Infrared absorptions of NH3(H2) complexes trapped in solid neon.
When a very small concentration of H2 is added to a Ne:NH3=800:1 sample and the resulting mixture is deposited at 4.3 K, a new absorption appears at 4151.1 cm(-1) which can be assigned to the H2 stretching fundamental of H2 (j=1) complexed with NH3. Other new absorptions which appear near the vibrational fundamentals of NH3 are assigned to the NH3 moiety in this complex and in the complex of NH3 with H2 (j=0). The results of experiments in which HD or D2 is added to the Ne:NH3 mixture support these assignments. Ab initio and density functional calculations predict the observed infrared activation of the H2-stretching vibration for a structure in which the axis of the H2 molecule is collinear with the threefold axis of the NH3. The dependence of the observed absorption patterns on the concentration of H2 in the sample indicates that complexes of NH3 with two or more H2 molecules also form readily.
Jacox
Marilyn E
ME
Optical Technology Division, National Institute of Standards and Technology, Gaithersburg, Maryland 20899-8441, USA. marilyn.jacox@nist.gov
Thompson
Warren E
WE