Observations of interstellar HNC, DNC, and HN13C: temperature effects on deuterium fractionation.
Abstract
An extensive search for DNC emission in 18 clouds with HNC emission is reported. The DNC molecule was found in 13 of these clouds. The HN(C-13) molecule was also sought in those clouds where saturation was thought to be important. The DNC/HNC abundance ratios are determined by incorporating the effects of saturation and radiation trapping. The extent of deuteration found in HNC is larger than for any other molecule yet observed. The DNC/HNC ratios are also found to anticorrelate strongly with the kinetic temperature of the cloud, suggesting that exchange reactions between HD and a molecular ion are ultimately responsible for the deuteration. The value of delta E/k for the exchange reaction that produces DNC is determined to be 240 + or - 60 K. Low values for the abundance of electrons and certain neutral species are similar to those determined from DCO(+)/HCO(+) and N2D(+)/N2H(+) abundance ratios.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- March 1979
- DOI:
- 10.1086/156900
- Bibcode:
- 1979ApJ...228..748S
- Keywords:
-
- Abundance;
- Chemical Fractionation;
- Deuterium Compounds;
- Interstellar Matter;
- Temperature Effects;
- Hydrogen Isotopes;
- Interstellar Chemistry;
- Ionic Reactions;
- Mass Ratios;
- Molecular Ions;
- Reaction Kinetics;
- Astrophysics;
- Deuterium:Interstellar Molecules;
- Interstellar Molecules:Radio Radiation