Formation of the H2SO4 ·HSO−4 dimer in the atmosphere as a function of conditions: a simulation study

ABSTRACT

The detailed structure and clustering free energy of aerosol particles are important for understanding of new particle formation from molecules and ions in the atmosphere. In this paper, configurations of the H₂SO₄ ·HSO^?₄ dimer were sampled with meta-dynamics aided ab initio molecular dynamics (MTD-AIMD) simulations. Based on the rigid rotor harmonic oscillator (RRHO) approximation and the law of mass action, the binding free energies (ΔG) of the dimer in the most stable configuration were calculated for three atmospheric circumstances, i.e. at the ground level and in the middle and upper troposphere. The results show that, the most stable H₂SO₄ ·HSO^?₄ dimer is combined via triple O–H???O hydrogen bonds. It can be generated efficiently in both the middle and upper troposphere, but not at the ground level. All our simulations were carried out at the level of hybrid density functional theory (PBE0, hybrid-DFT), which is more accurate than DFT only.     

Phase transitions and energy storage properties of some compositions in the (1−x)Li2SO4–xNa2SO4 system

In the binary system (1?x)Li₂SO₄–xNa₂SO₄, the solid–solid phase transitions and energy storage properties of Li₂SO₄, Na₂SO₄, the binary compound LiNaSO₄ and two eutectoids (E₁: 0.726Li₂SO₄–0.274Na₂SO₄; E₂: 0.03Li₂SO₄–0.97Na₂SO₄) were investigated by X-ray diffraction and differential scanning calorimetry. Li₂SO₄ has a solid–solid phase transition at 578 °C with the transition enthalpy 252 J g^?1. The binary compound LiNaSO₄ gives a slightly lower enthalpy value, 214 J g^?1 and its transition temperature is clearly reduced to 514 °C. The transition enthalpy of the eutectoid E₁ is maintained to 177 J g^?1 and its transition temperature is further reduced to 474 °C. Li₂SO₄, LiNaSO₄ and the eutectoid E₁ are applicable phase transition materials because of their large transition enthalpies. The enthalpies of Na₂SO₄ and the eutectoid E₂ are not very high (～45 J g^?1), but their transition temperatures are quite low (～250 °C); thus their transition properties may be applied at such low temperatures.     

Low-temperature phase transitions and dynamics of ammonium in (NH4)3H(SO4)2 and [(NH4)1−x Rbx]3H(SO4)2 crystals

The (NH₄)₃H(SO₄)₂ and [(NH₄)_0.82Rb_0.18]₃H(SO₄)₂ crystals are investigated by dielectric spectroscopy, inelastic incoherent neutron scattering (IINS), and neutron powder diffraction. A comparative analysis of the data obtained is given. It is shown that the phase transitions II ? III, III ? IV, IV ? V, and V ? VII in the (NH₄)₃H(SO₄)₂ crystal are accompanied by changes in the orientation ordering of the NH ₄ ⁺ ions. In the [(NH₄)_0.82Rb_0.18]₃H(SO₄)₂ crystal, these phase transitions are completely suppressed and the long-range order inherent in the II phase is retained over the entire temperature range covered (6–300 K). It is revealed that this crystal at the temperature T _g≈70 K undergoes a transition to the dipole glass phase, which is attended by “freezing” the orientation disordering of the ammonium ions.     

Isotopic effect in Brillouin light-scattering spectra of a Cs5H3(SO4)4 · xH2O crystal

A Brillouin scattering study of the behavior of hypersonic longitudinal acoustic phonons in crystalline pentacesium trihydrogen tetrasulfate Cs₅H₃(SO₄)₄ · xH₂O (PCHS) and its deuterated analog Cs₅D₃(SO₄)₄ · xD₂O (DPCHS) at temperatures ranging from 420 to 120 K is reported. The effect of deuteration on the crystal lattice dynamics is investigated. The differences in the behavior of hypersonic acoustic phonons in the PCHS and DPCHS crystals suggest the existence of a hydrogen isotope effect in both the high-and low-temperature phases. A possible model of the isotopic effect in the high-temperature phase is discussed. An analysis is made of the acoustic response of the PCHS and DPCHS crystals in the region of the transition to the glasslike phase.     

Spectrum of the H− Ion in the s-Wave Model

 The H⁻ ion in the s-wave model has one bound state and a Rydberg series of resonances, one associated with each inelastic threshold of the electron hydrogen system. We calculate the energy of the bound state and the energies of the resonances as well as their total widths up to N = 9 and partial widths up to N = 7. Received July 5, 1999; revised February 18, 2000; accepted for publication February 22, 2000     

Proton diffusion in the room-temperature phase of [(NH4)1−xRbx]3H(SO4)2 as studied by 1H spin-lattice relaxation in the rotating frame

Proton diffusion in the room-temperature phase (phase II) of [(NH₄)_1?xRb_x]₃H(SO₄)₂ (0≤x≤1) has been studied by means of ¹H spin-lattice relaxation times in the rotating frame, T_1ρ. The ¹H T_1ρ values were measured at 200.13 MHz in the range of 380–490 K. The ammonium protons and the acidic protons have independent T_1ρ values in the higher temperature range of phase II, suggesting that the spin diffusion between the two species is ineffective. The translational diffusion of the acidic protons is the most dominant mechanism to relax both the ammonium protons and the acidic protons in phase II. The ¹H T_1ρ values in phase II are analyzed theoretically and the motional parameters are obtained. The results of NMR well explain the macroscopic proton conductivity.     

