The unique balanced measurement method used in the Gemini permits small amounts of surface area to be measured with nitrogen gas that otherwise would be measurable only with krypton. Low surface area samples often displace many times more nitrogen than they adsorb, especially if composed of low-density materials of large particle size. The standard, built-in, helium free-space difference measurement and mathematical compensation routine typically can remove the effects of more than 99% of this sample displacement, but the small amount remaining uncompensated can still be significant. 研究级超高性能全自动气体吸附仪系统