The B̃2B1 ← X̃2A1 absorption system of NO2 in Xe matrices: evidence for Renner—Teller interaction

A tentative vibrational assignment of the B?²B₁ ← X?²A₁ absorption system of NO₂ in solid Xe is reported. About 65 bands were analysed, yielding normal vibration energies of ν₁ = 1230, ν₂ = 450 and ν₃ = 2040 cm^?1. The electronic transition energy can be estimated to be T₀₁₀ = 14160 cm^?1 (14220 cm^?1 for the gaseous phase). These observations are in good agreement with predictions made using ab initio calculations. Evidence for Renner—Teller interaction is documented by a systematic staggering of frequency intervals between successive bands in the ν₂ progression of the B? state.     

Thermal energy rate constants for the reactions NO2 + Cl2 → Cl2 + NO2, Cl2 + NO2 → Cl + NO2Cl,SH + NO2 → NO2 + SH,SH + Cl2 → Cl2 + SH,and S + NO2 → NO2 + S

It is found that charge-transfer on NO⁻₂ with Cl₂ is fast at thermal energy. The Cl⁻₂ ion reacts with NO₂ to produce Cl⁻ and NO₂Cl, and SH⁻ charge-transfers rapidly with both Cl₂ and NO₂. From the exothermicities implied it is deduced that EA (SH)<EA (NO₂)< EA (Cl₂) or EA (NO₂) = 2.38 ± 0.06 eV and EA (Cl₂ = 2.46 ± 0.14 eV.     

Intergrowth in tunnel structures: The titanates A2Ti6O13)n·A′Ti4Og

A new structural family, (A₂M₆O₁₃)_n·A′M₄O₉, was isolated and studied by means of X-ray diffraction, electron diffraction, and electron microscopy. The structure consists of an ordered intergrowth of two types of structural units: A₂Ti₆O₁₃ and hypothetical A′M₄O₉, both characterized by zigzag ribbons of, respectively, 2 × 3 and 2 × 2 edge-sharing octahedra, joined by corner sharing to form a series of open tunnels containing A and A′ cations. The monoclinic unit-cell parameters can be deduced, for an “n” term, from those of A₂Ti₆O₁₃.     

Comparison of the force field in various pyrochlore families. I. The A2B2O7 oxides

A complete vibrational study of various pyrochlore compounds A₂B₂O₇ shows the role of the different chemical bonds in the structure and how the physico-chemical characteristics of the A and B cations influence these bonds and the rigidity of the two lattices of the structure. Relations between vibrational spectra and structural features are established.     

Nonadiabatic theory of triatomics: Formalism for 1Πu/1Φg interaction,for electronic spin,and for 2Λ Renner–Teller effect

A recent theory of nonadiabatic effects in triatomic molecules is specialized to the four-state Renner–Teller and Jahn–Teller ¹Π_u/¹Φ_g interactions and is then generalized by including the electronic spin and by considering the ²Λ Renner–Teller effect.     

Measurement of atomic L shell fluorescence (ω1, ω2, ω3) and Auger (a1, a2 and a3) yields for some elements in the atomic number range 59≤Z≤85

A comprehensive set of theoretical Coster–Kronig and fluorescence yields are presented for atomic numbers 18≤Z≤100. These quantities are based on ab initio relativistic calculations. Agreement with experimental values is fair for ω₁ and generally good for ω₂, ω₃ (Z≥54) [1]. Therefore, atomic L shell fluorescence (ω₁, ω₂, ω₃) and Auger yields (a₁, a₂ and a₃) for some elements in the atomic number range 59≤Z≤85 were determined. These selected measured semi-empirical values were also fitted by least squares to polynomials in the Z of the form ∑_na_nZⁿ and compared with theoretical and with earlier fitted values.     

Non-Condon effects in triplet-singlet spectra. The 3B1-1A1 system of NO2− in NaNO2 and NaHCO2

Spin-level resolved spectra of the ³B₁-¹A₁ (T₁-S_o) transition of NO₂^? in neat NaNO₂ and in a NaHCO₂ host at ? 4 K show different intensity envelopes for the totally symmetric bending progression, indicating a breakdown of the Condon approximation. The non-Condon effects are associated predominantly with the τ₂ spin level of the ³B₁ state and are particularly severe in NaHCO₂/NO₂^?. The results can be reasonably interpreted in terms of an empirical linear dependence of the transition moment on the bending coordinate, but the detailed origin of the effect is unclear.     

