Kinetic anharmonic coupling in the trihalomethanes: A mechanism for rapid intramolecular redistribution of CH stretch vibrational energy

Journal Article · Mon Jun 01 04:00:00 EDT 1987 · J. Chem. Phys.; (United States)

DOI:https://doi.org/10.1063/1.452487· OSTI ID:6855744

Green, Jr, W H; Lawrance, W D; Moore, C B

The coupling of CH stretching and CH bending vibrations in trisubstituted methanes is analyzed. Improved spectroscopic constants, especially the cubic anharmonic stretch--bend coupling constants, are extracted from Fermi resonances in the overtone spectra of HCF/sub 3/ and HCCl/sub 3/. Both harmonic oscillator and Morse oscillator basis functions are used in the analysis and the results compared. That part of the coupling which arises from the kinetic energy as expressed in curvilinear coordinates is calculated and compared to the coupling calculated using the more conventional rectilinear treatment. Use of curvilinear coordinates is found to provide significant advantages. The formalism for curvilinear normal coordinates is clarified and generalized. From these calculations and the spectral analysis, one of the cubic anharmonic constants of the potential energy surface is extracted for comparison with ab initio calculations. The curvilinear model of the CH stretch--bend interaction tested for these isolated CH chromophores is expected to be useful in understanding CH bonds and vibrational energy flow in larger hydrocarbons.

• Research Organization: Materials and Molecular Research Division of the Lawrence Berkeley Laboratory and Department of Chemistry, University of California, Berkeley, California 94720
• DOE Contract Number: AC03-76SF00098
• OSTI ID: 6855744
• Journal Information: J. Chem. Phys.; (United States), Journal Name: J. Chem. Phys.; (United States) Vol. 86:11; ISSN JCPSA
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201 -- Chemical & Physicochemical Properties
640302* -- Atomic
Molecular & Chemical Physics-- Atomic & Molecular Properties & Theory
74 ATOMIC AND MOLECULAR PHYSICS
CHLORINATED ALIPHATIC HYDROCARBONS
CHLOROFORM
COORDINATES
CURVILINEAR COORDINATES
ENERGY LEVELS
ENERGY TRANSFER
EXCITED STATES
FERMI RESONANCE
FLUORINATED ALIPHATIC HYDROCARBONS
FLUOROFORM
FUNCTIONS
HALOGENATED ALIPHATIC HYDROCARBONS
INFRARED SPECTRA
ORGANIC CHLORINE COMPOUNDS
ORGANIC COMPOUNDS
ORGANIC FLUORINE COMPOUNDS
ORGANIC HALOGEN COMPOUNDS
RESONANCE
SPECTRA
SPECTRAL FUNCTIONS
VIBRATIONAL STATES