The missing part of the greenhouse effect

Summary Global average temperatures from 1860 to 1989 were analysed with a simple fitting procedure. The temperature records can be fitted with a rising exponential up to 1946 and with the same exponential minus an increasing cooling action from 1946 to 1989. It is shown that the results are compatible with the hypothesis of an albedo increase caused by SO₂ emissions. This hypothesis gives satisfactory explanations of the temperature drop in the years 1940–1970, of the different warming of the northern and southern hemispheres and of the slower warming observed over North America. The results give an indication that the greenhouse warming in the next years could be faster than predicted until now. Due to the relevance of its scientific content, this paper has been given priority by the Journal Direction.     

Spectroscopic Detection of Sulfur Oxides in the Aircraft Wake

The absorption/emission spectral regions of SO, SO₂, SO₃, S₂O and HSO are analyzed for the range from UV (λ ≥ 0.2 μm) to IR (λ < 30 μm) and are compared with the atmospheric transmission spectrum. It is shown that many vibrational bands of the compounds considered fall into atmospheric transmission windows. For the vibrational bands of SO, SO₂, SO₃, S₂O, and HSO molecules there are some gases which hinder the absorption diagnostics of the indicated compounds. These interfering gases are natural components of atmospheric air as well as specific gases of aircraft engine exhaust. It is found that the least influence of the interference takes place in the 2400–2700 cm⁻¹ IR region. The spectroscopic techniques used for the detection of aircraft engine exhaust compounds are briefly reviewed, with much consideration given to SO₂. The IR absorption spectra of SO₂ and other gases are calculated for the conditions of the aircraft engine nozzle exit. Narrow spectral intervals suitable for SO₂ detection in a hot flow are determined. An analysis is made for the detection capabilities of CO₂ lasers (including isotope CO₂ lasers) and CO lasers (both fundamental band and first-overtone ones) as applied to SO₂ detection in aircraft engine exhaust. Published in English as Preprint No. 5 of the P. N. Lebedev Physical Institute, Moscow (2004).     

High-resolution photoacoustic and direct absorption spectroscopy of main greenhouse gases by use of a pulsed entangled cavity doubly resonant OPO

An entangled cavity doubly resonant optical parametric oscillator (ECOPO) has been developed to provide tunable narrow line width (<100 MHz) pulsed (8 ns) radiation over the 3.8–4.3 μm spectral range at a multi-kilohertz repetition rate with up to 100-W peak power. We demonstrate that coarse single mode tuning is obtained over the full spectral range of oscillation (300 cm⁻¹), while automated mode-hop-free fine tuning is carried out over more than 100 GHz. High-resolution spectra of main greenhouse gases (CO₂, N₂O, SO₂ and CH₄) have been obtained in good agreement with calculated spectra from the HITRAN database. These experiments outline the unique capabilities of the ECOPO for multi-gas sensing based on direct absorption as well as photoacoustic spectroscopy.     

Structural and electrical properties of γ-alumina - lithium sulphate films

Li₂SO₄ as a model ionic conductor has received very much attention over several decades. Especially, in recent years Li₂SO₄ and Li₂SO₄-Al₂O₃ have been mentioned as promising proton conducting electrolytes for applications such as intermediate temperature fuel cells and novel cogeneration systems regarding H₂S handling devices. This has encouraged us to strive towards further improvement of the properties of the materials to meet the demands of the applications. In order to improve the properties of this system, a new process, a suspension technique, has been recently developed to prepare nanostructured powder and thin film Li₂SO₄-Al₂O₃ membranes. The powders and thin films have a well crystallised structure composed of two phases, Li₂SO₄ and γ-Al₂O₃, and excellent mechanical strength. The thin film thickness is in the scale of a few to several mm with a smooth and shining surface and a homogeneous macroscopic structure. It is a very interesting phenomenon that all samples show no significant conductivity increase at the temperature of the phase transition (∼ 577 °C) from β to α phase of pure Li₂SO₄. This transition has important significance for applications. The conductivity of the two-phase film materials has been greatly enhanced, where the xLi₂SO₄-(1-x)Al₂O₃ (x=58) sample shows the highest conductivity, about 1 S/cm at 600 °C; the activation energy decreases with increasing Li₂SO₄ content. These results agree with the so called composite effect for the conductivity enhancement observed earlier for two-phase bulk materials. Based on the four-step proton conducting mechanism in sulphate-based materials, this work may propose a new mechanism. The protons might jump in a water network associated with the water molecular re-orientation, which is accompanied with the single proton jump of the four-step transportation among SO ₄ ²⁻ groups from one Li₂SO₄ molecule to another. The former mechanism occur in the interfacial region between the Li₂SO₄ and the Al₂O₃ grains, while the latter occur in the bulk of the Li₂SO₄ grains. These thin film materials are intended for use as proton conducting ceramic membranes in applications such as desulphurisation and fuel cell co-generation plants. Paper presented at the 5th Euroconference on Solid State Ionics, Benalmádena, Spain, Sept. 13–20, 1998.     

