Determination and validation of water droplet size distributions probed by cavity enhanced Raman scattering

Sayer, Robert M.; Gatherer, Robert D. B.; Gilham, Richard; Reid, Jonathan P.

doi:10.1039/b304599d

Cited by 40 publications

(46 citation statements)

References 37 publications

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“…The silica orifice is generated by pulling 100 µm ID silica tubing to the desired size with a commercial CO 2 laser micropipette puller. The piezo is driven with a 0-20 V square wave at 200 -1000 kHz to generate a uniform droplet train with a spread in radius of less than 0.1 µm (Sayer et al, 2003). The radii of the droplets produced is calculated from the liquid flowrate and the oscillation frequency (Smith et al, 2006).…”

Section: Methodmentioning

confidence: 99%

“…Viewports on the chamber allow the introduction of the 514.5 nm line from an argon ion laser operating at ~250 mW or less, which is focused onto the droplet train. The laser power is sufficiently low to avoid heating the droplets or otherwise affecting their evaporation (Sayer et al, 2003;Smith and Baker, 1981). Raman scatter from the droplets is filtered and collected at 90 degrees through a fiber-optic cable and routed to a spectrometer with a liquid nitrogen cooled CCD camera.…”

Section: Methodmentioning

confidence: 99%

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Determination of the evaporation coefficient of D2O

Drisdell¹,

Cappa²,

Smith³

et al. 2008

Preprint

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Abstract. The evaporation rate of D2O has been determined by Raman thermometry of a droplet train (12–15 µm diameter) injected into vacuum (~10-5 torr). The cooling rate measured as a function of time in vacuum was fit to a model that accounts for temperature gradients between the surface and the core of the droplets, yielding an evaporation coefficient (γe) of 0.57±0.06. This is nearly identical to that found for H2O (0.62±0.09) using the same experimental method and model, and indicates the existence of a kinetic barrier to evaporation. The application of a recently developed transition-state theory (TST) model suggests that the kinetic barrier is due to librational and hindered translational motions at the liquid surface, and that the lack of an isotope effect is due to competing energetic and entropic factors. The implications of these results for cloud and aerosol particles in the atmosphere are discussed.

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Section: Methodmentioning

confidence: 99%

Section: Methodmentioning

confidence: 99%

Determination of the evaporation coefficient of D2O

Drisdell¹,

Cappa²,

Smith³

et al. 2008

Preprint

View full text Add to dashboard Cite

show abstract

“…The iterative procedure follows the general algorithm of Eversole et al 28,39 In this study, the droplets were rather large and this ultimately limits the accuracy of the analysis. 40 Notwithstanding this limitation, the intention here is to demonstrate the precision and reproducibility of the droplet generation technique and to monitor controllable changes in droplet size.…”

Section: Methodsmentioning

confidence: 99%

Drop-on-demand microdroplet generation: a very stable platform for single-droplet experimentation

