Optical Stark and Zeeman Spectroscopy of Thorium Fluoride (ThF) and Thorium Chloride (ThCl).

Experimentally and theoretically determined magnetic and electric dipole moments, bond distances, and vibrational spacings are used for a comparative study of the bonding in ThF and ThCl. Numerous bands in the visible electronic spectra between 16 400 and 18 800 cm-1 of supersonically cooled molecular beam samples have been detected using medium-resolution (Δν ≈ 0.1 cm-1) 2D spectroscopy. High-resolution (Δν < 20 MHz) field-free, Stark, and Zeeman spectroscopy of the detected [18.6]Ω = 3/2 - X2Δ3/2 band of ThF near 538.4 nm and the [18.2]Ω = 3/2 - X2Δ3/2 band of ThCl near 551.0 nm have been recorded and analyzed. Stark shifts and splitting were analyzed to produce | µâƒ—el| values of 1.453(7) D and 0.588(9) D for the X2Δ3/2 and [18.6]Ω = 3/2 states of ThF, respectively, and 2.022(35) D and 3.020(55) D for the X2Δ3/2 and [18.2]Ω = 3/2 states of ThCl. Zeeman splittings and shifts were analyzed to produce ge values of 1.038(4) and 1.079(4) for the X2Δ3/2 and [18.6]Ω = 3/2 states of ThF and 1.130(4) and 1.638(4) for the X2Δ3/2and [18.2]Ω = 3/2 states of ThCl. Analysis of ge values demonstrates that the X2Δ3/2 and [18.6]Ω = 3/2 states of ThF and the X2Δ3/2 state of ThCl are predominately 2Δ3/2 spin-orbit components, whereas the [18.2]Ω = 3/2 state of ThCl is an admixture of 2Δ3/2 and 2Π3/2 spin-orbit components. A molecular orbital description of the ground states is used to rationalize the observed | µâƒ—el|values for the ThX (X = F, Cl, O, and S) series and garner insight into the bonding mechanism. The dipole moments in the ground state of ThF and ThCl have been calculated using relativistic coupled-cluster methods. It is demonstrated that the systematic inclusion of electron-correlation contributions plays an essential role in obtaining accurate predictions for the dipole-moment values in ThF and ThCl.

Characterization of the [18.28]0--a3Δ1 (0,0) band of tantalum nitride, TaN.

The [18.28]0--a3Δ1 (0,0) band near 647 nm of tantalum nitride, TaN, has been recorded and analyzed field-free and in the presence of static electric and magnetic fields. The fine and hyperfine parameters for the a3Δ1 and [18.28]0- states are determined. The 181Ta(I = 7/2) axial nuclear electric quadrupole coupling constant, eQq0, and the effective magnetic hyperfine coupling constant, h1, are used to garner insight into the nature of electronic states. The Stark tuning of the P(2) and Q(1) lines was analyzed to determine the molecular frame permanent electric dipole moment, µâ†’el, for the a3Δ1 state of 4.49 ± 0.09 D. The Zeeman effect on the P(1) line was analyzed to determine an upper limit of the magnetic moment, µâ†’m, for the a3Δ1 state. Scalar-relativistic coupled-cluster calculations for eQq0 and µâ†’el of the a3Δ1 state are also reported and compared with experimental results. The determined properties are compared with the predicted values and the implication of the proposed scheme for determination of the 181Ta magnetic quadrupole moment is discussed.

Optical Zeeman spectroscopy of the (0,0) B4Γ-X4Φ band systems of titanium monohydride, TiH, and titanium monodeuteride, TiD.

