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The isoelectronic molecules UN and UO+ are known to have Ω = 3.5 and Ω = 4.5 ground states, respectively (where Ω is the unsigned projection of the electronic angular momentum along the internuclear axis). A ligand field theory model has been proposed to account for the difference [Matthew and Morse, J. Chem. Phys. 138, 184303 (2013)]. The ground state of UO+ arises from the U3+(5f3(4I4.5))O2− configuration. Owing to the higher nominal charge of the N3− ligand, the U3+ ion in UN is stabilized by promoting one of the 5f electrons to the more polarizable 7s orbital, reducing the repulsive interaction with the ligand and rendering U3+(5f27s(4H3.5))N3− the lowest energy configuration. In the present work, we have advanced the characterization of the UN ground state through studies of two electronic transitions, [18.35]4.5-X(1)3.5 and [18.63]4.5-X(1)3.5, using sub-Doppler laser excitation techniques with fluorescence detection. Spectra were recorded under field-free conditions and in the presence of static electric or magnetic fields. The ground state electric dipole moment [μ = 4.30(2) D] and magnetic ge-factor [2.160(9)] were determined from these data. These values were both consistent with the 5f27s configurational assignment. Dispersed fluorescence measurements were used to determine vibrational constants for the ground and first electronically excited states. Electric dipole moments and magnetic ge-factors are also reported for the higher-energy electronically excited states. [ABSTRACT FROM AUTHOR]

Properties of gas-phase thorium nitride, ThN, have been experimentally determined from a combined optical and microwave spectroscopic study. An intense band near 555 nm has been assigned as the [18.0]1.5–X2Σ+ (0,0) transition and recorded at high resolution in the presence of static electric and magnetic fields. The observed optical Stark shifts were analyzed to determine permanent electric dipole moments, μ → e l for the [18.0]1.5 and X2Σ+ states of 4.38 ± 0.02D and 5.11 ± 0.09D, respectively. Zeeman shifts were used to determine the magnetic g-factors. The pure rotational spectrum was recorded using a separated field optical pump/probe microwave repopulation scheme and analyzed to determine the bond length and 14N magnetic hyperfine and nuclear electric quadrupole parameters. A molecular orbital correlation diagram and ligand field electronic structure models are used to provide a qualitative interpretation of the electronic state ordering, magneto- and electro-static properties, and hyperfine interactions. Electronic structure calculations for the X2Σ+ state were performed, and results were compared with observations. Observed trends in μ → e l for the ThX (X = N, S, O, F, and Cl) series are discussed. [ABSTRACT FROM AUTHOR]

The B2Σ- - X2Π3=2(0, 0) bands of a cold molecular beam sample of gold monoxide, AuO, and gold monosulfide, AuS, have been recorded at high resolution both field free and in the presence of a static electric field. The observed electric field induced splittings and shifts were analyzed to produce permanent electric dipole moments, μ⃗el , of 2.94 ± 0.06 D and 2.22 ± 0.05 D for theX2 Π3/2(v = 0) states ofAuOand AuS, respectively.Amolecular orbital correlation diagram is used to rationalize the trend in ground state μ⃗el values forAuX(X = F, Cl, O, and S) molecules. The experimentally determined μ⃗el are compared to those computed at the coupled-cluster singles and doubles (CCSD) level augmented with a perturbative inclusion of triple excitations (CCSD(T)) level of theory. [ABSTRACT FROM AUTHOR]

A number of low-rotational lines of the E4Δ7/2←X4Δ7/2 (1,0) band system of cobalt monoxide, CoO, were recorded field free and in the presence of a static electric field. The magnetic hyperfine parameter, h7/2, and the electron quadrupole parameter, eQq0, for the E4Δ7/2(υ = 1) state were optimized from the analysis of the field-free spectrum. The permanent electric dipole moment, ̄μel, for the X4Δ7/2 (υ = 0) and E4Δ7/2 (υ = 1) states were determined to be 4.18 ± 0.05 D and 3.28 ± 0.05 D, respectively, from the analysis of the observed Stark spectra of F' = 7←F" = 6 branch feature in the Q(7/2) line and the F' = 8←F" = 7 branch feature in the R(7/2) line. The measured dipole moments of CoO are compared to those from theoretical predictions and the trend across the 3d-metal monoxide series discussed. [ABSTRACT FROM AUTHOR]

