Fourier spectrometry: Rovibrational analysis of an infrared Π → Σ system of yttrium monoiodide

The infrared spectrum of yttrium monoiodide has been excited in an electrodeless microwave discharge and explored between 2500 and 12 000cm⁻¹ with a high-resolution Fourier transform spectrometer. A unique system is observed (ν₀₀ = 9905.520 cm⁻¹), which we attribute to a ¹Π → ¹Σ transition and an extensive analysis is made. Rovibrational constants are obtained for both states mainly from a simultaneous multiband fitting. This procedure is applied to the whole set of 2231 observed line wavenumbers in the 1-0, 0-0, and 0–1 bands, yielding a final weighted standard deviation of 0.0038 cm⁻¹. Furthermore, a partial analysis of the 2-0 and 3-1 bands is performed. The following equilibrium constants are derived (cm⁻¹): ω′_e=192.210 ω′_ex′_e=0.463B′_e=0.0399133 α′_e=0.0001150ω″_e=215.815 ω″_ex″_e=0.514B″_e=0.0422163 α″_e=0.0001125 High-order constants D_v and H_v are also calculated for the various vibrational levels (v′ = 0, 1, 2, 3; v″ = 0, 1).     

Argon matrix absorption spectra of ClO, BrO, and IO and emission spectra of IO

Absorption spectra of ClO, BrO, and IO and the emission spectrum of IO have been observed from argon matrix samples prepared by microwave discharging the reagent mixture before condensation. Vibronic progressions were observed for each system. The spectroscopic scopic constants T_e, ω′_e, ω_ex′_e, ω″_e, and ω_ex″_e were evaluated from the absorption and emission data for comparison with gas-phase constants. Very good agreement is found for ClO. The argon matrix observations dictate a revision of the gas-phase vibronic assignments for BrO. The ground-state vibrational fundamental and T_e for argon matrix isolated IO are similar to the gas-phase values, but a lower excited-state spacing is found in the matrix.     

On the spectroscopy in ee annihilation

The properties of the radial excitations of the , ω and mesons are discussed. In particular it is proposed to identify the recently observed states at √s 1.5, 1.82 and 2.13 GeV in e⁺e⁻ annihilation with the _D ≡ ³D₁(λλ), ″ and ′″ mesons respectively. The ′ meson is suggested to lie in the vicinity of 1.5 GeV and strongly coupled to the _D. The ″(1.6) width is also suggested to be smaller than previously reported.     

The Electronic Spectrum of Tellurium Dioxide

The electronic spectrum of gas-phase tellurium dioxide has been recorded between 345 and 406 nm using the technique of laser-induced fluorescence spectroscopy. The TeO₂ sample was prepared by direct heating of the solid and by seeding it in a continuous free-jet expansion in argon. Twenty-seven cold bands and thirty-two hot bands were assigned. The wavenumbers of the band origin and symmetric stretching and bending vibrational modes for the upper and lower states were determined in a simple least-squares fit: ν₀ = 25526 cm⁻¹, ω₁^′ = 679 cm⁻¹, ω₂^′ = 220 cm⁻¹, ω₁^″ = 823 cm⁻¹, ω₂^″ = 282 cm⁻¹.     

Relativistic calculations of the spectroscopic properties of low-lying states of ICI

Relativistic quantum calculations which include spin-orbit interactions and correlations were carried out for the low-lying states of ICl. Spectroscopic properties (R₃, ω_e, T_e) were calculated for these states. Based on the energies and wave functions both the absorption and emission spectra of ICl in the region below 45000 cm⁻¹ were interpreted. These calculations confirm the predissociation of the B0⁺ state and the existence of a second minimum (B′0⁺) in the 0⁺(II) state. Properties of the 0⁻(I)(³Π_0⁻) state which is yet to be observed were also predicted. The calculated properties for the 2(I)(³Π₂) state are in very good agreement with the properties obtained by the very recent characterization of the A′ state by optical three-photon resonance. The continuous and diffuse absorption spectra of ICl in the region below 45000 cm⁻¹ were interpreted and assigned to the appropriate electronic transitions.     

