Existence of the Møller wave operators for V(r)=γ sin(μrα)rβ

We prove the existence of the Møller wave operators and the unitarity of the S operator for quantum mechanical potential scattering by potentials of the form

This includes the Special case $\text{V(r) =}\text{sin}\text{(r)}\text{r}$.     

Triviality of ϕ44 theory: Small volume expansion and new data

We study a renormalized coupling g and mass m   in four-dimensional ?⁴${?}^4$ theory on tori with finite size z=mL$z=mL$. Precise numerical values close to the continuum limit are reported for z=1,2,4$z=1,2,4$, based on Monte Carlo simulations performed in the equivalent all-order strong coupling reformulation. Ordinary renormalized perturbation theory is found to work marginally at z=2$z=2$ and to fail at z=1$z=1$. By exactly integrating over the constant field mode we set up a renormalized expansion in z and compute three nontrivial orders. These results reasonably agree with the numerical data at small z. In the new expansion, the universal continuum limit exists as expected from multiplicative renormalizability. The triviality scenario is corroborated with significant precision.     

High-resolution study of the ν1/ν5 and 2ν1/ν1+ν5 P-H stretching bands of PH2D

The P-H stretching bands ν₁/ν₅ and 2ν₁/ν₁+ν₅ were recorded using a Bruker 120 HR interferometer with a resolution of 0.0042 and 0.0088 cm⁻¹, respectively, and analyzed. From the fits 33 and 50, respectively, vibrational, rotational, centrifugal distortion, and resonance interaction parameters were obtained. These reproduce 668 and 497 rovibrational energies of the pairs of states ν₁/ν₅ and 2ν₁/ν₁+ν₅ with experimental accuracies, rms=0.00016 and , respectively. “Local mode” behavior of the PH₂ fragment is established and discussed in detail.     

Vibrational analysis of Fourier transform spectrum of the A3Π0-X1Σ+ and B3Π1-X1Σ+ transitions of indium monobromide

The emission spectrum of InBr molecule has been recorded in the region 350–400 nm on BOMEM DA8 Fourier transform spectrometer at an apodized resolution of 0.06 cm⁻¹ using microwave excitation technique. About 61 violet degraded and single headed bands have been recorded and are classified into two band systems, viz. A³Π₀-X¹Σ⁺ and B³Π₁-X¹Σ⁺. A few new bands have been observed and are fitted in the vibrational schemes of the two systems. Revised vibrational constants have been determined. The vibrational assignments have been confirmed by observing isotope effect due to InBr⁸¹ in the 30 bands of the A³Π₀-X¹Σ⁺ system and 19 bands of the B³Π₁-X¹Σ⁺ system. The analysis is further supported by calculating the Franck-Condon factor for InBr⁷⁹ and InBr⁸¹ molecules. The following vibrational constants (in cm⁻¹) have been determined from the analysis:      

High resolution study of the 3ν1 band of SO2

The second overtone band 3ν₁ of sulfur dioxide has been studied for the first time with high resolution rotation-vibration spectroscopy. About 3000 transitions involving about 900 upper state energy levels with have been assigned to the 3ν₁ band. In the analysis, an effective Hamiltonian taking into account accidental interactions between the vibrational states (3 0 0), (2 2 0), and (0 4 1) was used. The Watson operator in A-reduction and I^r representation was used in the diagonal blocks of the Hamiltonian. As the result of analysis a set of parameters reproducing the initial experimental data with the rms = 0.00028 cm⁻¹ was obtained.     

P-branch emission spectra of the A1Π-X1Σ+ system of IrN

The P-branch emission spectra of (4,1) and (3,1) bands of the A¹Π-X¹Σ⁺ system of IrN molecule are studied using an analytical formula which is derived from elementary expression of molecular total energy by taking multiple spectral differences. It not only reproduces the known experimental transition lines, but also predicts the unknown spectral lines up to J= 80 for each band by using a group of fifteen known experimental transition lines.     

Rotational and vibrational analysis of bands of the f1Δ-a1Δ system of titanium oxide

Five new bands of the f¹Δ-a¹Δ TiO system have been observed in emission between 17774.0 cm^?1 and 19801.0 cm^?1. Rotational and vibrational analyses of the 0-1, 1-0, 1-2, 2-1, and 1-1 bands, as well as a reanalysis of the 0-0 band, yielded the following molecular constants (cm^?1):

     

8.

