Quasi-liquid layers on ice crystal surfaces - PowerPoint Presentation

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Slide2

Quasi-liquid layers on ice crystal surfaces

Sazaki

, et al., 2012:

Quasi-liquid layers on ice crystal surfaces are made up of two different phases

, PNAS,

109

, 1052-1055.

Asakawa

, et al., 2015:

Prism and Other High-Index Faces of Ice Crystals Exhibit Two Types of Quasi-Liquid Layers

,

CGD,

15

, 3339-3344.Slide3

Quasi-liquid layers: why do we care?

Because they’re really cool.Slide4

Introduction: measurements of surface properties

Different ways to measure surface properties

X-ray diffraction

Neutron backscattering

Electron scattering

Low-energy electron scattering

Infrared spectroscopy

Voltammetry

Tunneling electron microscopy

Atomic force microscopySlide5

Introduction: measurements of surface properties

Different ways to measure surface properties

X-ray diffraction

Neutron backscattering

Electron scattering

Low-energy electron scattering

Infrared spectroscopy

Voltammetry

Tunneling electron microscopyAtomic force microscopy

Penetrates surface

Penetrates surface

Penetrates surfaceSlide6

Introduction: measurements of surface properties

Different ways to measure surface properties

X-ray diffraction

Neutron backscattering

Electron scattering

Low-energy electron scattering

Infrared spectroscopy

Voltammetry

Tunneling electron microscopyAtomic force microscopy

Penetrates surface

Penetrates surface

Penetrates surfaceSlide7

Introduction: measurements of surface properties

Different ways to measure surface properties

X-ray diffraction

Neutron backscattering

Electron scattering

Low-energy electron scattering

Infrared spectroscopy

Voltammetry

Tunneling electron microscopyAtomic force microscopy

High vacuum

High vacuumSlide8

Introduction: measurements of surface properties

Different ways to measure surface properties

X-ray diffraction

Neutron backscattering

Electron scattering

Low-energy electron scattering

Infrared spectroscopy

Voltammetry

Tunneling electron microscopy

Atomic force microscopyHigh vacuum

High vacuumSlide9

Introduction: measurements of surface properties

Different ways to measure surface properties

X-ray diffraction

Neutron backscattering

Electron scattering

Low-energy electron scattering

Infrared spectroscopy

Voltammetry

Tunneling electron microscopy

Atomic force microscopyEllipsometry

Grazing-incidence x-ray diffractionConfocal laser scanning microscopyNuclear magnetic resonanceInterference microscopyInterferometrySlide10

Introduction: measurements of surface properties

Different ways to measure surface properties

X-ray diffraction

Neutron backscattering

Electron scattering

Low-energy electron scattering

Infrared spectroscopy

Voltammetry

Tunneling electron microscopy

Atomic force microscopyEllipsometry

Grazing-incidence x-ray diffractionConfocal laser scanning microscopyNuclear magnetic resonanceInterference microscopyInterferometry

Ice destroys AFM tips

Difficult and questionable precision

Poor resolution

Ice is mostly transparent Slide11

Introduction: measurements of surface properties

Different ways to measure surface properties

X-ray diffraction

Neutron backscattering

Electron scattering

Low-energy electron scattering

Infrared spectroscopy

Voltammetry

Tunneling electron microscopy

Atomic force microscopyEllipsometryGrazing-incidence x-ray diffraction

Confocal laser scanning microscopyNuclear magnetic resonanceInterference microscopyInterferometry

Ambiguous results

n

ice

≈

n

water

Very difficult interpretationSlide12

Introduction: so who’s tried this?

Faraday (1840’s) (1860, PRSL)

Several clever experiments showing that “

water particles

” on

ice can briefly turn to liquid

before freezing again (experimental)

Thomson and Lord Kelvin (1850-1870’s)

“Faraday must be daft.”

The surface of ice is just melting because the extra pressure lowers the melting point

Fletcher (1962, Phil. Mag.)

First theoretical treatment

of QLL, used thermodynamics and kinetics to show QLL’s are possible and probable (theoretical)

Jellinek

(1967, JCIS)

First literature review

in the field of water ice QLL

Kuroda and

Lacmann

(1982, JCG)

QLL’s modulate vapor depositional growth

at high temperatures with different temperature dependence for the two different facets (theoretical)

Elbaum

, et al. (1993, JCG)

Optical measurements (

ellipsometry

and interference microscopy)

detected possible QLLSlide13

Introduction: so who’s tried this?

Knight (1996, JGR)

QLL’s don’t make physical sense,

they’re not thermodynamically possible

, and even as a conceptual model they’re useless (comment)

Baker and Dash (1996, JGR)

Charlie Knight is applying macroscopic thermodynamics to a nanoscale system (reply)

Nelson and Knight (1998, JAS)

“There is little doubt that the ice surface is rather badly disturbed at temperatures not far below zero…” but

Kuroda and

Lacmann

are

wrong

about QLL

.

(theoretical)

Ewing (2004, JPCB)

QLL is difficult to measure, but IR can tell us some things.

QLL kind of appears to be a different phase

(experimental review)

Nunes, et al. (2007, Solid State NMR)

No evidence of QLL

, but proving NMR as a possible technique (theoretical)

Sazaki, et al. (2012, PNAS)

First unambiguous observation of two types of QLL on basal facets

Asakawa, et al. (2015, CGD)

First unambiguous observation of two types of QLL on prism facetsSlide14

0.37-nm

vertical resolution

Creates images by scanning the laser across the crystal

Allows video imaging of individual step growth

(

Sazaki

, et al., 2012:

Quasi-liquid layers on ice crystal surfaces are made up of two different phases

, PNAS.)

