Design, characterization, and first field deployment of a novel aircraft-based aerosol mass spectrometer combining the laser ablation and flash vaporization techniques
Authors: Hünig Andreas , Appel Oliver , Dragoneas Antonis , Molleker Sergej , Clemen Hans-Christian , Helleis Frank , Klimach Thomas , Köllner Franziska , Böttger Thomas , Drewnick Frank , Schneider Johannes , Borrmann Stephan 
Published: May 2022

Abstract. In this paper, we present the design, development, and characteristics of the novel aerosol mass spectrometer ERICA (ERC Instrument
for Chemical composition of Aerosols; ERC – European Research Council) and
selected results from the first airborne field deployment. The instrument
combines two well-established methods of real-time in situ measurements of
fine particle chemical composition. The first method is the laser desorption and ionization technique, or laser ablation technique, for single-particle mass spectrometry (here with a frequency-quadrupled Nd:YAG laser at λ = 266 nm). The second method is a combination of thermal particle
desorption, also called flash vaporization, and electron impact ionization
(like the Aerodyne aerosol mass spectrometer). The same aerosol sample flow
is analyzed using both methods simultaneously, each using time-of-flight
mass spectrometry. By means of the laser ablation, single particles are
qualitatively analyzed (including the refractory components), while the flash vaporization and electron impact ionization technique provides quantitative information on the non-refractory components (i.e., particulate sulfate, nitrate, ammonia, organics, and chloride) of small particle ensembles. These
techniques are implemented in two consecutive instrument stages within a
common sample inlet and a common vacuum chamber. At its front end, the
sample air containing the aerosol particles is continuously injected via an
aerodynamic lens. All particles which are not ablated by the Nd:YAG laser in the first instrument stage continue their flight until they reach the second instrument stage and impact on the vaporizer surface (operated at 600 ∘C). The ERICA is capable of detecting single particles with
vacuum aerodynamic diameters (dva) between ∼ 180 and 3170 nm (d50 cutoff). The chemical characterization of single particles is achieved by recording cations and anions with a bipolar time-of-flight mass spectrometer. For the measurement of non-refractory components, the particle size range extends from approximately 120 to 3500 nm (d50 cutoff; dva), and the cations are detected with a time-of-flight mass
spectrometer. The compact dimensions of the instrument are such that the
ERICA can be deployed on aircraft, at ground stations, or in mobile laboratories.
To characterize the focused detection lasers, the ablation laser, and the
particle beam, comprehensive laboratory experiments were conducted. During
its first deployments the instrument was fully automated and operated during 11 research flights on the Russian high-altitude research aircraft M-55
Geophysica from ground pressure and temperature to 20 km altitude at 55 hPa and
ambient temperatures as low as −86 ∘C. In this paper, we show
that the ERICA is capable of measuring reliably under such conditions.