Infrared spectra of two isomers of OCS-C₂H₂ and OCS-C₂D₂ in the region of OCS ν₁ fundamental     

J. Norooz Oliaee  M. Dehghany  A.R.W. McKellar 《Journal of Molecular Spectroscopy》2009,257(2):133-10422

Infrared spectra of OCS-C₂H₂ and OCS-C₂D₂ complexes in the region of the C-O stretching fundamental of OCS (∼2060 cm⁻¹) are studied in a pulsed supersonic slit-jet expansion using a tunable diode laser. For each complex, two bands are observed and assigned to distinct near-parallel and the T-shaped isomers. Ground state parameters were previously determined from microwave studies, so analysis of the infrared spectra gives information on the vibrational shifts upon complex formation as well as rotational and centrifugal distortion parameters for the excited states. All four bands show a red shift with respect to the monomer band origin, with the T-shaped isomer having a much larger shift than the near-parallel isomer. Disappearance of the T-shaped isomer when argon is used as a carrier gas supports the notion that the near-parallel isomer is the lowest energy form of the complex.     

9.

MRCI study of spectroscopic and molecular properties of X¹Σ_g⁺ and A¹Π_u electronic states of the C₂ radical          下载免费PDF全文

张小妞  施德恒  孙金锋  朱遵略 《中国物理 B》2011,20(4):43105-043105

The potential energy curves (PECs) of X1Σ+g and A1Πu electronic states of the C2 radical have been studied using the full valence complete active space self-consistent field (CASSCF) method followed by the highly accurate valence internally contracted multireference configuration interaction (MRCI) approach in conjunction with the aug-cc-pV6Z basis set for internuclear separations from 0.08 nm to 1.66 nm. With these PECs of the C2 radical,the spectroscopic parameters of three isotopologues ( 12C2 ,12C13C and 13C2 ) have been determined. Compared in detail with previous studies reported in the literature,excellent agreement has been found. The complete vibrational levels G(υ),inertial rotation constants B υ and centrifugal distortion constants D υ for the 12C2 ,12C13C and 13C2 isotopologues have been calculated for the first time for the X1Σ+g and A1Πu electronic states when the rotational quantum number J equals zero. The results are in excellent agreement with previous experimental data in the literature,which shows that the presented molecular constants in this paper are reliable and accurate.     

10.

Dielectric properties of solid solutions (1 ? x)(KBi)_1/2TiO₃-xNa_1/4Bi_3/4Fe_1/2Ti_1/2O₃ near the morphotropic phase boundary     

Yu. V. Radyush  N. M. Olekhnovich  A. V. Pushkarev 《Physics of the Solid State》2012,54(1):91-97

The dielectric properties of solid solution ceramics (1 − x)(KBi)_1/2TiO₃-(x/2)(NaBi)_1/2TiO₃-(x/2)BiFeO₃ near the morphotropic phase boundary lying near x = 0.75 and separating the compositions with the orthorhombic (x < 0.75) and rhombohedral (x > 0.75) structures have been studied. The solid solutions are shown to undergo a diffuse phase transition with the Curie temperature T _C = 640–650 K. Based on an analysis of the frequency dependence of the imaginary component of the electric modulus in the range T > T _C, it is concluded that the transition of the system of solid solutions near the morphotropic phase boundary (x = 0.75) to the dipole-ordered state is accompanied by the formation of heterophase microregions with different relaxation times of the dielectric polarization. The activation energies of the relaxation of the dielectric polarization (ΔE _M ) in the aforementioned temperature range and of the dc charge carriers (ΔE _dc ) are determined. It is found that ΔE _dc stepwise increases near 570 K in going toward higher temperatures. It is shown that the behavior of the characteristics of the dielectric response of the solid solutions below 400 K corresponds to a relaxor ferroelectric. For the compositions 0.7 ≤ x ≤ 0.8, the estimated freezing temperature of dipole clusters of the relaxation state is about 240 K, and their activation energy decreases with increasing x.     

11.

