Estimating the contribution of organic acids to northern hemispheric continental organic aerosol
Using chemical ionization mass spectrometry to detect particle-phase acids (acid-CIMS) and aerosol mass spectrometry (AMS) measurements from Colorado, USA, and two studies in Hyytiala, Finland, we quantify the fraction of organic aerosol (OA) mass that is composed of molecules with acid functional groups (facid). Molecules containing one or more carboxylic acid functionality contributed approximately 29% (45-51%) of the OA mass in Colorado (Finland). Organic acid mass concentration correlates well with AMS m/z 44 (primarily CO2+), a commonly used marker for highly oxidized aerosol. Using the average empirical relationship between AMS m/z 44 and organic acids in these three studies, together…
Luminosity determination in pp collisions at s=7 TeV using the ATLAS detector at the LHC
Measurements of luminosity obtained using the ATLAS detector during early running of the Large Hadron Collider (LHC) at s√=7 TeV are presented. The luminosity is independently determined using several detectors and multiple algorithms, each having different acceptances, systematic uncertainties and sensitivity to background. The ratios of the luminosities obtained from these methods are monitored as a function of time and of μ, the average number of inelastic interactions per bunch crossing. Residual time- and μ-dependence between the methods is less than 2% for 0<μ<2.5. Absolute luminosity calibrations, performed using beam separation scans, have a common systematic uncertainty of ±11%, do…
The seaweeds &lt;i&gt;Fucus vesiculosus&lt;/i&gt; and &lt;i&gt;Ascophyllum nodosum&lt;/i&gt; are significant contributors to coastal iodine emissions
Abstract. Based on the results of a pilot study in 2007, which found high mixing ratios of molecular iodine (I2) above the intertidal macroalgae (seaweed) beds at Mweenish Bay (Ireland), we extended the study to nine different locations in the vicinity of Mace Head Atmospheric Research Station on the west coast of Ireland during a field campaign in 2009. The mean values of I2 mixing ratio found above the macroalgae beds at nine different locations ranged from 104 to 393 ppt, implying a high source strength of I2. Such mixing ratios are sufficient to result in photochemically driven coastal new-particle formation events. Mixing ratios above the Ascophyllum nodosum and Fucus vesiculosus beds …
Aerosol Chemistry Resolved by Mass Spectrometry: Linking Field Measurements of Cloud Condensation Nuclei Activity to Organic Aerosol Composition.
Aerosol hygroscopic properties were linked to its chemical composition by using complementary online mass spectrometric techniques in a comprehensive chemical characterization study at a rural mountaintop station in central Germany in August 2012. In particular, atmospheric pressure chemical ionization mass spectrometry ((-)APCI-MS) provided measurements of organic acids, organosulfates, and nitrooxy-organosulfates in the particle phase at 1 min time resolution. Offline analysis of filter samples enabled us to determine the molecular composition of signals appearing in the online (-)APCI-MS spectra. Aerosol mass spectrometry (AMS) provided quantitative measurements of total submicrometer or…
In situ submicron organic aerosol characterization at a boreal forest research station during HUMPPA-COPEC 2010 using soft and hard ionization mass spectrometry
The chemical composition of submicron aerosol during the comprehensive field campaign HUMPPA-COPEC 2010 at Hyytiälä, Finland, is presented. The focus lies on online measurements of organic acids, which were achieved by using atmospheric pressure chemical ionization (APCI) ion trap mass spectrometry (IT-MS). These measurements were accompanied by aerosol mass spectrometry (AMS) measurements and Fourier transform infrared spectroscopy (FTIR) of filter samples, all showing a high degree of correlation. The soft ionization mass spectrometer alternated between gas-phase measurements solely and measuring the sum of gas and particle phase. The AMS measurements of C, H and O elemental composition s…
Analysis of Organic Aerosols Using a Micro-Orifice Volatilization Impactor Coupled to an Atmospheric-Pressure Chemical Ionization Mass Spectrometer
We present the development and characterization of a combination of a micro-orifice volatilization impactor (MOVI) and an ion trap mass spectrometer (IT/MS) with an atmospheric-pressure chemical ionization (APCI) source. The MOVI is a multi-jet impactor with 100 nozzles, allowing the collection of aerosol particles by inertial impaction on a deposition plate. The pressure drop behind the nozzles is approximately 5%, resulting in a pressure of 96 kPa on the collection surface for ambient pressures of 101.3 kPa. The cut-point diameter (diameter of 50% collection efficiency) is at 0.13 μm for a sampling flow rate of 10 L min–1. After the collection step, aerosol particles are evaporated by he…
Biogenic and biomass burning organic aerosol in a boreal forest at Hyytiälä, Finland, during HUMPPA-COPEC 2010
Abstract. Submicron aerosol particles were collected during July and August 2010 in Hyytiälä, Finland, to determine the composition and sources of aerosol at that boreal forest site. Submicron particles were collected on Teflon filters and analyzed by Fourier transform infrared (FTIR) spectroscopy for organic functional groups (OFGs). Positive matrix factorization (PMF) was applied to aerosol mass spectrometry (AMS) measurements and FTIR spectra to identify summertime sources of submicron aerosol mass at the sampling site. The two largest sources of organic mass (OM) in particles identified at Hyytiälä were (1) biogenic aerosol from surrounding local forest and (2) biomass burning aerosol, …
