Observation and interpretation of the Li2 diffuse band in the region of 420 nm

We report the first observation of the Li₂ diffuse band in the region of 420 nm which is the analog of the diffuse bands in other alkali dimer spectra, for example, at 436.5 and 575 nm for the sodium and potassium cases, respectively. The observed diffuse band appears to arise from the 2³Π_g-1³Σ_u⁺ transition where the upper state corresponds to the 2p + 2p asymptote, and is subjected to the interesting configuration interaction with the potential curve of the ionic molecule Li^?(³P) + Li⁺(¹S) with the same symmetry. The origin of the 420 nm band is interpreted in terms of theoretical calculations of various Li₂ potential difference curves.     

Photodissociation of NO2. Internal energy distribution and anisotropies in the fragments

The near-UV photodissociation of NO₂ has been investigated at excess energies from −600 up to 1700 cm⁻¹ above the NO X ν = 1 + O³P dissociation limit. A complete analysis of the NO X ν = 1 fragment, including internal and translational energy as well as the angular properties of its vectorial parameters, has been carried out using REMPI combined with TOF mass spectrometry. The high-precision state-selective measurements of the NO fragment velocity have been used to evaluate the internal energy of the O atoms formed in coincidence. Concerning the internal energy of the NO X ν = 1 fragment, two types of final state distributions of the fragments have been found; the difference depending upon the excess energy with respect to the NO X ν = 1 + O₃P dissociation limit. Above the threshold, statistical rotational behaviour with nonvanishing anisotropies has been observed. Below the threshold, an efficient R→V transfer, allowed by a significant molecular distortion, was detected. The influence of the parent rotation on the NO fragment rotational distribution is discussed.     

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.     

Inter- and intra-molecular radiationless transitions of NO2 at around 454.6 nm

The continuum emission of NO₂ was investigated on the basis of time-resolved excitation and fluorescence spectra. The analysis of the observed spectra indicated the coexistence of inter- and intra-molecular relaxation processes of NO₂. The continuum emission, the relative intensity of which at longer wavelengths increases more drastically as time goes on after excitation (2–6 μs), was concluded to originate predominantly from molecular collisions in a stepwise deactivation process. A fast component of the continuum emission, with a relative intensity with respect to the discrete band (I_C/I_D) independent of time and of NO₂ pressure, appeared in collision-free conditions (<20 ns, 15 mTorr), and it was concluded to originate from radiationless transitions in isolated molecules.     

Kinetics of the reaction of NH2 with NO2

The absolute rate constant of the reaction of NH₂ with NO₂ has been measured using a flash-photolysis laser resonance-fluorescence technique. The value obtained at room temperature is k₁ = 2.3 (± 0.2) × 10^?11 cm³ molecule ^?1 s^?1. A negative temperature coefficient has been found between 298 and 505 K for this reaction, k₁ = 3.8 × 10^?8 × T^?1.30 cm³ molecule^?1 s^?1. It is thought that this is the major reaction of NH₂ in the troposphere.     

Effect of conversion of NO2 into no on the catalytic reduction of NO2 with C3H6 in excess O2

During the reduction of NO₂ by C₃H₆ in O₂ over alumina-supported Au, Rh and Pt it was found that three parallel reactions take place,i.e., reduction of NO₂ to N₂ and N₂O, partial decomposition of NO₂ to NO and oxidation of C₃H₆ to CO and CO₂. In the absence of C₃H₆, the NO₂→NO+O₂ reaction reaches a fast equilibrium on Rh and Pt but not on Au and γ-Al₂O₃. Addition of C₃H₆ to the NO₂+O₂ mixture leads to the formation of NO above equilibrium conversion levels.     

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.     

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.     

Absorption cross-sections of NO2 in the UV and visible region (200 – 700 nm) at 298 K

The absorption cross-sections of NO₂ have been measured in the wavelength range 200 – 700 nm at 298 K with a spectral resolution of 0.04 nm. The data were acquired digitally, allowing post-processing such as integration in different wavelength intervals. The cross-sections are averaged over 1 nm intervals and over the atmospheric wavelength intervals used in solar photolysis calculations.     

EPR study of the NO2+3 radical in irradiated K(UO2)(NO3)3 and K2(UO2)(NO3)4 single crystals

A new radical observed at low temperature in γ-irradiated K₂(UO₂)(NO₃)₄ single crystals has been tentatively assigned to a hitherto unknown oxyanion radical, NO²⁺₃. The assignment and the lack of ¹⁴N hyperfine structure, together with the g factors which are lower than the free-spin value, are discussed in terms of an orbital level scheme.     

Thermodynamics of Sr(NO3)2 and Cd(NO3)2 in mixed solvents from viscosity data

The viscosities of Sr(NO₃)₂ and Cd(NO₃)₂ have been determined in dioxane, glycol and methyl alcohol+water mixtures at 10, 20 and 30% by weight. The B values have been computed at different temperatures both from the Jones—Dole and Das's equation. From the B values, the effective rigid molar volume, its change with % of organic solvent, temperature and the ion—solvent interaction have been inferred. Activation parameters have also been calculated and the structure breaking effect has been deduced.     

