Grégory David

Grégory David
ETH Zurich | ETH Zürich

PhD

About

37
Publications
3,335
Reads
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573
Citations
Citations since 2017
16 Research Items
402 Citations
2017201820192020202120222023020406080
2017201820192020202120222023020406080
2017201820192020202120222023020406080
2017201820192020202120222023020406080
Additional affiliations
October 2010 - January 2014
University of Lyon
Position
  • PhD Student

Publications

Publications (37)
Article
Full-text available
It has recently been reported that reactions can occur faster in microdroplets than in extended condensed matter. The electric charge of droplets has also been suggested as a possible cause of this phenomenon. Here, we investigate the influence of electric charges on the photodegradation of single, optically trapped oleic acid aerosol droplets in t...
Article
Optical confinement (OC) structures the optical field and amplifies light intensity inside atmospheric aerosol particles, with major consequences for sunlight-driven aerosol chemistry. Although theorized, the OC-induced spatial structuring has so far defied experimental observation. Here, x-ray spectromicroscopic imaging complemented by modeling pr...
Article
Full-text available
We report the photodegradation of optically trapped oleic acid droplets by visible light in the absence of additional reactive gaseous species. The temporal evolution of the droplet's chemical composition and size is monitored by Raman spectroscopy and elastic light scattering, respectively. The dependencies on the oxygen amount in the surrounding...
Article
Full-text available
Optical traps are used to isolate and manipulate small objects in air and liquids, enabling the thorough characterization of their properties in situ. However, no broadly applicable technique for mass measurements of optically trapped objects is currently available. Here we propose an optical balance for mass measurements of optically trapped aeros...
Article
Full-text available
Correction for ‘Assessing relative humidity dependent photoacoustics to retrieve mass accommodation coefficients of single optically trapped aerosol particles’ by Matus E. Diveky et al. , Phys. Chem. Chem. Phys. , 2019, 21 , 4721–4731, DOI: 10.1039/C8CP06980H.
Article
Full-text available
The partitioning of components between droplets and the gas phase in e-cigarette aerosols has a significant impact on deposition within the respiratory tract. However, exclusive detection of droplet composition has, so far, been elusive. Consequently, the dynamics of partitioning between droplets and the gas phase remains unknown. Here, we combine...
Article
Full-text available
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...
Article
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 tet...
Article
Full-text available
Many processes taking place in atmospheric aerosol particles are accompanied by changes in the particles’ morphology (size and shape), with potentially significant impact on weather and climate. However, the characterization of dynamic information on particle morphology and position over multiple time scales from microseconds to days under atmosphe...
Article
Fast dynamics (down to 10 ms) during exposure to changing relative humidity of single, optically trapped K2CO3 particles were observed in the submicron to micron size range with time-resolved broadband light scattering and Raman spectroscopy. The study shows that complex multiple processes accompany efflorescence and deliquescence of unsupported ae...
Article
Our understanding of the contribution of mineral dust to the Earth's radiative budget is limited by the complexity of these particles, which present a wide range of sizes, are highly-irregularly shaped, and are present in the atmosphere in the form of particle mixtures. To address the spatial distribution of mineral dust and atmospheric dust mass c...
Article
We describe a broadband light scattering setup for the characterization of size and refractive index of single submicron-to-micron sized aerosol particles. Individual particles are isolated in air by a quadruple Bessel beam optical trap or a counter-propagating optical tweezer. The use of very broadband radiation in the wavelength range from 320 to...
Article
In this contribution, we present the results of two recent papers [1,2] published in Optics Express, dedicated to the development of two new lidar methodologies. In [1], while the carbon aerosol (for example, soot particles) is recognized as a major uncertainty on climate and public health, we couple lidar remote sensing with Laser-Induced-Incandes...
Conference Paper
The dynamics of aerosol droplets in a quadruple Bessel beam (QBB) trap and a counter-propagating Bessel beam (CPBB) trap are compared by combining experimental results with simulations of the three-dimensional droplet dynamics. The major focus is on the influence of additional constant and pulsed external forces on the droplet stability and confine...
Article
We report on the dynamics of aerosol droplets in optical traps under the influence of additional constant and pulsed external forces. Experimental results are compared with simulations of the three-dimensional droplet dynamics for two types of optical traps, the counter-propagating Bessel beam (CPBB) trap and the quadruple Bessel beam (QBB) trap. U...
Article
Full-text available
Understanding new particles formation in the free troposphere is key for air quality and climate change, but requires accurate observation tools. Here, we discuss on the optical requirements ensuring a backscattering device, such as a lidar, to remotely observe nucleation events promoted by nonspherical desert dust or volcanic ash particles. By app...
