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Sistem za površinske analize z nizkotemperaturnim vrstičnim
tunelskim mikroskopom (STM) na Institutu Jožef Stefan.
STM je hlajen s kriostatom na kopel z notranjim rezervoarjem,
napolnjenim s tekočim helijem (4,2 K), in z zunanjim rezervoarjem,
napolnjenim s tekočim dušikom (77 K). Ko je bila slika posneta,
smo ravno natočili tekoči dušik, zato ta hitro izpareva.
The surface-analysis system with a low-temperature scanning tunneling microscope (STM) at the Jožef Stefan Institute. The STM is cooled down using a bath cryostat with an inner liquid helium (4.2 K) reservoir and an outer liquid nitrogen (77 K). When this picture was taken the liquid nitrogen had just been filled and the nitrogen is rapidly boiling off. |
Absolute zero is the lowest temperature that can be obtained in any macroscopic system. Absolute temperature means temperature measured on a scale with absolute zero as 0. This is conventionally measured in kelvins: absolute zero corresponds to 0 K (-273,15 oC).
At very low temperatures in the vicinity of absolute zero, matter exhibits many unusual properties including superconductivity, superfluidity, and Bose-Einstein condensation. In order to study such phenomena, scientists have worked to obtain ever lower temperatures.
Cryogenics is the study of very low temperatures or the production of the same. Liquefied gases, such as liquid nitrogen and liquid helium, are used in many cryogenic applications. These gases are held in either special containers known as Dewar flasks, which are generally about six feet tall and three feet in diameter. Liquid nitrogen is the most commonly used element in cryogenics and is legally purchaseable around the world. (It's in the air we breathe!) Liquid helium is also commonly used and allows for the lowest attainable temperatures to be reached. The boiling points of liquid helium and liquid nitrogen are 4.2 K and 77.4 K.