Krypton specific radioactivity

Clathrates provide cavities of a specific size and shape and therefore they can be used very effectively for separating gases with different sizes of molecules. For example, urea clathrates have been used to separate linear from branched hydrocarbons. The hydroquinone clathrate can be used to store and deliver radioactive krypton. In addition, if the host is chiral, there can be chiral discrimination so that one enantiomer of a guest is enclosed in the clathrate structure in preference to the other enantiomer. The trapped guest molecules can be liberated, for example, by solution in an apolar solvent, at the convenience of the user,... 

An important property of the MOT is the ability to catch atoms whose optical frequencies are shifted from the laser frequency by only a few natural linewidths. This property has been applied for ultrasensitive isotope trace analysis. Chen et al. (1999) developed the technique in order to detect a counted number of atoms of the radioactive isotopes Kr and Kr, with abundances 10 and 10 relative to the stable isotope Kr. The technique was called atom trap trace analysis (ATTA). At present, only the technique of accelerator mass spectrometry (AMS) has a detection sensitivity comparable to that of ATTA. Unlike the AMS technique based on a high-power cyclotron, the ATTA technique is much simpler and does not require a special operational environment. In the experiments by Chen et al. (1999), krypton gas was injected into a DC discharge volume, where the atoms were excited to a metastable level. 2D transverse laser cooling was used to collimate the atomic beam, and the Zee-man slowing technique was used to load the atoms into the MOT. With the specific laser frequency chosen for trapping the Kr or Kr isotope, only the chosen isotope could be trapped by the MOT. The experiment was able to detect a single trapped atom of an isotope, which remained in the MOT for about a second. 

The FDD chromatograms show a great similarity to the classical FID detector and offers comparable performance without the use of a flame, radioactive emitter or combustible gases. The FDD in helium photoionization mode is an excellent replacement for FIDs in petrochemical or refinery environments, where the flame and use of hydrogen can be problematic. In addition, when the helium discharge gas is doped with a suitable noble gas, such as argon, krypton or xenon (depending on the desired cut-off point), the FDD can function as a specific photoionization detector for selective determination of aliphatics, aromatics, amines, as well as other species. 

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