Spectroscopy of Growing and Evaporating Water Droplets:  Exploring the Variation in Equilibrium Droplet Size with Relative Humidity

Mitchem, Laura; Buajarern, Jariya; Hopkins, Rachel; Ward, Andrew D.; Gilham, Richard; Johnston, Roy L.; Reid, Jonathan P.

doi:10.1021/jp061135f

Cited by 88 publications

(128 citation statements)

References 75 publications

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“…As a typical soluble organic chemical with many hydroxyl groups, sucrose is able to form strong hydrogen bonds with water. The addition of sodium chloride, recognised as a structure breaking solute in aqueous solution (Mitchem et al, 2006) can be expected to have a significant impact on the hydrogen bonding network in the aqueous sucrose droplets, hence influencing physical properties such as viscosity and the glass transition temperature.…”

Section: Formation Of Glassy Raffinose Particles and Mixed Component mentioning

confidence: 99%

Measurements of the timescales for the mass transfer of water in glassy aerosol at low relative humidity and ambient temperature

et al. 2011

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Abstract. The influence of glassy states and highly viscous solution phases on the timescale of aerosol particle equilibration with water vapour is examined. In particular, the kinetics of mass transfer of water between the condensed and gas phases has been studied for sucrose solution droplets under conditions above and below the glass transition relative humidity (RH). Above the glass transition, sucrose droplets are shown to equilibrate on a timescale comparable to the change in RH. Below the glass transition, the timescale for mass transfer is shown to be extremely slow, with particles remaining in a state of disequilibrium even after timescales of more than 10 000 s. A phenomenological approach for quantifying the time response of particle size is used to illustrate the influence of the glassy aerosol state on the kinetics of mass transfer of water: the time is estimated for the droplet to reach the halfway point from an initial state towards a disequilibrium state at which the rate of size change decreases below 1 nm every 10 000 s. This half-time increases above 1000 s once the particle can be assumed to have formed a glass. The measurements are shown to be consistent with kinetic simulations of the slow diffusion of water within the particle bulk. When increasing the RH from below to above the glass transition, a particle can return to equilibrium with the gas phase on a timescale of 10's to 100's of seconds, once again forming a solution droplet. This is considerably shorter than the timescale for the size change of the particle when glassy and suggests that the dissolution of the glassy core can proceed rapidly, at least at room temperature. Similar behaviour in the slowing of the mass transfer rate below the glass transition RH is observed for binary aqueous raffinose solution droplets. Mixed component droplets of suCorrespondence to: J. P. Reid (j.p.reid@bristol.ac.uk) crose/sodium chloride/water also show slow equilibration at low RH, illustrating the importance of understanding the role of the bulk solution viscosity on the rate of mass transfer with the gas phase, even under conditions that may not lead to the formation of a glass.

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Section: Formation Of Glassy Raffinose Particles and Mixed Component mentioning

confidence: 99%

Measurements of the timescales for the mass transfer of water in glassy aerosol at low relative humidity and ambient temperature

et al. 2011

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“…90 In situ chemical analysis of ambient uncharged atmospheric aerosol particles with diameters 9 1 μm was captured using an electrodynamic balance and levitated while Raman spectroscopy with a chargecoupled device (CCD) detector was successfully employed to identify chemical substances in the aerosol particles. 91 Raman chemical imaging using SEM and confocal laser scanning microscopy (CLSM) has also been used in the mapping of fine particulate atmospheric aerosols, 92,93 mass and heat transfer effects on evaporating aerosol droplets, 94,95 aerosol water droplet growth, 96,97 single aerosol droplet physical and chemical dynamics, 98 104 and interfacial hydrogen bonding in water aerosols. 105 As seen with nonaerosol systems, enhanced Raman scattering signal was observed in aerosol chemicals analyzed by resonance Raman spectroscopy.…”

Section: Raman Spectroscopy In Atmospheric Aerosols and Aerosol Partimentioning

confidence: 99%

Raman characterization and chemical imaging of biocolloidal self-assemblies, drug delivery systems, and pulmonary inhalation aerosols: A review

Mansour

Hickey

2007

AAPS PharmSciTech

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This review presents an introduction to Raman scattering and describes the various Raman spectroscopy, Raman microscopy, and chemical imaging techniques that have demonstrated utility in biocolloidal self-assemblies, pharmaceutical drug delivery systems, and pulmonary research applications. Recent Raman applications to pharmaceutical aerosols in the context of pulmonary inhalation aerosol delivery are discussed. The "molecular fingerprint" insight that Raman applications provide includes molecular structure, drug-carrier/ excipient interactions, intramolecular and intermolecular bonding, surface structure, surface and interfacial interactions, and the functional groups involved therein. The molecular, surface, and interfacial properties that Raman characterization can provide are particularly important in respirable pharmaceutical powders, as these particles possess a higher surface-area-to-volume ratio; hence, understanding the nature of these solid surfaces can enable their manipulation and tailoring for functionality at the nanometer level for targeted pulmonary delivery and deposition. Moreover, Raman mapping of aerosols at the micro-and nanometer level of resolution is achievable with new, sophisticated, commercially available Raman microspectroscopy techniques. This noninvasive, highly versatile analytical and imaging technique exhibits vast potential for in vitro and in vivo molecular investigations of pulmonary aerosol delivery, lung deposition, and pulmonary cellular drug uptake and disposition in unfixed living pulmonary cells.

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“…[19][20][21][22][23][24][25][26][27][28] Furthermore, a laser beam used as a trapping light source can be used simultaneously as an excitation light source for Raman spectroscopy, which provides an opportunity to study a droplet size in nanometer accuracy. The equilibrium size of a trapped water droplet in air varies sensitively through water evaporation/ condensation in accordance with relative humidity (RH), temperature, and solute concentration.…”

Section: Introductionmentioning

confidence: 99%

Near-infrared Laser-induced Temperature Elevation in Optically-trapped Aqueous Droplets in Air

Ishizaka

Fujiwara

et al. 2016

ANAL. SCI.

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Near-infrared laser-induced temperature elevation in single aqueous ammonium sulfate droplets levitated in air were evaluated by means of laser trapping and Raman spectroscopy. Since the vapor pressure in an aqueous solution droplet should be thermodynamically in equilibrium with that of water in air, the equilibrium size of the droplet varies sensitively through evaporation/condensation of water in accordance with the temperature change of the droplet. In this study, we demonstrated that the changes in the size of an optically levitated aqueous ammonium sulfate droplet were induced by irradiation of a 1064-nm laser beam as a heat source under an optical microscope. Temperature elevation in the droplet was evaluated successfully by means of Raman spectroscopy, and the values determined were shown to be in good agreement with those by the theoretical calculations based on the absorption coefficient of water at 1064-nm and the thermal conductivity of air. To the best of our knowledge, this is the first experimental demonstration showing that the absorption coefficient evaluated from changes in the size of optically-trapped aqueous droplets is consistent with that of pure water.

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Spectroscopy of Growing and Evaporating Water Droplets: Exploring the Variation in Equilibrium Droplet Size with Relative Humidity

Cited by 88 publications

References 75 publications

Measurements of the timescales for the mass transfer of water in glassy aerosol at low relative humidity and ambient temperature

Measurements of the timescales for the mass transfer of water in glassy aerosol at low relative humidity and ambient temperature

Raman characterization and chemical imaging of biocolloidal self-assemblies, drug delivery systems, and pulmonary inhalation aerosols: A review

Near-infrared Laser-induced Temperature Elevation in Optically-trapped Aqueous Droplets in Air

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