Matus Diveky

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Diveky

First Name

Matus

ORCID

0000-0003-2806-2847

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Publications 1 - 10 of 11

Experimental study on a direct water heating PV-T technology
Cen, Jiajun; du Feu, Roan; Diveky, Matus; et al. (2018)
Solar Energy
Photoacoustics of single aerosol droplets immobilised by counter-propagating optical tweezers
Diveky, Matus; Gleichweit, Michael; Roy, Sandra; et al. (2020)
Optical Trapping and Optical Micromanipulation XVII ~ Proceedings Volume c, Optical Trapping and Optical Micromanipulation XVII; 1146316 (2020)
In this contribution we discuss the influence of relative humidity on photoacoustic measurements from both an experimental and theoretical perspective. We present a refined model of the photoacoustic (PA) signal that accounts for elevated particle temperatures and different levels of relative humidity. We use this new model together with the photoacoustic data collected with our photothermal single-particle spectrometer (PSPS) to retrieve the mass accommodation coefficients of water on organic aerosol particles. The single-particle nature of our experiments is achieved by employing counter-propagating tweezers. Furthermore, we investigate the influence of relative humidity on the eigenfrequency of the PA cell.
Coupling between modulated Mie scattering and photoacoustic signal generation in optically trapped, single aerosol particles
Gleichweit, Michael; Azizbaig Mohajer, Mercede; Borgeaud, Dominique; et al. (2022)
Proceedings of SPIE ~ Optical Trapping and Optical Micromanipulation XIX
Photoacoustic spectroscopy and photothermal spectroscopy are two common methods to probe aerosol particle absorption coefficients and can be performed both on aerosol ensembles and on the single particle level. With photothermal spectroscopy typically changes in the particle’s light scattering pattern upon heating or cooling are observed with photo-diodes or cameras. In photoacoustic spectroscopy, the acoustic response to periodic light absorption is recorded e.g. with a microphone. Although both methods are closely related through their excitation process, the detection pathways are quintessentially different. In our single particle optical trapping setup, however, we observe a previously unnoticeable, unidirectional coupling between modulated Mie scattering (result of the photothermal effect) and photoacoustic spectroscopy. The coupling manifests itself via differently shaped, sudden features in the acoustic signal. Our analysis suggests a non-trivial interaction between light scattering of single, optically trapped particles and the photoacoustic signal generation based on interactions of light with the acoustic resonator’s walls. Measurements over several trapping powers and photoacoustic excitation powers support this conclusion. How the coupling manifests itself, such as shape and strength, can be conclusively explained by the structure of the particle’s momentary phase function (scattering intensity) calculated by classical Mie theory. This allows us to formulate conditions to either utilise or minimise the coupling effects in future experiments.
Assessing relative humidity dependent photoacoustics to retrieve mass accommodation coefficients of single optically trapped aerosol particles
Diveky, Matus; Roy, Sandra; Cremer, Johannes; et al. (2019)
Physical Chemistry Chemical Physics
Photoacoustic spectroscopy is widely used to measure the light absorption of aerosols. However, the impact of key factors such as the effect of relative humidity and mass exchange on photoacoustic measurements are still poorly understood. We assess such measurement biases and their physical origin by analysing the photoacoustic signal of single tetraethylene glycol (TEG) particles at varying relative humidities. Our results show a decrease in the photoacoustic signal at elevated relative humidities for small particles (0.8–1.5 μm), while for larger sizes (2.2–3.2 μm) the trend is reversed. We model the photoacoustic signal to interpret the observed behaviour in terms of mass and heat flux contribution. The single particle photoacoustic signal analysis presented in this paper additionally allows for the retrieval of the mass accommodation coefficient. Fitting our experimental data to the theoretical model reveals values of αM ≈ 0.02–0.005 for water on TEG in the temperature range 295–309 K.
A Multilayer Heat and Mass Transfer Model for Photoacoustics of Aerosol Particles (MHM-PA)
Corral Arroyo, Pablo; Gleichweit, Michael; Diveky, Matus; et al. (2023)
Aerosol Science and Technology
A diffusion multi-layer model is introduced which allows time-dependent simulations of heat and mass transfer for photoacoustic experiments on aerosol particles (MHM-PA model). It provides spatial and temporal information on the particle temperature, composition and size during photoacoustic modulation cycles, and thus enables accurate simulations of the photoacoustic amplitude and phase at different modulation frequencies. Simulations for micrometer-sized, mixed water-tetraethylene glycol droplets at different relative humidity and at different modulation frequencies between 4 and 100 kHz reveal a substantial loss of the information content of the photoacoustic signal above ∼30 kHz. The photoacoustic amplitude reduces by two orders of magnitude, causing sensitivity issues. The photoacoustic phase converges to the same constant value for all droplet sizes and humidities, meaning that useful information on heat and mass transfer is essentially lost in the phase.
