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1.
We have previously determined an analytical ab initio six-dimensional potential energy surface for the HCl dimer, and in the present paper we use this potential, with the HCl bond lengths held fixed, in a full (four-dimensional) close-coupling calculation to determine the energies of the lowest 24 vibrational states. These vibrational states involve the intermolecular stretch ν 4, the trans-bend tunneling vibration ν 5, and the torsion ν 6. The highest of the 24 levels is the (ν 4ν 5ν 6)=(111) state, for which we calculate an energy of 200 cm −1 above the (000) state. As well as determining tunneling energies up to 5ν 5=183 cm −1, we determine ν 4=49 cm −1, 2ν 4=93 cm −1, 3ν 4=134 cm −1, 4ν 4=172 cm −1, ν 6=137 cm −1 and ν 4+ν 6=178 cm −1, together with tunneling energies in all these states. Making allowance for the HCl stretching zero-point energy we determine the dissociation energy D0 as 390 cm −1 on this analytical surface. We determine that below 300 cm −1 there are 72 vibrational ( J=K=0) states, and below dissociation there are 162 vibrational ( J=K=0) states, for this potential surface. 相似文献
2.
High resolution vibration-rotation spectra of 13C 2H 2 were recorded in a number of regions from 2000 to 5200 cm −1 at Doppler or pressure limited resolution. In these spectral ranges cold and hot bands involving the bending-stretching combination levels have been analyzed up to high J values. Anharmonic quartic resonances for the combination levels ν 1 + mν 4 + nν 5, ν 2 + mν 4 + ( n + 2) ν 5 and ν 3 + ( m − 1) ν 4 + ( n + 1) ν 5 have been studied, and the l-type resonances within each polyad have been explicitly taken into account in the analysis of the data. The least-squares refinement provides deperturbed values for band origins and rotational constants, obtained by fitting rotation lines only up to J ≈ 20 with root mean square errors of ≈ 0.0003 cm −1. The band origins allowed us to determine a number of the anharmonicity constants xij0. 相似文献
3.
The methylene-bridged, mixed-chalogen compounds Fe 2(CO) 6(μ-SeCH 2Te) (1) and Fe 2(CO) 6(μ-SCH 2Te) (3) have been synthesised from the room temperature reaction of diazomethane with Fe 2(CO) 6(μ-SeTe) and Fe 2(CO) 6(μ-STe), respectively. Compounds 1 and 3 have been characterised by IR, 1H, 13C, 77Se and 125Te NMR spectroscopy. The structure of 1 has been elucidated by X-ray crystallography. The crystalsare monoclinic,space group P2 1/ n, A = 6.695(2), B = 13.993(5), C = 14.007(4)Å, β = 103.03(2)°, V = 1278(7) Å 3, Z = 4, Dc = 2.599 g cm −3 and R = 0.030 ( Rw = 0.047). 相似文献
4.
The molecular structure (equilibrium geometry) and binding energy of the dimethylzinc (DMZn)-hydrogen selenide (H 2Se) adduct, (CH 3) 2Zn:SeH 2, have been computed with ab initio molecular orbital and density functional theory (DFT) methods and, where possible, compared with experimental results. The structure of the precursors DMZn and H 2Se are perturbed to only a small extent upon adduct formation. (CH 3) 2Zn:SeH 2 was found to be 3 kcal mol −1 less stable than the precursors at the B3LYP/6-311 + G(2 d, p)//B3LYP/6-311 + G(2 d, p) level of computation, indicating that the (CH 3) 2Zn:SeH 2 adduct is unlikely to be a stable gas-phase species under chemical vapour deposition conditions. Further calculations at the B3LYP/6-311 + G(2 d, p)//B3LYP/6-311 + G(2 d, p) level of computation suggest that the 1:2 adduct species, (CH 3) 2Zn:(SeH 2) 2, is much less stable than the 1:1 adduct and consequently the precursors by 19 kcal mol −1. 相似文献
5.
