The permanent electric dipole moments and magnetic g factors of uranium monoxide

Permanent electric dipole moments and magnetic g factors for uranium monoxide (UO) have been determined from analyses of optical Stark and Zeeman spectra recorded at a spectral resolution that approaches the natural linewidth limit. Numerous branch features in the previously characterized [L. A. Kaledin et al., J. Mol. Spectrosc. 164, 27 (1994)] (0,0) [18403]5-X(1)4 and (0,0) [18404]5-X(1)4 electronic transitions were recorded in the presence of tunable static electric (Stark effect) or magnetic (Zeeman effect) fields. The lines exhibited unusually large Zeeman tuning effects. A ligand field model and an ab initio electronic structure calculation [R. Tyagi, Ph.D. thesis, The Ohio State University (2005)] were used to interpret the ground state properties. The results indicate that the low energy electronic states of UO are sufficiently ionic for the meaningful application of ligand field theory models. The dipole moments and g factors were distinctly different for the three electronic states examined, which implies that these properties may be used to deduce the underlying electronic state configurations.     

Communication: The permanent electric dipole moment of thorium monoxide, ThO

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.     

The permanent electric dipole moments of WN and ReN and nuclear quadrupole interaction in ReN

The high-resolution laser induced fluorescence spectra of tungsten mononitride WN and rhenium mononitride ReN have been recorded in a laser ablation/molecular beam spectrometer. The field free spectrum of the (0,0)A (4)Pi(3/2)-X (4)Sigma(1/2) (-) band system of (186)WN has been analyzed to produce B("), B('), and gamma(") values of 0.4659(2), 0.4554(2), and 0.0518(1) cm(-1), respectively. The permanent electric dipole moments mu for the X (4)Sigma(1/2) (-) and A (4)Pi(3/2) state were determined to be 3.77(18) and 2.45(3) D, respectively, from the analysis of the optical Stark effect. The (0,0)[26.0]0(+)-X0(+) band system of ReN was recorded in the presence of a variable static electric field. The ground and excited state electric dipole moments of (187)ReN were determined to be mu(X0(+))=1.96(8) D and mu([26.0]0(+))=3.53(4) D. Splittings in the field free (187)ReN spectrum were analyzed to produce (187)Re (I=5/2) nuclear electric quadrupole coupling constants e(2)Qq(0) of -0.0304(8) and 0.0328(9) cm(-1) for the X0(+) and [26.0]0(+) states, respectively. A molecular orbital correlation model is used to interpret the observation and a comparison is made to CrN and MoN.     

The permanent electric dipole moment of chromium monodeuteride, CrD

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.     

The permanent electric dipole moment of calcium monodeuteride

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.     

A theoretical study of calcium monohydride, CaH: low-lying states and their permanent electric dipole moments

Potential energy curves, energy parameters, and spectroscopic values for the X (2)Sigma(+), A (2)Pi, B (2)Sigma(+), a (4)Pi, and b (4)Sigma(+), states of CaH have been calculated using the multireference configuration interaction and coupled cluster levels of theory, while employing quantitative basis sets (of augmented quintuple-zeta quality) and taking also into account core/valence correlation and one-electron relativistic effects. For the ground (X (2)Sigma(+)) and the first two following excited states (A (2)Pi, B (2)Sigma(+)) of CaH, the permanent electric dipole moments have been calculated. Our best finite field dipole moment of the A (2)Pi state of 2.425 D (upsilon = 0) is in very good agreement with the experimental literature value of 2.372(12) D. However, a discrepancy is observed in the dipole moment of the X (2)Sigma(+) state. Our most extensive calculation gives mu = 2.623 D (upsilon = 0), which is considerably smaller than the experimental value of mu = 2.94(16) D (upsilon = 0). Small van der Waals minima were found for both "repulsive" quartet states. Spectroscopic constants and energy parameters for all states are in remarkable agreement with available experimental values.     

An upper bound to bond electric dipole moments

An upper bound can be set to the dipole moment of the X-H bond (with X+H^– polarity) for symmetrical molecules of XH₄ and XH₃ type from the experimental values of the g factor and bond length. The following upper bounds have been found to the bond dipole moments: CH₄ (C+H^–<0.902 D, SiH₄, (Si+H^–)<4.21 D, GeH₄+ (Ge+H^–)<3.59 D, NH₃ (N+H^–)<0, PH₃ (P+H^–)<2.74 D. These results enable one to rule out certain published data on the dipole moment of the C-H bond in methane as certainly incorrect. In the case of the ammonia molecule, the possibility of N+H^– polarity is ruled out.Translated from Teoreticheskaya i Éksperimental'naya Khitniya, No. 3, pp. 346–350, May–June, 1985.     

