Search results for "AMMONIA"

First experimental proof of asymmetric charge transfer in ICP-MS/MS (ICP-QQQ-MS) through isotopically enriched oxygen as cell gas

2014

The quantification of a variety of elements in the field of ICP-MS is restricted by isobaric interferences. The recent development of ICP-MS/MS (“triple quadrupole” configuration) offers a new way to solve the problem of the detection of such elements affected by interferences because the signal caused by either the analyte or the isobaric interference can be shifted to another m/z through reactions with the cell gas (oxygen, ammonia or hydrogen). This system consists of two quadrupoles (Q1 and Q2) with a collision/reaction cell in between. When using the MS/MS mode of this configuration it becomes possible to restrict the ions entering the cell to a defined m/z and therefore get a better i…

New n-type molecular semiconductor–doped insulator (MSDI) heterojunctions combining a triphenodioxazine (TPDO) and the lutetium bisphthalocyanine (Lu…

2018

International audience; Molecular semiconductor–doped insulator (MSDI) heterojunctions were designed using a new family of sublayers, namely triphenodioxazines (TPDO). The device obtained by combining the tetracyano triphenodioxazine bearing two triisopropylsilylethynyl moieties as a sublayer with the lutetium bisphthalocyanine (LuPc2) as a top layer showed a nonlinear current–voltage characteristic independent of the sign of the polarization, which is the signature of MSDI heterojunctions. Thus, a TPDO was used in a chemical sensor for the first time. Despite LuPc2 being the only material exposed to the atmosphere, the positive response of the device under ammonia revealed the key role pla…

Nanostructured Solids from Freeze-Dried Precursors: Multigram Scale Synthesis of TiO2 -Based Powders

2012

Nanocrystalline TiO2 and Ti1−xVxO2 (x = 0.01) powders have been prepared by thermal decomposition, in air, of amorphous precursors resulting from the freeze-drying of appropriate solutions. In addition, TiO2−xNy (anatase and rutile) and TiOxNy (rock-salt) have been prepared by thermal treatment in ammonia of a crystalline precursor (TiO2 obtained at 673 K). TEM and SEM images, as well as the analysis of the X-ray diffraction (XRD) patterns, show the nanoparticulated character of those solids obtained at low temperatures, with typical particle sizes in the 10–20 nm range when prepared at 673 K. The UV–Vis results indicate both the insertion of V in the anatase lattice and the feasibility of …

H-2, H-3(+) and the age of molecular clouds and prestellar cores

2012

Measuring the age of molecular clouds and prestellar cores is a difficult task that has not yet been successfully accomplished although the information is of paramount importance to help in understanding and discriminating between different formation scenarios. Most chemical clocks suffer from unknown initial conditions and are therefore difficult to use. We propose a new approach based on a subset of deuterium chemistry that takes place in the gas phase and for which initial conditions are relatively well known. It relies primarily on the conversion of H 3 + into H 2D + to initiate deuterium enrichment of the molecular gas. This conversion is controlled by the ortho/para ratio of H2 that i…

The driving factors of new particle formation and growth in the polluted boundary layer

2021

Publisher Copyright: © 2021 Mao Xiao et al. New particle formation (NPF) is a significant source of atmospheric particles, affecting climate and air quality. Understanding the mechanisms involved in urban aerosols is important to develop effective mitigation strategies. However, NPF rates reported in the polluted boundary layer span more than 4 orders of magnitude, and the reasons behind this variability are the subject of intense scientific debate. Multiple atmospheric vapours have been postulated to participate in NPF, including sulfuric acid, ammonia, amines and organics, but their relative roles remain unclear. We investigated NPF in the CLOUD chamber using mixtures of anthropogenic vap…

2017

Abstract. Concurrent in situ analyses of interstitial aerosol and cloud droplet residues have been conducted at the Schmücke mountain site during the Hill Cap Cloud Thuringia campaign in central Germany in September and October 2010. Cloud droplets were sampled from warm clouds (temperatures between −3 and +16 °C) by a counterflow virtual impactor and the submicron-sized residues were analyzed by a compact time-of-flight aerosol mass spectrometer (C-ToF-AMS), while the interstitial aerosol composition was measured by an high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS). During cloud-free periods, the submicron out-of-cloud aerosol was analyzed using both instruments, all…

2011

Abstract. The ability of coated mineral dust particles to act as ice nuclei (IN) was investigated at LACIS (Leipzig Aerosol Cloud Interaction Simulator) during the FROST1- and FROST2-campaigns (Freezing of dust). Sulphuric acid was condensed on the particles which afterwards were optionally humidified, treated with ammonia vapour and/or heat. By means of aerosol mass spectrometry we found evidence that processing of mineral dust particles with sulphuric acid leads to surface modifications of the particles. These surface modifications are most likely responsible for the observed reduction of the IN activation of the particles. The observed particle mass spectra suggest that different treatme…

Determination of alkylamines in atmospheric aerosol particles: a comparison of gas chromatography–mass spectrometry and ion chromatography approaches

2014

Abstract. In recent years low molecular weight alkylamines have been recognized to play an important role in particle formation and growth in the lower atmosphere. However, major uncertainties are associated with their atmospheric processes, sources and sinks, mostly due to the lack of ambient measurements and the difficulties in accurate quantification of alkylamines at trace level. In this study, we present the evaluation and optimization of two analytical approaches, i.e., gas chromatography–mass spectrometry (GC-MS) and ion chromatography (IC), for the determination of alkylamines in aerosol particles. Alkylamines were converted to carbamates through derivatization with isobutyl chlorof…

On the regeneration of thermally regenerative ammonia batteries

2018

In the past few years, thermally regenerative ammonia battery (TRAB) has been proposed as an effective tool to recover waste heat at temperatures below 130 °C. Most of the literature available is devoted to the power production step, with less attention being given to the regeneration step (e.g. the removal of ammonia from the anolyte). In this paper, the TRAB is analyzed with particular attention to the regeneration step and to the study of various generation of energy-regeneration cycles. It was shown that approximately 90 °C is necessary for the regeneration step due to the fact that ammonia is present in the anolyte mainly as a complex. Various cycles were performed with success, demons…

Development of a membrane-less microfluidic thermally regenerative ammonia battery

2021

Thermally regenerative ammonia battery is a promising approach to make use of waste heat and generate electrical energy. However, according to literature, the price of the energy obtained by this device is much higher than alternative renewable technologies (such as wind, solar, geothermal, etc.). To make the process more viable for applicative purposes, it would be necessary to reduce dramatically the cost of the membrane or to avoid it. Hence, the aim of the present work is to increase the economic figures of thermally regenerative ammonia battery avoiding the use of membranes. It was concluded that this result can be obtained by developing the process in a microfluidic flow cell with lam…