′,v″, which is the difference of the upper and lower state spin-doubling constants (γ′_v and γ″_v). The parameters from individual bands have been merged to single-valued estimates, as well as to polynomial representations in ($\text{v +}\text{1}\text{2}$). Although the spin-doubling constants are not found absolutely for either state, their vibrational dependences are well determined. The data are employed in the computation of RKR potential energy curves and an array of Franck-Condon factors and r-centroids.     

Infrared spectrum of boron chloride (BCl)

The spectrum of the Δv = 1 band of BCl was measured between 828 and 870 cm^?1 with a tunable diode laser. The absorptions of the v = 1-0, 2-1, 3-2, and 4-3 transitions of BCl were observed in both a microwave discharge and a dc discharge through BCl₃. Spectra of ¹¹B³⁵Cl, ¹¹B³⁷Cl, ¹⁰B³⁵Cl, and ¹⁰B³⁷Cl were observed in natural abundance. A set of eight Dunham coefficients was determined by fitting the data for all observed isotopic species with the appropriate reduced mass factors. A BCl bond distance, r_e = 0.1715283(31) nm, was determined which agrees with the value derived from the electronic spectrum of BCl. The band center for the v = 1-0 transition of ¹¹B³⁵Cl is ν₀ = 829.4087(8) cm^?1.     

Relative probabilities of spontaneous transitions in v″ progressions of the G1Σ g + , v′→B 1Σ u + , v″ bands of the H2 molecule

The probabilities of spontaneous transitions in v″ progressions of the G ¹Σ _g ⁺ →B ¹Σ _u ⁺ bands of the H₂ molecule (the 3D→2B electronic transition in notations of G.H. Dieke) are, for the first time, experimentally studied. The line strength ratios were measured for 78 G ¹Σ _g ⁺ , v′, J′→B ¹Σ _u ⁺ , v″, J″ electronic-vibrational-rotational spectral lines having a common upper level but belonging to different bands of v″ progressions (the vibrational branching coefficients). For this purpose, the intensities of lines of the P and R branches, emitted by a low-pressure plasma and corresponding to different values of the rotational (J′=0–11) and vibrational (v′=0–3 and v″=0–7) quantum numbers, were used. It was found that the changes in the vibrational branching coefficients with variation of v′ and v″ are significant (up to a factor of 20). For most bands studied, the dependences of the vibrational branching coefficients on the rotational quantum number J′ of an upper level are rather weak and do not exceed 30%. It was established that the difference between the experimental values of ratios of the vibronic transition probabilities (summed over J″) and the results of calculation in the adiabatic approximation strongly depends on v′, reaching a factor of 25 for a transition from the v′=2 level. At the same time, the discrepancy between the experimental data and the results of nonadiabatic ab initio calculations lies between 1.0 and 2.3.     

New measurements and global analysis of chloromethane in the region from 0 to 1800 cm

New high resolution Fourier transform spectra of pure ¹²CH₃³⁵Cl and ¹²CH₃³⁷Cl isotopomers of chloromethane have been recorded in Wuppertal covering the region from 600 to 3800 cm⁻¹. New rotational transitions within the v₂=1, v₅=1, and v₃=2 states have been measured at Lille. A first global analysis of the lower four band systems of the molecule (700-1800 cm⁻¹) is reported. The model was based on an effective Hamiltonian and dipole moment expressed in terms of irreducible tensor operators. A common set of 125 effective hamiltonian parameters (sixth order) has been adjusted to fit simultaneously some 11 000 IR data for each of the isotopomers including 153 mm wave data for 12CH₃35Cl. The assignments involve 12 sets of transitions (6 cold bands, 3 hot bands, and 3 pure rotational systems for ¹²CH₃³⁵Cl). The standard deviation was on average 0.00014 cm⁻¹ and 175 kHz for the IR and MMW data, respectively. The v₃=v₆=1 state was analysed for the first time principally from observed hot band transitions.     

An investigation of radiative transition probabilities for the A1Σu+-X1Σg+ bands of Na2

The absolute radiative transition probabilities are calculated for previously observed spontaneous emission from A¹Σ_u⁺ (v′,J′) → X¹Σ_g⁺ (v″, J″ = J′ ± 1) reported in the preceding paper and by Woerdman (Chem. Phys. Lett.53, 219 (1978)). The calculations employ accurate hybrid potential energy curves, based on Rydberg-Klein-Rees (RKR), ab initio and long-range results, and a hybrid transition moment function, based on ab initio calculations. These calculated probabilities are compared with the various experimental results; while overall agreement is reasonable, detailed differences do occur.     

