A low energy ICR study of the symmetric charge transfer reaction 3He+ + 4He → 4He+ + 3He

The kinetic energy dependence of the charge reactions ³He⁺ + ⁴He ? ³He + ⁴He⁺ was investigated using a modified ion cyclotron double resonance technique. The rate constant increases monotonically from (5.0 ± 0.5) × 10^?10 cm³ molecule^?1 sec^?1 at 0.1 eV to 55 × 10^?10 cm³ molecule^?1 sec^?1 at a relative kinetic energy of 25 eV. The results compare favorably with theoretical predications for symmetric resonance charge transfer.     

14N quadrupole coupling in thermochromic N-5-chlorosalicylideneaniline

The temperature dependence on the proton—¹⁴N double resonance spectra demonstrates that thermochromism in solid N-5-chlorosalicylideneaniline is accompanied by intramolecular proton transfer and an enol—keto transformation.     

SiC-doped boron nitride nanotubes: computations of 11B and 14N quadrupole coupling constants

Abstract  

Density-functional theory calculations have been performed to investigate the properties of the electronic structures of silicon–carbon-doped boron nitride nanotubes (BNNTs). The geometries of zigzag and armchair BNNTs were initially optimized and the quadrupole coupling constants subsequently calculated. The results indicate that doping of B and N atoms by C and Si atoms has more influence on the electronic structure of the BNNTs than does doping of B and N atoms by Si and C atoms. The changes of the electronic sites of the N atoms are also more significant than those of the B atoms.     

Calculation of the 14N and 2H quadrupole coupling tensor in trimeric imidazole

The ¹⁴N and ²H quadrupole coupling tensors at both nitrogen and at all hydrogen sites, have been calculated by ab initio SCF MO methods, in a trimeric imidazole molecule having the geometry found in the solid state. The ¹⁴N changes produced at N(1)H by hydrogen bonding are correctly reproduced to a noteworthy degree of precision, as is the ²H quadrupole interaction at the same site. The changes in the values of the three principal components of the tensor, which have been inferred from NQR measurements when imidazole passes from the gas to the solid state, are supported by the calculations, both for N(1)H and N(3).     

An ab initio calculation of 14n quadrupole coupling constants

Ab initio SCF-MO calculations of ¹⁴N quadrupole coupling constants are reported for HCN, HNC, CH₃CN, CH₃NC, NH₃, NH₂NH₂, FCN, N₂O, (CN)₂, BrCN, pyridine and pyrazine. There is excellent correlation between calculation and experiment yielding Q = 1.503 ± 0.159 × 10^?26 cm² for the ¹⁴N nuclear quadrupole moment. Dunning sp basis sets are more than adequate for such calculations, STO/4G basis sets yielding almost identical results for pyridine and pyrazine. Unsuccessful attempts were made to correlate coupling constants with electronic population analysis indices.     

12,52-二羟基-15,55-二甲基-14,16,34,36,54,56,74,76-八硝基-2,4,6,8-四氧桥连-1,3,5,7（1,3）-杯[4]芳烃的合成

以1,5-二氟-2,4-二硝基苯和3,4,5-三甲氧基甲苯为起始原料,经环化、甲基化、硝化和去甲基化反应,合成了一种新型杯芳烃衍生物,其结构经¹H NMR,¹³C NMR,¹⁵N NMR和元素分析表征。      

BF分子X1∑+,A1∏和B1∑+电子态的势能函数

使用SAC/SAC-CI和D95++,6-311++g,6-311++g**及D95(d)基组,分别对BF分子的基态X1∑+、第一简并激发态A1∏和第二激发态B1∑+的平衡结构和谐振频率进行优化计算.对所有计算结果进行比较,得出6-311++g**基组为最优基组.运用6-311++g**基组和SAC方法对基态X1∑+,SAC-CI方法对激发态A1∏和B1∑+进行单点能扫描计算,并用正规方程组拟合Murrell-Sorbie函数,得到相应电子态的势能函数解析式,由得到的势能函数计算了与X1∑+,A1∏和B1∑+态相对应的光谱常数,结果与实验数据较为一致.     

Carbony- 3C hyperfine coupling tensor in 3(nπ*) benzophenone

The carbonyl- ³C hyperfine coupling tensor of ³(nπ*) benzophenone has the principal values A^C(O) = (44.7, ?11.7, ?10.9) MHz as determined by optically-detected ENDOR techniques in high field. These values are substantially less than expected for a highly-localized π-electron spin density distribution on the carbonyl fragment.     