Thermodynamics of Sr(NO3)2 and Cd(NO3)2 in aquo-organic solvents from conductance data

The ion-solvent interaction of Sr(NO₃)₂ and Cd(NO₃)₂ in 10, 20 and 30 wt.% organic solvent (dioxane, glycol, methyl alcohol)-water mixtures at different temperatures has been studied using electrolytic conductivity data. The dissociation constant of the ion-pair Sr(NO₃)⁺ and Cd(NO₃)⁺ has been calculated along with ΔG⁰_t, ΔG⁰_t(cl) and ΔG⁰_t(ch). The ion pairs interact with the solvents and the interaction is of the order dioxane+water>methyl alcohol+water>glycol+water.     

Magnetic field decoupling experiments in NO2

Magnetic field decoupling experiments in the optically excited states of NO₂ yield decoupling signals with a width of 10 to 40 mG. We attribute these signals to the non-rigidity of the excited molecule.     

Photodissociation Dynamics of Dichlorodifluoromethane (CF2Cl2) around 235 nm using Time-Sliced Velocity Map Imaging Technology

Photodissociation dynamics of dichlorodifluoromethane (CF₂Cl₂) around 235 nm has been studied using the time-sliced velocity map imaging technology in combination with the resonance enhanced multi-photon ionization technology. By measuring the raw images of chlorine atoms which are formed via one-photon dissociation of CF₂Cl₂, the speed and angular distributions can be directly obtained. The speed distribution of excited-state chlorine atoms consists of high translation energy (E_T) and low E_T components, which are related to direct dissociation on ³Q₀ state and predissociation on the ground state induced by internal conversion, respectively. The speed distribution of ground-state chlorine atoms also consists of high E_T and low E_T components which are related to predissociation between ³Q₀ and ¹Q₁ states and predissociation on the ground state induced by internal conversion, respectively. Radical dissociation channel is confirmed, nevertheless, secondary dissociation and three-body dissociation channels are excluded.     

Photodissociation of molecular beams of N2O4

A molecular beam of N₂O₄ molecules was photodissociated by an excimer laser at 193 and 248 nm. The time-of-flight distribution of NO₂ photofragments is consistent with the formation of two electronically excited NO_2* molecules in the ā(²B₂) or B?(²B₁) state. Visible emission from NO₂^* was observed in the photolysis at both 193 and 248 nm excitation. The parallel angular distribution of the NO₂ photofragments shows that at.193 nm N₂O₄ has a transition dipole along the N-N axis and the dissociative lifetime is estimated to be less than 1 ps.     

Relative quantum yield of the S2 → S1 fluorescence from azulene

The quantum yield ratio r = φ_{2 → 0}/φ_{2 → 1} of the S₂ → S₀ and S₂ → S₁ fluorescences from azulene has been redetermined. With azulene in isopentane at 190 K, r = 455 ± 100. This value agrees with the lower limit, given by Huppert, Jortner and Rentzepis, but is an order of magnitude lower than that given by Gillispie and Lim.     

Conductivities of the Ternary Systems Y(NO3)3+La(NO3)3+H2O, La(NO3)3+Ce(NO3)3+H2O, La(NO3)3+Nd(NO3)3+H2O and Their Binary Subsystems at Different Temperatures

Electrical conductivities were measured for the ternary systems Y(NO₃)₃+La(NO₃)₃+H₂O, La(NO₃)₃+Ce(NO₃)₃+H₂O, La(NO₃)₃+Nd(NO₃)₃+H₂O, and their binary subsystems Y(NO₃)₃+H₂O, La(NO₃)₃+H₂O, Ce(NO₃)₃+H₂O, and Nd(NO₃)₃+H₂O at (293.15, 298.15 and 308.15) K. The measured conductivities were used to test the generalized Young’s rule and the semi-ideal solution theory. The comparison results show that the generalized Young’s rule and the semi-ideal solution theory can yield good predictions for the conductivities of the ternary electrolyte solutions, implying that the conductivities of aqueous solutions of (1:3 + 1:3) electrolyte mixtures can be well predicted from those of their constituent binary solutions by the simple equations.     

Catalytic oxidation of no to NO2 over Cr/TiO2 and Cu/TiO2 under oxidizing atmosphere

The catalytic activity of Cr/TiO₂ and Cu/TiO₂ for the oxidation of NO under an oxidizing atmosphere has been examined. Both catalysts had excellent ability for the oxidation of NO to NO₂ in the temperature range of 350–400°C.     

Absorption cross sections for NO3 between 565 and 673 nm

Absorption cross sections for NO₃ in the wavelength region of 565–673 nm have been measured using a tunable dye laser. NO₃ was generated by the reaction of F with HNO₃ in a discharge flow tube and its concentration was determined by titration with NO. The measured cross sections are compared with literature values.