question: Hvornår kan sublimation anvendes som en proces med adskillelse?
context: Sublimation (phase transition)
  Sublimation er en teknik, som kemikere bruger til at rense forbindelser. Et fast stof anbringes typisk i et sublimeringsapparat og opvarmes under vakuum. Under det reducerede tryk fordamper det faste stof og kondenserer som en renset forbindelse på en afkølet overflade (kold finger), hvorved der efterlades en ikke-flygtig rest af urenheder. Når opvarmningen ophører, og vakuumet fjernes, kan den rensede forbindelse opsamles fra den afkølende overflade. For at opnå endnu højere rensningseffektivitet anvendes en temperaturgradient, som også gør det muligt at adskille forskellige fraktioner. Typiske opsætninger anvender et evakueret glasrør, der gradvist opvarmes på en kontrolleret måde. Materialestrømmen går fra den varme ende, hvor det oprindelige materiale anbringes, til den kolde ende, der er forbundet med en pumpe. Ved at regulere temperaturen langs rørets længde kan operatøren styre rekondensationszonerne, således at meget flygtige forbindelser pumpes helt ud af systemet (eller opfanges af en separat kold fælde), moderat flygtige forbindelser rekondenserer langs røret i henhold til deres forskellige flygtighed, og ikke-flygtige forbindelser forbliver i den varme ende. Vakuumsublimation af denne type er også den foretrukne metode til rensning af organiske forbindelser til brug i den organiske elektronikindustri, hvor der er behov for meget høj renhed (ofte > 99,99 %) for at opfylde standarderne for forbrugerelektronik og andre anvendelser.
context_en: Sublimation (phase transition)
  Sublimation is a technique used by chemists to purify compounds. A solid is typically placed in a sublimation apparatus and heated under vacuum. Under this reduced pressure, the solid volatilizes and condenses as a purified compound on a cooled surface (cold finger), leaving a non-volatile residue of impurities behind. Once heating ceases and the vacuum is removed, the purified compound may be collected from the cooling surface. For even higher purification efficiencies a temperature gradient is applied, which also allows for the separation of different fractions. Typical setups use an evacuated glass tube that is gradually heated in a controlled manner. The material flow is from the hot end, where the initial material is placed, to the cold end that is connected to a pump stand. By controlling temperatures along the length of the tube the operator can control the zones of recondensation, with very volatile compounds being pumped out of the system completely (or caught by a separate cold trap), moderately volatile compounds recondensating along the tube according to their different volatilities, and non-volatile compounds remaining in the hot end. Vacuum sublimation of this type is also the method of choice for purification of organic compounds for the use in the organic electronics industry, where very high purities (often > 99.99%) are needed to satisfy the standards for consumer electronics and other applications.
title_en: Sublimation (phase transition)