The Zeeman effect in the (0,0) bands of the B(4)Γ(5/2)-X(4)Φ(3/2) system of titanium monohydride, TiH, and titanium monodeuteride, TiD, has been recorded and analyzed. Magnetic tuning of the spectral features recorded at high resolution (full width at half maximum ≅ 35 MHz) and at a field strength of 4.5 kG is accurately modeled using an effective Zeeman Hamiltonian. The determined magnetic g-factors for the X(4)Φ(3/2) (v = 0) state deviate only slightly from those expected for an isolated (4)Φ(3/2) state whereas those for the B(4)Γ(5/2)(v = 0) deviate significantly from those of an isolated (4)Γ(5/2) state. The rotational dependence of the magnetic tuning in the B(4)Γ(5/2)(v = 0) state is attributed to perturbations from a nearby (4)Φ state.

Hyperfine interactions in the A3Φ4 and X3Φ4 states of iridium monofluoride, IrF.

Laser induced-fluorescence spectra of the 1-0 band of the A(3)Φ(4)-X(3)Φ(4) transition of iridium monofluoride, IrF, have been obtained at near natural linewidth resolution using supersonic molecular beam techniques. The spectra show a complex, clearly resolved hyperfine structure which has significant contributions from the magnetic and quadrupole hyperfine terms in (193)Ir and (191)Ir, both with I = 3/2, and the fluorine magnetic hyperfine term (I = 1∕2). The spectra of both (193)IrF and (191)IrF isotopologues have been assigned and analyzed. The hyperfine structure was interpreted with the aid of atomic hyperfine parameters, which were used to determine the configurational composition of the ground state and to estimate the individual molecular hyperfine parameters.

The electric dipole moment of iridium monofluoride, IrF.

The P(5) branch features of the A (3)Φ(4)←X (3)Φ(4) (1,0) band near 628.2 nm of a molecular beam of iridium monofluoride, (193)IrF, were recorded field free and in the presence of a static electric field. The (193)Ir (I(1)=3/2) and (19)F (I(2)=1/2) hyperfine interactions in the A (3)Φ(4) (υ=1) and X (3)Φ(4) (υ=0) states were analyzed. The permanent electric dipole moments, µ(el), for the A (3)Φ(4) (υ=1) and X (3)Φ(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.

Accurate analytic potentials for Li(2)(X (1)Sigma(g) (+)) and Li(2)(A (1)Sigma(u) (+)) from 2 to 90 A, and the radiative lifetime of Li(2p).

Extensions of the recently introduced "Morse/long-range" (MLR) potential function form allow a straightforward treatment of a molecular state for which the inverse-power long-range potential changes character with internuclear separation. Use of this function in a direct-potential-fit analysis of a combination of new fluorescence data for (7,7)Li(2), (6,6)Li(2), and (6,7)Li(2) with previously reported data for the A((1)Sigma(u) (+)) and X((1)Sigma(g) (+)) states yields accurate, fully analytic potentials for both states, together with the analytic "adiabatic" Born-Oppenheimer breakdown radial correction functions which are responsible for the difference between the interaction potentials and well depths for the different isotopologues. This analysis yields accurate well depths of D(e)=8516.709(+/-0.004) and 8516.774(+/-0.004) cm(-1) and scattering lengths of 18.11(+/-0.05) and 23.84(+/-0.05) A for the ground-states of (7,7)Li(2) and (6,6)Li(2), respectively, as well as improved atomic radiative lifetimes of tau(2p)=27.1018(+/-0.0014) ns for (7)Li(2p) and 27.1024(+/-0.0014) ns for (6)Li(2p).

The permanent electric dipole moments and magnetic g(e)-factors of praseodymium monoxide (PrO).

The R(4.5) and P(6.5) branch features of the XX (0, 0) band of praseodymium monoxide (PrO) have been studied at a resolution of approximately 50 MHz field free and in the presence of static electric and magnetic fields. The permanent electric dipole moments, mu(el), of 3.01(6) D and 4.72(5) D for the X(2) (Omega = 4.5) and [18.1] (Omega = 5.5) states, respectively, were determined from the analysis of the Stark spectra. The magnetic g(e)-factors of 4.48(8) and 5.73(6) for the X(2) (Omega = 4.5) and [18.1] (Omega = 5.5) states, respectively, were determined from the analysis of the Zeeman spectra. The g(e)-factors are compared with those computed using wave functions predicted from ligand field theory and ab initio calculations. The mu(el) value for the X(2) (Omega = 4.5) state is compared to ab initio and density functional predicted values and with the experimental values of other lanthanide monoxides.

