The ν3Q branch of SF 6 at high resolution: Assignment of the levels pumped by P(16) of the CO 2 laser
The Q branch of the ν3 stretching fundamental of 32SF 6 (ca. 947.6-948.3 cm -1) has been recorded at 109-142 K with a resolution of <10 -4 cm -1, and the individual transitions have been assigned. Several series of lines arising from different subbranches can be followed up to high J values ( J ≈ 80 in one case). Some of these subbranches form prominent band-heads that dominate the gross structure of the Q branch, especially at higher temperatures. A moderately strong transition at 947.742 cm -1, displaced -8 MHz from the P(16) CO 2 laser line, has been assigned as Q(38) F 10 + E 0 + F 20; 39 other transitions that fall within ±300 MHz of the laser line have also been identified. The Q branch of 33SF 6, present in natural abundance (0.76%), has been recored and analyzed; the isotope shift is 8.97 cm -1.