The nu(1)+5 nu(3) dyad of (CO2)-C-12 and (CO2)-C-13

The (1 0(0) 5)(1,2) --> (1 0(0) 4)(1,2) and (1 0(0) 6)(1,2) --> (1 0(0) 5)( 1,2) emission bands of (CO2)-C-12-O-16 have been recorded near 4.5 mu m by Fourier transform spectroscopy of a CO2 + N-2 mixture excited by de dischar ge. The spectroscopic parameters of the (1 0(0) v(3))(1,2) vibrational stat es with v(3) = 0-6 have been obtained from a global rotational analysis of the six (1 0(0) v(3))(1,2) --> (1 0(0) (v(3)-1))(1,2) emission bands (v(3) = 1-6). The (1 0(0) 5)(1,2) vibrational states of both (CO2)-C-12-O-16 and (CO2)-C-13-O-16 have been observed by direct absorption from the vibrationa l ground state by Intracavity Laser Absorption Spectroscopy near 12 700 and 12 400 cm(-1), respectively. The rovibrational energy levels obtained by t he two experimental techniques are discussed and compared with those calcul ated in the framework of the effective operator approach. (C) 1999 Academic Press.