The electronic spectrum of the Ar–vinoxy van der Waals complex

The Ar–vinoxy radical van der Waals complex has been observed in a free-jet expansion. The complex was detected by laser excitation of the bands associated with the vinoxy B̃–X̃ transition. A van der Waals vibrational mode, with a frequency of approximately 41 cm−1, was found to be active in this spectrum. Rotational contour analyses showed that the complex is nonplanar, with the Ar atom ‘‘in contact’’ with the CCO frame. The extreme congestion of the rotational contours has been ascribed to a tunneling inversion motion.