© Copyright 1997 by the American Chemical Society
VOLUME 101, NUMBER 32, AUGUST 7, 1997
Physics and Chemistry of Ice 1996 Dartmouth College, Hanover, New Hampshire August 27-31, 1996
34 Years of Ice Physics Symposia John W. Glen
School of Physics and Space Research, UniVersity of Birmingham, Birmingham B15 2TT, England ReceiVed: October 11, 1996X
The first informal meeting to discuss ice physics was held at Erlenbach, Switzerland, in 1962, and the decision to make some formal structure for this series of symposia was taken in Munich in 1968 at the end of a meeting called by the group in the Technische Hochschule Mu¨nchen. Since then, there have been six conferences organized at four- or five-year intervals. In this paper the developments in ice physics over this period are reviewed to help put the present work in some perspective. The multidisciplinary nature of the studies and applications of ice physics research are demonstrated, with important inputs from solid-state physics, chemistry, crystallography, and field glaciology, and with applications beyond these subjects in meteorology, planetary and cometary physics, and biophysics.
This symposium, unlike many others, neither has been arranged under the auspices of an international union nor is an ad hoc conference called by the Local Organising Committee. It has been arranged as the result of a decision by a small and informal International Committee, which has been responsible for arranging symposia at suitable intervals since 1968. This committee came into being after symposia on ice physics were announced in the same year by both the group at Mu¨nchen, Germany, and the group at Pau, France. In fact only the Mu¨nchen symposium was successful, as that was the year when there was enormous disruption in France following the Algerian crisis; I am told that the only foreign participant who managed to get to Pau was Claude Jaccard, who had to carry in his car enough gasoline for the entire trip, as none was obtainable in X
Abstract published in AdVance ACS Abstracts, June 15, 1997.
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France. However this clash caused the participants at Mu¨nchen to decide that a little order should be put into the calling of future symposia, and I was asked to act as convener of a committee composed of ice physicists from different countries to decide where future meetings should be held, a role I have been asked to undertake ever since. At first this was quite a challenge, as we had to find some group ready to undertake the task with no outside financial support; however in recent years there have been several offers made, so the committee had the pleasant task of deciding which bid to accept, rather like the International Olympic Committee! It remains to be seen whether this state of affairs will continue. The system seems to have worked well; a series of conferences have taken place at intervals of between four and five years, and all have been well attended (numbers have varied between © 1997 American Chemical Society
6080 J. Phys. Chem. B, Vol. 101, No. 32, 1997 TABLE 1: Previous Ice Physics Symposia 1962 [1966 1968 1972 1977 1982 1986 1991 1996
Informal symposium, Erlenbach, Switzerland Conference on Physics of Snow and Ice, Sapporo, Japan] International Symposium on Physics of Ice, Mu¨nchen, Germany Symposium on the Physics and Chemistry of Ice, Ottawa, Canada Symposium on the Physics and Chemistry of Ice, Cambridge, England Sixth International Symposium on the Physics and Chemistry of Ice, Rolla, U.S.A. VIIth Symposium on the Physics and Chemistry of Ice, Grenoble, France International Symposium on the Physics and Chemistry of Ice, Sapporo, Japan International Symposium on the Physics and Chemistry of Ice, Hanover, U.S.A Published Proceedings of the Symposia
O ˆ ura, H., Ed. Physics of snow and ice. International Conference on Low Temperature Science, Sapporo, Japan, August 14-19, 1966; Hokkaido University, The Institute Low Temperature Science: Sapporo, 1967; Vol. 1, 2 Parts, xxix, 1414 pages [Part 1, pp 1-712, Part 2, pp 713-1414]. Riehl, N., Bullemer, B., Engelhardt, H., Eds. Physics of ice. Proceedings of the International Symposium on Physics of Ice, Munich, Germany, September 9-14, 1968; Plenum Press: New York, 1969; xix, 642 pages. Whalley, E., Jones, S. J., Gold, L. W., Eds. Physics and chemistry of ice. Papers presented at the Symposium on the Physics and Chemistry of Ice, Ottawa, Canada, August 14-18, 1972; Royal Society of Canada, Ottawa, 1973; xiii, 403 pages. Symposium on the Physics and Chemistry of Ice, Cambridge, September 12-16, 1977; J. Glaciol. 1977, 21, 714 pages. Sixth International Symposium on the Physics and Chemistry of Ice, University of Missouri-Rolla, August 2-6, 1982; J. Phys. Chem. 1983, 87 (21), 4015-340. VIIth Symposium on the Physics and Chemistry of Ice, Grenoble, France, September 1-5, 1986; J. Phys. 1987, 48, Colloq. No. 1, Suppl. Fasc. 3, xv, 707 pages. Maeno, N., Hondoh, T., Eds. Physics and chemistry of ice. Proceedings of the International Symposium on the Physics and Chemistry of Ice, Sapporo, Japan, September 1-6, 1991; Hokkaido University Press: Sapporo, Japan, 1992; xii, 516 pages.
