http://scitechdaily.com/new-method-uses-centrifugal-force-decelerate-particles-creates-new-research-opportunities/
They site N2 molecules going around 1700 meters per second at room temperature so this method is like having a vertical column 2000 meters high.
I guess if you actually did that, you would need to start at 2000 meters underground if your experiments were to be at ground level. That would be an expensive proposition then.
Wonder if anyone ever made such a column? Wouldn't use much energy🙂