Laser-induced-fluorescence spectroscopy of jet-cooled C sub 3

• Published in: The Journal of chemical physics 1989-10, Vol.91:8
• Main Author: Rohlfing, E.A.
• Format: Article
• Language: English
• Subjects: 400800 - Combustion, Pyrolysis, & High-Temperature Chemistry; 640302 - Atomic, Molecular & Chemical Physics- Atomic & Molecular Properties & Theory; ABSORPTION SPECTRA; ADDUCTS; ATMOSPHERES; ATOMIC AND MOLECULAR PHYSICS; CARBON; COMBUSTION PRODUCTS; COMETS; ELEMENTS; EMISSION SPECTROSCOPY; FLUORESCENCE SPECTROSCOPY; INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; NONMETALS; SOOT; SPECTRA; SPECTROSCOPY; STELLAR ATMOSPHERES
• ISSN: 0021-9606; 1089-7690
• DOI: 10.1063/1.456791

We present a spectroscopic study of jet-cooled C{sub 3} in which laser-induced-fluorescence (LIF) excitation spectra and dispersed-fluorescence (DF) spectra are taken for a new, vibronically induced band system ({sup 1}{Pi}{sub {ital g}} and/or {sup 1}{Delta}{sub {ital u}})--{ital {tilde X}} {sup 1}{Sigma}{sup +}{sub {ital g}} in the ultraviolet. In addition, DF spectra are taken for the well-known cometary band system, {ital {tilde A}} {sup 1}{Pi}{sub {ital u}}--{ital {tilde X}}{sup 1}{Sigma}{sup +}{sub {ital g}}. The DF spectra of the new system are very rich and display strong fluorescence bands in stretch--bend progressions that reach as high as 17 000 cm{sup {minus}1} in the {sup 1}{Sigma}{sup +}{sub {ital g}} ground state. The data from the DF spectra of both systems is used to assign vibrational term energies to 144 ground-state levels that cover the range: 0{le}{ital v}{sub 1}{le}8, 0{le}{ital v}{sub 2}{le}37, and 0{le}{ital v}{sub 3}{le}4. The observed level structure clearly demonstrates the highly anharmonic nature of the potential energy surface of C{sub 3} and the unusual internal dynamics that occurs upon it. These include pronounced barriers to linearity in the {ital v}{sub 3}=2 and {ital v}{sub 3}=4 states and an increase in molecular rigidity as the symmetric stretch is excited.