Microwave Cavity Spectroscopy
Abstract
The influence of vibrational and collision energy on ion-molecule reactions was investigated by measuring the cross sections for reactions of NH3(+) created with varying degrees of excitation in the umbrella bending and symmetric stretching modes. Under these conditions, the three major product channels for the NH3(+)/CD3NH2(+) system are CD3NH2(+), CD2=NH2(+) and CD3NH3(+). Two minor product channels correspond to NH3D(+) and NH4(+). This reaction is found to be mode selective based on the reactivity of two isoenergetic vibrational states having differing concerted atom motions. The reaction of state selected ammonia ions with CD4 produces two major products, deuterium abstraction (NH3D(+)) and collision induced dissociation (NH2D(+)). The reaction was found not to be mod selective. In the NH3(+)/THF system, four products were identified: hydrogen abstraction (NH4(+)), charge transfer (C4H8O(+)), proton transfer (C4H9O(+)) and an endothermic product corresponding to charge transfer with loss of H (C4H7O(=)). The branching ratios show a dependence on ammonia ion vibrational state In separate experiments, it was demonstrated that the new class of quantum cascade lasers that produce tunable infrared coherent radiation are well suited to cavity ring-down detection of ammonia. A detection limit of less than one part per billion was achieved.
Document Details
- Document Type
- Technical Report
- Publication Date
- Feb 26, 2001
- Accession Number
- ADA395582
Entities
People
- Richard Zare
Organizations
- Stanford University