Single-particle instrument simulator: Bridging experiments and models

Aerosol mixing state, the distribution of chemical species across individual aerosol particles, is crucial for quantifying aerosol optical, chemical, and micro-physical properties. For example, a particle’s absorptivity depends on whether light-absorbing components such as black carbon are externally or internally mixed. Particle-resolved models such as PartMC track the mass of each species per particle, whereas single-particle mass spectrometers report ion signals as a function of mass-to-charge ratios. Since ion signals depend not only non-linearly on species mass but also on species-specific ionization efficiencies, fragmentation patterns, and overlapping signals, there is no straightforward mapping between mass spectra and model species masses. To bridge this gap, we develop SPIN-sim (Single-Particle Instrument Simulator), a framework that converts mass spectrometer ion signals into model-comparable composition estimates. SPIN-sim uses Non-negative Matrix Factorization (NMF) to decompose the measured mass spectra and estimate the fractional contribution of individual species in mixed particles. Tests on synthetic mixtures show that SPIN-sim can reconstruct species fractions with errors below 5% for most particles. Tests with two contrasting systems, NaCl + ammonium sulfate and NaCl + KI, show that accurate interpretation requires instrument-specific calibration, since signal–composition relationships differ even in simple binary mixtures. By providing a path towards a quantitative mapping between single-particle measurements and particle-resolved model outputs, SPIN-sim enables direct evaluation of mixing state representation in models. This approach advances model-measurement integration in aerosol science and supports improved characterization of aerosol impacts on climate and air quality.

Name thesis:degree_name

M.S.

Level thesis:degree_level

Thesis

Discipline thesis:degree_discipline

Atmospheric Sciences

Grantor

University of Illinois Urbana-Champaign

Year dc:date

2025

Author dc:creator

• Lee, Kyuhaeng

Contributors dc:contributor

• Riemer, Nicole
• West, Matt
• Nesbitt, Steve

• aerosol
• mixing state
• mass spectrometer
• non-negative matrix factorization

Statement dc:rights

• Copyright 2025 Kyuhaeng Lee

Language dc:language

en

Handle dc:identifier

https://hdl.handle.net/2142/132638

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/132638