Comparison of semiempirical and ab initio absolute probabilities of rovibronic transitions for the I 1Π g − , J 1Δ g − →C 1Π u ± system of bands of the H2 molecule

The absolute values of probabilities of the I ¹Π _g ^? , v′, J′; J ¹ Δ _g ^? , v′, J′→C ¹Π _u ^± , v″, J″ spontaneous transitions in the H₂ molecule (for the vibrational and rotational quantum numbers v′=v″=0–3, J′=1–6, and J″=J′, J′ ±1) are calculated by using ab initio and semiempirical data on the dipole moments of the 3dπ ¹Π_g, 3dδ¹Δ_g→2pπ¹Π_u electronic transitions. In both cases, the calculations are performed both in the adiabatic approximation and with an allowance for the nonadiabatic effect of electronic-rotational interaction. The coefficients of expansion of the wave functions of perturbed rovibronic states in the Born-Oppenheimer basis functions used in the calculations were obtained in the approximation of pure precession from experimental values of the terms. It was found that the values of transition probabilities based on the ab initio calculations systematically exceed the corresponding semiempirical data by a factor of 1.2–1.9 for the I ¹Π_g→C ¹Π _u ^± transition and by a factor of 1.4–1.6 for the J ¹Δ _g ^? →C ¹Π _u ^± transition. It was established that the difference between the ab initio and semiempirical values of electronic transition moments virtually has no effect on the dependence of the transition probabilities on the vibrational quantum numbers. The discrepancies between the results of adiabatic and nonadiabatic calculations are significant and reach two orders of magnitude, which is indicative of the important role of perturbations in the probabilities of the transitions considered.     

Microwave spectrum and molecular force field of tetratomic C2v molecules: NO2Cl

The rotational constants and quartic centrifugal distortion constants for NO₂³⁵Cl and NO₂³⁷Cl have been determined from an analysis of rotational transitions in the microwave and millimeter wave regions between 8.2–40 and 90–120 GHz, respectively.The values of the in-plane force constants in the general harmonic potential field have been obtained by combination of infrared and microwave data. Vibrational frequencies of ¹⁴NO₂Cl and ¹⁵NO₂Cl, inertia defects of NO₂³⁵Cl in the excited vibrational states v₃ = 1 and v₅ = 1, and first-order centrifugal distortion constants of NO₂³⁷Cl are the experimental data used in the least-squares fitting determination of force constants.     

Microwave spectra of the Cl and Cl isotopomers of dichloromethylene: Nuclear quadrupole-, spin-rotation-, and nuclear shielding constants from the hyperfine structures of rotational lines

The rotational spectra of the isotopomers C³⁵Cl³⁷Cl and C³⁷Cl₂ of dichloromethylene in the ground vibronic state were recorded in the range 10-33 GHz using a molecular beam Fourier transform microwave spectrometer. CCl₂ was generated by flash pyrolysis using different precursors. The observed spectra were analyzed to yield rotational and centrifugal distortion constants, as well as the complete Cl nuclear quadrupole coupling tensors and the spin-rotation interaction constants from the hyperfine structure of the rotational lines. With inclusion of data from previous work on the most abundant species C³⁵Cl₂ [N. Hansen, H. Mäder, F. Temps, Phys. Chem. Chem. Phys. (3) (2001) 50-55.] a refined r₀ structure was determined. The spin-rotation interaction constants of all three isotopomers were used to derive ³⁵Cl and ³⁷Cl principal inertial axis nuclear magnetic shielding components which have not yet been determined by NMR spectroscopy.     

Intensities of the v1-bands of 12CH335Cl and 12CH337Cl near 3 μm

Strengths of individual lines in the v₁ fundamental of methyl chloride have been measured at low pressure and at 296.35 K using a Fourier transform interferometer. The band strengths S_v⁰ obtained by fitting these measurements are 85.8±1.0 and 86.6±1.0 cm^-2 atm^-1 for ¹²CH₃³⁵Cl and ¹²CH₃³⁷Cl, respectively. The Q₃-branch appears to be useful for atmospheric detection of methyl chloride.     

Franck-Condon Factors and r-Centroids for the (B [sbnd] X) and (C [sbnd] X) Bands of the 107Ag 109Ag Molecule

Arrays of Franck-Condon factors q(v′, v″) and r-centroids r(v′, v″) were computed using Morse potentials for C¹Π [sbnd] X¹Σ⁺ _g and B O⁺ _u [sbnd] X¹Σ⁺ _g bands of the ¹⁰⁷Ag ¹⁰⁹Ag molecule.