The ν₁ and 3ν₁ bands of HNCO     

M. Carlotti  G. di Lonardo  G. Galloni  A. Trombetti 《Journal of Molecular Spectroscopy》1976,62(2):192-200

The infrared absorption of HNCO has been measured in the region of the NH stretching fundamental and in that of the second overtone. The results for the excited states are (in cm^?1):

		$\text{f}{}^1\text{Δ}$		$\text{a}{}^1\text{Δ}$
v	$\text{B}{}_{\mathrm{v}}$	$\text{D}{}_{\mathrm{v}}$ (×106)	$\text{B}{}_{\mathrm{v}}$	$\text{D}{}_{\mathrm{v}}$ (×106)
0	0.502277 (17)	0.6411 (57)	0.536168 (20)	0.5938 (76)
1	0.499198 (32)	0.630 (15)	0.533227 (13)	0.5971 (46)
2			0.530335 (26)	0.636 (13)
	$\text{ω}{}_{\mathrm{e}}\text{= 874.104 (4)}$		$\text{ω}{}_{\mathrm{e}}\text{= 1018.273 (4)}$
	$\text{ω}{}_{\mathrm{e}}\text{χ}{}_{\mathrm{e}}\text{= 2.501 (4)}$		$\text{ω}{}_{\mathrm{e}}\text{χ}{}_{\mathrm{e}}\text{= 4.521 (4)}$
	$\text{T′}{}_{\mathrm{e}}\text{?T″}{}_{\mathrm{e}}\text{= 19140.567 (8)}$

     

12.

Rotational Analysis of the ÃA₁-X?A₁ Band System of Yttrium Dicarbide, YC₂     

Timothy C. Steimle  Robert R. BousquetKei-ichi C. Namiki  Anthony J. Merer 《Journal of Molecular Spectroscopy》2002,215(1):10-28

The 000-000 and 3¹₀ bands of the 775-nm electronic transition of YC₂(òA₁←X?²A₁) have been studied at high resolution, using the laser-induced fluorescence from a supersonic jet expansion. Three types of experiment have been carried out. First, the complete rotational and hyperfine structures of the two bands were recorded. To measure the small asymmetry splittings in the K=2 levels of the X?²A₁ state, portions of the b-type 3¹₀ band were then recorded in the presence of a weak static electric field. Finally, a number of pure rotational transitions between the K=0 levels of the ground state were recorded by pump/probe microwave optical double resonance. A few small rotational perturbations occur in the upper electronic state but, omitting the perturbed lines, the combined data sets could be modeled using an effective Hamiltonian operator appropriate for the rotation, electron spin, and hyperfine structure of a rigid asymmetric top molecule. The molecule is confirmed as being “T-shaped,” where the Y atom is bonded to the side of a C₂ group; the rotational constants determined are for the òA₁, 3¹ level, A=1.76128, B=0.189949, C=0.170056 cm⁻¹, and for the X?²A₁, v=0 level, A=1.742731, B=0.201947, C=0.181285 cm⁻¹. Allowing for electron orbital corrections to the rotational constants, the geometrical structures are found to be òA₁ state, r (Y-C)=2.2795 Å, r (C-C)=1.2630 Å, ∠C-Y-C=32.17°; X?²A₁ state, r (Y-C)=2.1946 Å, r (C-C)=1.2697 Å, ∠C-Y-C=33.63°. A molecular orbital diagram is given for the states of YC₂ and the interpretation of the electron spin and hyperfine parameters is discussed.     

13.

Stretch-Bender Calculations of the Rovibronic Energies in the Excited, ÃA₁, Electronic State of NH₂ and of the Near-Resonant High-Lying Levels of the X?B₁ State     

Geoffrey DuxburyAlexander Alijah 《Journal of Molecular Spectroscopy》2002,211(1):31-57

