An efficient method for deriving volatility basis sets from thermodenuder and particle levitation data.

Andrey Khlystov 

Deriving a volatility basis set (VBS) from measurements of particle evaporation in a thermodenuder or single-particle levitation apparatus has traditionally relied on repeated numerical solution of the evaporation equations to find the VBS that best reproduces observed particle sizes. This approach is computationally demanding and offers little insight into the factors that control the retrieval. Building on the characteristic-time framework of Khlystov (2024), it is shown that the mass fraction remaining of each volatility bin can be expressed through a single integral evaluated directly from the measured particle-size evolution. This reduces VBS retrieval to a constrained linear inversion, eliminating iterative integration of differential equations and making the method about four orders of magnitude faster than the conventional approach. The temperature dependence of the saturation concentration and Kelvin effect is included in the inversion, and the enthalpy of vaporization may be prescribed per bin or retrieved as a single volatility-dependence parameter. Applied to thermodenuder thermograms measured at Duke Forest, NC, and Reno, NV, the method reproduces the VBS obtained with the conventional technique while requiring milliseconds rather than minutes. Using synthetic measurements, we quantify the method's accuracy and sensitivity to assumed surface tension and thermogram temperature resolution. The ambient thermograms constrain the enthalpy of vaporization dependence on bin volatility to be much weaker than the commonly assumed parameterization, with a steep dependence incompatible with the gradual evaporation observed. The method enables rapid processing of large volatility datasets and provides guidance for the design of evaporation measurements.