Analysis of the 2ν3 band of CD3F at 5.06 μm recorded under high resolution

The 2ν₃(A₁) band of ¹²CD₃F near 5.06 μm has been recorded with a resolution of 20–24 × 10⁻³ cm⁻¹. The value of the parameter (α^B − α^A) for this band was found to be very small and, therefore, the K structure of the R(J) and P(J) manifolds was unresolved for J < 15 and only partially resolved for larger J values. The band was analyzed using standard techniques and values for the following constants determined: ν₀ = 1977.178(3) cm⁻¹, B″ = 0.68216(9) cm⁻¹, D″_J = 1.10(30) × 10⁻⁶ cm⁻¹, α^B = (B″ − B′) = 3.086(7) × 10⁻³ cm⁻¹, and β^J = (D″_J − D′_J) = −3.24(11) × 10⁻⁷ cm⁻¹. A value of α^A = (A″ − A′) = 2.90(5) × 10⁻³ cm⁻¹ has been obtained through band contour simulations of the R(J) and P(J) multiplets.     

Phase transitions in [Ni(NH3)6](NO3)2

Electric permittivity ^* = ′ − i″ of nickel-hexammino nitrate (NHN) has been measured within the range of temperature from 9 to 300 K at a frequency of 8.8 GHz (X-band). It has been found that the phase transitions at T_k1 = 247 K and T_k2 = 90 K are discontinuous structural transitions between centrosymmetric phases, whereas the transition at T_c = 63 K is a continuous phase transition (glass?).     

Examination of two new low-lying electronic states of SiS observed in chemiluminescent flame spectra

Diatomic silicon sulfide molecules have been produced in the chemiluminescent reaction of silicon atoms with OCS. Spectra of the resulting flame consist mainly of two new band systems in the region 350–400 and 385–600 nm. These systems have been assigned as b ³Π_r-X ¹Σ⁺ and a ³Σ⁺-X ¹Σ⁺ on the basis of band structure, spin-orbit splitting, molecular constants, and comparison with chemiluminescent spectra of isovalent molecules. Vibrational assignments were made with the help of the isotope effect and vibrational constants were obtained. Rotational structure was observed in some a-X bands and a partial analysis yielded an approximate rotational constant, B 0.247 ± 0.007 cm⁻¹, for the a ³Σ⁺ state. Franck-Condon factors, calculated for the a-X system, are shown to fit the general trend of the intensity distribution. Irregularities in spin-orbit splitting and in relative intensities of the spin-orbit components of the b ³Π-X ¹Σ⁺ system were observed and an attempt is made to explain them in terms of interactions with neighboring states. Addition of active nitrogen to the flame was shown to greatly increase the intensity of the b-X system relative to the a-X system. Constants (in cm⁻¹) obtained for the new state are: a³σ⁺: T_e=24 582.1 ± 1.3, ω_e=503.8±1.0, ω_ex_e=1.86±0.21b³σ⁺: T_e=27 314.5 ± 2.2, ω_e=619.4±2.0, ω_ex_e=5.75±0.52b³σ⁺: T_e=27 407.9 ± 1.1, ω_e=524.3±1.2, ω_ex_e=3.97±0.28     

Analysis of inelastic scattering processes of electrons by localized electrons in quantum dots

The inelastic Coulomb scattering rate 1/τ_in of conduction electrons has been theoretically evaluated in the presence of localized states such as quantum dots. By a diagrammatical method, we have formulated 1/τ_in and its relation to the conductivity σ_loc(ω) through localized states. The dependence of τ_in on temperature T is examined in the case that σ_loc(ω) follows the Mott's model. It is found that 1/τ_in varies as T²(ln Δ/T)^d+1 where d is the dimensionality and Δ is tunneling energy between the localized states in the asymptonic T = 0 limit, in agreement with Imry's calculation. It is also found that calculated 1/τ_in deviates from T²(ln Δ/T)^d+1 as T increases, suggesting the importance of correction term at high temperature.     

New ferromagnetic La3Co2TaO9 double perovskite: Structural and magnetic properties

The new double perovskite La₃Co₂TaO₉ has been prepared by a solid-state procedure. The crystal and magnetic structures have been studied from X-ray powder diffraction (XRPD) and neutron powder diffraction (NPD) data. Rietveld refinements were performed in the monoclinic space group P2₁/n. The structure consists of an ordered array of alternating B′O₆ and B″O₆ octahedra sharing corners, tilted along the three pseudocubic axes according to the Glazer notation a⁻b⁻c⁺. Rietveld refinements show that at RT the cell parameters are a=5.6005(7) Å, b=5.6931(7) Å, c=7.9429(9) Å and β=89.9539(7)°, and the refined crystallographic formula of this “double perovskite” can be written as La₂(Co)_2d(Co_1/3Ta_2/3)_2cO₆. Magnetization measurements and low-temperature NPD data show that the perovskite is a ferromagnet with T_C=72 K. At high T it follows the Curie–Weiss law with an effective magnetic moment of 3.82μ_B per Co ion which is very close to spin only Co²⁺ (HS).     