The extended stretch-bender Hamiltonian, incorporating spin-orbit coupling and overall rotation, has been used to calculate the spin-vibronic structure of the rovibronic energies in the region where the vibronic states of the excited òA₁ electronic state of NH₂ interact with near-resonant high-lying levels of the X?²B₁ state of NH₂. A detailed comparison has been made with the experimental measurements which were made of these rovibronic states, the majority of which are due to Ramsay, Vervloet, and their collaborators. We have shown that, as in our study of the vibronic levels of the X?²B₁ state below the barrier to linearity, in order to fit the variation of the effective vibronic spin-orbit coupling constant over the whole of this energy regime, the effective linear molecule spin-orbit coupling constant, A_SO must be increased from the earlier value of 50 cm⁻¹ of Ch. Jungen, K.-E. J. Hallin, and A. Merer (Mol. Phys.40, 65-94 (1980)) to 61.6 cm⁻¹. The impact of Fermi resonance, in both the òA₁ and X?²B₁ states, on the observed rovibronic structure has been assessed. The pattern of calculated spin-rovibronic levels, including the effects of spin uncoupling, is in good agreement with that measured experimentally.     

14.

Analysis of irreducible representations of the group

$\text{U (4) ⊃ U}{}_{\mathrm{p}}\text{(2) × U}{}_{\mathrm{n}}\text{(2)}$

    

V.A. Knyr  Yu.F. Smirnov  V.N. Tolstoy 《Reports on Mathematical Physics》1984,20(3):347-355

The general method of projection operators is used to construct the noncanonical nonorthogonal basis of arbitrary irreducible representation of the group U (4) in the reduction

$\text{U (4) ? U}{}_{\mathrm{p}}\text{(2) × U}{}_{\mathrm{n}}\text{(2)}$

, where

$\text{U}{}_{\mathrm{p}}\text{(2)(U}{}_{\mathrm{n}}\text{(2))}$

is the transformation group in the proton (neutron) spin space. The completeness of this basis is proved and the matrices of the U (4) group generators and of the Bargmann-Moshinsky operator Ω in this basis are obtained. The matrix 6Ω6 exhibits a nondegenerate spectrum of the eigenvalues which may be used as the missing quantum number.     

15.

Fluorination of perovskite-related phases of composition La_1−xSr_xFe_1−yCo_yO_3−δ     

Frank J. Berry  Xiaolin Ren  Peter Slater 《Journal of Physics and Chemistry of Solids》2008,69(8):2032-2036

We report here on the fluorination of the perovskite-related phases La_1−xSr_xFe_1−yCo_yO_3−δ. The introduction of fluorine in place of oxygen is achieved through a low-temperature (400 °C) reaction with poly(vinylidene fluoride). X-ray powder diffraction data show that in all cases the fluorination leads to an expansion in the unit cell, which is consistent with partial replacement of oxygen by fluorine and consequent reduction in the oxidation state of iron and/or cobalt. This reduction in oxidation state is confirmed by X-ray absorption- and Mössbauer-spectroscopy. The Mössbauer spectra show complex magnetically split hyperfine patterns for the fluorinated samples, reflecting the interactions between Fe³⁺ ions, which are not possible in oxides containing Fe⁴⁺.     

16.

CO₂ and N₂O laser Stark spectroscopy of the ν₁ band of the ClO₂ radical     

Keiichi Tanaka  Takehiko Tanaka 《Journal of Molecular Spectroscopy》1983,98(2):425-452

The ν₁ fundamental band of the ClO₂ radical has been studied by means of the 10.6-μm CO₂ and N₂O laser Stark spectroscopy. More than 250 and 150 Stark resonances were assigned for the ³⁵ClO₂ and ³⁷ClO₂ species, respectively, and were analyzed together with the recent microwave and laser-microwave double resonance results to give molecular constants including spin-rotation interaction constants. The ν₁ band origins and electric dipole moments both in the ground and ν₁ states were determined accurately

Band	$\text{ν}{}_0$	$\text{A-}\text{B}$	B	C
$\text{ν}{}_1$	3533.1	27.0	—	—
$\text{3ν}{}_1$	10145.79	22.6713	0.368426	0.361722

     

17.

Line intensities of the: ν₃, 4ν₂, ν₁+ν₃, 3ν₁ and 2ν₁+2ν₂ bands of OCS molecule     

L. Régalia-Jarlot  A. HamdouniX. Thomas  P. Von der HeydenA. Barbe 《Journal of Quantitative Spectroscopy & Radiative Transfer》2002,74(4):455-470

     

18.

