Neutron scattering analysis of water’s glass transition and micropore collapse in amorphous solid water : Revisited

Kwang-Hua, Chu Rainer

doi:10.1016/j.physa.2018.12.026

Cited by 2 publications

(1 citation statement)

References 33 publications

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“…The glass transition with a small step-wise increase in heat capacity only becomes observable after prolonged annealing at 130 K. [33] The mechanism of the glass transition of LDA is still debated. [31,[34][35][36][37][38][39][40] However, it seems likely that the collapse of pores upon heating is connected with the underlying process that leads to an endothermic increase in heat capacity. The translational component of the sintering process should thereby not be taken as evidence for a transition to a supercooled liquid since it may merely reflect the unrelaxed state of the starting material.…”

Section: Introductionmentioning

confidence: 99%

Gaseous “nanoprobes” for detecting gas-trapping environments in macroscopic films of vapor-deposited amorphous ice

Talewar

Halukeerthi

Riedlaicher

et al. 2019

The Journal of Chemical Physics

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Vapor-deposited amorphous ice, traditionally called amorphous solid water (ASW), is one of the most abundant materials in the Universe and a prototypical material for studying physical vapor-deposition processes. Its complex nature arises from a strong tendency to form porous structures combined with complicated glass transition, relaxation and desorption behavior. To gain further insights into the various gas-trapping environments that exist in ASW and hence its morphology, films in the 25 to 100 µm thickness range were co-deposited with small amounts of gaseous 'nanoprobes' including argon, methane, helium and carbon dioxide. Upon heating in the 95-185 K temperature range, three distinct desorption processes are observed which we attribute to the gas desorption out of open cracks above 100 K, from internal voids that collapse due to the glass transition at ~125 K and finally from fully matrix-isolated gas induced by the irreversible crystallization to stacking disordered ice (ice Isd) at ~155 K. Nanoscale films of ASW have only displayed the latter desorption process which means that the first two desorption processes arise from the macroscopic dimensions of our ASW films. Baffling the flow of water vapor towards the deposition plate greatly reduces the first desorption feature, and hence the formation of cracks, but it significantly increases the amount of matrix-isolated gas. The complex nature in which ASW can trap gaseous species is thought to be relevant for a range of cosmological processes.

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