The propargyl radical (CH2C≡CH) produced by the ArF excimer laser photolysis of allene was observed by time-resolved infrared diode laser spectroscopy. More than one hundred and fifty absorption lines have been assigned to the v6 (CH2-wagging) fundamental band of propargyl. Most of the absorption lines were observed as doublets due to the spin-rotation interaction in the 2B1 ground electronic state. The rotational and spin-rotation interaction constants derived for the ground vibrational state are, A0 = 9.608 47(36), B0 = 0.317 674(24), C0 = 0.307 098(24), ∈aa = -0.017 58(95), and ∈bb = -0.000 355(76) cm-1, where the figures in parentheses are 2.5 times standard deviations to be attached to the last digit. The v6 band origin is 687.176 03(62) cm-1, consistent with the infrared spectrum observed in the argon matrix. Anomalously large vibrational changes in the A rotational constant and the ΔK centrifugal distortion constant are accounted for by the a-type Coriolis interaction between the v6 and v10 states, where v10 is the CH2-rocking vibration.
All Science Journal Classification (ASJC) codes
- Physics and Astronomy(all)
- Physical and Theoretical Chemistry