FTIR Study of the ν₁/ν₄ Bands of D₃SiCl near 1600 cm     

K. AkkadN.Ben Sari-Zizi  H. BürgerE.B. MKadmi 《Journal of Molecular Spectroscopy》2002,213(1):35-45

The ν₁ (A₁, 1583.22 cm⁻¹) and ν₄ (E, 1615.33 cm⁻¹) Si-D stretching bands of monoisotopic D₃Si³⁵Cl have been studied by FTIR spectroscopy with a resolution of 3.3×10⁻³ cm⁻¹. We have assigned 2341 rovibrational lines for ν₁ (J_max=70, K_max=19) and 6207 for ν₄ (J_max=75, K_max=27). Both (ΔK=±1, Δ?=±1) and (ΔK=±2, Δ?=?1) interactions connect the v₁=1 and v₄=1 levels, the latter exerting moreover a weak ?(2, 2) interaction. These interactions were taken into account in a nonlinear least-squares fit, refining 29 free parameters with a standard deviation of 0.257×10⁻³ cm⁻¹ over 6722 nonzero-weighted data. Blended lines and about 250 of the 330 lines belonging to the K=11 subband of ν₁ and the KΔK=−6 subband of ν₄ were zero-weighted because they are locally perturbed respectively by the neighboring upper states of the 2ν₃+ν₆ (E, 1561.95 cm⁻¹) and 3ν₃ (A₁, 1604.81 cm⁻¹) bands. Equivalent fits were obtained for altogether three different models obeying constraints according to the theory of unitary equivalent reductions of the rovibrational Hamiltonian. By means of a band contour simulation both the transition moment ratio |M₁:M₄|=0.67 and a positive sign of the Coriolis intensity perturbation were determined.     

19.

Stimulated Emission Pumping Spectroscopy of SiH₂: First Observation of the Spin-Orbit Interaction between the X?A₁ and the ãB₁ States     

Haruki IshikawaYasuhiko Muramoto  Naohiko Mikami 《Journal of Molecular Spectroscopy》2002,216(1):90-97

Stimulated emission pumping spectra of the ùB₁-X?¹A₁ transition of the SiH₂ radical were observed in order to obtain information about the ã³B₁ state through the spin-orbit interaction. The vibrational level structure of the X? state, which is the basis for the present observation of the triplet state, was well described with a polyad structure, in which both the 1ν₁ : 2ν₂ Fermi and the 2ν₁ : 2ν₃ Darling-Dennison anharmonic resonances were considered. In the P=10 polyad, four sets of spin-orbit perturbations were observed for the first time. The triplet state observed at about 9640 cm⁻¹ from the (000) level of the X? state was tentatively assigned as the ã³B₁ (030) level. An analysis of the spin-orbit interaction showed that the interaction energies of the spin-orbit coupling are 0.73-3.13 cm⁻¹. This value is rather smaller than that expected based on the comparison with CH₂. This is considered to be due to poor overlap between the vibrational wave functions in the ã and the X? state.     

20.

Relativistic calculations of 3s^{2 1}S₀-3s3p ¹P₁ and 3s^{2 1}S₀-3s3p ³P_1,2 transition probabilities in the Mg isoelectronic sequence          下载免费PDF全文

程诚  高翔  青波  张小乐  李家明 《中国物理 B》2011,20(3):33103-033103

Using the multi-configuration Dirac-Fock self-consistent field method and the relativistic configuration-interaction method,calculations of transition energies,oscillator strengths and rates are performed for the 3s 2 1 S 0-3s3p 1 P 1 spinallowed transition,3s 2 1 S 0-3s3p 3 P 1,2 intercombination and magnetic quadrupole transition in the Mg isoelectronic sequence(Mg I,Al II,Si III,P IV and S V).Electron correlations are treated adequately,including intravalence electron correlations.The influence of the Breit interaction on oscillator strengths and transition energies are investigated.Quantum electrodynamics corrections are added as corrections.The calculation results are found to be in good agreement with the experimental data and other theoretical calculations.     

