OBSERVATION OF MAGNETIC VIBRATIONAL CIRCULAR DICHROISM OF THE $\nu_{4}+\nu_{5}$ COMBINATION BAND OF ACETYLENE
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Date
1995
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Ohio State University
Abstract
The rotationally resolved magnetic vibrational circular dichroism (MVCD) of the $\nu_{4}+\nu_{5}$ combination band of acetylene has been measured. A large relative intensity variation in terms of $\Delta A/A$ between the P-branch and R-branch was found. The rotational bands are comparatively well resolved and moment analysis has been carried out to determine the $A_{1}/D_{0}$ parameters for each ro-vibrational transition observed. The anomaly seen in attributed to the relatively large difference between the g-value in the ground vibrational state and that in the $(\nu_{4} = 1, \nu_{5} = 1)$ state. The MVCD determined g-values for these 2 states are +0.77 and +0.64 respectively. Using the well known theory for the ro-vibrational spectrum for acetylene, the IR absorption and MVCD spectra have been simulated using the g-values determined from the MVCD experiment for both the ground and excited vibrational staets. Good agreement has been observed between the experimental and simulated spectra. In addition, a SCF-level calculation of the g-value for acetylene in the ground vibrational state show excellent agreement with the g-value determined by MVCD.
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Author Institution: University of Illinois at Chicago, 845 W. Taylor, Chicago, IL 60607.; Academy of Sciences of the Czech Republic, Flemingovo Nam. 2, 16610, Praha, 6, Czech Republic.