Disentangling the confounding spectroscopy of C1 molecules: Without symmetry as a guide, everything is allowed
Abstract
The spectra of C1 molecules are confounding in that each of the fundamental vibrational modes transform as the same irreducible representation (A) and hence each band consists of a seemingly random distribution of a-, b-, and c-type transitions. This is in contrast to higher symmetry molecules for which band types are readily deduced by simple symmetry rules. Herein, we present a method to simulate the convoluted rotational contours in the gas-phase spectra of C1 molecules by combining existing ab initio calculations with Colin Western’s pgopher rotational contour program. Specifically, ab initio calculations in the NWChem suite of programs were employed to predict the components of the dipole moment derivatives along the principal axes of the moments of inertia. This information was then input into pgopher to model the fundamental band contours as a sum of a-, b-, and c-type transitions. This method was applied to simulate the rotational contour spectra of a series of representative C1 molecules which were then compared against both ab initio stick spectra and experimentally measured broadband IR spectra from the Pacific Northwest National Laboratory infrared gas-phase database. In addition to providing further insight beyond what is revealed in a typical stick spectrum, the simulated contours showed good agreement with the measured spectra.
Document Details
- Document Type
- Pub Defense Publication
- Publication Date
- May 01, 2023
- Source ID
- 10.1063/5.0155054
Entities
People
- Michael J. Wilhelm
- Tanya L Myers
- Timothy J Johnson
Organizations
- Strategic Environmental Research and Development Program
- United States Department of Energy