Nuclear magnetic resonance studies of 13 C-enriched acetylene

Analysis of ¹H and ¹³C spectra of 1-¹³ C-acetylene gives the same relative sign for ^J_CH and ^J'_CH. Precise chemical     

Potential energy curve of 1Σ+ Li+/He

The potential energy curve of the system Li⁺/He has been determined with moderately large basis sets for 0.5 ? r ? 10.0 a₀ both at the SCF level and including correlation. The present SCF results predict a deeper well (?0.00248 au) at a smaller r(3.66 a₀) compared with earlier calculations. Correlation deepens the well further (?0.00274 au), but pulls it inward slightly (3.63 a₀). In the repulsive part the calculated curve lies above the experimental one, especially at shorter distances. A similar behavior has been noted in the systems Li⁺/H₂, Li⁺/CO and Li⁺/N₂, suggesting that the experimental determinations may underestimate the interaction in this region by 10–20%.     

η3:η1⇌η2-tautomerism in carbonyliron complexes. Thermodynamic characteristics

The thermodynamic characteristics of the equilibrium between the chelate tricarbonylmethyl-π-allyl-σ-R-carbamoyliron complex (R = c-C₆H₁₁) and its π-olefinic isomer in hexane and in hexane/dichloromethane were determined. The observed values fit fairly well with the thermodynamic scale of tautomerism and allow a quantitative conclusion on the influence of solvent, temperature and polarity on the relative stabilities of the tautomeric forms to be reached.     

CAS SCF Cl calculations for the 3Σ−g, 1Σ+g, 3Σ+u, and 5Δu states of Sc2

CAS SCF CI (SD) calculations have been carried out for the ³Σ^?_g, ¹Σ⁺_g, ³Σ⁺_u, and ⁵Δ_u states of Sc₂ using large gaussian basis sets. The ³Σ^?_g, ¹Σ⁺_g, and ³Σ⁺_u states arise from the ²D(4s² 3d¹) + ²D(4s² 3d¹) limit of Sc₂ and are found to be only weakly bound (D_c ≈ 0.06 eV and R_c ≈ 8.0a₀). The ⁵Δ_u state arises from the ²D(4s² 3d¹) + ⁴F(4s¹ 3d¹ 4p¹) atomic limit. This state is found to be strongly bound relative to its limits (D_c ≈ 0.8 eV and R_c ≈ 7.0a₀).     

Laser-induced charge transfer in the LiH3+ quasi-molecule

The laser-induced charge-transfer cross section for Li³⁺ + H collisions is calculated using the perturbation approach of Copelang and Tang, and is compared to the collision-induced cross section. The validity of perturbation theory and the use of simple criteria based on the Landau-Zener formula to extend the usefulness of the theory are examined.     

Electron-gas interaction potentials for collisions of CaCl(X 2Σ+) and KCl(X 1Σ+) with Ar

Interaction potentials for CaCl(X ²Σ⁺)-Ar and KCl(X ¹Σ⁺)-Ar have been determined. They include a Gordon-Kim electron-gas repulsive part smoothly joined to the long-range van der Waals potential. The van der waals potential for KClAr was taken from Meyer and Toennies. For CaClAr, the necessary molecular parameter were estimated from the Rittner model, which predicts both the dipole and quadrupole moments fairly accurately. The CaClAr interaction potential is quite different from that of KClAr. Due to the outer 4s electron on the Ca⁺ ion. the CaClAr potential exhibits a deep minimum in the odd-order Legendre terms which is expected to have a large effect on the cross sections for collisional rotational excitation. The KClAr potential determined here also shows significant differences in the repulsive and well regions from that predicted by Meyer and Toennies using a site-site model for the repulsive contribution.     

η3:η1⇌η2-tautomerism in carbonyliron complexes. Influence of substituents

A number of chelate η³-allylcarbamoyl iron complexes (I) with different substituents (R in the allyl ligand and R′ at the nitrogen atom) were synthesized. The influence of structural features on the equilibrium between the complexes I and their η²-azadiene tautomers (II) was studied by IR spectroscopy. It was established that the equilibrium position is determined in the first place by steric factors. When R is a bulky substituent the equilibrium is shifted towards the cyclic form I, whereas the branching of the alkyl substituent R′ at the nitrogen atom favours the open olefinic form II. Furthermore π-σ-(N) rearrangement of complexes II to σ-(N) derivatives (III), and the conversion of III into η⁴-azadiene complexes (IV) also depend on the steric requirements of the substituents R and R′.     

Lifetimes of N2O+(Ã2Σ+) and COS+(Ã2Π) in selected vibronic levels

Lifetimes of selected vibrational levels of the predissociated òΣ⁺ and Ã²Π electronic states of N₂O⁺ and COS⁺, re- spectively, have been measured. These values have been used in conjunction with previous data on fluorescence quantum yields to obtain predissociation rates for the various vibrational levels.     

b 1Σ+ and a 1Δ emissions from group VI—VI diatomic molecules: b0+ → X10+, X21 emissions of TeSe

Near-infrared emissions of the b0⁺ → X₁0⁺, X₂1 band systems of TeSe have been observed in a discharge flow system. Analysis of the spectra yielded T_e values of the X₂1 and b0⁺ states of 1235 ± 5 cm^?1 and 8794 ± 5 cm^?1, respectively, and a vibrational spacing in the b0⁺ state of ω_e(b) = 294 ± 3 cm^?1.