The ternary system H2O–Fe(NO3)3–Co(NO3)2 isotherms 0 and 15 °C

The solid–liquid equilibria of the ternary system H₂O–Fe(NO₃)₃–Co(NO₃)₂ were studied by using a synthetic method based on conductivity measurements.

Two isotherms were established at 0 and 15 °C, and the stable solid phases which appear are the iron nitrate nonahydrate (Fe(NO₃)₃·9H₂O), the iron nitrate hexahydrate (Fe(NO₃)₃·6H₂O), the cobalt nitrate hexahydrate (Co(NO₃)₂·6H₂O) and the cobalt nitrate trihydrate (Co(NO₃)₂·3H₂O).     

Synthesis of thromboxane A2 analogs—1 : (±)-Dimethanothromboxane A2

The stable thromboxane A₂ analog (±)-dimethanothromboxane A₂ 1 was synthesized from bicyclo[3.1.1]heptane 2 via the tricyclic compound 4.     

Isomorphism in the (NH4)2Th(NO3)6-K2Th(NO3)6-Rb2Th(NO3)6 system

Syntheses were developed, and compounds of composition (NH₄)_2x K_2y Rb_2z Th(NO₃)₆(x + y + z = 1) were prepared. These compounds were structurally studied using X-ray diffraction and IR spectroscopy. Incomplete miscibility in the solid phase of the title system was found, and the impossibility of existence of a hexanitratothorate complex in the (NH₄)₂Th(NO₃)₆-K₂Th(NO₃)₆ system at 298.15 K and the component molar ratio 1: 3 was demonstrated. Calorimetric standard enthalpies of formation and mixing at 298.15 K were determined. Original Russian Text ? N.G. Chernorukov, A.V. Knyazev, A.A. Sazonov, 2009, published in Zhurnal Neorganicheskoi Khimii, 2009, Vol. 54, No. 7, pp. 1066–1071.     

细胞内不同形态Gd基MRI造影剂的T1/T2弛豫性能及造影效果

将具有良好生物膜穿透性的异烟肼(INH)和Gd-DO3A偶联,合成了小分子MRI造影剂Gd-DO3A-INH;利用脉冲电转染技术标记间充质干细胞,有效提高了进入细胞的Gd-DO3A-INH浓度,并诱导部分游离态Gd-DO3A-INH在细胞质中自组装成纳米粒子。细胞样品的TEM观察到细胞内形成了Gd-DO3A-INH纳米粒子;细胞传代实验和体外MRI揭示了2种不同状态的Gd-DO3A-INH对细胞水质子弛豫速率的影响机制,以及细胞传代过程中细胞内2种不同状态Gd-DO3A-INH的浓度涨落引起的MRI造影效果的变化机制。     

Production of 1 Δg O2 from microwave discharges in CO2, NO2 and SO2

The production of ¹Δ_g O₂ in microwave discharges in CO₂ and NO₂ has been confirmed by the observation of its EPR spectrum. Quantitative measurements of the EPR spectra of ¹Δ_g and ³Σ⁺_g O₂ and ³P O atoms yield conversion efficiencies for these species. These combined measurements its show that the observed ¹Δ_g O₂ is not formed by simple excitation of ³Σ⁺_g O₂ formed in the discharge. Rather there must exist a direct mechanism for the production of ¹Δ_g O₂ from CO₂ and NO₂. The SO₂ discharge products give rise to no ¹Δ_g O₂ EPR spectrum.     

The S1 ← S0 vibronic spectra and structure of the (CH3)2 CHCHO and (CH3)2 CHCDO 2-methylpropanal molecules

A multipass cell with an optical path up to 120 m long was used to measure the vibronic absorption spectra of 2-methylpropanal-h₁ (MPA-h₁, (CH₃)₂CHCHO)) and 2-methylpropanal-d₁ (MPA-d₁, (CH₃)₂CHCDO)) over the frequency range 28200–31600 cm⁻¹. The most intense spectral lines were assigned to transitions from vibrational levels of the cis and gauche MPA-h₁ and MPA-d₁ conformers in the ground electronic state (S ₀) to vibrational levels of conformers 1 and 3 in the lowest singlet excited electronic state (S ₁). According to our estimates, the origins (0 ₀ ⁰ ) of the 1 S ₁) ← cis(S ₀) and 3(S ₁) ← cis(S ₀) and also 1(S ₁) ← gauche(S ₀) and 3(S ₁) ← gauche(S ₀) electronic transitions were situated at 29147 and 29177, 29391 and 29417 cm⁻¹, respectively, for MPA-h₁ and at 29226 and 29240, 29480 and 29500 cm⁻¹ for MPA-d₁. The structure of conformers 1 and 3 in the S ₁ state was shown to differ from the structure of the cis and gauche conformers in the S ₀ state by the angle of rotation of the (CH₃)₂CH-isopropyl top and “pyramidal distortion” of the CCHO/CCDO carbonyl fragment. A series of fundamental frequencies of MPA conformers in different electronic states were found. The potential functions of inversion were determined for the conformer 1-conformer 3 pairs of MPA-h₁ and MPA-d₁ from the experimental energy levels of inversion vibrations. The potential barriers to inversion and equilibrium displacements of the CH/CD bond out of the CCO plane were found to be 735/675 cm⁻¹ and ±34°/±32° for MPA-h₁ and MPA-d₁, respectively. Original Russian Text ? I.A. Godunov, S.L. Lur’e, N.N. Yakovlev, V.A. Bataev, 2007, published in Zhurnal Fizicheskoi Khimii, 2007, Vol. 81, No. 1, pp. 52–62.     