		35ClO2		37ClO2
$\text{ν}{}_0$		945.592 357(60)		939.602 909(66)		cm?1
μ′		1.788 39(13)		1.788 46(15)		D
μ″		1.791 95(10)		1.792 10(13)		D
δμ		?0.003 56(18)		?0.003 64(26)		D

Infrared spectra of two isomers of OCS-C2H2 and OCS-C2D2 in the region of OCS ν1 fundamental

Infrared spectra of OCS-C₂H₂ and OCS-C₂D₂ complexes in the region of the C-O stretching fundamental of OCS (∼2060 cm⁻¹) are studied in a pulsed supersonic slit-jet expansion using a tunable diode laser. For each complex, two bands are observed and assigned to distinct near-parallel and the T-shaped isomers. Ground state parameters were previously determined from microwave studies, so analysis of the infrared spectra gives information on the vibrational shifts upon complex formation as well as rotational and centrifugal distortion parameters for the excited states. All four bands show a red shift with respect to the monomer band origin, with the T-shaped isomer having a much larger shift than the near-parallel isomer. Disappearance of the T-shaped isomer when argon is used as a carrier gas supports the notion that the near-parallel isomer is the lowest energy form of the complex.     

MRCI study of spectroscopic and molecular properties of X1Σg+ and A1Πu electronic states of the C2 radical

The potential energy curves (PECs) of X1Σ+g and A1Πu electronic states of the C2 radical have been studied using the full valence complete active space self-consistent field (CASSCF) method followed by the highly accurate valence internally contracted multireference configuration interaction (MRCI) approach in conjunction with the aug-cc-pV6Z basis set for internuclear separations from 0.08 nm to 1.66 nm. With these PECs of the C2 radical,the spectroscopic parameters of three isotopologues ( 12C2 ,12C13C and 13C2 ) have been determined. Compared in detail with previous studies reported in the literature,excellent agreement has been found. The complete vibrational levels G(υ),inertial rotation constants B υ and centrifugal distortion constants D υ for the 12C2 ,12C13C and 13C2 isotopologues have been calculated for the first time for the X1Σ+g and A1Πu electronic states when the rotational quantum number J equals zero. The results are in excellent agreement with previous experimental data in the literature,which shows that the presented molecular constants in this paper are reliable and accurate.     

Dielectric properties of solid solutions (1 ? x)(KBi)1/2TiO3-xNa1/4Bi3/4Fe1/2Ti1/2O3 near the morphotropic phase boundary

The dielectric properties of solid solution ceramics (1 − x)(KBi)_1/2TiO₃-(x/2)(NaBi)_1/2TiO₃-(x/2)BiFeO₃ near the morphotropic phase boundary lying near x = 0.75 and separating the compositions with the orthorhombic (x < 0.75) and rhombohedral (x > 0.75) structures have been studied. The solid solutions are shown to undergo a diffuse phase transition with the Curie temperature T _C = 640–650 K. Based on an analysis of the frequency dependence of the imaginary component of the electric modulus in the range T > T _C, it is concluded that the transition of the system of solid solutions near the morphotropic phase boundary (x = 0.75) to the dipole-ordered state is accompanied by the formation of heterophase microregions with different relaxation times of the dielectric polarization. The activation energies of the relaxation of the dielectric polarization (ΔE _M ) in the aforementioned temperature range and of the dc charge carriers (ΔE _dc ) are determined. It is found that ΔE _dc stepwise increases near 570 K in going toward higher temperatures. It is shown that the behavior of the characteristics of the dielectric response of the solid solutions below 400 K corresponds to a relaxor ferroelectric. For the compositions 0.7 ≤ x ≤ 0.8, the estimated freezing temperature of dipole clusters of the relaxation state is about 240 K, and their activation energy decreases with increasing x.     

