LASER-INDUCED FLUORESCENCE SPECTROSCOPY OF THE (C)OVER-TILDE(2)SIGMA(+)-(X)OVER-TILDE(2)PI(1/2) BAND SYSTEM OF JET-COOLED CCN RADICAL

摘要

Laser-induced-fluorescence spectra of the (C) over tilde (2) Sigma(+) - (X) over tilde (2) Pi(r) system of the CCN radical were observed under jet-cooled conditions. The radical was generated in a supersonic expansion by a pulsed electric discharge of methyl cyanide diluted in Ar. Sixteen (C) over tilde (2) Sigma(+) (v(1),v(2)(l),v(3))-(X) over tilde (2) Pi(1/2)(0,0(0),0) vibronic bands with v(1) = 0-3, v(2) = 0-2 (l = 0-2), and v(3) = 0-2 were observed, including some very weak vibronically induced parallel-type transitions with v(2)=1 (I = 1). Rotational analyses were performed to give the band origins and the rotational constants for vibrationally excited states of all the three normal modes and their combinations in the (C) over tilde (2) Sigma(+) state. From the determined band origins, the term value and the vibrational parameters in the (C) over tilde (2) Sigma(+) State have been determined: T-e = 24 627.1(20) cm(-1), omega(1) = 1903.1(11) cm(-1), omega(2) = 469.88 (38) cm(-1), omega(3) = 1256.6(40) cm(-1), and g(22)= 0.86(11) cm(-1). A combination of the present omega(2) frequency in the (C) over tilde state with the data on the hot bands reported so far in literature has yielded the vibronic structures in the (X) over tilde (2) Pi(r) and (A) over tilde (2) Delta states, which are subject to a prominent Renner-Teller effect. (C) 1997 American Institute of Physics. [References: 30]