Ultrahigh-Resolution Mass Spectrometry in Real Time: Atmospheric Pressure Chemical Ionization Orbitrap Mass Spectrometry of Atmospheric Organic Aerosol
The accurate and precise mass spectrometric measurement of organic compounds in atmospheric aerosol particles is a challenging task that requires analytical developments and adaptations of existing techniques for the atmospheric application. Here we describe the development and characterization of an atmospheric pressure chemical ionization Orbitrap mass spectrometer (APCI-Orbitrap-MS) for the measurement of organic aerosol in real time. APCI is a well-known ionization technique, featuring minimal fragmentation and matrix dependencies, and allows rapid alternation between the positive and negative ionization mode. As a proof of principle, we report ambient organic aerosol composition in rea…
&lt;i&gt;Fucus&lt;/i&gt; and &lt;i&gt;Ascophyllum&lt;/i&gt; seaweeds are significant contributors to coastal iodine emissions
Abstract. Based on the results of a pilot study in 2007, which found high mixing ratios of molecular iodine (I2) above the intertidal macroalgae (seaweed) beds at Mweenish Bay (Ireland), we extended the study to nine different locations in the vicinity of Mace Head Atmospheric Research Station on the west coast of Ireland during a field campaign in 2009. I2 mixing ratios from 104 to 393 ppt were found above the macroalgae beds, implying a high source strength of I2. Such mixing ratios are sufficient to result in photochemically-driven coastal new-particle formation events. Mixing ratios above the Ascophyllum nodosum and Fucus vesiculosus beds increased with exposure time – after 6 h exposur…
Upgrade of the ATLAS Central Trigger for LHC Run-2
The increased energy and luminosity of the LHC in the run-2 data taking period requires a more selective trigger menu in order to satisfy the physics goals of ATLAS. Therefore the electronics of the central trigger system is upgraded to allow for a larger variety and more sophisticated trigger criteria. In addition, the software controlling the central trigger processor (CTP) has been redesigned to allow the CTP to accommodate three freely configurable and separately operating sets of sub detectors, each independently using the almost full functionality of the trigger hardware. This new approach and its operational advantages are discussed as well as the hardware upgrades.
Aerosol Chemistry Resolved by Mass Spectrometry: Insights into Particle Growth after Ambient New Particle Formation
Atmospheric oxidation of volatile organic compounds (VOCs) yields a large number of different organic molecules which comprise a wide range of volatility. Depending on their volatility, they can be involved in new particle formation and particle growth, thus affecting the number concentration of cloud condensation nuclei in the atmosphere. Here, we identified oxidation products of VOCs in the particle phase during a field study at a rural mountaintop station in central Germany. We used atmospheric pressure chemical ionization mass spectrometry ((-)APCI-MS) and aerosol mass spectrometry for time-resolved measurements of organic species and of the total organic aerosol (OA) mass in the size r…
The Topological Processor for the future ATLAS Level-1 Trigger: From design to commissioning
The ATLAS detector at the Large Hadron Collider (LHC) is designed to measure decay properties of high energetic particles produced in the proton-proton collisions. During its first run, the LHC collided proton bunches at a frequency of 20 MHz, and therefore the detector required a Trigger system to efficiently select events down to a manageable event storage rate of about 400 Hz. By 2015 the LHC instantaneous luminosity will be increased up to 3×1034cm−2s−1: this represents an unprecedented challenge faced by the ATLAS Trigger system. To cope with the higher event rate and efficiently select relevant events from a physics point of view, a new element will be included in the Level-1 Trigger …
Upgrade of the ATLAS Level-1 Trigger with event topology information
The Large Hadron Collider (LHC) in 2015 will collide proton beams with increased luminosity from \unit{10^{34}} up to \unit{3 \times 10^{34}cm^{-2}s^{-1}}. ATLAS is an LHC experiment designed to measure decay properties of high energetic particles produced in the protons collisions. The higher luminosity places stringent operational and physical requirements on the ATLAS Trigger in order to reduce the 40MHz collision rate to a manageable event storage rate of 1kHz while at the same time, selecting those events with valuable physics meaning. The Level-1 Trigger is the first rate-reducing step in the ATLAS Trigger, with an output rate of 100kHz and decision latency of less than 2.5$\mu s$. It…
Online atmospheric pressure chemical ionization ion trap mass spectrometry (APCI-IT-MS&lt;sup&gt;n&lt;/sup&gt;) for measuring organic acids in concentrated bulk aerosol – a laboratory and field study
Abstract. The field application of an aerosol concentrator in conjunction with an atmospheric pressure chemical ionization ion trap mass spectrometer (APCI-IT-MS) at the boreal forest station SMEAR II at Hyytiälä, Finland, is demonstrated in this study. APCI is a soft-ionization technique allowing online measurements of organic acids in the gas and particle phase. The detection limit for the acid species in the particle phase was improved by a factor of 7.5 to 11 (e.g. ∼40 ng m3 for pinonic acid) by using the miniature versatile aerosol concentration enrichment system (mVACES) upstream of the mass spectrometer. The APCI-IT-MS was calibrated in the negative ion mode with two biogenic organic…