Durante m\u00e1s de siglo y medio, los cient\u00edficos han estado debatiendo las propiedades f\u00edsicas y el comportamiento de la superficie del hielo (por ejemplo, c\u00f3mo pod\u00eda ser tan resbaladizo). En una nueva publicaci\u00f3n en Nature, titulada “Obtenci\u00f3n de im\u00e1genes de la estructura de la superficie y prefusi\u00f3n del hielo Ih con resoluci\u00f3n at\u00f3mica”, un grupo de investigadores chinos observ\u00f3 la imagen de resoluci\u00f3n at\u00f3mica de una superficie de hielo y descubri\u00f3 que la superficie del hielo comienza a derretirse a -153 grados Celsius.\u00a0Se cre\u00eda com\u00fanmente que el punto de partida para la prefusi\u00f3n de la superficie del hielo era alrededor de -70 grados Celsius.<\/p>\n
A team of physicists affiliated with several institutions in China has uncovered the reason behind the slipperiness of ice. In their\u00a0study<\/a>, published in the journal\u00a0Nature<\/i>, the group used atomic force microscopy to get a closer look at the surface of ice at different temperatures.<\/p>\n Prior research and a lot of anecdotal evidence have shown that ice is slippery, even when temperatures are well below the\u00a0freezing point<\/a>. Research has suggested this is because of a pre-melt coating that develops at the\u00a0surface<\/a>, which serves as a lubricant.<\/p>\n In this new study, the research team used an atomic force microscope fitted with a carbon monoxide atom on its tip to get a better look at the structure of normal ice and its pre-melt coating.<\/p>\n The researchers began by chilling ice inside the microscope chamber to -150\u00b0C and then using the microscope to look at its\u00a0atomic structure<\/a>. They could see that the internal ice (known as ice Ih), and the ice at the surface were different.<\/p>\n The ice Ih, as expected, was arranged in stacked hexagons. The ice on the surface, by contrast, was only partially hexagonal. The researchers also found defects in the ice at the border between the two types of ice that occurred as the different ice shapes met one another.<\/p>\n The researchers then raised the\u00a0temperature<\/a>\u00a0in the chamber slightly, which resulted in more disorder as the differences in shape became more pronounced. The team then created a simulation showing how such disorder would impact the surface as a whole unit\u2014it showed the disorder expanding all the way across the surface, giving the ice a liquid-like appearance that would be slippery if trod upon.<\/p>\n The research team explains that the reason their experiments were done at such low temperatures was that the microscope had to be operated in a vacuum;\u00a0warmer temperatures<\/a>\u00a0would have led to sublimation, making it difficult to study the ice at the atomic level.<\/p>\n They also note that they plan to continue their study by using short laser bursts to heat the ice for very short amounts of time, allowing them to see what happens under warmer conditions.<\/p>\n