Jinhai Chen

The permanent electric dipole moments of calcium monohydride, CaH.

Numerous branch features in the (0,0) A 2Pi-X 2Sigma+ band system of calcium monohydride CaH have been studied by optical Stark spectroscopy. The Stark shifts, Stark splittings, and appearance of electric-field-induced transitions in the high resolution laser-induced fluorescence spectra are analyzed to produce values for the magnitude of the permanent electric dipole moments mid R:micromid R: of 2.94(16) D and 2.372(12) D for the X 2Sigma+(v=0) and A 2Pi(v=0) states, respectively. A comparison with values predicted from a semiempirical electrostatic model and previous ab initio calculations for mid R:micromid R: (X 2Sigma+) is presented. The change in mid R:micromid R: upon excitation from the X 2Sigma+ state to the A 2Pi state is rationalized using a simple molecular orbital description.

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.

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 Zeeman effect on lines in the (1,0) band of the F4Δ- X4Δ transition of the FeH radical

We report measurements of the magnetic tuning and broadening of single rotational lines in the (1,0) band of the F4Δ-X4Δ transition of FeH. Since the Zeeman effect of FeH in the lowest rotational levels of the ground X4Δ state has been measured previously, the present measurements provide information on g-factors for two upper state rotational levels. The Zeeman splitting in the Q(7/2) line of the (1,0) band of the F4Δ7/2-X4Δ7/2 transition was successfully modeled using a phenomenological approach. The observation of Zeeman broadening in the corresponding R(7/2) line has also made it possible to extract an approximate g-factor for the J = 9/2 level of the F4Δ7/2(v = 1) vibronic state. The g-factors determined have been used to predict spectral patterns for numerous rotational lines in the F4Δ7/2-X4Δ7/2 system; these are compared with observed features in the sunspot umbral spectrum.

A molecular-beam optical Stark study of lines in the (1,0) band of the FΔ7∕24-XΔ7∕24 transition of iron monohydride, FeH

A supersonic molecular beam of iron monohydride, FeH, has been generated using a laser ablation/chemical reaction scheme and probed at near-natural linewidth resolution by optical Stark spectroscopy utilizing laser-induced fluorescence detection. The observed Stark splitting in Q(3.5) and R(3.5) lines of the F4Δ7/2← X4Δ7/2 (1,0) transition were analyzed to determine values for the magnitudes of the permanent electric dipole moments, |μ|, which were found to be 2.63(3) and 1.29(3) D for the X4Δ (υ=0) and F4Δ (υ=1) states, respectively. A comparison with ab initio theoretical predictions is made. The Λ doubling in the low-J levels of the F4Δ7/2(υ=1) state is also modeled.

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.

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.