A high-resolution emission spectrum of a low-pressure Ar-diluted CO + N 2O → CO 2 + N 2 flame catalyzed by Na metal vapor has been obtained and examined for vibrational disequilibrium. Emission in the 1900-2400 cm −1 spectral region, which includes the fundamental and “hot” bands of CO, CO 2(ν 3), and N 2O(ν 3), was recorded with high resolution and the CO emission was analyzed in detail to determine vibrational and rotational temperatures which were found to be unequal, Tv = 2050°K and TR = 1100°K. An examination of vib-vib and vib-trans energy transfer mechanisms results in the conclusion that an excess of 14% of the chemical energy is preferentially deposited in the resonantly-coupled N 2, CO, CO 2 (ν 3), and N 2O(ν 3) vibrational modes. It is further observed that CO vibrational levels for ν > 4 are excessively populated, presumably due to quenching of Na*(3p) by CO; the flame is accompanied by intense Na D-line chemiluminescence. 相似文献
6.
We have recorded and analyzed the molecular beam spectra of allene in the regions of the ν 1 + ν 5 and 2 ν 8 bands around 5947.5 and 6135.5 cm −1, respectively. The ν 1 + ν 5 band only shows minor perturbations and we suspect the presence of a doorway state that causes parallel Coriolis coupling to the bath states. Perpendicular Coriolis interactions do not seem to play an important role since the size of the matrix elements does not increase systematically with J′. The spectrum in the region of the 2 ν 8 band is more complicated; a total of six sub-bands has been identified with K = 0–2. Based on the lack of any systematic dependence on J′ and an inverse dependence of the coupling on K, we expect that neither parallel nor perpendicular Coriolis coupling is present in this band. The effective lifetime for both bands is calculated to be about 200 ps, which is very similar to the lifetimes of an acetylenic C---H stretch overtone. 相似文献
7.
Zeeman spectral data are presented for the 2Π 3/2: J = 7/2 → J= 9/2, 2Π 3/2: J= 7/2→ 2Π 1/2: J= 5/2 and 2Π 3/2 J= 3/2→ J = 5/2 transitions in OD. Data for the 2Π 3/2. J=3/2→ J= 5/2 and 2Π 3/2 J= 5/2 → 2Π l/2 : J= 3/2 transitions in OH, taken under similar conditions, are included. 相似文献
8.
Some qualitative effects of anharmonicity on the spectra of H 3+ and D 3+ between low vibrational levels are described. Using large-basis vibration-rotation calculations with a Morse-based discrete variable representation for the vibrations and a symmetric-top basis for the rotations, new spectra of H 3+ and D 3+ have been assigned. This procedure was assisted by adjusting eight coefficients for H 3+ and six coefficients for D 3+ in the Meyer-Botschwina-Burton ab initio potential function, and eventually 621 new and old lines of H 3+ to levels up to 3ν 2 and 529 new and old lines of D 3+ to levels up to 2ν 2 have been fitted with standard deviations of 0.118 and 0.059 cm −1, respectively. An attempt is made to compare five different potential energy functions for the H 3+ system, two ab initio and three adjusted to fit spectra of H 3+ or D 3+, by expanding them by the same procedure in the same variables. For extension of the present work to higher vibrational levels, more accurate boundary behaviour at linear configurations will be required, and some aspects of the use of hyperspherical coordinates are discussed. 相似文献
9.
A 2 MHz resolution electric-resonance optothermal spectrometer and a microwave-sideband CO 2 laser have been used with microwave-infrared double resonance to investigate high-order torsional couplings in the 10 μm infrared spectrum of 3,3,3-trifluoropropene. Three normal mode vibrations are studied with band origins at 963.4, 980.2 and 1025.2 cm −1. The 963.4 cm −1 band is well characterized by an asymmetric-top Hamiltonian, except for the presence of a weak perturbation for J′ = 7, Ka′ = 2 affecting only the A-symmetry internal-rotor state. Microwave-infrared double resonance is used to study the microwave spectrum of the perturbing or ‘dark’ state. The observed dark-state K-doublet asymmetry splittings and rotational-state selection rules indicate that the perturbing state has five quanta of excitation in the torsional mode (ν 21) built upon the A″ ν 19 fundamental. The precise frequency determined for 5 β 21 of 421(2) cm −1 leads to the first accurate determination of the barrier to CF 3 internal rotation as 641(5) cm −1. In contrast to the 963.4 cm −1 vibration, the 980.2 and 1025.2 cm −1 modes show a large number of J′ and Ka′ perturbations which differentially affect the A and E symmetry internal-rotor states. The magnitude of the perturbation-induced A/E splittings indicate that the perturbing states must have at least four quanta of torsional excitation. The present results suggest that high-order vibrational interactions are important in the vibrational dynamics of molecules at low levels of overall vibrational excitation. 相似文献
10.
