The nuclear shielding for both the 1H and 19F nuclei of CH3F and CHF3 was investigated as a function of pressure and temperature. The density region investigated extended from low, gas-like conditions to study pair-wise intermolecular interactions to high, liquid-like densities to study multi-body effects on nuclear shielding. The temperature range was from 30 to 150 degrees C. Both neat solutions of CH3F and CHF3 along with CO2 mixtures of these fluorocarbons were investigated by 1H and 19F high pressure NMR. Moelcular dynamics simulations were underaken to describe the pair distribution functions for both the neat and solution mixtures to aid in the interpretation of the 1H and 19F nuclear shielding determined from high pressure NMR. The NMR of the neat fluoromethanes and their CO2 mixtures suggests that there are no distinct or specific interactions between the fluoromethanes and CO2 and that as temperature increases, the multi-body effects play less of a role in nuclear shielding.
Revised: February 9, 2001 |
Published: January 18, 2001
Yonker C.R., and B.J. Palmer. 2001.Investigation of CO2-Fluorine Interactions through the Intermolecular Effects on theH-1and F-19 Shielding of CH3F and CHF3 at Various Temperatures and Pressures.Journal of Physical Chemistry A 105, no. 2:308-314.PNNL-SA-33558.