Fundamental investigation of photoacoustic signal generation from single aerosol particles at varying relative humidity
Diveky, Matus; Roy, Sandra; David, Grégory; et al. (2020)
Photoacoustics
Photoacoustic (PA) spectroscopy enjoys widespread applications across atmospheric sciences. However, experimental biases and limitations originating from environmental conditions and particle size distributions are not fully understood. Here, we combine single-particle photoacoustics with modulated Mie scattering to unravel the fundamental physical processes occurring during PA measurements on aerosols. We perform measurements on optically trapped droplets of varying sizes at different relative humidity. Our recently developed technique – photothermal single-particle spectroscopy (PSPS) – enables fundamental investigations of the interplay between the heat flux and mass flux from single aerosol particles. We find that the PA phase is more sensitive to water uptake by aerosol particles than the PA amplitude. We present results from a model of the PA phase, which sheds further light onto the dependence of the PA phase on the mass flux phenomena. The presented work provides fundamental insights into photoacoustic signal generation of aerosol particles.
Shining new light on the kinetics of water uptake by organic aerosol particles
Diveky, Matus; Gleichweit, Michael; Roy, Sandra; et al. (2021)
The Journal of Physical Chemistry A
The uptake of water vapor by various organic aerosols is important in a number of applications ranging from medical delivery of pharmaceutical aerosols to cloud formation in the atmosphere. The coefficient that describes the probability that the impinging gas-phase molecule sticks to the surface of interest is called the mass accommodation coefficient, αM. Despite the importance of this coefficient for the description of water uptake kinetics, accurate values are still lacking for many systems. In this Feature Article, we present various experimental techniques that have been evoked in the literature to study the interfacial transport of water and discuss the corresponding strengths and limitations. This includes our recently developed technique called photothermal single-particle spectroscopy (PSPS). The PSPS technique allows for a retrieval of αM values from three independent, yet simultaneous measurements operating close to equilibrium, providing a robust assessment of interfacial mass transport. We review the currently available data for αM for water on various organics and discuss the few studies that address the temperature and relative humidity dependence of αM for water on organics. The knowledge of the latter, for example, is crucial to assess the water uptake kinetics of organic aerosols in the Earth's atmosphere. Finally, we argue that PSPS might also be a viable method to better restrict the αM value for water on liquid water.
Correction: Assessing relative humidity dependent photoacoustics to retrieve mass accommodation coefficients of single optically trapped aerosol particles (vol 21, pg 4721, 2019)
Diveky, Matus; Roy, Sandra; Cremer, Johannes; et al. (2020)
Physical Chemistry Chemical Physics
Characterization and control of droplets optically trapped in air
David, Grégory; Reich, Oliver; Diveky, Matus; et al. (2019)
Proceedings Volume 11083, Optical Trapping and Optical Micromanipulation XVI 1108322 (2019)
In this contribution we present experiments used to control and characterize single optically trapped aerosol particles. These experiments include a counter-propagating optical tweezer, a feedback control mechanism to stabilize the particle in the trap and a two-angle optical scattering measurement to monitor the time-evolution of the particle size. Experimental setups and results are presented for these experiments.
Mass Accommodation Coefficients of Water on Organics from Complementary Photoacoustic and Light Scattering Measurements on Laser-Trapped Droplets
Roy, Sandra; Diveky, Matus; Signorell, Ruth (2020)
The Journal of Physical Chemistry C ~ 124
The mass accommodation coefficient, $\alpha_M$, describes evaporation and condensation kinetics at the liquid-vapor interface. In spite of numerous experimental efforts, reliable values of $\alpha_M$ are still not available for many substances. Here, we present a novel experimental technique, photothermal single-particle spectroscopy (PSPS), that allows for a robust retrieval of mass accommodation coefficients from three simultaneous independent measurements. PSPS combines resonant photoacoustic absorption spectroscopy with modulated Mie scattering measurements on single particles. We study the mass transport of water on organic aerosol droplets that are optically trapped using counter-propagating tweezers. We find the mass accommodation coefficient of water on a pure model organic that is fully miscible with water to be 0.021 at 296K, and to decrease by more than an order of magnitude when the temperature increases to 309K. The experimentally observed temperature dependence of $\alpha_M$ shows an Arrhenius behavior. Furthermore, the water content of the droplets is found to have a profound effect on $\alpha_M$. No concentration dependence of $\alpha_M$ is observed at low water concentrations, while at elevated water concentrations we observe a fivefold increase in $\alpha_M$. The technique presented in this work has the potential to become a reliable method for the retrieval of $\alpha_M$ values at liquid-vapor interfaces, which are essential for accurate global climate and pharmaceutical aerosol inhalation modeling, to mention but a few.

Publications 1 - 10 of 11

Matus Diveky

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