Andrew W Rollins

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Laboratory studies have established a number of chemical pathways by which nitrogen oxides (NO(x)) affect atmospheric organic aerosol (OA) production. However, these effects have not been directly observed in ambient OA. We report measurements of particulate organic nitrates in Bakersfield, California, the nighttime formation of which increases with NO(x)(More)
The yields of organic nitrates and of secondary organic aerosol (SOA) particle formation were measured for the reaction NO3+β-pinene under dry and humid conditions in the atmosphere simulation chamber SAPHIR at Research Center Jülich. These experiments were conducted at low concentrations of NO3 (NO3+N2O5<10 ppb) and βpinene (peak∼15 ppb), with no seed(More)
A novel instrument is described that quantifies total particle-phase organic nitrates in real time with a detection limit of 0.11 microg m(-3) min(-1), 45 ppt min(-1) (-ONO(2)). Aerosol nitrates are separated from gas-phase nitrates with a short residence time activated carbon denuder. Detection of organic molecules containing -ONO(2) subunits is(More)
Four hydroxynitrates (R(OH)R’ONO2) representative of atmospheric volatile organic compound (VOC) oxidation products were synthesized, nebulized and sampled into an Aerodyne High Resolution Time of Flight Aerosol Mass Spectrometer (HR-ToF-AMS). The resulting mass spectrum was used to evaluate calibration factors for elemental analysis of organic nitrates by(More)
The formation of organic nitrates and secondary organic aerosol (SOA) were monitored during the NO3 + limonene reaction in the atmosphere simulation chamber SAPHIR at Research Center Jülich. The 24-h run began in a purged, dry, particle-free chamber and comprised two injections of limonene and oxidants, such that the first experiment measured SOA yield in(More)
Acquiring accurate measurements of water vapor at the low mixing ratios (< 10 ppm) encountered in the upper troposphere and lower stratosphere (UT/LS) has proven to be a significant analytical challenge evidenced by persistent disagreements between high-precision hygrometers. These disagreements have caused uncertainties in the description of the physical(More)
We present a sensitive, compact detector that measures total reactive nitrogen (NOy), as well as NO2, NO, and O3. In all channels, NO2 is directly detected by laser diode based cavity ring-down spectroscopy (CRDS) at 405 nm. Ambient O3 is converted to NO2 in excess NO for the O3 measurement channel. Likewise, ambient NO is converted to NO2 in excess O3.(More)
An enhanced aerosol layer near the tropopause over Asia during the June-September period of the Asian summer monsoon (ASM) was recently identified using satellite observations. Its sources and climate impact are presently not well-characterized. To improve understanding of this phenomenon, we made in situ aerosol measurements during summer 2015 from(More)
A laboratory chilled mirror hygrometer (CMH), exposed to an airstream containing water vapor (H2O) and nitric acid (HNO3), has been used to demonstrate the existence of a persistent water-nitric acid condensate that has a saturation H2O vapor pressure greater than that of hexagonal ice (Ih). The condensate was routinely formed on the mirror by removing HNO3(More)
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