slush nitrogen 半固體液態氮
利用vacuum真空吸引造成負壓以下降liquid nitrogen 溫度-196達-210

Cooling Solution

To achieve a rapid decrease in temperature, the cooling solution most often used is liquid nitrogen (–196°C). We used slush nitrogen (–210°C), which is obtained by a vacuum pump (Telstar TOP-3; Telstar S.A., Terrassa, Spain) that solidifies part of the liquid nitrogen in few minutes. On return to normal atmospheric pressure, the nitrogen collapses, and the subcooled liquid nitrogen has solid particles in it commonly referred to as “slush” (Fig. 2). The advantage of slush nitrogen lies not only in the temperature difference with respect to liquid nitrogen (∼20°C less) but also in the reduction of the Leiden frost effect, which is the formation of a layer of vapor around the sample when immersed in the cryogenic liquid from room temperature decreasing the cooling rate 14 and 15.

Figure 2. 

Slush nitrogen.

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