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The sub-Doppler laser induced fluorescence spectra of numerous branch features in the B 2Sigma+ -X 2Sigma+(0,0) band of calcium monodeuteride were recorded field-free and in the presence of a static electric field of up to 7 kV/cm. The field-free spectra were analyzed to produce an improved set of fine structure parameters for the B 2Sigma+(v=0) state. The observed electric field induced splittings and shifts were analyzed to produce permanent electric dipole moments of 2.57(3) and 2.51(3) D for B 2Sigma+(v=0) and X 2Sigma+(v=0) states, respectively. The permanent electric dipole moment for the X 2Sigma+(v=0) state of CaH is estimated to be 2.53(3) D. 相似文献
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M. Farjallah C. Ghanmi H. Berriche 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2012,86(8):1226-1235
The structure and spectroscopic properties of the alkaline hydride BeH2+ ion have been investigated using an ab initio approach based on nonempirical pseudopotentials and parameterized l-dependent polarization potentials. The adiabatic potential energy curves and their spectroscopic constants for the ground and seventeen excited electronic states, dissociating into Be+(2s, 2p, 3s, 3p, 3d, 4s, 4p, and 4d) + H+ and Be2+ + H(1s and n = 2), of 2??+, 2??, and 2?? symmetries have been determined. As no experimental data are available, our results are discussed and compared with the few existing theoretical calculations. A very good agreement has been found with the previous theoretical data for the ground state; however many potential energy curves for the higher excited states are presented here, for the first time. Numerous avoided crossings between electronic states for 2??+ and 2?? symmetries have been localized and analyzed. Their existence is related to the interaction between the electronic states and to the charge transfer process between the two ionic systems Be2+H and Be+H+. In addition, we have calculated the vibrational energy level spacings of the bound electronic states. Furthermore, the adiabatic transition dipole functions from the X 2??+ and 22??+ states to the higher excited states of 2??+ and 2?? symmetries have been evaluated and compared with the available theoretical work. This study represents the necessary initial step towards the investigation of the charge transfer processes in collision between Be+-H+ and Be2+-H. 相似文献
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Force constants and dipole moment derivatives were calculated for the symmetric stretching and asymmetric stretching and bending vibrational modes for the silane molecule. The orbital exponents of small basis sets of Slater orbitals were optimized for silane in several geometrical configurations. It was determined that the addition of d orbitals to the silicon basis set has negligible effect on the calculated properties. 相似文献
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In this work, we provide highly accurate theoretical estimates for spectroscopic constants of the ground-state alkaline-earth
dimers (Ca2, Sr2, and Ba2). Electron correlation energies are calculated with coupled-cluster method at the single, double, and noniterative triple
excitations [CCSD(T)] level, and the effects of full triples as well as quadruple excitations are also taken into account
at the CCSDT and the CCSDT(Q) level. Our results demonstrate that high-order electron correlation is important to achieve
results with high accuracy. We also find that results for Ca2 with counterpoise corrections, which are designed to eliminate the basis set superposition error, deviate further away from
those at the complete basis set limit than the uncorrected ones. The calculated binding energies and equilibrium bond lengths
for Ca2 and Sr2 are in excellent agreement with recent experimental data. On the other hand, our results for Ba2 are quite different from previous theoretical data, and there is no available experimental equilibrium bond length and binding
energy for calibration. Based on the performance of the adopted approach for Ca2 and Sr2, our results should be more reliable and could be helpful for future investigations. 相似文献