92 and 134). Each has resulted in a published volume (sometimes separately published, sometimes as a special issue of a journal) that has included most of the papers presented and that as a series form an impressive record of achievement in ice physics and chemistry. I need perhaps to refer to one rather annoying discrepancy: the numbering of the symposia (Table 1). All the volumes have referred back to an informal symposium held at Erlenbach, Switzerland, in 1962, and there is no doubt that this is generally regarded as the first serious symposium dealing with our subject. However some volumes have also referred to a conference held in Sapporo, Japan, in 1966. This was one of two conferences held simultaneously in an “International Conference on Low Temperature Science” to mark the 25th anniversary of the Institute of Low Temperature Science at Hokkaido University, Sapporo, the other conference being on cryobiology, its volume (Vol. 2 of the proceedings) being entitled “Cellular injury and resistance in freezing organisms”. The first conference, entitled “Physics of snow and ice” was far wider in its subject matter than Erlenbach or indeed any of the later symposia in our list and was not regarded by the Institute that hosted it as being appropriately included in a list of ice physics symposia. It had, for example, 44 papers on snow and avalanches, 17 on sea ice, 9 each on glaciers and frost heaving, and only 29 on the main subject matter of the other symposia. Nevertheless, it was listed by the Rolla symposium and was the justification for their giving the number “sixth” to that symposium, and this led to the next
Glen TABLE 2: Number of Papers on Different Topics in Earlier Symposia (Using the Subject Subdivisions of the 1996 Symposium) symposiuma H
S
G
R
biological ice nucleation 1 4 1 1 chemical and photochemical 3 3 reactions clathrate hydrates 14 6 7 3 defects in ice 10 12 13 14 electrical properties 12 8 17 13 high-pressure and low20 13 13 6 temperature forms ice in space 2 4 3 8 lattice vibrations/phonons 2 2 2 mechanical properties 18 10 15 3 optical properties 3 2 1 phase transformations 13 23 15 6 proton transfer along 3 1 1 1 hydrogen bonds structure of ice 10 10 10 6 surface of ice 22 5 9 4 thermal properties 3 1 glaciological subjects 2 4 total number of papers 136 100 113 80 number of participants 124 134 108 120
C
O
2 14 11 4
5 6 11 11 13 4 3
4 11 2 3
1 6 7 4 3
M
1 5 1 5 4
S1
3 2
9 7
4 7 8 2 5 5 1 5 2 1 3 1 3 79 65 60 55 108 92 118 99 105
a Key to symposia: H ) Hanover, S ) Sapporo, G ) Grenoble, R ) Rolla, C ) Cambridge, O ) Ottawa, M ) Mu¨nchen S1 ) Sapporo 1966.
symposium being described as the seventh. However when the symposium was held in Sapporo (on the occasion of the 50th anniversary of the Institute of Low Temperature Science), the organizers refrained from putting a number into the title and listed the six previous symposia (i.e. including Erlenbach and excluding Sapporo, 1966) that were seen as being truly on ice physics. Chemistry was added into the title by the Ottawa group because of their interest in the chemical side of molecular processes involving ice and has been included in the title ever since. It probably comes as no surprise to any participant that the physics and chemistry of ice provide enough matter for a symposium every four or five years, but to many outside our subject it does seem remarkable. There are, as far as I know, no comparable series of symposia on, say, H2S or any other single oxide. The reason for this is of course the great importance of the water molecule to so many processes and the very unusual properties it has. It is therefore of some interest to see what properties have given rise to significant numbers of papers over this series of symposia. The Erlenbach symposium was the only one I did not personally attend, and it is also the only one not published. However, I did attend a meeting at the Royal Society of London shortly afterwards at which a number of the participants gave papers, and on the basis of this I conclude that this was really the first symposium at which the interesting questions of the hydrogen bond and the implications of the random arrangement of the protons on these bonds were first addressed. For me this was the time when I first realized that we needed to look in detail at how the bonds were behaving when ice was polarized or when a current was passed through it. This was linked with the behavior of Bjerrum defects, and attention was directed to the form that such defects, particularly the D-defect, could take. In other words this was the time when the detailed molecular processes involved in ice physics began to be taken seriously. The Mu¨nchen symposium took up these themes again (Table 2), and there were 17 papers on the electrical properties of ice (including proton transfer) and how these could be related to
