Predissociation dynamics of the Rydberg 3 s state and vibrational structure of the [tilde X] [sup 2]A[double prime][sub 2] state of the methyl radical

Thesis/Dissertation · Wed Jan 01 04:00:00 EST 1992

OSTI ID:5424012

Westre, S G

The first examination of the predissociation dynamics of the methyl radical [tilde B] [sup 2]A[prime][sub 1] state has been performed. The Raman excitation profile technique was utilized to obtain J[prime]-resolved Raman excitation profiles of CH[sub 3] and CD[sub 3] in resonance with the [0000]-[0000] [tilde B] [sup 2]A[prime][sub 1]-[tilde X][sup 2]A[double prime][sub 2] absorption. The structure and dynamics of vibronic levels above the Rydberg 3 s origin level were examined. The predissociation of the CD[sub 3] [0100]Rydberg 3 s level was examined by rotationally resolved Raman excitation profile analysis. The excitation profile analysis places the band origin of the [0100]-[0100] vibronic feature at 47271 cm[sup [minus]1]. The out-of-plane bend frequency, [nu][sub 2][prime], in the Rydberg 3 s state is determined to be 1094 cm[sup [minus]1]. Q branch excitation profiles of the [nu][sub 1] and 2[nu][sub 1] Raman features yield a band origin of 206.85 nm for the [1000]-[0000] transition. The symmetric stretching frequency in the Rydberg 3 s state is estimated to be 2040 cm[sup [minus]1]. The Q branch excitation profiles yield a dephasing constant in the [1000] level of approximately 400 cm[sup [minus]1]. The methyl radical ground state ([tilde X] [sup 2]A[double prime][sub 2]) stretching potential was experimentally investigated. Resonance Raman spectra of isotopomers CH[sub 3], Ch[sub 2]D, CHD[sub 2] and CD[sub 3] were obtained. The bonding in the methyl radical was compared to a variety of sp[sup 2] hybridized ethylenic molecules. The Morse harmonic frequency and anharmonicity constant indicate the bonding in the methyl radical and ethylenic molecules is primarily a function of the sp[sup 2] hybridization of the central carbon. The local mode-coupled Morse oscillator analysis reveals that the vibrational states of the methyl radical are described by wavefunctions containing a significant percentage of normal model character.

• Research Organization: California Univ., Davis, CA (United States)
• OSTI ID: 5424012
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201* -- Chemical & Physicochemical Properties
664200 -- Spectra of Atoms & Molecules & their Interactions with Photons-- (1992-)
74 ATOMIC AND MOLECULAR PHYSICS
ALKYL RADICALS
CHEMICAL BONDS
CHEMICAL REACTION KINETICS
DISSOCIATION
ENERGY LEVELS
EXCITED STATES
KINETICS
METHYL RADICALS
PREDISSOCIATION
RADICALS
RAMAN SPECTRA
REACTION KINETICS
RYDBERG STATES
S STATES
SPECTRA
VIBRATIONAL STATES