Hailing Wang

Characterization of the 1A1 and Ã1B2 electronic states of titanium dioxide, TiO2

The strong band system at 536 nm, tentatively assigned as the A (1)B(2)<-- X[combining tilde] (1)A(1)(000-000) vibronic transition, in TiO(2) has been recorded at a spectral resolution of 40 MHz, both field free and in the presence of a static electric field. The Stark induced shifts were analyzed to determine the permanent electric dipole moments of 6.33 +/- 0.07 D and 2.55+/- 0.08 D for the X[combining tilde] (1)A(1) and A (1)B(2) state, respectively. The bond angle, theta, and length, R(Ti-O), for the A (1)B(2) state were determined to be 100.1 degrees and 1.704 A. The dispersed fluorescence was analyzed to determine the nu(2) bending frequency, omega(2) (a(1)), of 322 +/- 6 cm(-1). A molecular orbital model is used to rationalize the change in bonding upon excitation and the results compared with electronic structure predictions.

High-resolution threshold photoelectron study of the propargyl radical by the vacuum ultraviolet laser velocity-map imaging method.

By employing the vacuum ultraviolet (VUV) laser velocity-map imaging (VMI) photoelectron scheme to discriminate energetic photoelectrons, we have measured the VUV-VMI-threshold photoelectrons (VUV-VMI-TPE) spectra of propargyl radical [C(3)H(3)(X̃(2)B(1))] near its ionization threshold at photoelectron energy bandwidths of 3 and 7 cm(-1) (full-width at half-maximum, FWHM). The simulation of the VUV-VMI-TPE spectra thus obtained, along with the Stark shift correction, has allowed the determination of a precise value 70 156 ± 4 cm(-1) (8.6982 ± 0.0005 eV) for the ionization energy (IE) of C(3)H(3). In the present VMI-TPE experiment, the Stark shift correction is determined by comparing the VUV-VMI-TPE and VUV laser pulsed field ionization-photoelectron (VUV-PFI-PE) spectra for the origin band of the photoelectron spectrum of the X̃(+)-X̃ transition of chlorobenzene. The fact that the FWHMs for this origin band observed using the VUV-VMI-TPE and VUV-PFI-PE methods are nearly the same indicates that the energy resolutions achieved in the VUV-VMI-TPE and VUV-PFI-PE measurements are comparable. The IE(C(3)H(3)) value obtained based on the VUV-VMI-TPE measurement is consistent with the value determined by the VUV laser PIE spectrum of supersonically cooled C(3)H(3)(X̃(2)B(1)) radicals, which is also reported in this article.

A vacuum-ultraviolet laser pulsed field ionization-photoelectron study of sulfur monoxide (SO) and its cation (SO+)

Vacuum ultraviolet (VUV) laser pulsed field ionization-photoelectron (PFI-PE) spectroscopy has been applied to the study of the sulfur monoxide radical (SO) prepared by using a supersonically cooled radical beam source based on the 193 nm excimer laser photodissociation of SO(2). The vibronic VUV-PFI-PE bands for the photoionization transitions SO(+)(X(2)Π(1∕2); v(+) = 0) ← SO(X(3)Σ(-); v = 0); and SO(+)((2)Π(3∕2); v(+) = 0) ← SO(X(3)Σ(-); v = 0) have been recorded. On the basis of the semiempirical simulation of rotational branch contours observed in these PFI-PE bands, we have obtained highly precise ionization energies (IEs) of 83,034.2 ± 1.7 cm(-1) (10.2949 ± 0.0002 eV) and 83,400.4 ± 1.7 cm(-1) (10.3403 ± 0.0002 eV) for the formation of SO(+)(X(2)Π(1∕2); v(+) = 0) and SO(+)((2)Π(3∕2); v(+) = 0), respectively. The present VUV-PFI-PE measurement has enabled the direct determination of the spin-orbit coupling constant (A(0)) for SO(+)(X(2)Π(1∕2,3∕2)) to be 365.36 ± 0.12 cm(-1). We have also performed high-level ab initio quantum chemical calculations at the coupled-cluster level up to full quadruple excitations and complete basis set (CBS) extrapolation. The zero-point vibrational energy correction, the core-valence electronic correction, the spin-orbit coupling, and the high-level correction are included in the calculation. The IE[SO(+)(X(2)Π(1∕2,3∕2))] and A(0) predictions thus obtained are found to be in remarkable agreement with the experimental determinations.

The permanent electric dipole moments and magnetic ge-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.

