Anomalous state of ice, which is a novel stable structures made from water molecules, can be induced to form under the action of ions in very dilute solutions, perhaps from a similar physical mechanism that forms ice VI. These stable structures change the UV transmission characteristic of water. Different structures formed from different ions are shown to have similar UV transmission characteristics. These structures can be filtered, concentrated and photographed using a transmission electron-microscope. A dipole-dipole interaction model is constructed to suggest an explanation of the elongated shape of these structures.
It is well known that water molecules form stable rigid structures: for example, ice VI at room temperature and at high pressure (> 7 kB).1 Generally, such a high pressure does not occur naturally on Earth. However, we wish to point out that such a high pressure could exist between an ion and its nearby water molecules due to the electrostatic attraction between the charge of an ion and the electric dipole moments of a water molecule. Anomalous state of ice which are stable rigid structures of water molecules similar to ice VI can be grown in water at room temperature and normal pressure provided that suitable dilution of ions in water is performed.
2. Growing Structures Around Ions in Very Dilute Solution
Positively or negatively charged ions in aqueous solutions attract water molecules which have electric dipole moments p that can be expressed as p = ned = 2.45 debyes, with e = charge of electron, d = size of water molecule = 0.278 nm and n = scale factor = 0.1837. The electric potential energy, U, experienced by a water molecule at a distance r from the ion is U = -p · E where E is the electric field exerted by the ion on the water molecule and is given by
3. UV Transmission Measurement
Evidence for IE structures shows up easily in UV transmission measurement. The standard method for preparing a very dilute solution is to dissolve a small amount of salt (NaCl), acid (HNO3), or base (NaOH) in pure water, then dilute it one part to ten parts of pure water.2 Shake the solution and dilute again one part to ten parts of pure water. Repeat this many times. The solution is measured for UV transmission via a dual beam Perkin-Elmer Lambda 2S machine with a standard reference cell filled with pure water. The absorbance readings from Lambda 2S, which also include effects from scattering as well as absorption of UV light, are displayed in Fig. 1 (a) for four solutions: sodium chloride NaCl, sodium hydroxide NaOH, and nitric acid HNO3 and pure water with molar concentration ranging from 10-3 to 10-13. There is clearly a drop of absorbance as molar concentration decrease. Then starting at molar concentration 10-5 to 10-7 they all fluctuate in the order of 10-2, regardless of their origin. We show selectively a few UV transmission measurements for these types of solutions in the range of wave length = 190 nm to 250 nm in Figs. 1 (b) and (c). There is no qualitative difference in the spectrum for various very dilute solutions (<10-7M) made up from different salts, acids, or base. The UV transmission characteristic of these very dilute solutions is significantly different from the dilute solution when ni/n0 > 10-7 or molar concentration > 10-5. It is important in the experimental procedure that we carefully wash the quartz cell to get rid of any IE structures each time a measurement is made. A clean quartz cell with pure water is verified by a flat UV transmission flat curve from the Lambda 2 machine. This is done each time prior to the next measurement.
We interpret these results as follows: As solutions become very dilute, IE structures are formed from water molecules around ions. These water molecules are formed under strong electric field, which is 2×106 V/m at three water molecules distance from ions. Hence water molecules in IE structures are expected to maintain the alignment of their dipole moments. The effective dipole moment of IE structure is negative towards a positive ion side and positive on the side opposite from the ion. Furthermore, the electric field has spherical symmetry. This condition is quite different from ice VI formed under high pressure which has translational invariance. Unit cell of ice VI is tetragonal and can be repeated in all directions indefinitely. No one so far has constructed a crystal with a spherical symmetry. Hence not much is known about a spherical symmetric crystal or any non-translational invariant unit cell.
The IE structures are first formed around ions in the solution and do not occur anywhere else. We could generate these structures by breaking them up with shaking. The spherical symmetric IE structures will break up into many small pieces. These small pieces have electric dipole moment which generate a strong electric field at the poles to attract nearby water molecules to form a bigger piece. These bigger pieces are magnet like except they have an electrical dipole and not a magnetic dipole. They exist independent of ions. They can be broken into smaller pieces and grow bigger. Therefore, as the solution is diluted further from molar concentration 10-7 to 10-13, IE structures remain undiminished by dilution many many times. Since shaking, breaking and then growing of IE are random, we do see a random spread of UV absorbance around 10-2 at wavelength = 190 nm for various very dilute solutions as shown in Fig. 1 (a). There are great similarity among very dilute solutions of HNO3, NaOH, and NaCl with different molar concentration and having IE structures. In Fig. 1 (c), the dilute solution N2 of HNO3 (1.15×10-5M) looks very different from both of the dilute solution NaOH (2.5×10-5M) and the very dilute solution nitric acid (2.1×10-11M) because UV transmission of N2 is still a characteristic of nitric acid.
