2 + 1 REMPI spectra of cyclic ketones in a cold molecular beam. 1. Studies of the n. -->. 3s Rydberg transition in unsubstituted rings
The 2-photon excitation of the 3s Rydberg states in cyclopentanone, cyclohexanone, cycloheptanone, cyclooctanone, and norcamphor has been investigated by resonance enhanced multiphoton ionization (REMPI). A pulsed and seeded molecular beam of cold sample gas was crossed with a pulsed laser beam from an excimer pumped dye laser. Spectra in the region of 405-380 nm were obtained at sufficient resolution (<1 cm/sup -1/) to allow identification of some rotational contours. The C=O stretch and bending modes were identified on the basis of laser light polarization studies (linear versus circular) and by deuterium substitution. In all cases, the C=O stretching frequency was found to occur around 1250 cm/sup -1/ in the Rydberg spectrum which is significantly reduced from its ground-state counterpart. This reflects the increased C=O bond distance in the excited electronic state. A correlation between the origin of the n ..-->.. 3s transition energy and the ground-state C-CO-C bond angle was found.
- Research Organization:
- Univ. of North Carolina, Chapel Hill (USA)
- OSTI ID:
- 6975005
- Journal Information:
- J. Am. Chem. Soc.; (United States), Vol. 109:23
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
CYCLOHEXANONE
ELECTRONIC STRUCTURE
RYDBERG STATES
BOND LENGTHS
DYE LASERS
EXCIMER LASERS
EXPERIMENTAL DATA
GROUND STATES
KETONES
MOLECULAR BEAMS
MULTI-PHOTON PROCESSES
NORMAL-MODE ANALYSIS
PHOTOIONIZATION
VISIBLE SPECTRA
BEAMS
DATA
DIMENSIONS
ENERGY LEVELS
EXCITED STATES
GAS LASERS
INFORMATION
IONIZATION
LASERS
LENGTH
LIQUID LASERS
NUMERICAL DATA
ORGANIC COMPOUNDS
SPECTRA
400201* - Chemical & Physicochemical Properties
400500 - Photochemistry