The gas-phase stabilities of cluster ions SF +m (SF 6) n with m = 0−5 were determined by using a high pressure mass spectrometer. The bond energies of SF +m (SF 6) 1 were found to be less than 10 kcal/mol and to decrease with m = 0 → 5. There appear to be rather large gaps in the bond energies between n = 1 and 2 for the clusters SF +m (SF 6) n with m = 0−4. The structures of SF +5, SF + (SF 6) 1, SF +3 (SF 6) 1, and SF +5 (SF 6) 1 were investigated by ab initio molecular orbital calculations. For SF +5, the D3h geometry is found to be most stable and C4v is a transition state of the Berry pseudorotation. For the ion-molecule complexes, the “on-top hat” models were found to be the most stable structures. 相似文献
11.
139La-NMR chemical shifts were measured for several anionic complexes of formulae Li(C 4H 8O 2) 3/2 [La(ν 3-C 3H 5) 4], [Li(C 4H 8O 2) 2][Cp′ nLa(ν 3-C 3]H 5) 4−n] (Cp′ = Cp(ν 5-C 5H 5); n = 1, 2 and Cp′ = Cp * (ν 5-C 5Me5); N = 1) and Li[R nLa(ν 3-C 3H 4) 4− n] (R = N(SiMe 3) 2; n = 1, 2 and R = CCsIMe 3; n = 4), as well as for neutral compounds for formulae La(ν 3-C 3H 5) 3L n (L = (C 4H 8O 2) 1.5, (HMPT) 2, TMED), Cp′ nLa(ν 3-C 3H 5) 3−n (Cp′= Cp(ν 5-Cp 5H 5), Cp *(ν 5-C 5Me 5); n = 1, 2) and La(ν 3-C 3H 2) 2X(THF) 2 X = Cl, Br, I). Typical ranges of the 139La-NMR chemical shifts were found for the different types of complex independent of number and kind of organyl groups directly bonded to lanthanum. Zusammenfassung139La-NMR-Spektroskopie wurde an einer Reihe anionischer Allyllanthanat(III)-Komplexe der Zusammensetzung
]- [La)ν3-C3H5)4, [Li(C4H8)2][Cp′nLa(ν3-C3H5)4−n(Cp′ = Cp(ν5-C5H5); n = 1, 2 und Cp′ = Cp * (ν5-C5Me5); N = 1) und Li[RnLa(ν3-C3H5)4−n (R = B(SiMe3)2; n = 1, 2 und R = CCSiMe3; n = 4 sowie neutraler Allyllanthan(III)-Komplexe der Zusammensetzung La(ν3-C3H5)3Ln (Ln = (C4H8O2)1.5, (HMPT)2, TMED), Cp′n, La(ν3-C3H5)3−n (Cp′ = Cp(ν5-C5H5), Cp * (ν5- Cp5Me5); n = 1, 2) und La(ν3-Cp3H5)2X(THF)2 (X = Cl, Br, I) durchgefürt. In Abhängikeit von der Anzahl und der Art der am Lanthan gebundenen Gruppen wurden für die verschieden Komplextypen charakteristische Resonanzbereiche ermittelt. 相似文献
12.
The spectrum of CD 2HF was measured by high-resolution interferometric Fourier-transform IR (FTIR) spectroscopy (apodised instrumental band with:0.004 cm −1 fwhm) between 800 and 1200 cm −1 covering the four lowest fundamentals. A complete rotational analysis using a semi-automatic assignment procedure yields accurate band centres (ν 9: 912.2028 cm −1, ν 6:964.4994 cm −1, ν 5: 1050.5104 cm −1, ν 4: 1093.8632 cm −1) and a complete set of first-order Coriolis coupling constants. The most important couplings occur between ν 9 and ν 6 (ξ a= 1.069 cm −1, ξ c= −0.3535 cm −1) and between ν 5 and ν 4 (ξ b= −0.80606 cm −1). The analysis was guided by and compared with results from our ab initio calculations for Coriolis constants and transition moments using CADPAC at TZP/MP2 level. 相似文献
13.
