TY - JOUR
T1 - Complex refractive indices in the near-ultraviolet spectral region of biogenic secondary organic aerosol aged with ammonia
AU - Flores, JM
AU - Washenfelder, RA
AU - Adler, G
AU - Lee, HJ
AU - Segev, Lior
AU - Laskin, J
AU - Laskin, A
AU - Nizkorodov, SA
AU - Brown, SS
AU - Rudich, Yinon
N1 - USA-Israel Binational Science Foundation (BSF) [2012013]; German Israel Science Foundation [1136-26.8/2011]; U.S. Department of Commerce, National Oceanic and Atmospheric Administration through Climate Program Office's Atmospheric Chemistry, Carbon Cycle and Climate (AC4) Program; NOAA AC4 program [NA13OAR4310066, NA13OAR4310062]; U.S. DOE's Office of Biological and Environmental Research; U.S. DOE by Battelle Memorial Institute [DE-AC06-76RL0 1830]; Jinich Postdoctoral Fellowship This research was supported by research grants from the USA-Israel Binational Science Foundation (BSF) grant #2012013 and by the German Israel Science Foundation (grant #1136-26.8/2011). We thank Avi Lavi for his help with the ToF-AMS measurements, and John Nowak and Charles Brock for their helpful suggestions. RAW and SSB acknowledge financial support from the U.S. Department of Commerce, National Oceanic and Atmospheric Administration through Climate Program Office's Atmospheric Chemistry, Carbon Cycle and Climate (AC4) Program. The PNNL and UCI groups acknowledge support by the NOAA AC4 program, awards NA13OAR4310066 (PNNL) and NA13OAR4310062 (UCI). The nano-DESI/HR-MS experiments described in this paper were performed at the Environmental Molecular Sciences Laboratory, a national scientific user facility sponsored by U.S. DOE's Office of Biological and Environmental Research and located at the Pacific Northwest National Laboratory (PNNL). PNNL is operated for U.S. DOE by Battelle Memorial Institute under Contract No. DE-AC06-76RL0 1830. JMF is supported by a research grant from the Jinich Postdoctoral Fellowship.
PY - 2014
Y1 - 2014
N2 - Atmospheric absorption by brown carbon aerosol may play an important role in global radiative forcing. Brown carbon arises from both primary and secondary sources, but the mechanisms and reactions of the latter are highly uncertain. One proposed mechanism is the reaction of ammonia or amino acids with carbonyl products in secondary organic aerosol (SOA). We generated SOA in situ by reacting biogenic alkenes (alpha-pinene, limonene, and alpha-humulene) with excess ozone, humidifying the resulting aerosol, and reacting the humidified aerosol with gaseous ammonia. We determined the complex refractive indices (RI) in the 360-420 nm range for these aerosols using broadband cavity enhanced spectroscopy (BBCES). The average real part (n) of the measured spectral range of the NH3-aged alpha-pinene SOA increased from n = 1.50 (+/- 0.01) for the unreacted SOA to n = 1.57 (+/- 0.01) after 1.5 h of exposure to 1.9 ppm NH3, whereas the imaginary component (k) remained below k <0.001 ((+0.002)(-0.001)) For the limonene and alpha-humulene SOA the real part did not change significantly, and we observed a small change in the imaginary component of the RI. The imaginary component increased from k = 0.000 to an average k = 0.029 (+/- 0.021) for alpha-humulene SOA, and from k <0.001((+0.002)(-0.001)) to an average k = 0.032 (+/- 0.019) for limonene SOA after 1.5 h of exposure to 1.3 and 1.9 ppm of NH3, respectively. Collected filter samples of the aged and unreacted alpha-pinene SOA and limonene SOA were analyzed off-line by nanospray desorption electrospray ionization high resolution mass spectrometry (nano-DESI/HR-MS), and in situ using a Time-of-Flight Aerosol Mass Spectrometer (ToF-AMS), confirming that the SOA reacted and that various nitrogen-containing reaction products formed. If we assume that NH3 aging reactions scale linearly with time and concentration, which will not necessarily be the case in the atmosphere, then a 1.5 h reaction with 1 ppm NH3 in the laboratory is e
AB - Atmospheric absorption by brown carbon aerosol may play an important role in global radiative forcing. Brown carbon arises from both primary and secondary sources, but the mechanisms and reactions of the latter are highly uncertain. One proposed mechanism is the reaction of ammonia or amino acids with carbonyl products in secondary organic aerosol (SOA). We generated SOA in situ by reacting biogenic alkenes (alpha-pinene, limonene, and alpha-humulene) with excess ozone, humidifying the resulting aerosol, and reacting the humidified aerosol with gaseous ammonia. We determined the complex refractive indices (RI) in the 360-420 nm range for these aerosols using broadband cavity enhanced spectroscopy (BBCES). The average real part (n) of the measured spectral range of the NH3-aged alpha-pinene SOA increased from n = 1.50 (+/- 0.01) for the unreacted SOA to n = 1.57 (+/- 0.01) after 1.5 h of exposure to 1.9 ppm NH3, whereas the imaginary component (k) remained below k <0.001 ((+0.002)(-0.001)) For the limonene and alpha-humulene SOA the real part did not change significantly, and we observed a small change in the imaginary component of the RI. The imaginary component increased from k = 0.000 to an average k = 0.029 (+/- 0.021) for alpha-humulene SOA, and from k <0.001((+0.002)(-0.001)) to an average k = 0.032 (+/- 0.019) for limonene SOA after 1.5 h of exposure to 1.3 and 1.9 ppm of NH3, respectively. Collected filter samples of the aged and unreacted alpha-pinene SOA and limonene SOA were analyzed off-line by nanospray desorption electrospray ionization high resolution mass spectrometry (nano-DESI/HR-MS), and in situ using a Time-of-Flight Aerosol Mass Spectrometer (ToF-AMS), confirming that the SOA reacted and that various nitrogen-containing reaction products formed. If we assume that NH3 aging reactions scale linearly with time and concentration, which will not necessarily be the case in the atmosphere, then a 1.5 h reaction with 1 ppm NH3 in the laboratory is e
U2 - https://doi.org/10.1039/c4cp01009d
DO - https://doi.org/10.1039/c4cp01009d
M3 - مقالة
SN - 1463-9076
VL - 16
SP - 10629
EP - 10642
JO - Physical Chemistry Chemical Physics
JF - Physical Chemistry Chemical Physics
IS - 22
ER -