On the profile of temperature dependent electrical and dielectric properties of Au/SiO2/n-GaAs (MOS) structures at various frequencies

The temperature (T) dependence of electrical and dielectric characteristics such as series resistance (R_s), dielectric constant (ε′), dielectric loss (ε″), dielectric loss tangent (tan δ), and real and imaginary part of electrical modulus (M′ and M″) of the Au/SiO2/n-GaAs (MOS) structures have been investigated in the temperature range of 80–350 K at various frequencies by using experimental capacitance (C) and conductance (G/w) measurements. Experimental results show that both C and G/w characteristics were quite sensitive to frequency and temperature at especially high temperatures and low frequencies due to a continuous density distribution of interface states and their relaxation time, and thermal restructuring and reordering of the interface. Series resistance values of this device obtained from Nicollian method decrease with increasing frequency and temperature. The ε′, ε″, tan δ, and M′ and M″ were found a strong function of frequency and temperature. While the values of ε′, ε″, and tan δ decrease, M′ and M″ increase with increasing frequency. Also, while ε′ and ε″ increase, M′ and M″ decrease with increasing temperature. The tan δ and M′ values are almost independent temperature especially at high frequencies (f≥500 kHz).     

Hyperfine structure in the BΠ0u state of Br2 and the influence of the perturbing 1u state

Using Doppler-free polarization spectroscopy, the hyperfine structure of the B-X system of ⁷⁹Br₂ was measured for the levels B³Π_0⁺u, v′ = 16–28, and X¹Σ_g⁺, v″ = 1, 2. Besides the nuclear electric quadrupole coupling, the magnetic spin-rotation interaction was analyzed, which varies strongly with the vibrational energy of the electronically excited state. This behavior originates from a perturbing repulsive state Ω = 1_u, the potential of which can be estimated in this way.     

Oxalyl halides : Analysis of the 3480 Å absorption system of oxalyl chloridefluoride

Oxalyl chloridefluoride (COCl)(COF) exhibits moderately strong discrete absorption in the 3050–3540Å region. The band spectrum has been analyzed as an allowed electronic transition of the planar trans molecule. The most active vibrations are the carbonyl stretching modes ν₁′ and ν₂′ and the in-plane bending mode ν₉. Various other fundamental frequencies in the combining electronic states have been identified. The 0₀⁰ band is at 28 724.5 cm⁻¹; partial rotational analysis confirms that this band is type C. The appearance of “line” structure in the wings of the band is discussed and an explanation offered. The vibrational and rotational analyses confirm that the transition is under the C_s point group, as expected for a singlet-singlet n → π^* type of excitation.     

Changes in electrical properties in α- and γ-exposed PADC track detector

The changes in the dielectric properties and temperature dependence of the d.c. conductivity of α-exposed poly allyl diglycol carbonate (PADC) have been studied. On α-irradiation the dielectric constant (′) as a function of frequency has been found to decrease significantly. The temperature dependence of resistivity in pristine and γ-irradiated samples is of the form ρ(T)=ρ_∝ exp(T₀/T) which can be attributed to conduction of thermally generated carriers. In case of (γ+α) irradiated samples the temperature dependence of resistivity is of the form ρ(T)=ρ_∝ exp(T₀/T)^1/2 which is due to one-dimensional hopping of carriers.     

Resonance excitation process for Ni-like gold

A detailed and large-scale calculation on the resonant excitation rate coefficients from the ground state to the 106 fine-structure levels belonging to 3l¹⁷4l^′(l=0,1,2;l^′=0,1,2,3) configurations of Ni-like gold have been performed using the relativistic distorted-wave approximation. The contributions through all possible Cu-like doubly excited states 3l¹⁷4l^′n^″l^″and 3l¹⁷5l^′n^″l^″(n^″≤15,l^″≤8) are calculated explicitly. The radiative damping effects on resonant excitation rates are studied. Significant effects arising from decays to autoionizing levels are also investigated. The n⁻³scaling law is investigated and is used to obtain the contributions from high-n configurations. Contributions from resonant excitation are found to be as important as direct excitation processes for most transitions. In some cases, resonant excitation can enhance the excitation rate coefficients by an order of magnitude. In addition, the total dielectronic recombination rate coefficients of Ni-like gold are also presented and compared with other works.     

