High-resolution absorption spectroscopy of the 3 nu(1) and 3 nu(1)+nu(3) bands of propyne

The 3v(1), and 3v(1) + v(3) bands of propyne have been recorded at Doppler- limited resolution by Fourier transform spectroscopy and intracavity laser absorption spectroscopy, respectively. The two bands show a mostly unpertur bed J rotational structure for each individual K subband. However, as a rul e the K structure ordering is perturbed in overtone transitions of propyne and different effective parameters associated with each K subband have been determined. From the vibrational energy levels, a value of -6.6 cm(-1) has been obtained for the x(13) cross anharmonicity in perfect agreement with the origins of the v(1) + v(3) and 2v(1) + v(3) combination bands estimated from the FTIR spectrum. Hot bands from the v(9) = 1 and v(10)= 1 levels as sociated with the 3v(1) + v(3) combination band have been partly rotational ly analyzed and the retrieved values of x(39) and x(3.10) are in good agree ment with literature values. Finally, the 4v(1) + v(9) - v(9) band centered at 12 636.6 cm(-1) has been recorded by ICLAS. The red shift of this hot b and relative to 4v(1),, and the Delta B-v, value are discussed in relation to the anharmonic interaction between the 4v(1) and 3v(1) + v(3) + v(5) lev els. (C) 2000 Academic Press.