nu. /sub 2/ +. nu. /sub 4/ band of /sup 12/CF/sub 4/

From a high-resolution diode laser spectrum of cooled /sup 12/CF/sub 4/, line assignments in ..nu../sub 2/ + ..nu../sub 4/ at 1066.4 cm/sup -1/ have been made for tetrahedral subspecies to J = 20, and in many cases to higher J. Spectroscopic constants have been obtained from a least-squares fit of the Hamiltonian, and the relative intensities of the assigned lines have been calculated. The ground- and excited-state rotational constants, Coriolis constant, and splitting of the F/sub 1/ and F/sub 2/ vibrational substates have the values B/sub 0/ = 0.191688 +- 0.000020 cm/sup -1/, B = 0.191442 +- 0.000020 cm/sup -1/, zeta/sub 4/ = 0.3605 +- 0.0002, ..delta.. = 0.5757 +- 0.0017 cm/sup -1/. The C-F bond length in the ground vibrational state is thus r/sub 0/ = 1.31752 +- 0.00007A. The analysis of a combination band such as this provides a method of obtaining ground-state spectroscopic constants of spherical-top molecules directly from the infrared spectrum, without the necessity of measuring weak forbidden transitions. The assignments allow accurate predictions of the frequencies emitted by the CO/sub 2/-pumped CF/sub 4/ laser.