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Ugo Molteni


chercheur invité


Institut fédéral de recherches sur la forêt, la neige et le paysage WSL
Zürcherstrasse 111
8903 Birmensdorf



My Research

I'm an environmental scientist, and my research stands at the interface between the biosphere and atmosphere. My research interest is on plant volatile organic compounds (VOC) and their atmospheric oxidation.

We are all familiar with the citrus aroma of orange as we peel it, the scent of roses or lavender bushes in bloom or, on a summer afternoon, the distinctive pine smell as we wander in a coniferous forest. Plants produce and emit hundreds of volatile compounds in the atmosphere. Through these compounds, plants communicate, fight herbivorous insects or attract pollinators.

In the atmosphere, emitted VOCs undergo oxidation and contribute to tropospheric ozone levels. Further, the oxidation products may condense and lead to secondary organic aerosol (SOA). Aerosol particle load is a crucial factor in defining the radiative forcing, a critical parameter in climate studies.

Climate change with anticipated springs, severe drought, and insect outbreaks have already shown their impact on plants. Plants react to this stress by changing the VOC emissions. Some compounds get promoted, some others get reduced. Consequently, this has an impact on air quality standards and climate.

Within my SNSF Postdoc.Mobility grant I investigate VOCs emissions and atmospheric oxidation from tree species characteristic of the Swiss and European temperate forests. My project is hosted at the University of California, Irvine, and co-hosted by the Ecosystem Ecology research group at WSL.



  • 2018 Doctoral degree in Environmental Science  (D-USYS, ETH Zurich)
  • 2013 Master in Applied and Environmental Chemical Sciences (Chemistry Department, Università degli Studi di Milano)

Scientific publication: peer reviewed article

Caudillo, L. et al. Chemical composition of nanoparticles from α-pinene nucleation and the influence of isoprene and relative humidity at low temperature, Atmos. Chem. Phys., 21, 17099–17114,doi:10.5194/acp-21-17099-2021,2021

Xiao, M. et al. The driving factors of new particle formation and growth in the polluted boundary layer, Atmos. Chem. Phys., 21(18), 14275–14291,doi:10.5194/acp-21-14275-2021, 2021

Surdu, M. et al. Molecular characterization of ultrafine particles using extractive electrospray time-of-flight mass spectrometry, Environ. Sci. Atmos., 1(6), 434–448,doi:10.1039/D1EA00050K, 2021

Bianchi, F. et al. Biogenic particles formed in the Himalaya as an important source of free tropospheric aerosols, Nat. Geosci., 14(1), 4–9,doi:10.1038/s41561-020-00661-5, 2021

Heinritzi, al. Molecular understanding of the suppression of new-particle formation by isoprene, Atmos. Chem. Phys., 20(20), 11809–11821,doi:10.5194/acp-20-11809-2020, 2020

Simon, M. et al. Molecular understanding of new-particle formation from alpha-pinene between -50 °C and 25 °C, Atmos. Chem. Phys., 1–42,doi:10.5194/acp-2019-1058, 2020

Wang, al. Photo-oxidation of Aromatic Hydrocarbons Produces Low-Volatility Organic Compounds, Environ. Sci. Technol., acs.est.0c02100,doi:10.1021/acs.est.0c02100, 2020

Yan, C. et al. Size-dependent influence of NO x on the growth rates of organic aerosol particles, Sci. Adv., 6(22), eaay4945,doi:10.1126/sciadv.aay4945, 2020

Molteni, U. et al. Formation of Highly Oxygenated Organic Molecules from α-Pinene Ozonolysis: Chemical Characteristics, Mechanism, and Kinetic Model Development, ACS Earth Sp. Chem., 3(5), 873–883,doi:10.1021/acsearthspacechem.9b00035, 2019

Lehtipalo, K. et al. Multicomponent new particle formation from sulfuric acid, ammonia, and biogenic vapors, Sci. Adv., 4(12), eaau5363,doi:10.1126/sciadv.aau5363, 2018

Stolzenburg, D. et al. Rapid growth of organic aerosol nanoparticles over a wide tropospheric temperature range, Proc. Natl. Acad. Sci., 115(37), 9122–9127,doi:10.1073/pnas.1807604115, 2018

Molteni, U. et al. Formation of highly oxygenated organic molecules from aromatic compounds, Atmos. Chem. Phys., 18(3), 1909–1921,doi:10.5194/acp-18-1909-2018, 2018

Frege, al. Influence of temperature on the molecular composition of ions and charged clusters during pure biogenic nucleation, Atmos. Chem. Phys., 18(1), 65–79,doi:10.5194/acp-18-65-2018, 2018

Frege, C. et al.Chemical characterization of atmospheric ions at the high altitude research station Jungfraujoch (Switzerland), Atmos. Chem. Phys., 17(4), 2613–2629,doi:10.5194/acp-17-2613-2017, 2017

Gordon, H. et al. Causes and importance of new particle formation in the present-day and preindustrial atmospheres, J. Geophys. Res. Atmos., 122(16), 8739–8760,doi:10.1002/2017JD026844, 2017

Wagner, R. et al. The role of ions in new particle formation in the CLOUD chamber, Atmos. Chem. Phys., 17(24), 15181–15197,doi:10.5194/acp-17-15181-2017, 2017

Bianchi, F. et al. New particle formation in the free troposphere: A question of chemistry and timing, Science , 352(6289), 1109–1112,doi:10.1126/science.aad5456, 2016

Gordon, H. et al. Reduced anthropogenic aerosol radiative forcing caused by biogenic new particle formation, Proc. Natl. Acad. Sci., 113(43), 12053–12058,doi:10.1073/pnas.1602360113, 2016

Hoyle, C. R. R. et al. Aqueous phase oxidation of sulphur dioxide by ozone in cloud droplets, Atmos. Chem. Phys., 16(3), 1693–1712,doi:10.5194/acp-16-1693-2016, 2016

Kirkby, J. et al. Ion-induced nucleation of pure biogenic particles, Nature, 533(7604), 521–526,doi:10.1038/nature17953, 2016

Krapf, M. et al. Labile Peroxides in Secondary Organic Aerosol, Chem, 1(4), 603–616,doi:10.1016/j.chempr.2016.09.007, 2016

Tröstl, J. et al. Contribution of new particle formation to the total aerosol concentration at the high-altitude site Jungfraujoch (3580 m asl, Switzerland), J. Geophys. Res. Atmos., 121(19), 11,692-11,711,doi:10.1002/2015JD024637, 2016

Tröstl, J. et al. The role of low-volatility organic compounds in initial particle growth in the atmosphere, Nature, 533(7604), 527–531,doi:10.1038/nature18271, 2016

Sandrini, S. et al. Spatial and seasonal variability of carbonaceous aerosol across Italy, Atmos. Environ., 99, 587–598,doi:10.1016/j.atmosenv.2014.10.032, 2014

Cuccia, E. et al. Carbonate measurements in PM10 near the marble quarries of Carrara (Italy) by infrared spectroscopy (FT-IR) and source apportionment by positive matrix factorization (PMF), Atmos. Environ., 45(35), 6481–6487,doi:10.1016/j.atmosenv.2011.08.004, 2011