Local electric dipole moments: A generalized approach

We present an approach for calculating local electric dipole moments for fragments of molecular or supramolecular systems. This is important for understanding chemical gating and solvent effects in nanoelectronics, atomic force microscopy, and intensities in infrared spectroscopy. Owing to the nonzero partial charge of most fragments, “naively” defined local dipole moments are origin‐dependent. Inspired by previous work based on Bader's atoms‐in‐molecules (AIM) partitioning, we derive a definition of fragment dipole moments which achieves origin‐independence by relying on internal reference points. Instead of bond critical points (BCPs) as in existing approaches, we use as few reference points as possible, which are located between the fragment and the remainder(s) of the system and may be chosen based on chemical intuition. This allows our approach to be used with AIM implementations that circumvent the calculation of critical points for reasons of computational efficiency, for cases where no BCPs are found due to large interfragment distances, and with local partitioning schemes other than AIM which do not provide BCPs. It is applicable to both covalently and noncovalently bound systems. © 2016 Wiley Periodicals, Inc.     

Effects of permanent dipole moments in transient four-wave mixing experiments

A two-pulse degenerate four-wave mixing experiment is analyzed in the case where the medium under investigation can be modeled by two-level systems having unequal permanent dipole moments. By modeling the light pulses by double exponentials [exp(-Gamma/t/)], we give an analytical expression of the third-order nonlinear polarization of the medium. We apply this result to simulate the measured signal in such experiment. We show that in the case of a two-photon transition, a signal can be detected if the pump pulse interacts with the medium before the probe pulse contrary to what is observed for excitations in the resonance region. An attempt to explain this behavior is made and the detected signal is analyzed in terms of pure coherent processes. This effect appears as a signature of the presence of permanent dipole moments. To test this property on a more realistic system, we then have considered a one-dimensional frequency-selected infrared degenerate four-wave mixing experiment on a molecular anharmonic vibrational mode modeled by a Morse potential and coupled to a dissipative bath of harmonic oscillators. We show that the two-photon transitions allowed by the presence of permanent dipole moments enable to analyze the multilevel system dynamics as if they were the one of a two-level system. Our results can also be extended to the case of inhomogeneous broadening and are of interest to study the infrared photon-echo response of anharmonic vibrational modes.     

Theoretical calculation of electric dipole moments for conjugated systems

A detailed survey has been made of the potentialities of the VESCF molecular orbital procedure for computing electric dipole moments of conjugated molecules. Forty-one molecules, ranging from non-alternant hydrocarbons to a wide variety of heterocycles and benzene derivatives have been studied. The agreement between theory and experiment is always within 0.4 D and notably better than has been achieved by any alternative theoretical procedure so far. Some assessment is made of the relative merits of alternative techniques for dealing with neutral-atom penetration integrals and with two-electron coulomb integrals. Comments are made on the contributions of -bond polarities and of hydrogen atom hybridization moments.The possibility that the present procedure for treating heterocyclic oxygen is less satisfactory than for nitrogen is indicated, the molecules showing greatest deviations from experiment being oxygen heterocycles.The present study points up the fact that for some of the key molecules studied the experimental values are of uncertain reliability or, occasionally, not yet available.

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Zusammenfassung Im Rahmen der VESCF-Methode sind die Dipolmomente von 41 Molekülen mit konjugierten Systemen berechnet worden, beginnend mit nicht alternierenden Kohlenwasserstoffen bis zu einer Reihe von Heterocyclen und Benzolderivaten. Theorie und Experiment stimmen in den meisten Fällen bis auf 0.4 D — und damit wesentlich besser als bei den meisten bisherigen Verfahren — überein. Einige Bemerkungen in bezug auf die Vorteile einzelner Methoden, Durchdringungs- und Coulombintegrale zu behandeln, auf den Beitrag der -Elektronen und der Wasserstoffhybridisierungsmomente werden zur Ergänzung gemacht.Die angewandte Methode scheint zur Behandlung von Heterosauerstoff weniger geeignet als für Stickstoff zu sein, da Moleküle mit Sauerstoff die größten Abweichungen vom Experiment zeigen. Andererseits zeigt sich, daß die experimentellen Werte für einige wichtige Moleküle zweifelhaft sind.