A new electronic transition of antimony chloride in the visible region

The emission spectrum of SbCl has been photographed at high resolution in the region 400 to 640 nm. In addition to bands of two previously reported transitions in this region, A₁-X and A₂-X, 36 bands of a new system have been identified. A vibrational analysis has been made with ν₀₀ ≈ 20 679 cm⁻¹, and 7 of the bands have been rotationally analyzed. The electronic transition has ΔΩ = 0 with lower state constants which match published data for the ground state X³Σ⁻(0⁺). The upper state is characterized by the following ¹²¹Sb³⁵Cl molecular parameters: B′₀ = 0.0922 cm⁻¹, D′₀ = 3.1 × 10⁻⁸ cm⁻¹.     

The ν1 and ν3 stretching fundamental bands of PD3

The infrared (IR) spectrum of PD₃ has been recorded in the 1580–1800 cm⁻¹ range at a resolution of 0.0027 cm⁻¹. About 2400 rovibrational transitions with J^′=K^′22 have been measured and assigned to the ν₁ (A₁) and ν₃ (E) stretching fundamentals. These include 506 “perturbation-allowed” transitions with selection rules Δ(k−l)=±3. Splittings of the K^′′=3 lines have been observed. Effects of strong perturbations are evident in the spectrum. Therefore the rovibrational Hamiltonian adopted for the analysis explicitly takes into account the Coriolis and k-type interactions between the v₁=1 and v₃=1 states, and includes also several essential resonances within these states. The rotational structure in the v₁=1 and v₃=1 vibrational states up to J^′=K^′=18 was reproduced by fitting simultaneously all experimental data. Thirty-four parameters reproduced 1950 transitions retained in the final cycle with a standard deviation of the fit equal to 4.9 × 10⁻⁴ cm⁻¹ (about the precision of the experimental measurements).     

The spectra and structure of indium iodide: The rotational and vibrational constants of the A0 state

The rotational constants of the A0⁺ state of InI are reported for the first time as B_e = 0.038077 cm⁻¹ and α_e = 0.0002373 cm⁻¹, while T_e = 24402.91 cm⁻¹ for the A0⁺-X0⁺ transition. Accurate vibrational constants for both the A0⁺ and X0⁺ states are computed from the derived band origins.     

Submillimeter-Wave Spectroscopy of CO in the aΠ State

Submillimeter-wave absorption spectrum of CO in electronically excited a³Π state was observed in the 540–830 GHz region by using a phase-locked BWO spectrometer. New rotational transitions up to J = 9–8 in the vibrational excited states up to v = 5 were analyzed accompanied with previous observations in the RF and millimeter-wave regions. A multivibrational states fit among a′ ³Σ⁺ (v = 0–3) and a³Π (v = 0–7) states was performed in order to analyze overall perturbation between the a³Π and a′ ³Σ⁺ states. As a result, the deperturbed rotational parameters were derived precisely to improve the RKR potential.     

Examining the redox and formate mechanisms for water–gas shift reaction on Au/CeO2 using density functional theory

We perform DFT calculations to investigate the redox and formate mechanisms of water–gas-shift (WGS) reaction on Au/CeO₂ catalysts. In the redox mechanism, we analyze all the key elementary steps and find that the OH cleavage is the key step. Three possible pathways of OH cleavage are calculated: (1) OH_ad^″+*^′→H_ad^′+O_ad^″; (2) H_ad^′+OH_ad^″→H₂(g)+O_ad^″+*^′; and (3) OH_ad^″+OH_ad^″→2O_ad^″+H₂(g) (*′: the free adsorption sites on the oxides; ad′: adsorption on the metal; ad″: adsorption on the oxide, respectively). In the formate mechanism, we identify all the possible pathways for the formation and decomposition of surface formates in the WGS reaction. It is found that there is a shortcoming in the redox and formate mechanisms which is related to surface oxygen reproduction. Four possible pathways for producing surface oxygen are studied, and all the barriers of the four pathways are more than 1 eV. Our results suggest that the processes to reproduce surface oxygen in the reaction circle are not kinetically easy.