Optical Zeeman spectroscopy of ytterbium monofluoride, YbF.

The Zeeman-induced shifts and splittings of low-J lines in the (O)P(12) branch of the (0,0) band of the A(2)Pi(1/2)-X(2)Sigma(+) electronic transition of a cold molecular beam sample of ytterbium monofluoride, YbF, have been recorded. The Zeeman spectra for the (171)YbF, (172)YbF, and (174)YbF isotopologues have been analyzed using a standard effective Hamiltonian approach. The magnetic g-factors determined for the A(2)Pi(1/2)(v = 0) state are rationalized using the predicted and observed electronic state distribution. The observed Zeeman tuning of the levels in the A(2)Pi(1/2)(v = 0) state is unexpectedly large; this is caused by mixing with the B(2)Sigma(+) state.

Permanent electric dipole moment of cerium monoxide.

Stark spectra of the [16.5]2-X(1)2 and [16.5]2-X(2)3 transitions of cerium monoxide (CeO) have been obtained at a resolution of approximately 50 MHz. Analysis of the Stark spectra yielded permanent electric dipole moments, mu(el), of 3.119(8), 3.115(7), and 2.119(8) D for the X(1)2, X(2)3, and [16.5]2 states, respectively. The ground X(1)2 state dipole moment is shown to follow the trend shown by other lanthanide oxides. While most ab initio calculations tend to overestimate the ground state dipole moment, the value calculated by using pseudopotentials in which the 4f orbital participates in the chemical bonding (Dolg,M.; Stoll, H.; Preuss, H. THEOCHEM 1991, 231, 243] is in very good agreement with our experimental value.

The permanent electric dipole moments and magnetic g(e) factors of neodymium monoxide.

Stark and Zeeman spectra of the [16.7]3-X4 transition of neodymium monoxide (NdO) have been obtained at a resolution of less than 40 MHz. Analysis of the Stark spectra yielded permanent electric dipole moments mu(el) of 3.742(16) and 3.369(13) D for the [16.7]3 and X4 states, respectively. The ground state value mu(el) is compared to that of isovalent uranium monoxide (UO) and those of other lanthanide monoxides using a molecular orbital description. Analysis of the Zeeman spectra yielded magnetic g(e) factors of 2.084(6) and 2.178(8) for the J=3 and 4 rotational levels, respectively, of the [16.7]3 state and a g(e) factor of 2.116(6) for the X4 state. A comparison with the g(e) factor expected from the ab initio [Allouche et al., J. Chem. Phys. 124, 184317 (2006)] and the ligand field theory [P. Carette and A. Hocquet, J. Mol. Spectrosc. 131, 301 (1988)] predictions for the X4 ground state is given.

The hyperfine interaction in the A 2Pi1/2 and X 2Sigma+ states of ytterbium monofluoride.

The fine and hyperfine interaction parameters in the A (2)Pi(1/2)(v=0) and X (2)Sigma(+)(v=0) states of the odd metal nuclear spin isotopologues of ytterbium monofluoride, (171)YbF and (173)YbF, have been determined from an analysis of high-resolution laser induced fluorescence spectra of the A (2)Pi(12)<--X (2)Sigma(+)(0,0) band. The observed ground X (2)Sigma(+)(v=0) state (171)Yb(I=1/2) Fermi contact parameter is significantly smaller than that determined from the matrix isolation electron spin resonance measurement [Van Zee et al., J. Phys. Chem. 82, 1192 (1978)]. An interpretation of the (173,171)Yb magnetic hyperfine and nuclear electric quadrupole coupling parameters is given.

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.