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The microwave spectrum of a second conformer of acrolein is reported for the first time. Ground-state rotational constants and quartic centrifugal distortion constants were determined from 42 transitions in the range 8–60 CHz. The small inertial defect establishes its planarity. The dipole moment of s-cis acrolein is μa = 2.010(5) D, μb = 1.573(3) D and μtotal = 2.552(3) D. 相似文献
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The optical Stark spectrum of the E(0(+)) - X(1)Σ(+) (1,0) band of thorium monoxide, ThO, was recorded and analyzed to determine the permanent electric dipole moments, μ, for the E(0(+)) (v = 1) and X(1)Σ(+) (v = 0) states. Values of 2.782 ± 0.012 D (X) and 3.534 ± 0.010 D (E) were obtained. The uncertainties are 2σ statistical error. The systematic errors are estimated to be less than 1%. The experimental results are used to access the quality of electronic structure calculations of the properties of the X(1)Σ(+) (v = 0) state. 相似文献
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Pentafluoropyridine has been analysed in the frequency range of 8 to 18 GHz at dry ice temperature, using a conventional 100 kHz Stark modulated microwave spectrometer. The rotational constants and centrifugal distortion constants are A = 1481.539 ± 0.003 MHz, B = 1075.348 ± 0.004 MHz and C = 623.101 ± 0.001 MHz; and dJ = ?0.39 ± 0.06 kHz, dJK = 1.86 ± 0.27 kHz, dK = 0.70 ± 0.1 kHz, dEJ = (0.3 ± 0.03) × 10?6 and dEK = (?1.5 ± 0.2) × 10?6. The electric dipole moment has been found to be 0.98 ± 0.08 D and the values of the quadrupole coupling constants are xaa = 1.94 ± 0.22 MHz, xbb = ?4.08 ± 0.06 MHz and xcc = 2.14 ± 0.22 MHz. A simple analysis based on Townes and Dailey theory points to a considerable increase in the π-electron density and excess charge on the nitrogen site. 相似文献
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The permanent dipole moment of para-amino benzoic acid has been calculated at various theoretical levels, including Hartree-Fock, second-order M?ller-Plesset perturbation (MP2), coupled cluster singles and doubles (CCSD), and triples corrections CCSD(T), and hybrid density functional theory at B3LYP level. It is found that the B3LYP method fails to provide correct results for the geometry and the permanent dipole moment. These results are significantly improved by MP2 calculations. Our best estimated dipole moments obtained at CCSD and CCSD(T) levels are in good agreement with experiment. 相似文献
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A number of low-N lines of the X (6)Sigma(+)<--A (6)Sigma(+)(0,0) band of chromium monodeuteride, CrD, have been recorded at near the natural linewidth limit by high resolution laser excitation spectroscopy of a supersonic molecular beam sample. The shifts and splitting of these lines caused by a static electric field have been analyzed to give the permanent electric dipole moments of the X (6)Sigma(+)(upsilon=0) and A (6)Sigma(+)(upsilon=0) states as 3.510(33) and 1.153(3) D, respectively. The dipole moment of the A (6)Sigma(+)(upsilon=0) state can be measured with higher precision because of some interesting near degeneracies in its level structure. The trends in the observed dipole moments for the first-row transition metal monohydrides are rationalized and compared with theoretical predictions. 相似文献
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The [11.9]Ω = 3∕2 ← X (2)Π(3∕2)(0,0) and (1,0) bands of platinum monofluoride, PtF, have been recorded field-free and in the presence of a static electric field. The (19)F(I = 1∕2) and (195)Pt(I = 1∕2) magnetic hyperfine interactions have been analyzed and compared with predicted values obtained using atomic information and a proposed molecular orbital correlation diagram. The optical Stark shifts were analyzed to produce the permanent electric dipole moments, μ?(el), of 2.47(11)D and 3.42(6)D for the [11.9]Ω = 3∕2 and X (2)Π(3∕2)states, respectively. The observed trend in μ?(el) for the PtX (X = C,N,O,S and F) series is discussed and a comparison with IrF made. 相似文献