Radiation-stimulated changes in the transmission of chalcogenide glasses of As2S3−Ge2S3

The radiative-optical properties of chalcogenide glass-like semiconductors of the As₂S₂−Ge₂S₃ system in the region of a topological 2D-3D-phase transition are investigated. It is shown that γ-irradiation of samples by an absorbed dose of 4.4 · 10⁶ Gy leads to a longwave shift of their optical-transmission edge in the spectrum. The effect observed depends on the structural type of the glasses investigated and changes considerably near the 2D-3D-phase transition. Two components of the transmission-edge shift are detected: a static component, which remains unchanged for a long time after irradiation of the samples, and a dynamic one, which gradually fades in 2–3 months. It is suggested that the microstructural mechanism of these changes is attributable to processes of coordination defect formation in the structural skeleton of the samples. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 66, pp. 657–660, September–October, 1999.     

Variations of phase transition temperature and enthalpy in the systems Na2Mo1− x W x O4 and Na2Mo1− y S y O4

The samples in two material systems, Na₂Mo_{1? x} W _x O₄ and Na₂Mo_{1? y} S _y O₄, were prepared by using conventional solid reactions and characterized by X-ray diffractometer (XRD), energy dispersive X-ray spectroscopy (EDX), and difference scanning calorimetry (DSC). The XRD and EDX data indicated that all the samples in both systems were in the solid solution range. The DSC data indicated that in the system Na₂Mo_{1? x} W _x O₄, the solid–solid transition temperatures increased and in the system Na₂Mo_{1? y} S _y O₄, the solid–solid transition temperatures decreased. The total enthalpy (ΔH _total) of the solid–solid transitions in the system Na₂Mo_{1? x} W _x O₄, decreased much less than that in the system Na₂Mo_{1? y} S _y O₄. This is probably because similar to Na₂MoO₄, the solid–solid transition of Na₂WO₄ has relatively large ΔH _total, but Na₂SO₄ has much smaller solid–solid transition enthalpy. In order to modify the transition temperatures of Na₂MoO₄ and also to keep its relatively large ΔH _total, it is necessary to choose a doping material with large ΔH _total.     

Study on the Relationship between the Depth of Spectral Absorption and the Content of the Mineral Composition of BiotiteSCIEI北大核心CSCD

The mineral composition of rock is one of the main factors affecting the spectral reflectance characteristics, and it' s an important reason for generating various rock characteristic' spectra. This study choose the rock samples provided by Jet Propulsion Laboratory (JPL) (including all kinds of mineral percentage of rocks, and spectral reflectances range from 0. 35 to 2. 50 Elm wavelength measured by ASD spectrometer), and the various types of mineral spectral reflectances contained within the rocks are the essential data. Using the spectral linear mixture model of rocks and their minerals, firstly, a simulation study on the mixture of rock and mineral composition is achieved, the experimental results indicate that rock spectral curves using the model which based on the theory of the linear mixture are able to simulate better and preserve the absorption characteristics of various mineral components well. Then, 8 samples which contain biotite mineral are picked from the rock spectra of igneous, biotite contents and the absorption depth characteristics of spectral reflection at 2. 332 tan, furthermore, a variety of linear and nonlinear normal statistical models are used to fit the relationship between the depth of absorption spectra and the content of the mineral composition of biotite, finally, a new simulation model is build up with the Growth and the Exponential curve model, and a statistical response relationship between the spectral absorption depth and the rock mineral contents is simulated by using the new model, the fitting results show that the correlation coefficient reaches 0. 998 4 and the standard deviation is 0. 572, although the standard deviation using Growth and Exponential model is less than the two model combined with the new model fitting the standard deviation, the correlation coefficient of the new model had significantly increased, which suggesting that the new model fitting effect is closer to the measured values of samples, it proves that the simulation results of new model is closer to the measured value.     

Comparative study of aerogels nanostructured catalysts: Ni/ZrO2–SO4 2− and Ni/ZrO2–Al2O3–SO4 2−

Ionics - A series of Ni/ZrO2–SO4 2− and Ni/ZrO2–Al2O3–SO4 2− catalysts were prepared in one step by the sol–gel method and dried in hypercritical conditions of...     

Domain structure and phase transitions of LiKSO4:EPR of SO−4 centers

Analysis of the EPR of SO⁻₄ centers in LiKSO₄ crystals indicates that the SO⁻₄ centers are associated with local positive-ion vacancies. Twin-domains of the 〉110〈 types are observed to be temperature-dependent. The anomaly at 215 K on cooling is associated with a sudden growth of the twins and the anomaly at 190 K is associated with a p6₃ to p6₃P6,mc structural phase transition.     

