Evaporating laminar microjets for studies of rapidly evolving structural transformations in supercooled liquids

Sub-lm thin samples are essential for spectroscopic purposes. The development of flat micro-jets enabled novel spectroscopic and scattering methods for investigating molecular systems in the liquid phase. However, the temperature of these ultra-thin liquid sheets in vacuum has not been systematically investigated. Here, we present a comprehensive temperature characterization using optical Raman spectroscopy of sub-micron flatjets produced by two different methods: colliding of two cylindrical jets and a cylindrical jet compressed by a high pressure gas. Our results reveal the dependence of the cooling rate on the material properties and the source characteristics, i.e., nozzle-orifice size, flow rate, and pressure. We show that materials with higher vapor pressures exhibit faster cooling rates, which is illustrated by comparing the temperature profiles of water and ethanol flatjets. In a sub-lm liquid sheet, the temperature of the water sample reaches around 268 K and the ethanol around 253 K close to the flatjet's terminus.

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“…The use of the gascompressed flatjet to reach the deeply supercooled regime of water is left for future studies. 39…”

Section: Gas Pressurementioning

confidence: 99%

Temperature measurements of liquid flat jets in vacuum

Chang

Yin

Balčiūnas

et al. 2022

Structural Dynamics

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“…However, cooling rare-gas liquids to temperatures significantly below their melting points is difficult, not to mention the subsequent probing of the rapidly evolving liquid-to-solid phase transition. Our approach was based on the generation of a microscopic laminar jet in vacuum, which offers a powerful method to investigate fast structural transformations in simple supercooled atomic and molecular liquids [19,20]. Figure 1a shows a schematic representation of the experiment.…”

mentioning

confidence: 99%

“…Liquid jets of varying krypton mole fraction x between x = 0 (pure argon jet) and x = 1 (pure krypton jet) were generated in a vacuum chamber (see Methods). The jets cooled rapidly by surface evaporation until they crystallized spontaneously by homogeneous nucleation, forming continuous solid filaments [20].…”

mentioning

confidence: 99%

Crystal growth rates in supercooled atomic liquid mixtures

et al. 2020

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Crystallization is a fundamental process in materials science, providing the primary route for the realization of a wide range of novel materials. Crystallization rates are considered also to be useful probes of glass-forming ability. [1][2][3]. At the microscopic level, crystallization is described by the classical crystal nucleation and growth theories [4, 5], yet in general solid formation is a far more complex process. Particularly the observation of apparently different crystal growth regimes in many binary liquid mixtures greatly challenges our understanding of crystallization [1, 6-12]. Here, we study by experiments, theory, and computer simulations the crystallization of supercooled mixtures of argon and krypton, showing that crystal growth rates in these systems can be reconciled with existing crystal growth models only by explicitly accounting for the non-ideality of the mixtures. Our results highlight the importance of thermodynamic aspects in describing the crystal growth kinetics, providing a major step towards a more sophisticated theory of crystal growth.The classical crystal nucleation and growth theories describe the microscopic steps by which a solid phase spontaneously forms in the supercooled liquid at some temperature T below melting.Homogeneous crystal nucleation is the process of the formation by thermal fluctuations of a small, localized nucleus of the newly ordered phase in the metastable liquid [4]. Once the nucleus has reached its critical size, it grows at a rate that within the kinetic theory of crystal growth is givenwhere f ≤ 1 is a geometrical factor representing the fraction of atomic collisions with the crystal surface that actually contribute to the growth, a(T ) is a characteristic interatomic spacing that can be identified with the lattice constant, ν(T ) is the crystal addition rate at the crystal/liquid interface, ∆S m is the molar entropy of fusion, R is the universal gas constant, and ∆G(T ) = G L (T ) − G C (T ) is the difference in liquid (L) and crystal (C) molar Gibbs free energies. In the Wilson-Frenkel (WF) theory [13], the crystal addition rate is proportional to the atomic diffusivity D(T ), ν WF (T ) = 6D(T )/Λ 2 (T ), and hence exhibits the strong temperature dependence associated with an activated process. Here, Λ(T ) = ca(T ) is an average atomic displacement that we assume to be proportional to a(T ), with c being a dimensionless parameter. In the collision-limited (CL) scenario [14], the crystal addition rate is proportional to the average thermal velocity of the particles, ν CL (T ) = 3k B T /m/Λ(T ), where k B is Boltzmann's constant and m is the particle's mass, and represents the extreme case in which there is no activation barrier for ordering.At the microscopic level, the WF and CL models can be characterized by limiting time scales

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“…The use of the gas-compressed flatjet to reach the deeply supercooled regime of water is left for future studies. 27…”

Section: Model Calculationsmentioning

confidence: 99%

“…[21][22][23][24] For a majority of molecular systems, the temperature can have a vital impact on the properties and the evolution of the system. Although temperature characterization of super-cooled water droplets and cylindrical jets have been conducted in previous studies 22,[25][26][27] using Raman spectroscopy, systematic investigation of liquid flatjets has not been performed yet. In this work, we present measurements of the temperature profiles of liquid water (H 2 O) and ethanol (C 2 H 5 OH) in flatjets in vacuum using Raman spectroscopy.…”

Section: Introductionmentioning

confidence: 99%

Temperature Measurements of Liquid Flat Jets in Vacuum

Chang,

Yin,

Balciunas

et al. 2021

Preprint

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Sub-µm thin samples are essential for spectroscopic purposes. The development of flat micro-jets enabled novel spectroscopic and scattering methods for investigating molecular systems in the liquid phase. However characterization of the temperature of these ultra-thin liquid sheets in vacuum has not been systematically investigated.Here we present a comprehensive temperature characterization of two methods producing sub-micron flatjets, using optical Raman spectroscopy: colliding of two cylindrical jets and a cylindrical jet compressed by a high pressure gas. Our results reveal the dependence of the cooling rate on the material properties and the source characteristics, i.e. nozzle orifice size, flowrate, pressure. We show that materials with higher vapour pressures exhibit faster cooling rates which is illustrated by comparing the temperature profile of liquid water and ethanol flatjets. In a sub-µm liquid sheet, the temperature of the water sample reaches around 268 K and the ethanol around 253 K.

show abstract

Evaporating laminar microjets for studies of rapidly evolving structural transformations in supercooled liquids

Cited by 8 publications

References 90 publications

Temperature measurements of liquid flat jets in vacuum

Temperature measurements of liquid flat jets in vacuum

Crystal growth rates in supercooled atomic liquid mixtures

Temperature Measurements of Liquid Flat Jets in Vacuum

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