CH4/air/SO2 premixed flame spectroscopy with a 7.5-μm diode laser

As sulfur dioxide (SO₂) is often involved in combustion processes, we present here SO₂-concentration measurements in the post-flame region of a CH₄/air/SO₂ premixed flame. SO₂ concentrations were deduced from high-resolution absorption spectra recorded with a mid-infrared tunable diode-laser (TDL) source operating at liquid nitrogen temperature. Single-mode, continuous frequency tuning around 1384.5 cm^-1 (or 7.5 μm) is achieved by a fine TDL temperature ramp. These experiments lead us to develop in situ combustion-pollutant measurements with compact apparatus. We show that this non-intrusive method is efficient for detection and allows the retrieval of SO₂ concentration and temperature. Received: 19 February 2001 / Revised version: 18 April 2001 / Published online: 7 June 2001     

Using broadband absorption spectroscopy to measure concentration of sulfur dioxide

A linear relationship between concentration of sulfur dioxide (SO₂) and optical parameter (OP) is established using the Beer–Lambert law. The SO₂ measuring system is set up to measure the concentration of sulfur dioxide in the wavelength range 275–315 nm. Experimental results indicate that the detection limit of the sulfur dioxide measuring system is below 0.2 ppm per meter of path length, and the measurement precision is better than ±1%. The proposed SO₂ measuring method features limited interference from other gases and dust, and high stability and short response time.     

Selectivity improvement of air pollution detection by using optothermal laser spectroscopy

Optothermal CO₂ laser spectroscopy of air polluted by CO₂ and SO₂ has been performed with improved selectivity in the low pressure range. The ability of kinetic cooling effects to give additional improvement of the detection selectivity is demonstrated.     

Space-borne remote sensing of CO2, CH4, and N2O by integrated path differential absorption lidar: a sensitivity analysis

CO₂, CH₄, and N₂O are recognised as the most important greenhouse gases, the concentrations of which increase rapidly through human activities. Space-borne integrated path differential absorption lidar allows global observations at day and night over land and water surfaces in all climates. In this study we investigate potential sources of measurement errors and compare them with the scientific requirements. Our simulations reveal that moderate-size instruments in terms of telescope aperture (0.5–1.5 m) and laser average power (0.4–4 W) potentially have a low random error of the greenhouse gas column which is 0.2% for CO₂ and 0.4% for CH₄ for soundings at 1.6 μm, 0.4% for CO₂ at 2.1 μm, 0.6% for CH₄ at 2.3 μm, and 0.3% for N₂O at 3.9 μm. Coherent detection instruments are generally limited by speckle noise, while direct detection instruments suffer from high detector noise using current technology. The wavelength selection in the vicinity of the absorption line is critical as it controls the height region of highest sensitivity, the temperature cross-sensitivity, and the demands on frequency stability. For CO₂, an error budget of 0.08% is derived from our analysis of the sources of systematic errors. Among them, the frequency stability of ± 0.3 MHz for the laser transmitter and spectral purity of 99.9% in conjunction with a narrow-band spectral filter of 1 GHz (FWHM) are identified to be challenging instrument requirements for a direct detection CO₂ system operating at 1.6 μm. PACS 42.68.Wt; 95.75.Qr     