Rotational structure of the origin band in the 1A′ ←X1σ+ electronic transition of C4H− and C4D−

The rotational structure of the origin band for the ¹A′←X¹σt⁺ electronic transition, lying just below the electron affinity of C⁴H, was recorded by means of a two-colour resonant photodetachment technique. This allowed a determination of the rotational constants in the X¹σt⁺ ground and ¹A′ dipole bound excited state. The low lying A²II excited state of C⁴H is inferred to be the parent of the dipole bound state. The excited electronic state is deduced to have a nonlinear planar structure whereas the ground is linear according to the spectral analysis. The rotational constants have been obtained: B′; = 0.1552(2)cm^?1 for the X¹σt⁺ state, and A′ = 30.73(1), B′ = 0.1587(2), C′ = 0.1581(2)cm^?1 for the ¹A′ state.     

Diffusion of ammonium ions in [(NH4)1−xRbx]3H(SO4)2 studied by 1H spin–lattice relaxation in the rotating frame

Translational diffusion of NH₄⁺ ions in [(NH₄)_1?xRb_x]₃H(SO₄)₂ has been evaluated quantitatively by means of ¹H spin–lattice relaxation times in the rotating frame, T_1ρ. In the high-temperature phase (phase I), the mean residence times of NH₄⁺ ions are three or four orders of magnitude larger than those of the acidic protons. In the room-temperature phase (phase II), they are two or three orders of magnitude larger than those of the acidic protons. The transition from phases II to I causes one order of magnitude enhancement in the diffusion of NH₄⁺ ions. The mean residence time of NH₄⁺ ions increases with increase in the Rb content. The similar trend is also observed in phase II.     

Measurement of the Electric Quadrupole Moment of the 9/2− and 21/2− Isomers in 173Ta

The electric quadrupole moments of the 9/2⁻ and 21/2⁻ isomeric states of ¹⁷³Ta at 165.8 keV and 1713.2 keV, respectively, were measured as Q(9/2⁻)=2.92(15) b and Q(21/2⁻)=6.23(18) b for the first time using the TDPAD technique. A 66 MeV pulsed ¹²C ion beam from the 15UD pelletron accelerator facility of the Nuclear Science Centre at New Delhi was used in the reaction ¹⁶⁵Ho(¹²C, 4nγ)¹⁷³Ta. The experimental values of equilibrium deformations β₂(9/2⁻)=0.251(7) and β₂(21/2⁻)=0.391(7) were extracted. This revised version was published online in July 2006 with corrections to the Cover Date.     

Implications of axion-like particles from the Fermi-LAT and H.E.S.S.observations of PG 1553+113 and PKS 2155−304

We investigate the axion-like particle(ALP)-photon oscillation effect in the high-energy y-ray spectra of PG 1553+113 and PK.S 2155-304 measured by Fermi-LAT and H.E.S.S.The choice of extragalactic background light(EBL)model,which induces the attenuation effect in observed y-ray spectra,affects the ALP implications.For the ordinary EBL model that prefers a null hypothesis,we set constraints on the ALP-photon coupling constant at 95% C.L.as gay 5×10^-11 GeV^-1 for the ALP mass 〜10 neV.We also consider the CIBER observation of the cosmic infrared radiation,which shows an excess at wavelengths of -1μm after the substraction of foregrounds.High-energy gamma-rays from extragalactic sources at high redshifts would suffer from a more significant attenuation effect caused by this excess.In this case,we find that the ALP-photon oscillation would improve the fit to the observed spectra of PKS 2155-304 and PG 1553+113 and find a favored parameter region at 95%CL..     

Analysis of the Isotopic Composition of Exhaled Air by the Diode Laser Spectroscopy Method in the 2-μm Region for Diagnosis of Helicobacter pylori-Associated Diseases

Optics and Spectroscopy - To diagnose digestive diseases associated with Helicobacter pylori infection, we applied laser spectroscopic analysis of the 13СО2/12СО2 isotope...     

The Application of Raman Spectroscopy to the Study of the Uranyl Mineral Coconinoite Fe2Al2(UO2)2(PO4)4(SO4)(OH)2 · 20H2O

ABSTRACT

Raman spectra of the uranyl-containing mineral coconinoite, Fe₂Al₂(UO₂)₂(PO₄)₄(SO₄)(OH)₂ · 20H₂O, are presented and compared with the mineral's infrared spectra. Bands connected with (UO₂)²⁺, (PO₄)^3?, (SO₄)^2?, (OH)^?, and H₂O stretching and bending vibrations are assigned. Approximate U?O bond lengths in uranyl, (UO₂)²⁺, and O?H…O hydrogen bond lengths are calculated from the wavenumbers of the U?O stretching vibrations and (OH)^? and H₂O stretching vibrations, respectively, and compared with published data for similar natural and synthetic compounds.