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| 2. |
- Reddington, C. L., et al.
(författare)
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Primary versus secondary contributions to particle number concentrations in the European boundary layer
- 2011
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Ingår i: Atmospheric Chemistry And Physics. - : Copernicus GmbH. - 1680-7316 .- 1680-7324. ; 11:23, s. 12007-12036
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Tidskriftsartikel (refereegranskat)abstract
- It is important to understand the relative contribution of primary and secondary particles to regional and global aerosol so that models can attribute aerosol radiative forcing to different sources. In large-scale models, there is considerable uncertainty associated with treatments of particle formation (nucleation) in the boundary layer (BL) and in the size distribution of emitted primary particles, leading to uncertainties in predicted cloud condensation nuclei (CCN) concentrations. Here we quantify how primary particle emissions and secondary particle formation influence size-resolved particle number concentrations in the BL using a global aerosol microphysics model and aircraft and ground site observations made during the May 2008 campaign of the European Integrated Project on Aerosol Cloud Climate Air Quality Interactions (EUCAARI). We tested four different parameterisations for BL nucleation and two assumptions for the emission size distribution of anthropogenic and wildfire carbonaceous particles. When we emit carbonaceous particles at small sizes (as recommended by the Aerosol Inter-comparison project, AEROCOM), the spatial distributions of campaign-mean number concentrations of particles with diameter >50 nm (N(50)) and >100 nm (N(100)) were well captured by the model (R(2)>= 0.8) and the normalised mean bias (NMB) was also small (-18% for N(50) and -1% for N(100)). Emission of carbonaceous particles at larger sizes, which we consider to be more realistic for low spatial resolution global models, results in equally good correlation but larger bias (R(2)>= 0.8, NMB = -52% and -29%), which could be partly but not entirely compensated by BL nucleation. Within the uncertainty of the observations and accounting for the uncertainty in the size of emitted primary particles, BL nucleation makes a statistically significant contribution to CCN-sized particles at less than a quarter of the ground sites. Our results show that a major source of uncertainty in CCN-sized particles in polluted European air is the emitted size of primary carbonaceous particles. New information is required not just from direct observations, but also to determine the effective emission size and composition of primary particles appropriate for different resolution models.
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| 3. |
- Manninen, H. E., et al.
(författare)
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EUCAARI ion spectrometer measurements at 12 European sites - analysis of new particle formation events
- 2010
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Ingår i: Atmospheric Chemistry And Physics. - : Copernicus GmbH. - 1680-7316 .- 1680-7324. ; 10:16, s. 7907-7927
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Tidskriftsartikel (refereegranskat)abstract
- We present comprehensive results on continuous atmospheric cluster and particle measurements in the size range similar to 1-42 nm within the European Integrated project on Aerosol Cloud Climate and Air Quality interactions (EUCAARI) project. We focused on characterizing the spatial and temporal variation of new particle formation events and relevant particle formation parameters across Europe. Different types of air ion and cluster mobility spectrometers were deployed at 12 field sites across Europe from March 2008 to May 2009. The measurements were conducted in a wide variety of environments, including coastal and continental locations as well as sites at different altitudes (both in the boundary layer and the free troposphere). New particle formation events were detected at all of the 12 field sites during the year-long measurement period. From the data, nucleation and growth rates of newly formed particles were determined for each environment. In a case of parallel ion and neutral cluster measurements, we could also estimate the relative contribution of ion-induced and neutral nucleation to the total particle formation. The formation rates of charged particles at 2 nm accounted for 1-30% of the corresponding total particle formation rates. As a significant new result, we found out that the total particle formation rate varied much more between the different sites than the formation rate of charged particles. This work presents, so far, the most comprehensive effort to experimentally characterize nucleation and growth of atmospheric molecular clusters and nanoparticles at ground-based observation sites on a continental scale.
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| 4. |
- Pawłów, J., et al.
(författare)
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Influence of ionic liquid and oleic acid assisted methods on the spectroscopic properties of Nd3+-doped GdPO4 nano-particles
- 2023
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Ingår i: Journal of Materials Chemistry C. - 2050-7526 .- 2050-7534. ; 11:22, s. 7227-7242
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Tidskriftsartikel (refereegranskat)abstract
- We report a detailed analysis of both the structural and spectroscopic properties of Nd3+-doped GdPO4 nano-powders obtained via various wet synthesis methods. This type of material may be useful in optoelectronics, bioimaging and biomedicine. Three series of Nd3+-doped nano-materials with different concentrations of the optical activator (1–10 mol%) were obtained via ionic liquid assisted classical hydrothermal (IL HT) and microwave (IL MW) methods as well as via an oleic acid assisted hydrothermal (OA HT) method. A powder X-ray diffraction (PXRD) technique confirmed that the obtained GdPO4 nano-powders crystallize in a monoclinic system (P21/n) with the average grain size ranging from 40 to 100 nm; the smallest grains are obtained via the ionic liquid assisted microwave method, and no other phase has been detected for any of the materials obtained. Electron microscopy techniques i.e. SEM and TEM were used to demonstrate the differences in the morphology and grain size, which resulted in the spectroscopic properties of nano-materials. The nine-fold coordinated Gd3+ ion in GdPO4 is easily substituted by the Nd3+ one with the C1 symmetry due to their similar ionic radii, so that high-resolution low-temperature absorption and emission spectra do not show any structural distortion. The 4F3/2 excited state dynamics studied at 77 K showed abnormal behavior, similar to that already observed for Nd3+ ions embedded in the YPO4 and LuPO4 tetragonal orthophosphates crystallizing in a xenotime-type crystal system.
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| 5. |
- Prokop, K. A., et al.
(författare)
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Nano-crystalline Nd3+-doped LuPO4 optical materials obtained by ionic liquid assisted synthesis route
- 2022
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Ingår i: Materials Science & Engineering. - : Elsevier BV. - 0921-5107 .- 1873-4944. ; 275
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Tidskriftsartikel (refereegranskat)abstract
- LuPO4 in the form of nano-powders can find potential application in bio-imaging and luminescence thermometry. To enable development of functional materials there is a need to acquire basic information about the effect of morphology and grain size on spectroscopic properties. So, we investigated a series of Nd3+-doped LuPO4 nanoparticles prepared with task-specific ionic liquid as the reactant and in-situ stabilizer. Thus, fast and facile preparation of the desired well-crystallized single-phase phosphate nanomaterials was possible. The XRD patterns and TEM analysis revealed the influence of the synthesis conditions on the morphology and nanoparticles size, which is reflected in their spectroscopic properties. Low-temperature high-resolution techniques i.e. absorption spectroscopy at 4.2 K and laser site-selective spectroscopy at 77 K with Nd3+ ion as structural probe were used. Micro-powdered Nd3+-doped LuPO4 obtained by a solid-state reaction was applied as a reference. The possible application of this material as an optical thermometer was considered.
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