Infrared spectra of BeSO4.4H2O and its deuterated analogue in 4000–1200 cm−1 region

IR spectra of BeSO₄.4H₂O and its deuterated analogue at ∼300 K and ∼110 K are reported in the region 4000–1200 cm⁻¹ using thin film and nujol mull techniques. The observed bands have been assigned as the internal modes of the water and the overtones and combinations of various modes using the recently revised assignments of SO₄ ²⁻ and Be(aq)₄ fundamentals in the region 1200–250 cm⁻¹ (Srivastavaet al 1976). The splitting of the internal modes of water has been discussed in the light of the effects of deuteration and cooling and it is shown that all the water molecules in a unit cell are asymmetric but crystallographically equivalent.     

Remote detection of sulfur dioxide by means of a CO2 laser

The possibility of remote detection of SO₂ in the 9-μm region of the spectrum by means of a TEA CO₂ laser was theoretically and experimentally investigated with regard to the real state of the atmosphere and the contribution of background concentrations of H₂O, CO₂ and NH₃ to absorption. For sounding along short paths (2L=2 km), the method of detection of small concentrations of SO₂ (at the MPC level) with the use of the lines of the CO₂-molecule regular transitions (00^o1–02^o0 band) has been devised and experimentally tested. It is shown that in sounding along longer paths (2L=6 km), a noticeable increase in sensitivity can be achieved by the generation lines of the CO₂-molecule sequential 00^o2–02^o1 band. B. I. Stepanov Institute of Physics of the National Academy of Sciences of Belarus, 70, F. Skorina Ave., Minsk, 220072, Belarus. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 65, No. 4, pp. 508–515, July–August, 1998.     

The impact of heat pumps on global warming and ozone depletion

The heat pump, a proven and reliable technology, has the potential to reduce primary energy consumption and the corresponding CO₂-emissions for heating and cooling in domestic, commercial and industrial applications. The basic principles of heat pump technology and the anthrogenic CO₂-formation under the given energy supply and demand situation in Europe and the related impact on global warming are described.An analysis of the energy flow between primary energy exploitation and the useful energy of different heating systems clearly demonstrates the ability of electric heat pumps to reduce primary energy consumption in Europe between 15 and 50%, compared with oil- and gas-heating systems. The corresponding reduction of CO₂-emissions will be between 20 and 60% and up to 85% of other pollutants.The present status of alternative working fluids which do not contribute to ozone depletion is presented and the direct (working fluids) and indirect (energy consumption) impact of different heat pumps on the greenhouse effect is discussed.     

Impedance and FTIR studies on plasticized PMMA–LiN(CF<Subscript>3</Subscript>SO<Subscript>2</Subscript>)<Subscript>2</Subscript> nanocomposite polymer electrolytes

Plasticized polymer electrolytes composed of poly(methyl methacrylate) (PMMA) as the host polymer and lithium bis(trifluoromethanesulfonyl)imide LiN(CF₃SO₂)₂ as a salt were prepared by solution casting technique at different ratios. The ionic conductivity varied slightly and exhibited a maximum value of 3.65 × 10⁻⁵ S cm⁻¹ at 85% PMMA and 15% LiN(CF₃SO₂)₂. The complexation effect of salt was investigated using FTIR. It showed some simple overlapping and shift in peaks between PMMA and LiN(CF₃SO₂)₂ salt in the polymer electrolyte. Ethylene carbonate (EC) and propylene carbonate (PC) were added to the PMMA–LiN(CF₃SO₂)₂ polymer electrolyte as plasticizer to enhance the conductivity. The highest conductivities obtained were 1.28 × 10⁻⁴ S cm⁻¹ and 2.00 × 10⁻⁴ S cm⁻¹ for EC and PC mixture system, respectively. In addition, to improve the handling of films, 1% to 5% fumed silica was added to the PMMA–LiN(CF₃SO₂)₂–EC–PC solid polymer electrolyte which showed a maximum value at 6.11 × 10⁻⁵ S cm⁻¹ for 2% SiO₂.     