Four novel tetranuclear macrocyclic complexes of the formula [(CuL i) 3Fe](ClO 4) 3·3H 2O ( i=1–4, L i are the dianions of the [14]N 4 and [15]N 4 macrocyclic oxamides, namely 2,3-dioxo-5,6:13,14-dibenzo-7,12-bis(ethoxycarbonyl)-1,4,8,11-tetraazacyclotetradeca-7,11-diene, 2,3-dioxo-5,6:13,14-dibenzo-9-methyl-7,12-bis(ethoxycarbonyl)-1,4,8,11-tetraazacyclotetradeca-7,11-diene and 2,3-dioxo-5,6:14,15-dibenzo-7,13-bis(ethoxycarbonyl)-1,4,8,12-tetraazacyclotetradeca-7,12-diene] have been prepared and characterized. These complexes are the first examples of oxamido-bridged Cu(II)–Fe(III) heterometallic species. Cryomagnetic studies on [(CuL 1) 3Fe](ClO 4) 3·3H 2O (1) and [(CuL 3) 3Fe](ClO 4) 3·3H 2O (3) (77–300 K) revealed that the Cu(II) and Fe(III) ions interact antiferromagnetically through the oxamido bridge, with the exchange integral J=−30.8 cm −1 for 1 and J=−28.7 cm −1 for 3 based on
. The interaction parameters have been compared with that of the related [Cu 3Mn] compound. 相似文献
14.
The profiles of the parallel and perpendicular bands ν 6 and ν 10 of allene in CS 2 and their temperature dependence have been studied. These profiles are sensibly lorentzian and consequently allow us to derive the components D and D of the rotational diffusion tensor and the corresponding activation energies; the accuracy of the results is discussed. In particular, it is not possible to determine unambiguously whether the activation energies U| and U are equal or different but, whichever the case, the ratio D/ D is of the order of 10. An application test of the extended J rotational diffusion model shows that the results concurrently obtained for the ν 6 and ν 10 bands are incompatible with this model and we come to the conclusion that the rotation of allene about its various axes is anisotropic. 相似文献
15.
The relative stabilities of thiourea in water are investigated computationally by considering thiourea–water complexes containing up to 1–6 water molecules (CS(NH 2) 2(H 2O) n=1–6) using density functional theory and MP2 ab initio molecular orbital theory. The results show that the thiourea complex is stable and has an unusually high affinity for incoming water molecules. The clusters are progressively stabilized by the addition of water molecules, as indicated by the increasing of the binding energy. The binding energy of the cluster to each H 2O molecule is about 33 kJ mol −1 for n=1–5.The C–S bond, N–C bond distance, Mulliken populations and binding energy keep approximately constant as the clusters increase in size with an increasing number of H 2O molecules. As the solvation progresses, the C–S distance increases monotonically while the Mulliken populations on the C–S bond reduces monotonically with the addition of each H 2O molecule, indicating that the C–S bond of the thiourea unit in the clusters is de-stabilized with an increasing number of H 2O molecules. Charge transfers for the clusters are mainly found at N, S atoms of the thiourea. 相似文献
16.
The convergence of ab initio calculations of the beryllium dimer potential is examined with several basis sets orders of perturbation theory. When the atomic pair natural orbital basis set calculations are extrapolated to the complete basis set and full CI limits, the calculated parameters: Re=2.447 Å, De=827 cm −1, ν 01=212.7 cm −1, ν 12=167.2 cm −1, ν 23=121.5 cm −1 and ν 34=77.7 cm −1 are in good agreement with the experimental parameters: Re=2.45 Å, De=839±10 cm −1, ν 01=223.2 cm −1, ν 12=169.7 cm −1, ν 23=122.5 cm −1, and ν 34=79 cm −1. 相似文献
17.