In order to further test the idea of IE structure, we search for a way to increase the IE structures in the very dilute solution. In our dipole model, IE structures created by ions cannot be big. The electric dipoles of the IE structures on the right hand side of a positively charged ion have the induced charges in the order of negative, positive, negative, positive, ... etc. with polarization vector pointing to the left while the electric dipoles of IE structure on the left hand side of a positive-charged ion will have exactly the opposite polarization; Hence, the total electric dipole around an ion will tend to cancel out. Less and less IE structure can grow away from the ion because of diminishing electric field. However for very dilute solutions with mostly IE structures and very little ions (say ni/n0 < 10-11), we introduce some dielectric material which does not ionize but has an uneven electronic distribution outside. Then IE structures can grow outside the dielectric material with polarization lining up on both sides of the molecules. The electric dipole moments of the total IE structure add up and there is no diminishing of the electric field at the boundary of the IE structures. So IE structures can easily grow bigger. For this to occur, we have experimented by introducing an dielectric material with high boiling point (~350°C) slowly in the very dilute solution to about several parts per million. And we see a much stronger UV absorbance as well as many more rod-like structures in the electron microscope pictures.
Since the dielectric material having a high boiling point (350°C) and does not evaporate with water, we have used a low pressure rotary evaporator and boil the solution at 67°C. The evaporated and condensed solution has similar UV transmission characteristic as shown in Fig. 2. This strongly suggests the increase of the UV absorbance is due to an increase in IE structures and not due to impurity such as the dielectric material that we add.
4. Electron Microscope Pictures of IE Structures
The direct evidence for existence of these stable IE structures comes from pictures taken with the electron microscope. The very dilute solution with IE structures is filtered through a 0.1 µm filter paper and then is sputter coated with carbon. The carbon coated filter paper is dissolved in boiling chloroform for twenty minutes. Water and IE structure will be dissolved away and only carbon skeletons remain. Hitachi transmission microscope H600A is used to take the pictures. The X-ray emitted by the striking electron beam is also examined. If there is any impurity such as solid salt or biological entity, a characteristic X-ray of their constituent atoms by atomic excitation will be emitted. No such characteristic X-rays are seen. Hence it is concluded that the skeleton pictures are not from impurities in the water or biological specimen such as bacteria or virus. The pictures are consistent with the hypothesis that the IE structures are made up of water molecules alone. Some of the typical pictures are shown in Fig. 3.3 They are from very dilute solutions of sodium chloride with small and large amount of UV absorbance. For control, we also treat pure water (reverse osmosis water from Millipore machine) the same way; we see none of these structures. Since these structures are of micron size, they can be observed by ordinary optical microscope with some patience also.
5. Dipole-Dipole Interaction Square Lattice Model
In order to understanding the rod-like structures as seen by the electron microscope, we propose the following mechanism. After the IE structures are created, broken and then grow to larger size, they have larger electric dipole moments. The electrostatic forces between any two adjacent pieces is huge. They either join each other head to tail or side by side. If they lie side by side, their electric dipole moment will be opposite each other to obtain the lowest energy states. The circular sizes of the order of 100 nm seen inside the rod-like structures are assumed to be electric dipoles. Let us assume they are of equal size and have the same amount of electric dipole moment p. The interaction between any two dipoles i and j is given by dipole-dipole interaction:
There are considerable experiments in the field of biology, biochemistry and pharmacology indicating that ultra low doses have significant effects on living organisms.4 Our experiments here show that ultra small amounts of acid, base or salt can induce a stable rigid IE structures in water itself. These IE structures have different UV transmission characteristics from pure water. Transmission electron microscope pictures are consistent with the idea that these IE structures are made up of electric dipoles. Further physical properties of IE structures will be presented in a separate paper.
I wish to thank Professor T.H. Chan of McGill University, Professor Alfred Wong of UCLA, Professor D. Tsui of Princeton University and Professor Sunney Chan of Caltech for suggestive and critical comments. David Gann's support is gratefully acknowledged.