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Submitted on 1 Jan 1987
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VITRIFIED LIQUID WATER : A COMPARISON WITH VAPOR DEPOSITED AMORPHOUS SOLID
WATER
E. Mayer
To cite this version:
E. Mayer. VITRIFIED LIQUID WATER : A COMPARISON WITH VAPOR DEPOSITED AMORPHOUS SOLID WATER. Journal de Physique Colloques, 1987, 48 (C1), pp.C1-671-C1-672.
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JOURNAL D E PHYSIQUE
Colloque C 1 , suppl6ment au n o 3, Tome 4 8 , mars 1 9 8 7
VITRIFIED LIQUID WATER : A COMPARISON WITH VAPOR DEPOSITED AMORPHOUS SOLID WATER
E. MAYER
Institut fiir Anorganische und Analytische Chemie, Universitat Innsbruck, A-6020 Innsbruck, Austria
Abstract : A new method for the vitrification of pure liquid water and dilute aqueous solutions is described which works as the only one without liquid cryomedium for heat transfer : rapid rooling of aqueous aerosol droplets on a solid cryoplate (1). The method can be applied in diverse fields such as cryobiology, crymicrosco~ and low temperature spectroscopy of water and aqueous solutions or suspensions to avoid the formation of crystalline ice during quenching to cryogenic temperatures, the elimination of a liquid crymedium being particularly helpful for in situ spectroscopic investigations.
Until now vitrified liquid water prepared by this method has been investigated by infrared spectroscopy (2) and by differential thermdL analysis (DTA) (3), and its properties compared with those of vapor deposited amorphous solid water, H@(as). A comparison of infrared spectra shows two differences : first, in the vitrified aerosol the peak maximum of the decoupled 0-D stretching transition at 20 K is at lower wavenumkrs, at 2416 cm-l, whereas in H@(as) it is at 2440 an-l. Second, in the coupled 0-H stretching band region of vitrified liquid water ,an additional shoulder is observed at approximately 3120 cm-l. These spectrd are probably related to structural differences, implying that the amorphous forms of water made from the liquid and the vapor have different structures.
The devitrification of quenched aerosol droplets as observed by DTA occurs in two steps, with peak maximum temperatures of 150 and 156 K. This stepwise devitr if ication has been observed previously for samples quenched in liquid cryamedium by high-pressure jet-freezing (4). To my knowledge water is the only vitrified pure liquid with this behaviour. The two exotherms are interpreted in terms of two fractions of vitrified liquid water formed in the cooling process with different properties, which devitrify during reheating at slightly different temperatures, and this interpretation is related to the anomdlous properties of supercooled liquid water. A comparison with the devitrification of H20(as) establishes a further difference, because H2O (as) prepared this way devitr if ies as expected in one step, the DTA curve showing only one exotherm.
References
(1) Mayer, E., J. Appl. Phys.,
2,
(1985), 663.(2) -Mayer, E., J. Appl. Phys.,
86,
(1985), 3474.(3) Mayer, E., J. Microsc., in press
(4) Mayer, E. and Briiggeller, P., J. Phys. Chem.,
87,
(1983), 4744.COMMENTS
Did you n o t i c e any e f f e c t o f t h e s p r e a d i n g f a c t o r o f t h e i m p i n g i n g d r o p l e t s ?
Answer :
Yes, a c c o r d i n g t o e l e c t r o n microscopy r e p l i c a s t h e d r o p l e t s a n p l a t t e n e d by t h e i m p a c t v e r y a p p r o x i m a t e l y t o 1 m ; t h i s v a l u e depends v e r y much on t h e p o s i t i o n o f impact.
Article published online by EDP Sciences and available at http://dx.doi.org/10.1051/jphyscol:19871103
JOURNAL DE PHYSIQUE
N. FUKUTA
I might have missed your presentation but how did you atomize 3 m droplets ? Did you observe ice nucleation before the droplets impinging the cold surface ?
Answer :
We used an ultrasonic nebulizer operating at 3 MHz. (LK9 instruments, model NB 108).
This produces according to the manufacturer droplets of 3 3 p m diameter.
No,we did not observe ice nucleation of droplets before impinging on the cryoplate for optimized conditions.
Of course, we cannot differentiate when the remaining N 5% crystalline material is formed.
J.P. DEVLIN
When you refer to cryopumping as necessary for good vitrification levels I presume this could equally well refer to the action of a fast vacuum pump.
Answer :
Yes, if a high-capacity pumping system is used.
R. GAGNON
What is the effect of varying the size of the droplets ? Answer :
Droplets of 20 to 3 0 p m diameter quenched the same way give mainly crystalline (cubic) ice.
Remark of J. DORE :
The relation between liquid water and low density amorphous ice has been investigated by some recent neutron diffraction measurements at Saclay(France). The main diffraction peak in normal D20 water is at w 2.0 A-' and that of low-density amorphous ice is at 1.7 A - ~ but as the liquid is cooled the position moves to lower Q-values. The new results (Bellisent-Frenel, Seeseeiver, Dove, Europhysics Letters, to be published and Dore ,Colson,Symposium on Water, 1936) show that in the super-cooled region (for results down to