Fig S2 (

Asakawa

, 2015)

Fig S2 (

Sazaki

, 2012)

Laser confocal microscopy-differential interference microscopy (LCM-DIM)Slide15

Round droplet-like features formed at -1.5 to -0.4

°C:

α

-QLLs

Interference measurements give heights of approximately

0.5

μ

m

for a width of

50

μmIndicates high wettability of ice surface by QLL

(

Sazaki

, et al., 2012:

Quasi-liquid layers on ice crystal surfaces are made up of two different phases

, PNAS.)

Round liquid-like droplets

-0.4

°C

-0.3

°C

-0.6

°C

-0.3

°C

Figure 1.

each band is 317 nmSlide16

Coalescence of

α

-QLLs shows they cannot be solid

They appear to serve as step sources (

Sazaki

, et al. say they nucleate steps)

(

Sazaki

, et al., 2012:

Quasi-liquid layers on ice crystal surfaces are made up of two different phases, PNAS.)

Coalescence of

α

-QLLs

temperature: -0.3

°C

duration: 38 seconds

Movie S1Slide17

Thin layers form at -1.0 to -0.2

°C:

β

-QLLs

Clearly thicker than steps, but too thin for interferometry:

thickness < 100 nm

Droplets and thin layers (not shown here) eventually coalesce

(

Sazaki

, et al., 2012:

Quasi-liquid layers on ice crystal surfaces are made up of two different phases, PNAS.)

Formation of thin layers

temperature: -0.1

°C

duration: 88 seconds

Movie S2Slide18

Adjusting image settings shows

steps underneath the

β

-QLL

Either

β

-QLL

deforms over steps

, or QLL refractive index is different than ice

Thin layers cannot be solid ice

(Sazaki, et al., 2012: Quasi-liquid layers on ice crystal surfaces are made up of two different phases, PNAS.)

Seeing “through”

β

-QLLs

temperature: -0.1

°C

duration: 163.5 seconds

Movie S3Slide19

Temperature decreased -0.5 to -1.0

°C

β

-QLL “decomposed and changed into

α

-QLLs” and many bunched steps

Shows reversibility and phase stability of the transitions between

α

- and

β

-QLLsα-QLLs are more stable than

β

-QLLs in the measured case

(

Sazaki

, et al., 2012:

Quasi-liquid layers on ice crystal surfaces are made up of two different phases

, PNAS.)

Refreezing of QLLs

temperature: -0.5 to -1.0

°C

duration: 163.5 seconds

Movie S4Slide20

According to classical thermodynamics:

β

-QLLs are more thermodynamically favorable

: high wettability means low interaction energy with ice

α

-QLLs are more stable

: lower appearance temperature

β

-QLLs always appear after

α-QLLs

(Sazaki, et al., 2012: Quasi-liquid layers on ice crystal surfaces are made up of two different phases

, PNAS.)

Other notes from

Sazaki

, et al.

Figure S1.Slide21

Roughening transition on prism/high-index facets

Screw dislocation growth at -4.4

°C (A)

Distances between steps decrease at ≈-3.0

°C

(B; 42.1 seconds later)

Surface becoming rounded (C; 501.0 seconds later)

Almost no reflection off surface (D; 1081.0 seconds later)

(

Asakawa

, et al., 2015:

Prism and Other High-Index Faces of Ice Crystals Exhibit Two Types of Quasi-Liquid Layers. CGD.

)

Figure 1.Slide22

QLL’s on prism/high-index facets

Prism facet experiencing a roughening transition/becoming rounded

Liquid-like droplets appear (little lumps on face)

(

Asakawa

, et al., 2015:

Prism and Other High-Index Faces of Ice Crystals Exhibit Two Types of Quasi-Liquid Layers. CGD.

)

Figure 2.Slide23

Liquid-like coalescing on a

a

prism/high-index facet

Two liquid-like droplets coalescing to form one droplet

(

Asakawa

, et al., 2015:

Prism and Other High-Index Faces of Ice Crystals Exhibit Two Types of Quasi-Liquid Layers. CGD.

)

Figure 3.

Movie S1.

-0.5

°CSlide24

(

Asakawa

, et al., 2015:

Prism and Other High-Index Faces of Ice Crystals Exhibit Two Types of Quasi-Liquid Layers. CGD.

)

Figure 4.

Thin liquid-like layers on a prism/high-index facet

Thin layers coalescing to cover the surface

Liquid-like layer appearing underneath liquid-like drop

Liquid-like drops apparently “condensing” in to a growing liquid-like layerSlide25

(

Asakawa

, et al., 2015:

Prism and Other High-Index Faces of Ice Crystals Exhibit Two Types of Quasi-Liquid Layers. CGD.

)

Figure 5.

Thin liquid-like layers coalescing againSlide26

(

Asakawa

, et al., 2015:

Prism and Other High-Index Faces of Ice Crystals Exhibit Two Types of Quasi-Liquid Layers. CGD.

)

Figure 6.

Summary of overall findings

β

-QLLs are less stable (probably)

α

-QLLs always form first

Both are difficult to observe on prism/high-index faces