2016

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. (2016). Drop-on-demand microdroplet generation: a very stable platform for single-droplet experimentation. RSC Advances: an international journal to further the chemical sciences, 6 (65), 60215-60222. Drop-on-demand microdroplet generation: a very stable platform for single-droplet experimentation AbstractThis paper reports the performance of drop-on-demand piezo-activated microdroplet generation investigated using microdroplet cavity enhanced fluorescence spectroscopy. Aqueous microdroplets, doped with a fluorescent dye, exhibit fluorescence spectra that are dominated by cavity resonances (termed whispering gallery modes) that, when analysed using Mie theory, allow for the determination of the radius of each microdroplet. The effect of controlled changes in the square-wave droplet generator voltage waveform on droplet size is investigated as well as the size reproducibility of successive microdroplets. Furthermore, using custom square-wave waveforms, microdroplet radii spanning ∼10 to 30 μm are produced from the same droplet dispenser. These non-standard waveforms do not sacrifice the reproducibility of microdroplet generation with <1% size variation. Tuning the single square-wave pulsewidths induces predictable changes in the microdroplet radius and steps on the order of tens of nanometers are detectable. With finer voltage adjustments the microdroplet size is essentially tunable. These results confirm the extremely high stability and reproducibility of on-demand microdroplet generation and that precise size control is possible, rendering them suitable platforms for many applications in fundamental and applied research in areas including mass spectrometry, aerosol investigations and liquid-phase chemistry Aqueous microdroplets, doped with a fluorescent dye, exhibit fluorescence spectra that are dominated by cavity resonances (termed whispering gallery modes) that, when analysed using Mie theory, allow for the determination of the radius of each microdroplet. The effect of controlled changes in the square-wave droplet generator voltage waveform on droplet size is investigated as well as the size reproducibility of successive microdroplets. Furthermore, using custom square-wave waveforms, microdroplet radii spanning ~10 to 30 μm are produced from the same droplet dispenser. These non-standard waveforms do not sacrifice the reproducibility of microdroplet generation with <1% size variation. Tuning the single squarewave pulsewidths induces predictable changes in the microdroplet radius with steps on the order of tens of nanometers are detectable. With finer voltage adjustments the microdroplet size is essentially tunable. These results confirm the extremely high stability and reproducibility of on-demand microdroplet generation and that precise size control is possible, rendering them suitable platforms for many applications in fundamental and applied research in areas including mass spectrometry, aerosol investigations and liquid-phase chemistry.3

show abstract

“…The silica orifice is generated by pulling 100 µm ID silica tubing to the desired size with a commercial CO 2 laser micropipette puller. The piezo is driven with a 0-20 V square wave at 200-1000 kHz to generate a uniform droplet train with a spread in radius of less than 0.1 µm (Sayer et al, 2003). The radii of the droplets produced is calculated from the liquid flowrate and the oscillation frequency (Smith et al, 2006).…”

Section: Methodsmentioning

confidence: 99%

Determination of the evaporation coefficient of D2O

et al. 2008

View full text Add to dashboard Cite

Abstract. The evaporation rate of D 2 O has been determined by Raman thermometry of a droplet train (12-15 µm diameter) injected into vacuum (∼10 −5 torr). The cooling rate measured as a function of time in vacuum was fit to a model that accounts for temperature gradients between the surface and the core of the droplets, yielding an evaporation coefficient (γ e ) of 0.57±0.06. This is nearly identical to that found for H 2 O (0.62±0.09) using the same experimental method and model, and indicates the existence of a kinetic barrier to evaporation. The application of a recently developed transition-state theory (TST) model suggests that the kinetic barrier is due to librational and hindered translational motions at the liquid surface, and that the lack of an isotope effect is due to competing energetic and entropic factors. The implications of these results for cloud and aerosol particles in the atmosphere are discussed.

show abstract

Determination and validation of water droplet size distributions probed by cavity enhanced Raman scattering

Cited by 40 publications

References 37 publications

Determination of the evaporation coefficient of D<sub>2</sub>O

Determination of the evaporation coefficient of D<sub>2</sub>O

Drop-on-demand microdroplet generation: a very stable platform for single-droplet experimentation

Determination of the evaporation coefficient of D<sub>2</sub>O

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Determination and validation of water droplet size distributions probed by cavity enhanced Raman scattering

Cited by 40 publications

References 37 publications

Determination of the evaporation coefficient of D&lt;sub&gt;2&lt;/sub&gt;O

Determination of the evaporation coefficient of D&lt;sub&gt;2&lt;/sub&gt;O

Drop-on-demand microdroplet generation: a very stable platform for single-droplet experimentation

Determination of the evaporation coefficient of D&lt;sub&gt;2&lt;/sub&gt;O

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Determination of the evaporation coefficient of D<sub>2</sub>O

Determination of the evaporation coefficient of D<sub>2</sub>O

Determination of the evaporation coefficient of D<sub>2</sub>O