Article
Atmospheric greenhouse gases and nanometer-sized particles are incriminated for their role on the Earth radiative budget and climate. This thesis relates the research performed on thepolarization-resolved backscattering of these nano-sized particles and demonstrates itsusefulness to address complex atmospheric processes like particles nucleation. G...
Article
Full-text available
We present the first experimental observation of exact backscattering of light by an ensemble of particles in ambient air. Our experimental set-up operates in the far-field single scattering approximation, covers the exact backscattering direction with accuracy (θ = π ± ε with ε = 3.5 × 10<sup>-3</sup> rad) and efficiently collects the particles ba...
Article
Full-text available
During transport by advection, atmospheric non-spherical particles, such as volcanic ash, desert dust or sea-salt particles experience several chemical and physical pro-cesses, leading to a complex vertical atmospheric layering at remote sites where intrusion episodes occur. In this paper, a new methodology is proposed to analyse this complex ver-t...
Article
Full-text available
In this paper, the first experimental demonstration of the optical correlation spectroscopy lidar (OCS-lidar) is proposed. It is a new active remote sensing methodology to measure range-resolved atmospheric gas concentrations, based on broadband laser spectroscopy and light amplitude modulation. As a first step, a numerical study is performed for O...
Article
Full-text available
During transport by advection, atmospheric nonspherical particles, such as volcanic, desert dust or sea-salt particles experience several chemical and physical processes, leading to a complex vertical atmospheric layering at remote sites where intrusion episodes occur. In this contribution, a new methodology is proposed to analyze this complex vert...
Article
Full-text available
Large quantities of mineral dust particles are frequently ejected into the atmosphere through the action of wind. The surface of dust particles acts as a sink for many gases, such as sulfur dioxide. It is well known that under most conditions, sulfur dioxide reacts on dust particle surfaces, leading to the production of sulfate ions. In this report...
Article
Full-text available
In this paper, we propose a new active remote sensing methodology, based on laser spectroscopy, to evaluate the content of atmospheric trace gases. Its principle consists in coupling a lidar with optical correlation spectroscopy (OCS-lidar). Our theoretical and numerical studies show that OCS-lidar is a robust measurement methodology allowing trace...
Article
In this paper, accurate UV polarization measurements are performed on a volcanic ash cloud after long-range transport at Lyon, France (45.76 degrees N, 4.83 degrees E). The volcanic particles are released from the mid-April 2010 eruption of the Eyjafjallajokull Icelandic volcano (63.63 degrees N, 19.62 degrees W). The aerosol UV depolarization, whi...
Article
Full-text available
An UV-VIS polarization Lidar has been designed and specified for aerosols monitoring in the troposphere, showing the ability to precisely address low particle depolarization ratios, in the range of a few percents. Non-spherical particle backscattering coefficients as low as 5 {\times} 10-8 m-1.sr-1 have been measured and the particle depolarization...
Article
In this paper, an UV-polarization Lidar is used to study the optical properties of volcanic aerosol in the troposphere. The particles were released by the mid-April 2010 eruption of the Eyjafjallajökull volcano (63.63°N, 19.62°W, Iceland) and passed in the troposphere above Lyon (45.76°N, 4.83°E, France) after advection over 2600 km. The FLEXPART p...
Conference Paper
Polarization and spectrally resolved light scattering of laser light into the atmosphere allows remote evaluation of atmospheric particulate matter and trace gases by applying the lidar technique.
Article
In this contribution, we present a new method to remotely evaluate Methane greenhouse gas concentration in the atmosphere. It is based on combining the Optical Correlation Spectroscopy (OCS) method with laser remote sensing (see fig. 1). The novelty of this work is that an Acoustic Optical Programmable Dispersive Filter (AOPDF) is used and is coupl...
Article
Full-text available
In this paper, an optical remote sensing method is proposed to retrieve the number concentration of non spherical volcanic ash particles. An UV-polarization sensitive remote sensing experiment is interpreted in the frame of the scattering matrix formalism. It follows that UV-optical scattering and depolarization, when they are used together and in...
Article
Full-text available
In this contribution, the optical backscattering properties of atmospheric non-spherical particles are analyzed after long-range transport with a highly sensitive and accurate UV-polarization lidar. Far from the source region, the aerosol cloud is considered as a mixture of spherical (s) and non-spherical (ns) particles. Aerosols UV-depolarization...
Article
In this paper, a ground-based UV-polarization Lidar is used to characterize the optical properties of volcanic particles that originated from the Eyjafjöll volcano (63.63°N, 19.62°W, Iceland) and advected over Lyon (45.76°N, 4.83°E, France), a distance 2,600 kilometers away. The volcanic origin of the observed particles has been confirmed with 7-da...

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Project (1)
Project
Using light to learn about atmospheric aerosols