The (1,0) [17.9]2.5-X2Δ3/2 band of hafnium monofluoride (HfF) has been recorded using high-resolution laser-induced fluorescence spectroscopy both field-free and in the presence of a static electric field. The field-free spectra of 177HfF, 179HfF, and 180HfF were modeled to generate a set of fine and hyperfine parameter for the X2Δ3/2(v = 0) and [17.9]2.5 (v = 1) states. The observed optical Stark shifts for the 180HfF isotopologue were analyzed to produce the molecular frame electric dipole moments of 1.66(1) D and 0.419(7) D for the X2Δ3/2 and [17.9]2.5 state, respectively. Both the generalized effective core potential and all-electron four component approaches were used in ab initio calculations to predict the properties of ground state HfF including equilibrium distance, dipole moments, quadrupole coupling, and magnetic hyperfine constants. [ABSTRACT FROM AUTHOR]

The [11.9]Ω = 3/2 ← X 2Π3/2(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 19F(I = 1/2) and 195Pt(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, μvector el, of 2.47(11)D and 3.42(6)D for the [11.9]Ω = 3/2 and X 2Π3/2states, respectively. The observed trend in μvector el for the PtX (X = C,N,O,S and F) series is discussed and a comparison with IrF made. [ABSTRACT FROM AUTHOR]

The laser induced fluorescence spectra of the 206Ã1A′′-X1A′ band of a rotationally cold (<20 K) molecular beam sample of chloro-methylene, HCCl, has been recorded, field-free and in the presence of a static electric field. The field-free spectrum has been analyzed to produce an improved set of spectroscopic parameters for the Ã1A′′ (060) vibronic state. The magnitude of the a-component of the permanent electric dipole moment, μa, for the X1A′ (000) vibronic state has been determined to be 0.501(1) D from the analysis of the observed electric field induced shifts. Comparisons with theoretical predictions and flouro-methylene, HCF, are presented. [ABSTRACT FROM AUTHOR]

The B1A′′(000)←X1A′(000) band system of a cold beam of CuOH has been studied field-free and in the presence of a static electric field. The Stark tuning of the low-J levels of the X1A′(000) state were analyzed to give a value of 3.968(32) D for the a-component of the permanent electric dipole moment, μa. An upper limit of 0.3 D for μa(B1A′′) is established from the lack of observable Stark tuning for the low-J levels of the B1A′′(000) state. The experimental value for μa(X1A′) is compared to theoretical predictions and other Cu-containing molecules. A molecular orbital correlation diagram is used to rationalize the large change in μa upon excitation. The electronegativity of OH was determined to be 2.81 from a comparison of the determined μa with the experimental μ values for CuF, CuO, and CuS. [ABSTRACT FROM AUTHOR]

The P(5) branch features of the A 3[uppercase_phi_synonym]4←X 3[uppercase_phi_synonym]4 (1,0) band near 628.2 nm of a molecular beam of iridium monofluoride, 193IrF, were recorded field free and in the presence of a static electric field. The 193Ir (I1=3/2) and 19F (I2=1/2) hyperfine interactions in the A 3[uppercase_phi_synonym]4 (υ=1) and X 3[uppercase_phi_synonym]4 (υ=0) states were analyzed. The permanent electric dipole moments, μvector el, for the A 3[uppercase_phi_synonym]4 (υ=1) and X 3[uppercase_phi_synonym]4 (υ=0) states were determined to be 1.88(5) and 2.82(6) D, respectively, from the analysis of the observed Stark shifts. A comparison of the electric dipole moments for IrC, IrN, and CoF is presented. [ABSTRACT FROM AUTHOR]

A number of low-rotational lines of the A 2Σ-←X 2Π3/2(0,0) subband of a molecular beam of copper monoxide, CuO, were recorded field free and in the presence of a static electric field. A set of optimized fine and hyperfine parameters for the A 2Σ-(υ′=0) state was produced from the analysis of the field-free spectrum. The permanent electric dipole moments μ for the A 2Σ-(υ=0) and X 2Π3/2(υ=0) states were determined to be 1.12(71) and 4.57(3) D, respectively, from the analysis of the observed Stark shifts. The error of the experimentally determined μ value for the X 2Π3/2(υ=0) state is approximately ten times less than that for the previously determined value: μ=4.45(30) D [T. C. Steimle et al., J. Chem. Phys. 87, 5670 (1987)]. The experimental μ values are compared with theoretical predictions. [ABSTRACT FROM AUTHOR]

