Hydrogen molecules densly packed (IMAGE) Max Planck Institute for Intelligent Systems Caption On the right is a representation of the 3D bulk phase of hydrogen, the H2-H2 distance is 3.76 Å, the hydrogen molecules are represented by red spheres. On the left a single layer of adsorbed hydrogen on silica, the intermolecular separation or H2-H2 distance is 2.9 Å, far below the bulk phase. Credit Max Planck Institute for Intelligent Systems Usage Restrictions none License Original content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.