An optical system for measuring nitric oxide using spectral separation techniques

An optical sensor based on differential absorption spectroscopy for real-time monitoring of industrial nitric oxide (NO) gas emission is described. The influence of gas absorption interference from sulfur dioxide (SO₂) in the environment was considered and a spectral separation technique was developed in order to eliminate this interference effect. The absorption spectrum of SO₂ around 226 nm was evaluated by the SO₂ concentration obtained using the experimentally recorded absorption spectrum around 300 nm. The absorption spectrum of NO around 226 nm was obtained by subtracting the absorption of SO₂ from the integral absorption spectrum of SO₂ and NO. The concentration measurements were performed at atmospheric pressure. The technique was found to have a lower detection limit of 0.8 ppm for NO per meter path length (SNR=2) and be immune from the influence from SO₂ on the NO measurement. The sensor based on this technique was successfully employed for in situ measurement of SO₂ and NO concentrations in the flue gas emitted from an industrial coal-fired boiler.     

Electrical properties of Na<Subscript>2</Subscript>SO<Subscript>4</Subscript>-based composite systems

Composite electrolytes are well-known multiphase systems and exhibit maxima in the conductivity at certain second-phase concentration. An attempt has been made to investigate a number of sodium sulfate (Na₂SO₄)-based composite systems. The dispersoids that have been used are MgO, Al₂O₃, and SiO₂. The samples have been characterized using impedance spectroscopy, X-ray diffraction, and differential scanning calorimetry. The maximum conductivity has been observed for MgO dispersed system, and the percolation threshold has been observed at 30-mol% dispersoid, MgO concentration. Interestingly, two maxima have been observed in case of the Na₂SO₄–SiO₂ and Na₂SO₄–Al₂O₃ composite systems. In the Na₂SO₄–SiO₂ system, the first maximum occurs at lower concentration, i.e., in the range between 10 and 20 mol%, whereas the second occurs at the 40-mol% dispersoid concentration. For the Na₂SO₄–Al₂O₃ system, although slightly indistinguishable, two peaks in the conductivity vs composition plot have been observed around 12- and 30-mol% Al₂O₃ concentrations.     

Short-Range Order of the Rotational Degree of Freedom of the Glycine Molecule in Triglycine Sulfate Glass State

The unit cell of triglycine sulfate (TGS) contains the following glycine ions: dimers (GIISHBGIII)⁺ with a short hydrogen bond (SHB) and a monomer (SO₄LHBGI)⁺ with a long hydrogen bond (LHB) to the SO₄ ²⁻ anion. The spontaneous polarization results from a statistical charge distribution and the Coulomb interaction between SO₄ ²⁻ and fast rotating –NH₃ ⁺ groups. In the lamellar model, chains of –SO₄–(GIISHBGIII)–SO₄–(GIISHBGIII)–SO₄ lying along the polar b-axis are linked perpendicularly to this axis by SO₄LHBGI⁺ units. Tilting the LHBGI⁺ ion around the axis in the mirror plane decides on the direction of the charge displacement from this symmetry plane. The reversal of the spontaneous polarization, i.e., −P _S↔ +P _S, is related to the rotation of the NH₃ group. If this rotation becomes slowed down at low temperature and/or under high pressure, the coercive field increases dramatically. Application of an external electric field E _⊥ perpendicular to the b-axis leads to a hysteresis loop of the polarity P(E), and finally to its disappearance. This phenomenon comes from an ordering of protons in hydrogen bonds perpendicular to the polar axis. This is the first study of the E _⊥ effect by nuclear magnetic resonance. Authors' address: Jan Stankowski, Institute of Molecular Physics, Polish Academy of Sciences, Smoluchowskiego 17, Poznań 60-179, Poland     

Direct methanol fuel cells: The influence of methanol on the reduction of oxygen over Pt/C catalysts with different particle sizes

