Grebenev S, Toennies JP, Vilesov AF
Max-Planck-Institut fur Stromungsforschung, Bunsenstrasse 10, 37073 Gottingen, Germany.
Science. 1998 Mar 27;279(5359):2083-6. doi: 10.1126/science.279.5359.2083.
The infrared spectrum of single oxygen carbon sulfide (OCS) molecules was measured inside large superfluid pure helium-4 droplets and nonsuperfluid pure helium-3 droplets, both consisting of about 10(4) atoms. In the helium-4 droplets, sharp rotational lines were observed, whereas in helium-3 only a broad peak was found. This difference is interpreted as evidence that the narrow rotational lines, which imply free rotations, are a microscopic manifestation of superfluidity. Upon addition of 60 helium-4 atoms to the pure helium-3 droplets, the same sharp rotational lines were found; it appears that 60 is the minimum number needed for superfluidity.
在由大约10⁴个原子组成的大型超流纯氦-4液滴和非超流纯氦-3液滴内部，测量了单氧硫化碳（OCS）分子的红外光谱。在氦-4液滴中，观察到了尖锐的转动谱线，而在氦-3中只发现了一个宽峰。这种差异被解释为窄转动谱线意味着自由转动，是超流性的微观表现的证据。向纯氦-3液滴中加入60个氦-4原子后，发现了同样尖锐的转动谱线；看来60是实现超流性所需的最小原子数。
