Density-dependent O-17 magnetic shielding in the gas phase

Density-dependent O-17 magnetic shielding has been measured for the first t ime. For pure CO, CO2, OCS and N2O gases at 300 K an increase in density li nearly diminishes the oxygen shielding constants. It permits to separate qu antitatively the shielding contributions due to intermolecular interactions (sigma (1)) and the shielding parameters of isolated molecules (sigma (0)) . The new experimental results may be used for the better verification of a b initio calculations of oxygen shielding. (C) 2001 Elsevier Science B.V. A ll rights reserved.