The ν1 and 3ν1 bands of HNCO

The infrared absorption of HNCO has been measured in the region of the NH stretching fundamental and in that of the second overtone. The results for the excited states are (in cm^?1):

Rotational Analysis of the ÃA1-X?A1 Band System of Yttrium Dicarbide, YC2

The 000-000 and 3¹₀ bands of the 775-nm electronic transition of YC₂(òA₁←X?²A₁) have been studied at high resolution, using the laser-induced fluorescence from a supersonic jet expansion. Three types of experiment have been carried out. First, the complete rotational and hyperfine structures of the two bands were recorded. To measure the small asymmetry splittings in the K=2 levels of the X?²A₁ state, portions of the b-type 3¹₀ band were then recorded in the presence of a weak static electric field. Finally, a number of pure rotational transitions between the K=0 levels of the ground state were recorded by pump/probe microwave optical double resonance. A few small rotational perturbations occur in the upper electronic state but, omitting the perturbed lines, the combined data sets could be modeled using an effective Hamiltonian operator appropriate for the rotation, electron spin, and hyperfine structure of a rigid asymmetric top molecule. The molecule is confirmed as being “T-shaped,” where the Y atom is bonded to the side of a C₂ group; the rotational constants determined are for the òA₁, 3¹ level, A=1.76128, B=0.189949, C=0.170056 cm⁻¹, and for the X?²A₁, v=0 level, A=1.742731, B=0.201947, C=0.181285 cm⁻¹. Allowing for electron orbital corrections to the rotational constants, the geometrical structures are found to be òA₁ state, r (Y-C)=2.2795 Å, r (C-C)=1.2630 Å, ∠C-Y-C=32.17°; X?²A₁ state, r (Y-C)=2.1946 Å, r (C-C)=1.2697 Å, ∠C-Y-C=33.63°. A molecular orbital diagram is given for the states of YC₂ and the interpretation of the electron spin and hyperfine parameters is discussed.     

Stretch-Bender Calculations of the Rovibronic Energies in the Excited, ÃA1, Electronic State of NH2 and of the Near-Resonant High-Lying Levels of the X?B1 State

The extended stretch-bender Hamiltonian, incorporating spin-orbit coupling and overall rotation, has been used to calculate the spin-vibronic structure of the rovibronic energies in the region where the vibronic states of the excited òA₁ electronic state of NH₂ interact with near-resonant high-lying levels of the X?²B₁ state of NH₂. A detailed comparison has been made with the experimental measurements which were made of these rovibronic states, the majority of which are due to Ramsay, Vervloet, and their collaborators. We have shown that, as in our study of the vibronic levels of the X?²B₁ state below the barrier to linearity, in order to fit the variation of the effective vibronic spin-orbit coupling constant over the whole of this energy regime, the effective linear molecule spin-orbit coupling constant, A_SO must be increased from the earlier value of 50 cm⁻¹ of Ch. Jungen, K.-E. J. Hallin, and A. Merer (Mol. Phys.40, 65-94 (1980)) to 61.6 cm⁻¹. The impact of Fermi resonance, in both the òA₁ and X?²B₁ states, on the observed rovibronic structure has been assessed. The pattern of calculated spin-rovibronic levels, including the effects of spin uncoupling, is in good agreement with that measured experimentally.     

Analysis of irreducible representations of the group U (4) ⊃ Up(2) × Un(2)

The general method of projection operators is used to construct the noncanonical nonorthogonal basis of arbitrary irreducible representation of the group U (4) in the reduction

$\text{U (4) ? U}{}_{\mathrm{p}}\text{(2) × U}{}_{\mathrm{n}}\text{(2)}$

, where

$\text{U}{}_{\mathrm{p}}\text{(2)(U}{}_{\mathrm{n}}\text{(2))}$

is the transformation group in the proton (neutron) spin space. The completeness of this basis is proved and the matrices of the U (4) group generators and of the Bargmann-Moshinsky operator Ω in this basis are obtained. The matrix 6Ω6 exhibits a nondegenerate spectrum of the eigenvalues which may be used as the missing quantum number.     

Fluorination of perovskite-related phases of composition La1−xSrxFe1−yCoyO3−δ

We report here on the fluorination of the perovskite-related phases La_1−xSr_xFe_1−yCo_yO_3−δ. The introduction of fluorine in place of oxygen is achieved through a low-temperature (400 °C) reaction with poly(vinylidene fluoride). X-ray powder diffraction data show that in all cases the fluorination leads to an expansion in the unit cell, which is consistent with partial replacement of oxygen by fluorine and consequent reduction in the oxidation state of iron and/or cobalt. This reduction in oxidation state is confirmed by X-ray absorption- and Mössbauer-spectroscopy. The Mössbauer spectra show complex magnetically split hyperfine patterns for the fluorinated samples, reflecting the interactions between Fe³⁺ ions, which are not possible in oxides containing Fe⁴⁺.     

