HIGH-RESOLUTION SPECTROSCOPY OF THE 16-MU-M BENDING FUNDAMENTAL OF CF4

The 16-μm bending fundamentals (ν4) of 12CF4, 13CF4, and 14CF4 have been observed at Doppler-limited resolution using a tunable PbSnSe semiconductor diode laser. The tetra-hedral splittings of the rotational manifolds have been observed in all three branches, and in particular the dense and partially overlapping transitions in the Q branches have been resolved and assigned. A least-squares fit of the Hamiltonian, including off-diagonal terms, yielded five scalar and three tensor spectroscopic constants for each of the three isotopes. From these constants the upper-state rotational constant B4 and the Coriolis constant ζ4 have been calculated, together with some of the other molecular constants. An absorption feature at about 0.18 cm-1 to the red of the main Q branch of each isotopic species has been identified as the Q branch of (ν2 + ν4) - ν2, which is the transition that lases when CF4 is pumped by a CO2 laser at 9.4 νm (i.e., in ν2 + ν4).1 This work was supported by the United States Department of Energy. The U. S. Government's right to retain a nonexclusive royalty-free license in and to the copyright covering this paper, for governmental purposes, is acknowledged. Copyright © 1980 by Academic Press, Inc.