Synthesis of thromboxane A2 analogs—2 : (±)-Thiathromboxane A2

The total synthesis of (±)-11a-methano- 9,11-thiathromboxane A₂(1), the sulfur analog of thromboxane A₂ is described     

Two-hole-one-particle configuration interaction approach for the ionization of open-shell molecules: Application to NO2

A special configuration interaction approach for the ionic states of open-shell molecules with a spatially nondegenerate ground state is presented. This approach takes into account all genuine one-hole and two-hole-one-particle excitations with respect to the ground state and allows for the determination of ionic energies and relative intensities for the whole energy range. A numerical application for NO₂ is reported providing in particular theoretical access to the inner-valence region where the interpretation of experimental data hitherto has been open to question.     

紫外光激励产生高振动激发ν1模的NO2分子

The photon-excited NO2 at 308 nm has been investigated by Time-Resolved FTIR spectroscopy. The IR fluorescence from highly excited NO2(X2 A1) in ν1 vibrational mode has been observed. These excited states are resulted from the strong vibronic mixing of electronic excited A2 B2/B2 B1 states with the ground X2 A1 state. It is considered that symmetric stretching ν1 mode is reserved from the photolysis because its vibrational style is unsuitable for dissociation.     

Two-colour bound—free—bound spectroscopy of the [E1/2]c6S Rydberg states of CH3I and CD3I

In this resonantly enhanced multiphoton ionization (REMPI) experiment, an extended vibrational progression in the CI stretching mode (v₃) of methyl iodide (-h₃ and -d₃) is observed in the 1 + 1′ excitation of the [1/2] 6s; 0 Rydberg state when the pump photon wavelength lies in the bound → free absorption continuum. This is in contrast with one-colour coherent (non-resonant) two-photon excitation, where the v₃ mode is not excited. By working at several different fixed probe wavelengths and scanning the pump frequency, the relative contributions from the three intermediate repulsive states can be explored through changes in the relative strengths of the Ω = 0 and 1 components of the final Rydberg states. Extensive predissociation in the Rydberg states curtails the vibrational progression.     

The vibrational state distributions in both products of the reaction: O(P) + NO2 → O2 + NO

A laser pulse-and-probe method has been used to determine the nascent vibrational populations in NO(v=0–4) and O₂(v=6–11) formed in the thermal reaction: O(³P) + NO₂ → O₂(v) + NO(v). A frequency-tripled Nd: YAG laser is used to photolyse NO₂, diluted tenfold in Ar, and laser-induced fluorescence spectroscopy in the NO A ²Σ⁺-X ²Π and O₂ B ³Σ⁻_u -X ³Σ⁻_g electronic band system is used both to follow the kinetics of individual vibrational states and to determine the nascent vibrational distributions. The majority of the NO product is formed in v = 0 and the average vibrational yield is ≈ 4.6%. The O₂ populations fall monotonically from v = 6 to 11 in a distribution close to what is expected on prior grounds. Based on a surprisal analysis, the average vibrational energy yield in O₂ is ≈ 26%. The nature of the reaction dynamics is discussed.     

The rate constant for the reaction O3 + NO2 → O2 + NO3 over the temperature range 259–362 °K

The rate constant for the reaction of ozone with nitrogen dioxide has been measured over the temperature range 259 to 362°K, using a stopped-flow system coupled to a beam sampling mass spectrometer. A fit of the data to the Arrhenius equation gave: k = (9.44 ± 2.46) × 10¹⁰ exp[(?2509 ± 76)/T] cm³ mol^?1 sec^?1.