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The J = 0 → 1 and J = 1 → 2 transitions of thirteen isotopic species of carbon monoxide-borane (BH3CO) have been measured. The heavy atom r2 structural parameters have been calculated in several ways so as to minimize the effects of the small carbon coordinate. The structural parameters found are: d(B-C) = 1.534 ± 0.01 Å, d(C-O)= 1.135 ± 0.01 Å. d(B-H)= 1.221 ± 0.001 Å, ∠HBC = 103.79 ± 0.06°, and ∠HBH = 114.50 ± 0.15°. In addition, a complete r0 structure has been calculated by least-squares fitting the moments of inertia of all the isotopic species. A dipole moment of 1.698 ± 0.02 D was determined. 相似文献
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By modifying the molecular dipole moments with lateral monofluorine substituent, improved mesophase stabilities were obtained for novel benzoxazole derivatives, 2-(4?-alkoxy-3-fluorobiphenyl-4-yl)-benzoxazole liquid crystals (coded as nPPF(3)Bx). The series of nPPF(3)Bx with lateral monofluorine substituent ortho to benzoxazole group have larger calculated dipole moments by about 2 D than the corresponding fluorine-substituted analogs (compounds I) with lateral monofluorine ortho to alkoxy group; it is interesting to note that they show lower melting and clearing points but better mesophase stability with wider mesophase ranges for the molecules with both polar (NO2, Cl) and nonpolar (CH3, H) terminal groups. Meanwhile, compounds nPPF(3)Bx show greater red-shifted photoluminescence emissions than compounds I, which suggest that π–π interaction between molecules is reinforced by the enhanced dipole–dipole interaction caused by increased dipole moments. These results suggest that modification of the molecular dipole moment is an effective method to improve the mesophase stability of the classical mesogenic compounds. 相似文献
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Ruthenium monofluoride, RuF, has been detected using low-resolution laser-induced fluorescence (LIF) in the visible and near infrared spectral regions. A visible band, designated as [18.2]5.5-X 4Phi(9/2), has been recorded field-free and in the presence of a static electric field using high-resolution LIF spectroscopy. The r0 internuclear distances for the [18.2]5.5 and X 4Phi(9/2) states were determined to be 1.911 and 1.916 A, respectively. The vibrational interval DeltaG(1/2) of 534(15) cm-1 for the X 4Phi(9/2) state was determined from the analysis of the dispersed LIF. The Stark shifts of the visible band were analyzed to produce permanent electric dipole moments of 1.97(8) and 5.34(7) D for the [18.2]5.5 and X 4Phi(9/2), states, respectively. The fluorine magnetic hyperfine structure associated with spectral features was analyzed. The hyperfine structure and dipole moments are interpreted using a molecular-orbital correlation model and compared with FeF and other ruthenium-containing molecules. 相似文献
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Stephen R. Langhoff Charles W. Bauschlicher Harry Partridge 《Chemical physics letters》1983,102(4):292-298
Theoretical X2II potentials and dipole moment functions for OF are presented at the CASSCF, externally contracted Cl, and MRCI(SD) levels using DZP and extended gaussian basis sets. The best theoretical results (with experiment in parentheses) are μν =0 = ?0.0089 (?0.0043) and μν=1 = ?0.0318 (?0.0267) D, where the minus sign implies O+F?. 相似文献
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《Chemical physics letters》1987,140(3):221-224
Stark effects were measured for the 212-101 (85 GHz) and 441-330 (266 GHz) transitions of cyclopropenylidene, C3H2 with a parallel-plate cell designed for transient molecules. From the least-squares analysis of the Stark shifts the dipole moment of C3H2 was determined to be 3.43(2) D, where the error is three standard deviations. The dipole moment obtained is in good agreement with predictions by ab initio calculations. 相似文献
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An experimental technique for detecting magnetic dipole allowed transitions by their dispersion-induced circular dichroism (DICD) is discussed. The DICD spectra of three nitrogen heterocycles (pyridine, pyrazine and tetraphenylporphyrin) are shown to be dominated by the n — π* transitions, as distinct from the normal absorption spectra which are dominated by the electric dipole allowed π — π* bands. 相似文献