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Résumé Etude détaillée des possibilités de la méthode des orbitales moléculaires SCF à électronégativité variable pour le calcul des moments dipolaires électriques des molécules conjuguées. L'étude a porté sur quarante et une molécules s'étendant d'hydrocarbures non alternants jusqu'à une large classe de dérivés benzéniques et d'hétérocycles. L'accord entre la théorie et l'expérience est presque toujours à moins de 0,4 D, étant notablement meilleur que celui obtenu jusqu'alors par une autre technique. On établit en partie les mérites relatifs des différentes techniques d'utilisation des intégrales de pénétration et des intégrales coulombiennes. On fait des commentaires sur les contributions des polarités des liaisons et des moments d'hybridation de l'atome d'hydrogène.On mentionne la possibilité pour le présent procédé de traiter l'oxygène hétérocyclique d'une manière moins satisfaisante que l'azote, les heterocycles oxygénés étant les molécules présentant le plus grand désaccord avec l'expérience.Cette étude souligne le fait que pour certaines molécules clés les données expérimentales sont peu certaines sinon inexistantes.

     

The permanent electric dipole moment and hyperfine interactions in platinum monofluoride, PtF

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.     

Amine-hydrogen halide complexes: experimental electric dipole moments and a theoretical decomposition of dipole moments and binding energies

The Stark effect has been observed in the rotational spectra of several gas-phase amine-hydrogen halide complexes and the following electric dipole moments have been determined: H(3)(15)N-H(35)Cl (4.05865 +/- 0.00095 D), (CH(3))(3)(15)N-H(35)Cl (7.128 +/- 0.012 D), H(3)(15)N-H(79)Br (4.2577 +/- 0.0022 D), and (CH(3))(3)(15)N-H(79)Br (8.397 +/- 0.014 D). Calculations of the binding energies and electric dipole moments for the full set of complexes R(n)()(CH(3))(3)(-)(n)()N-HX (n = 0-3; X = F, Cl, Br) at the MP2/aug-cc-pVDZ level are also reported. The block localized wave function (BLW) energy decomposition method has been used to partition the binding energies into contributions from electrostatic, exchange, distortion, polarization, and charge-transfer terms. Similarly, the calculated dipole moments have been decomposed into distortion, polarization, and charge-transfer components. The complexes studied range from hydrogen-bonded systems to proton-transferred ion pairs, and the total interaction energies vary from 7 to 17 kcal/mol across the series. The individual energy components show a much wider variation than this, but cancellation of terms accounts for the relatively narrow range of net binding energies. For both the hydrogen-bonded complexes and the proton-transferred ion pairs, the electrostatic and exchange terms have magnitudes that increase with the degree of proton transfer but are of opposite sign, leaving most of the net stabilization to arise from polarization and charge transfer. In all of the systems studied, the polarization terms contribute the most to the induced dipole moment, followed by smaller but still significant contributions from charge transfer. A significant contribution to the induced moment of the ion pairs also arises from distortion of the HX monomer.     

Calculation of molecular electric polarizabilities and dipole moments. II. The LiH molecule

We use a variation–perturbation method to calculate the electric polarizabilities and the electric dipole moment of the LiH molecule. We obtain 4.455 for the perpendicular polarizability and 4.001 (×10^?24 cm³) for the parallel polarizability. Our result for the electric dipole moment at equilibrium nuclear distance is 5.866, which is in excellent agreement with the experimental value 5.828 debye units.     

The polar nature of 2,1,3-benzoxadiazole, -benzothiadiazole, -benzoselenadiazole and derivatives as determined by their electric dipole moments

Permanent electric dipole moments have been determined in benzene solutions at 25° for the oxygen, sulfur, and selenium series of 2,1,3-benzodiazoles. The derivatives studied contained 4, 5, and 6 substituted methyl, chloro, nitro, and amino groups. The dipole moment data of the derivatives were analyzed relative to that of the parent species which allowed deductions to be made about the mesomeric structures operating in the compounds. The mesomeric charge transfer increases regularly from the oxygen to the selenium structures, being nearly undetected in 2,1,3-benzoxadiazole derivatives and very pronounced in the 2,1,3-benzoselenadiazoles.