Sub-Doppler, infrared laser spectroscopy of the propyne 2ν1 band: Evidence of z-axis Coriolis dominated intramolecular state mixing in the acetylenic CH stretch overtone.

التفاصيل البيبلوغرافية
العنوان:	Sub-Doppler, infrared laser spectroscopy of the propyne 2ν1 band: Evidence of z-axis Coriolis dominated intramolecular state mixing in the acetylenic CH stretch overtone.
المؤلفون:	McIlroy, Andrew, Nesbitt, David J., Kerstel, Erik R. Th., Pate, Brooks H., Lehmann, Kevin K., Scoles, Giacinto
المصدر:	Journal of Chemical Physics; 2/15/1994, Vol. 100 Issue 4, p2596, 16p
مصطلحات موضوعية:	INFRARED spectroscopy, ACETYLENE, ABSORPTION, MOLECULAR beams
مستخلص:	The eigenstate-resolved 2ν1 (acetylenic CH stretch) absorption spectrum of propane has been observed for J’=0–11 and K=0–3 in a skimmed supersonic molecular beam using optothermal detection. Radiation near 1.5 μm was generated by a color center laser allowing spectra to be obtained with a full-width at half-maximum resolution of 6×10-4 cm-1 (18 MHz). Three distinct characteristics are observed for the perturbations suffered by the optically active (bright) acetylenic CH stretch vibrational state due to vibrational coupling to the nonoptically active (dark) vibrational bath states. (1) The K=0 states are observed to be unperturbed. (2) Approximately 2/3 of the observed K=1–3 transitions are split into 0.02–0.25 cm-1 wide multiplets of two to five lines. These splittings are due to intramolecular coupling of 2ν1 to the near resonant bath states with an average matrix element of 1/2=0.002 cm-1 that appears to grow approximately linearly with K. (3) The K subband origins are observed to be displaced from the positions predicted for a parallel band, symmetric top spectrum.The first two features suggest that the coupling of the bright state to the bath states is dominated by parallel (z-axis) Coriolis coupling. The third suggests a nonresonant coupling (Coriolis or anharmonic) to a perturber, not directly observed in the spectrum, that itself tunes rapidly with K; the latter being the signature of diagonal z-axis Coriolis interactions affecting the perturber. A natural interpretation of these facts is that the coupling between the bright state and the dark states is mediated by a doorway state that is anharmonically coupled to the bright state and z-axis Coriolis coupled to the dark states. Z-axis Coriolis coupling of the doorway state to the bright state can be ruled out since the ν1 normal mode cannot couple to any of the other normal modes by a parallel Coriolis interaction. Based on the range of... [ABSTRACT FROM AUTHOR]
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قاعدة البيانات:	Complementary Index

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