Variable temperature (−105 to −150 °C) studies of the infrared spectra (3500–400 cm −1) of 1,1-dimethylhydrazine, (CH 3) 2NNH 2, in liquid krypton have been carried out. No convincing spectral evidence could be found for the trans conformer which is expected to be at least 600 cm −1 less stable than the gauche form. The structural parameters, dipole moments, conformational stability, vibrational frequencies, and infrared and Raman intensities have been predicted from MP2/6-31G(d) ab initio calculations. The predicted infrared and Raman spectra are compared to the experimental ones. The adjusted r0 parameters from MP2/6-311+G(d,p) calculations are compared to those reported from an electron diffraction study. The energy differences between the gauche and trans conformers have been obtained from MP2 ab initio calculations as well as from density functional theory by the B3LYP method calculations from a variety of basis sets. All of these calculations indicate an energy difference of 650–900 cm −1 with the B3LYP calculations predicted the larger values. The potential function governing the conformational interchange has been predicting from both types of calculations and comparisons have been made. The barrier to internal rotation by the independent rotor model of the inner methyl group is predicted to have a value of 1812 cm −1 and that of the outer one of 1662 cm −1 from ab initio MP2/6-31G(d) calculations. These values agree well with the experimentally determined values of 1852±16 and 1558±12 cm −1, respectively, from a fit of the torsional transitions with the coupled rotor model. For the coupled rotor model the predicted V′ 33 (sin 3τ 0 sin 3τ 1 term) value which ranged from 190 to 232 cm −1 is in reasonable agreement with the experimental value of 268±3 cm −1 but the predicted V33 (cos 3τ 0 cos 3τ 1 term) value of −73 to −139 cm −1 is 25% smaller and of the opposite sign of the experimental value of 333±22 cm −1. These theoretical and spectroscopy results are compared to similar quantities of some corresponding molecules. 相似文献
18.
A novel tetranuclear terbium(III) complex [Tb 4(OH) 4(pybet) 6(H 2O) 8][Tb 4(OH) 4(pybet) 6(H 2O) 7 (NO 3)](ClO 4) 14·6H 2O has been synthesized and shown by X-ray crystallography to have a cubane-like Tb 4(μ 3-OH) 4(μ 2-carboxylato-O,O′) 6 core. The ligand pybet is pyridinoacetate, C 5H 5+N-CH 2CO 2−. Magnetic susceptibility data were measured for this Tb 4 complex in the range of 2.0–320 K and in fields of 1.0 G to 50.0 kG. It is concluded that either there is very weak antiferromagnetic exchange interaction ( J = −0.015 cm −1) or there is a small crystal-field splitting of the 7F 6 Tb III ground state. 相似文献
19.
The influence of intramolecular hydrogen bonding on the photodissociation of cis-HONO is probed via measurements on the OH fragment ejected by specific ---N=0 stretching (ν 2) vibrational levels of the à state. Due to hydrogen bonding between the H atom and the terminal oxygen, the ν 2 motion is coupled to the in-plane HON bend ν 3. Since the latter evolves into fragment rotation, the rotational energy and anisotropy of the OH product increases with the number of ν 2 quanta. By contrast, ν 2 in trans HONO is a relatively isolated ---N=O vibration and thus does not influence the OH photofragment's properties. 相似文献
20.
The IR polarized spectra of gypsum CaSO 4·2H 2O were recorded at incidence angles of approximately 10 and 16 degrees. Band singlet or doublet was observed for the higher frequency ν 3(SO 42−) mode of Bu symmetry type, depending on polarization ( n or p). A doublet was observed for the lower frequency ν 3(SO 42−) mode of Bu symmetry type too, irrespectively of the type of polarization. In order to give an explanation for the doublets origin, a model permittivity function was constructed. Quite good agreement exists between the reflectance based on the model permittivity function and the experimentally measured one for the high-frequency doublet. The origin of the lower frequency doublet could not be explained in this way, but may be speculated to result from an Evans type interaction between a combination of a water libration and ν 2(SO 42−), with the lower frequency ν 3(SO 42−) mode. 相似文献
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