is Amorphous

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Intro catchy phrase

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Plan

Water Molecule

Condensed phase

Water Models

Hexagonal Ice

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Plan

Key Litterature:

• [Narten et al., 1976]

• Scihub link - review Angell

Links

• 1

• 2

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Definitions

Hover the term to see definition appear or click on the link to be directed toward Teaching. Classified per difficulty (⭐)

⭐

⭐ ⭐

• Clathrate
  
  

⭐ ⭐ ⭐

• Fugacity

Amorphous Ices

Litterature

Study Title Year “Infrared spectra of amorphous solid water” by G.A. Baratta and J.A. Westley 1989 “Infrared spectra of amorphous solid water: Implications for interstellar and cometary ice” by L.D. Deshmukh et al. 2004 “H2O ice in the interstellar medium: a comparison between observed and simulated infrared spectra” by C.A. Boogert et al. 2015 “Ice grain morphology and infrared spectra in protoplanetary disks” by M. Min et al. 2016 “The Low-Temperature Infrared Spectrum of Amorphous Solid Water: A Spectroscopic and Theoretical Study” by J. P. Lewis et al. 2000 “Mid-infrared spectroscopy of interstellar ice analogs” by J.M. Brown et al. 2007 “A laboratory study of the mid-infrared spectra of amorphous solid water and water-rich ices” by A.G.G.M. Tielens et al. 2008 “Spectroscopic properties of amorphous solid water: a review” by P. Ehrenfreund et al. 2015

Review

• Review [Angell, 2004]

Bulk Organisation

Definition

Experiments

• Variation of the deposition angle

Controlling the Morphology of Amorphous Solid Water

• Deposition temperature variations

• Annealing processes

Porosity

[Carmack et al., 2023]

Definition

• Controlling the

Experiments

• Different types

Insert here table of different groups:

• NASA Ames: Mastrapa, Sandford

  • Is data available, yes

Infrared Spectroscopy

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Key Papers:

• Mastrapa (2008, 2009)

• Jenny

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What did we leran

• ASW is porous

• 3 µm band is changing when the T is increased

• Water ice IR Band assignement taken from [Mastrapa et al., 2009]

Crystaline (cm -1) [Bertie and Whalley, 1964]	Amorphous (cm -1) [Hardin and rvey, 1973]	Assignment	A values (cm/molecule) [Hudgins et al., 1993]
840	802	𝜈R [Ockman, 1958]	2.8 × 10-17
1650	1660	𝜈2 [Ockman, 1958]	1.0 × 10-17
2266	2220	𝜈2 + 𝜈R [Whalley, 1977]	3.3 × 10-18
3150	3191	𝜈1 in phase [Whalley, 1977]
3220	3253	𝜈3 TO [Whalley, 1977]	1.7 × 10-16
3380	3367	𝜈3 LO, 𝜈1 out of phase [Whalley, 1977]

to cite:

• a [Bertie and Whalley, 1964]

• b [Hardin and rvey, 1973]

• c [Hudgins et al., 1993]

• d [Ockman, 1958]

• e [Whalley, 1977]

Note

• TO, LO, what does this mean ?

Insert own crystaline and amorphous spectra with different asssignments vertical bar

Link with Optical Constants

• Real and imaginary part (how do they relate to what we observe in space)

Differential Scanning Calorimetry

tg at 136K (ramp 30K.min-1) –> Increase in heat capacity (lower than other amorphous solid: similar to SiO2 - GeO2) –> Imply limited number of entropically different configurational states in the fluid state following tg

Dielectric relaxation behaviour expected to be determined by two processes both involving a thermaly activated dipolar reorientation:

• translational-rotational diffusion of water molecules if the whole H-Bonded network relaxed within limitation of entropically different configurations

• rotational diffusion of water molecules within a fixed H-Bonded structure as breaches of the Bernal-Fowler rules. –> 2 kinds of Bjerrum defects

  • Scattering

ASW at 140K - true glass or very viscous liquid ? What is the difference

Crystalisation

At molecular scales (few molecules up to 100 ?) - Matrix isolation techniques

Desorption

[Rosu-Finsen et al., 2022]

Porosity

[Cazaux et al., 2014]

• [Bossa et al., 2014]

Is it Amorphous ?

Fig. 11 Source