CO2 and N2O laser Stark spectroscopy of the ν1 band of the ClO2 radical

The ν₁ fundamental band of the ClO₂ radical has been studied by means of the 10.6-μm CO₂ and N₂O laser Stark spectroscopy. More than 250 and 150 Stark resonances were assigned for the ³⁵ClO₂ and ³⁷ClO₂ species, respectively, and were analyzed together with the recent microwave and laser-microwave double resonance results to give molecular constants including spin-rotation interaction constants. The ν₁ band origins and electric dipole moments both in the ground and ν₁ states were determined accurately

FTIR Study of the ν1/ν4 Bands of D3SiCl near 1600 cm

The ν₁ (A₁, 1583.22 cm⁻¹) and ν₄ (E, 1615.33 cm⁻¹) Si-D stretching bands of monoisotopic D₃Si³⁵Cl have been studied by FTIR spectroscopy with a resolution of 3.3×10⁻³ cm⁻¹. We have assigned 2341 rovibrational lines for ν₁ (J_max=70, K_max=19) and 6207 for ν₄ (J_max=75, K_max=27). Both (ΔK=±1, Δ?=±1) and (ΔK=±2, Δ?=?1) interactions connect the v₁=1 and v₄=1 levels, the latter exerting moreover a weak ?(2, 2) interaction. These interactions were taken into account in a nonlinear least-squares fit, refining 29 free parameters with a standard deviation of 0.257×10⁻³ cm⁻¹ over 6722 nonzero-weighted data. Blended lines and about 250 of the 330 lines belonging to the K=11 subband of ν₁ and the KΔK=−6 subband of ν₄ were zero-weighted because they are locally perturbed respectively by the neighboring upper states of the 2ν₃+ν₆ (E, 1561.95 cm⁻¹) and 3ν₃ (A₁, 1604.81 cm⁻¹) bands. Equivalent fits were obtained for altogether three different models obeying constraints according to the theory of unitary equivalent reductions of the rovibrational Hamiltonian. By means of a band contour simulation both the transition moment ratio |M₁:M₄|=0.67 and a positive sign of the Coriolis intensity perturbation were determined.     

Stimulated Emission Pumping Spectroscopy of SiH2: First Observation of the Spin-Orbit Interaction between the X?A1 and the ãB1 States

Stimulated emission pumping spectra of the ùB₁-X?¹A₁ transition of the SiH₂ radical were observed in order to obtain information about the ã³B₁ state through the spin-orbit interaction. The vibrational level structure of the X? state, which is the basis for the present observation of the triplet state, was well described with a polyad structure, in which both the 1ν₁ : 2ν₂ Fermi and the 2ν₁ : 2ν₃ Darling-Dennison anharmonic resonances were considered. In the P=10 polyad, four sets of spin-orbit perturbations were observed for the first time. The triplet state observed at about 9640 cm⁻¹ from the (000) level of the X? state was tentatively assigned as the ã³B₁ (030) level. An analysis of the spin-orbit interaction showed that the interaction energies of the spin-orbit coupling are 0.73-3.13 cm⁻¹. This value is rather smaller than that expected based on the comparison with CH₂. This is considered to be due to poor overlap between the vibrational wave functions in the ã and the X? state.     

Relativistic calculations of 3s2 1S0-3s3p 1P1 and 3s2 1S0-3s3p 3P1,2 transition probabilities in the Mg isoelectronic sequence

Using the multi-configuration Dirac-Fock self-consistent field method and the relativistic configuration-interaction method,calculations of transition energies,oscillator strengths and rates are performed for the 3s 2 1 S 0-3s3p 1 P 1 spinallowed transition,3s 2 1 S 0-3s3p 3 P 1,2 intercombination and magnetic quadrupole transition in the Mg isoelectronic sequence(Mg I,Al II,Si III,P IV and S V).Electron correlations are treated adequately,including intravalence electron correlations.The influence of the Breit interaction on oscillator strengths and transition energies are investigated.Quantum electrodynamics corrections are added as corrections.The calculation results are found to be in good agreement with the experimental data and other theoretical calculations.