Two Pt/C catalysts with different particle sizes (Pt/C: 2.5 nm, Pt/C-700Ar: 5.1 nm) were investigated by applying a half-cell configuration —rotating disk electrode (RDE) technique in H₂SO₄ aqueous solutions in the absence of or in the presence of methanol with different concentrations. Pt/C catalyst exhibited higher mass activity in H₂SO₄ aqueous solution without methanol and slightly lower mass activity in H₂SO₄ plus 0.1 mol/L CH₃OH in comparison with that of Pt/C-700Ar catalyst. On the contrary,single direct methanol fuel cell (DMFC) tests showed that Pt/C exhibited higheroxygen reduction reaction (ORR) activity and better cell performance, mainly due to the different kinds of electrolyte properties. Furthermore, it suggested that a better single DMFC performance could be obtained with a smaller particle size Pt-based cathode catalyst. Paper presented at the Patras Conference on Solid State Ionics — Transport Properties, Patras, Greece, Sept. 14 — 18, 2004.     

Vibrational spectra of two BEDT-TTF-based organic conductors: charge order

Infrared and Raman investigations of two phases of bis(ethylenedithio)tetrathiafulvalene (BEDT-TTF) based organic conductors with the same CF₃CF₂SO₃⁻ anion: β′-(BEDT-TTF)₂CF₃CF₂SO₃ and δ′-(BEDT-TTF)₂CF₃CF₂SO₃, are shortly reviewed and compared with the most typical infrared properties of the family of (BEDT-TTF)₂RR′SO₃ organic conductors, where R = SF₅, CF₃, and R′ are CH₂, CF₂, CHF, CHFCF₂, and CH₂CF₂. The role of the molecular structur and spatial organization of the counterions is discussed. Presented at 2-nd International Conference on Functional Materials and Devices, ICFMD 2008, June 16–19, 2008, Kuala Lumpur, Malaysia     

Structural and ionic conductivity studies of solid polymer electrolytes based on poly (vinylchloride) and poly (methylmethacrylate) blends

Thin film of poly (vinylchloride) and poly (methylmethacrylate) blend polymer electrolytes plasticized with a combination of DBP and Li₂SO₄ salts have been prepared by solution casting technique. The prepared films were subjected to a.c. impedance measurements as a function of temperature ranging from 304–373 K. The maximum conductivity at 304 K was found to be 1.24 × 10⁻⁸ S·cm⁻¹ for PVC-PMMA-Li₂SO₄-DBP (7.5-17.5-5-70 mole-%). Temperature dependence studies on the ionic conductivity in the PVC-PMMA-Li₂SO₄-DBP system suggest that the ion conduction follows the Williams-Landel-Ferry (WLF) mechanism, which is further confirmed by Vogel-Tamman-Fulcher (VTF) plots. XRD, FTIR, SEM and thermal studies revealed complex formation in.     

Luminescence Characterisation of the Reaction System Histidine–KBrO3–Tb(III)–H2SO4

Chemiluminescence of the system containing Tb(III) ions, histidine and bromate ions in acid solution was studied. The kinetic curves and CL emission spectra of the system were discussed. The emission spectrum of the histidine–Tb(III)–KBrO₃–H₂SO₄ system revealed two emission maxima at ∼490 and 550 nm, characteristic of Tb(III) ions. Values of lifetimes of the Eu(III) excited states in Eu(III)–histidine system have shown that the histidine formed ML and ML₂ complexes in neutral solution and did not make them in acidic environment. On the basis of the results, a possible mechanism of reaction system: histidine–Tb(III)–KBrO₃–H₂SO₄ is presented.     

EPR spectra of γ-irradiated hydrated barium dithionate single crystals

EPR spectra of barium dithionate hydrate single crystals γ-irradiated at low (80 Gy) and high (10 kGy) doses are studied. Four lines, the strongest of which is due to the SO₃⁻ radical, are observed in the EPR spectrum of the low-irradiated samples. Another line seems to belong to SO₂⁻. The strong line and weak lines with hyperfine structure and lines for pairs of closely spaced SO₃⁻ centers with a strong angular dependence are observed at high irradiation doses. The main values of the SO₃⁻ hyperfine coupling tensor and the dipole-dipole coupling constants of the SO₃⁻ pairs are determined. A quantum-chemical calculation of the electronic structure of isolated SO₃⁻ and SO₂⁻ radicals is performed. Values of the g tensors and hyperfine couplings are calculated. __________ Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 75, No. 1, pp. 18–22, January–February, 2008.