The low-rotational levels of the b 3Π-X 1∑+(0,0) band of copper monofluoride, CuF, were recorded field free and in the presence of a static electric field. The field-free spectrum was analyzed to produce a refined set of fine and hyperfine parameters for the b 3Π(v=0) state. The permanent electric dipole moment, μ, for the b 3Π(v=0) and X 1∑+(v=0) states were determined to be 2.36(2) and 5.26(2) D, respectively, from the analysis of the observed Stark shifts. The experimental μ values are compared to theoretical predictions. The change in μ upon excitation and the hyperfine parameters are discussed in terms of the proposed electronic configuration for the b 3Π and X 1∑+ states. The optical Stark spectroscopy of the A 2Π3/2-X 2∑+(0,0) subband of YO was also recorded and analyzed to precisely calibrate the electric field strength. The determined μ values are 3.714(5) and 4.542(40) D for the A 2Π3/2(v=0) and X 2∑+(v=0) states, respectively. [ABSTRACT FROM AUTHOR]

The sub-Doppler laser induced fluorescence spectra of numerous branch features in the B 2Σ+-X 2Σ+(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 2Σ+(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 2Σ+(v=0) and X 2Σ+(v=0) states, respectively. The permanent electric dipole moment for the X 2Σ+(v=0) state of CaH is estimated to be 2.53(3) D. [ABSTRACT FROM AUTHOR]

Numerous branch features in the (0,0) [12.0] Ω=2←X³Λ[sub 3] and (0,0) [13.1] ³Φ[sub 4] ←X³A[sub 3] band systems of the iron monocarbide, FeC, have been studied using optical Stark spectroscopy. The electric field induced splittings in the high resolution laser induced fluorescence spectra were analyzed to produce values for the permanent electric dipole moments, μ, of 4.02(6) D, 4.44(6) D, and 2.36(3) D for the [12.0] Ω=2, [13.1] ³Φ[sub 4], and X³Λ[sub 3] states, respectively. A comparison with other iron containing molecules and theoretical predictions is made. [ABSTRACT FROM AUTHOR]

We have observed and measured seven microwave transitions in D2+, which are vibration–rotation components of the 2pσu–1sσg electronic band system. We also report two microwave rotational components involving the 1sσ v=21 level of HD+, which lies close to the first dissociation limit. Our experiments use ion beam techniques in which state selection is achieved by electric field dissociation. The techniques and theory of electric field dissociation are discussed, and fragment ion kinetic energy spectra described. Ab initio calculations of the transition frequencies for both D2+ and HD+ are in excellent agreement with experiment, and the hyperfine structure of the rotational transitions in HD+ confirms previous demonstrations of the increasing asymmetry in the electron distribution as the dissociation limit is approached. The electronic transition in D2+ which involves the highest bound level of the ground state shows an unexpected hyperfine splitting, which is interpreted in terms of g/u symmetry breaking by the deuteron Fermi contact interaction. [ABSTRACT FROM AUTHOR]

Abstract: The (000)← (000) system of a cold beam of barium hydroxide, BaOH, has been studied field-free and in the presence of a static electric field. Stark tuning of the low-J branch features in the (000)← (000) transition were analyzed to give permanent electric dipole moments, μ, for the (000) and (000) states of 0.477(7) D and 1.43(4) D, respectively. The results are compared with other alkaline earth monohydroxides and values predicted using an electrostatic polarization model and ligand field theory. [Copyright &y& Elsevier]

The A ²Π-X ²Σ+ (0,0) band system of barium monofluoride (BaF) has been recorded using high-resolution laser-induced fluorescence spectroscopy both field-free and in the presence of static magnetic and electric fields. The field-free spectra for the 135BaF, 137BaF, and 138BaF isotopologues were modeled to generate an improved set of spectroscopic constants for the A ²Π(υ=0) and X ²Σ+(υ=0) states. The observed optical Stark shifts for the 138BaF isotopologue were analyzed to produce the permanent electric dipole moments of 1.50(2) and 1.31(2) D for the A ²Π½(υ=0) and A ²Π3/2 (υ=0) states, respectively. The observed optical Zeeman shifts for the 138BaF isotopologue were analyzed to produce a set of magnetic g factors for the A ²Π(υ=0) and X ²Σ+(υ=0) states. [ABSTRACT FROM AUTHOR]

The [17.6]2← X3Δ1(1,0) band of tungsten monocarbide, WC, was recorded using laser induced fluorescence both field-free and in the presence of a static electric field. The Stark induced shifts of the R(1) and Q(2) lines were analyzed to produce values for the permanent electric dipole moments, μ, of 3.90 ± 0.04 D and 2.57 ± 0.04 D for the X3Δ1(v = 0) and [17.6]2(v = 1) states, respectively. An upper limit to the Ω-doubling parameter, õΔ, of 2 MHz is established. The 183W(I = 1/2) Fermi contact parameter, bF, for the X3Δ1(v = 0) is estimated to be 1363 MHz. The results are compared with theoretical predictions and a molecular orbital correlation description. [ABSTRACT FROM AUTHOR]