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Volume 120, Issue 15, 15 April 2004
120(2004); http://dx.doi.org/10.1063/1.1707011View Description Hide Description
Polyynes represent a unique class of conjugated organic compounds. The third-order nonlinear optical response of polyynes has been extensively modeled theoretically, and it is generally believed that the increase in molecular second hyperpolarizability (γ) as a function of length for polyynes should be lower than that for polyenes. Experimental evidence to test this prediction, however, has been absent. We have synthesized conjugated polyynes that contain up to 20 consecutive sp-hybridized carbons, and we have determined their nonresonant γ-values as a function of the number of acetylene repeat units These γ-values demonstrate a power-law behavior versus with an exponent that is both larger than theoretically predicted for polyynes and substantially higher than that observed for polyenes or polyenynes. Furthermore, no saturation of the linear or nonlinear optical properties is observed.
120(2004); http://dx.doi.org/10.1063/1.1711589View Description Hide Description
The Huggins band of ozone is investigated by means of exact dynamics calculations using a new (diabatic) potential energy surface for the state. The remarkable agreement with the measured spectrum strongly suggests that the Huggins band is due to the two potential wells of the state. The vibrational assignment, based on the nodal structure of wave functions, supports the most recent experimental assignment.