Spectroscopy and structure of vibrationally excited singlet methylene

Miscellaneous · Wed Jan 01 00:00:00 EST 1992

OSTI ID:5601357

Xie, W

Using Stimulated Emission Pumping, Laser Induced Fluorescence, and Time-Resolved Fourier Transform spectroscopy, the author was able to characterize the rovibrational structures of methylene and its deuterium substitute, generated by the laser flash photolysis of ketene or deuterated ketene. For CH[sub 2], its J [le] 7 and K[sub a] [le] 3 rotational levels of the (0,2,0), (0,3,0), and (0,4,0) bending overtones, and the (1,1,0) combination band in the [tilde a][sup 1]A[sub 1] state were characterized by stimulated emission pumping spectroscopy. Spectroscopic analyses using a rigid rotor Hamiltonian produced the vibrational term values and rotational constants. The latter were found to be strongly J and K[sub a] dependent. Abnormally intense [Delta]K[sub a] = 3 transitions were observed in the SEP spectra of [tilde a] [l arrow] [tilde b], 2[sub 2][sup 16] and 2[sub 3][sup 16] bands. [Delta]K[sub a] = 5 transitions were observed in the LIF spectrum of [tilde b] [l arrow] [tilde a], 2[sub 0][sup 16] band. The intensity abnormalities are attributed to the Renner-Teller effect coupling the [tilde a] and [tilde b] electronic states. For [sup 1]CD[sub 2], its (0,0,0) level in the [tilde a] electronic state was characterized by laser induced fluorescence of the [tilde b] [l arrow] [tilde a] transitions. The rotational assignment has been made on six vibronic bands in the [tilde b] [l arrow] [tilde a] (0,0,0) transitions of [sup 1]CD[sub 2]. The [tilde a] (0,3,0) vibrational level of [sup 1]CD[sub 2] was observed through the stimulated emission pumping and its rotational constants and vibrational term value have been determined. A dispersed LIF spectrum of I[sub 2] molecule demonstrated the TR-FT technique. A new vibrational level, [tilde a] (1,2,0), was identified from the dispersed LIF between 11,850--13,825 cm[sup [minus]1]. Some other applications of TR-FT spectroscopy were discussed with special interest on the spectroscopy of difluorovinylidene molecule.

• Research Organization: Pennsylvania Univ., Philadelphia, PA (United States)
• OSTI ID: 5601357
• Resource Relation: Other Information: Thesis (Ph.D.)
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
74 ATOMIC AND MOLECULAR PHYSICS
METHYLENE RADICALS
ROTATIONAL STATES
STRUCTURAL CHEMICAL ANALYSIS
VIBRATIONAL STATES
ACCURACY
CHEMICAL BONDS
COUPLING
DEUTERIUM
FLUORESCENCE
FOURIER TRANSFORM SPECTROMETERS
KETENES
PHOTOLYSIS
PUMPING
RESOLUTION
STIMULATED EMISSION
CHEMICAL REACTIONS
DECOMPOSITION
EMISSION
ENERGY LEVELS
ENERGY-LEVEL TRANSITIONS
EXCITED STATES
HYDROGEN ISOTOPES
ISOTOPES
LIGHT NUCLEI
LUMINESCENCE
MEASURING INSTRUMENTS
NUCLEI
ODD-ODD NUCLEI
ORGANIC COMPOUNDS
ORGANIC OXYGEN COMPOUNDS
PHOTOCHEMICAL REACTIONS
RADICALS
SPECTROMETERS
STABLE ISOTOPES
400201* - Chemical & Physicochemical Properties
664000 - Atomic & Molecular Physics- (1992-)