Rotationally Resolved Spectrum of the \mathitA^2A'' - \mathitX^2A'' 0_0^0 Band of 1-Indanyl Radical

The rotationally resolved spectrum of the A^2A'' - X^2A'' 0 ^0_0 band of jet-cooled 1-indanyl near 473 nm is recorded by laser induced fluorescence with a spectral resolution of \sim 0.014 cm ^-1 . Accurate spectroscopic constants for both A^2A'' and X^2A'' states of 1-indanyl are determined from rotational analysis of the experimental spectrum. These indicative spectroscopic parameters are applied to test the calculated structure of 1-indanyl. The calculations show good agreements with the experimental data. Based on the computational molecular orbitals and spin densities for 1-indanyl, the delocalization of unpaired p _\pi electron that stabilizes the 1-indanyl radical is discussed.