Molecular beam optical Stark study of rhodium mononitride

The optical Stark effect in the Q(1) and R(0) lines of the [15.1]1-X (1)Sigma+ (1,0) band of rhodium mononitride (RhN) were recorded and analyzed to determine the permanent electric dipole moments mu for the X (1)Sigma+(upsilon=0) and [15.1]1(upsilon=1) states to be 2.43(5) and 1.75(1) D, respectively. The determined dipole moments are compared to predicted values obtained from density functional theory [Stevens et al., Chem. Phys. Lett. 421, 281 (2006)] and an all-electron ab initio calculation [Shim et al., J. Mol. Struct. THEOCHEM 393, 127 (1997)]. A simple single configuration molecular orbital correlation diagram is used to rationalize the relative values of mu for the 4d mononitrides and RhO. An electronic configuration for the [15.1]1 state is proposed based on the interpretation of the (103)Rh and (14)N magnetic hyperfine interactions.

Permanent electric dipole moment of molybdenum carbide

High resolution optical spectroscopy has been used to study a molecular beam of molybdenum monocarbide (MoC). The Stark effect of the R(e)(0) and Q(fe)(1) branch features of the [18.6] (3)Pi(1)-X (3)Sigma(-)(0,0) band system of (98)MoC were analyzed to determine the permanent electric dipole moments mu(e) of 2.68(2) and 6.07(18) D for the [18.6] (3)Pi(1)(nu=0) and X (3)Sigma(-)(nu=0) states, respectively. The dipole moments are compared with the experimental value for ruthenium monocarbide [T. C. Steimle et al., J. Chem. Phys. 118, 2620 (2003)] and with theoretical predictions. A molecular orbital correlation diagram is used to interpret the observed and predicted trends of ground state mu(e) values for the 4d-metal monocarbides series.

The Zeeman effect in the (0,0) band of the A Π7−X Σ7+ transition of manganese monohydride, MnH

The Zeeman tuning of the P(1)(0) line (nu=17 568.35 cm(-1)) of the A (7)Pi-X (7)Sigma(+) (0,0) band of manganese monohydride, MnH, has been investigated. The laser induced fluorescence spectrum of a supersonic molecular beam sample was recorded at a resolution of approximately 40 MHz and with field strengths of up to 362.0 mT. The observed spectrum was successfully fitted using a traditional effective Zeeman Hamiltonian to determine an effective magnetic g-factor for the J=2 level of the F(1)-spin component of the A (7)Pi(v=0) state. Spectral predictions of the P(1)(0) line at field strengths used in magnetic trapping experiments are presented.

The electric dipole moment of magnesium deuteride, MgD.

The (0,0) A(2)Π-X (2)Σ(+) band of a cold molecular beam sample of magnesium monodeuteride, MgD, has been recorded field-free and in the presence of a static electric field of up to 11 kV/cm. The lines associated with the lowest rotational levels are detected for the first time. The field-free spectrum was analyzed to produce an improved set of fine structure parameters for the A(2)Π (v = 0) state. The observed electric field induced splittings and shifts were analyzed to produce permanent electric dipole moments, μ(el) of 2.567(10)D and 1.31(8)D for A(2)Π (v = 0) and X(2)Σ(+)(v = 0) states, respectively. The recommended value for μ(el)(X(2)Σ(+) (v = 0)) for MgH, based upon the measured value for MgD, is 1.32(8)D.

Molecular beam optical Stark study of the [18.1]Π1∕22-XΣ1∕2−4 band system of rhodium monosulfide

The optical Stark effect in the R13R(0.5) branch feature of the [18.1]Π1∕22-XΣ1∕2−4 (v′,v″=0) band of rhodium monosulfide (RhS) has been recorded and analyzed to determine the permanent electric dipole moment μe of 3.40(2)D for the ground XΣ1∕2−4 (v=0) state and an upper limit of 1.5D for the [18.1]Π1∕22 state. Molecular orbital correlation diagrams are used to interpret the relative values of μe for RhN, RhO, and RhS. The Rh103(I=1∕2) magnetic hyperfine interaction in the XΣ1∕2−4 and [18.1]Π1∕22 states is analyzed.

Dependences of Q-branch integrated intensity of linear-molecule pendular spectra on electric-field strength and rotational temperature and its potential applications.

We calculate the pendular-state spectra of cold linear molecules, and investigated the dependences of “Q-branch” integrated intensity of pendular spectra on both electric-field strength and molecular rotation-temperature. A new multi-peak structure in the “Q-branch” spectrum is appearing when the Stark interaction strength ω = μE/B equal to or larger than the critical value. Our study shows that the above results can be used not only to measure the electric-field vector and its spatial distribution in some electrostatic devices, such as the Stark decelerator, Stark velocity filter and electrostatic trap and so on, but also to survey the orientation degree of cold linear molecules in a strong electrostatic field.