LASER SPECTROSCOPY OF THE (A)OVER-TILDE(2)PI-(X)OVER-TILDE(2)SIGMA(-0BAND OF THE CACCH RADICAL() 0)

The 0-0 band of the (A) over tilde(2) Pi-(X) over tilde(2) Sigma(+) tr ansition of CaCCH has been rotationally analyzed through CW dye laser excitation. A total of 440 rotational lines of this band were recorded with high precision, 0.0035 cm(-1). A least-squares fit of the line p ositions using a standard (2) Pi-(2) Sigma(+) model provides accurate molecular constants for both electronic states and confirms a linear e quilibrium geometry of CaCCH. From the Lambda-type doubling constant p (v) determined in this work, the (B) over tilde(2) Sigma(+) electronic state is predicted to lie approximate to 1080 cm(-1) above the (A) ov er tilde(2) Pi state. (C) 1996 Academic Press, Inc.