34 Years of Ice Physics Symposia the detailed behavior of water molecules. There were eight papers related to the structure of ice Ih and three on the structure of the other phases of ice, both H2O and D2O, data on which were just becoming available. At the Ottawa symposium the largest batch of papers was still concerned with electrical properties (14), with seven each on structure of ice and on mechanical properties. There were also four on other phases and five on clathrate hydrates, which appeared on the program for the first time, and there was also an invited talk on ice in astronomy. By the time of the Cambridge symposium, the largest single group was on defects (14) and there were more (11) devoted to the mechanical properties of ice and how these could be linked to our understanding of the fundamental processes of water molecule rotation, with still 11 on electrical properties. The Rolla symposium also had the largest numbers of papers on defects (14) and on electrical properties (14), and now there was a full session with 8 papers on extraterrestrial ice, as the importance of ice in comets, in satellites of outer planets, and in interstellar dust became apparent. At Grenoble there were 18 papers on electrical properties, 15 on each of phase transformations and mechanical properties, and 13 on defects and on high-pressure/low-temperature phases. Finally at Sapporo the largest group (23) were devoted to phase transofmrations, with 13 on the other phases of ice, 12 on defects, and 10 each on structure and mechanical properties. So what has changed in our knowledge of ice physics over the years? Why are we still producing papers on the same themes? Have we made much progress? I believe we have, and the main reason is the use of more sophisticated techniques which have enabled us to study in detail processes that in the earlier symposia were simply matters of conjecture. For example, in the field of electrical properties we first discovered how to obtain ice that was pure enough to give us something approaching intrinsic properties, and then we learned how to make good connections between the electronic conduction in ordinary circuits and the protonic conduction in the ice, thus enabling good experimental tests of theory to be made. In the field of mechanical properties, we have seen the development of X-ray techniques for observing the movement of individual dislocations in ice and hence have been able to see the way in which dislocations on different planes can move; this allowed us not only to test earlier theories but also to see that the processes are much more complex than we had earlier thought. Surface properties were largely mysterious at the beginning of this period; now detailed experiments on, for example, the statistics of external bonds with or without protons are possible. At the beginning of our period, the question of a phase transformation to a proton-ordered phase of ice was still wide open; now we know how to catalyze such a transition and are able to study the ordered ice so produced and so, at last, determine its ordered structure. Ice physics and chemistry have also been developed in order to understand other phenomena in a wide range of subjects. An
J. Phys. Chem. B, Vol. 101, No. 32, 1997 6081 obvious example is field glaciology, where the electrical conductivity of ice has to be known to interpret resistivity soundings, and the propagation of electromagnetic waves through ice is the key to interpreting reflections found in radio echo-sounding, to give but two examples. In meteorology the electrical properties of ice are important to understanding thunderstorm electricity, and the growth characteristics of ice dendrites are the key to interpreting snow crystal shapes in terms of the conditions in clouds at the time of their formation. The increased interest in ice as a cometary material has led to a number of experiments to test cometary theories, and understanding of the role of ice on other planets and their satellites has turned to ice physics for a base for these theories. Similarly in biology there has long been an interest in using frozen samples and hence in the way ice grows in biological systems (frequently quite differently from the growth in pure water or ionic solutions), but over the years there has been increased interest in the existence of both biological ice nucleators and ice inhibitors, such as those that prevent Antarctic fishes from freezing. These work not by depressing the freezing point but by inhibiting growth of any ice crystals nucleated or introduced. There is also increased interest in proton transfer as a mechanism for electrical conduction in biological systems, for which ice as a simpler proton conductor can serve as a model. The range of subjects covered is thus very wide, and I see that this will also be true of the present symposium, where I am sure we shall see further advances of the kind I have been talking about. The range of subjects is as large as ever; the three largest groups are the surface of ice (22), the high-pressure and low-temperature phases (20), and mechanical properties (18); there are 15 on electrical properties if we add those on proton transfer (as I have done above for earlier symposia) and 14 on clathrate hydrates. There are however nine other main themes, and I view this as one of the great strengths of this series of symposia. Ice is indeed a very complex material, and its many different properties are interrelated. The different techniques used to study them mean that any one group cannot hope to be fully equipped for all of them, but at a meeting such as this it is possible to meet people doing virtually all of them and to hear what can be discovered in these various ways; by doing so, much light can often be thrown on their interrelations. An obvious example of this from the past was the information that electrical measurements gave on the way water molecules can turn around in ice crystals, and this provided the key to understanding how a disordered material such as ice could undergo plastic deformation by the passage of dislocations, which normally require an ordered crystal for their passage. These symposia provide admirable opportunities for participants to discover what other techniques can do to throw light on properties of ice that are puzzling them. For those unable to attend the symposium, the published issue of The Journal of Physical Chemistry B can, I hope, do the same.
