ac5b01541_si_001.pdf (1.52 MB)
Measurement of Gas and Aerosol Phase Absorption Spectra across the Visible and Near-IR Using Supercontinuum Photoacoustic Spectroscopy
journal contribution
posted on 2015-07-21, 00:00 authored by James
G. Radney, Christopher D. ZangmeisterWe demonstrate a method to measure
the absorption spectra of gas
and aerosol species across the visible and near-IR (500 to 840 nm)
using a photoacoustic (PA) spectrometer and a pulsed supercontinuum
laser source. Measurements of gas phase absorption spectra were demonstrated
using H2O(g) as a function of relative humidity
(RH). The measured absorption intensities and peak shapes were able
to be quantified and compared to spectra calculated using the 2012
High Resolution Transmission (HITRAN2012) database. Size and mass
selected nigrosin aerosol was used to measure absorption spectra across
the visible and near-IR. Spectra were measured as a function of aerosol
size/mass and show good agreement to Mie theory calculations. Lastly,
we measured the broadband absorption spectrum of flame generated soot
aerosol at 5% and 70% RH. For the high RH case, we are able to quantifiably
separate the soot and water absorption contributions. For soot, we
observe an enhancement in the mass specific absorption cross section
ranging from 1.5 at 500 nm (p < 0.01) to 1.2 at
840 nm (p < 0.2) and a concomitant increase in
the absorption Ångström exponent from 1.2 ± 0.4 (5%
RH) to 1.6 ± 0.3 (70% RH).
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sootmeasure absorption spectraRH2Osupercontinuum laser sourceAerosol Phase Absorption SpectraPA2012 High Resolution Transmissionwater absorption contributionsbroadband absorption spectrumMie theory calculationsgas phase absorption spectraSupercontinuum Photoacoustic SpectroscopyWe840 nmaerosolHITRAN
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