Stark spectroscopy with the CO laser: The ν3 fundamental band of H2CO

The ν₃ fundamental band of H₂CO (CH₂ scissoring motion) has been studied by means of CO laser Stark spectroscopy and conventional infrared absorption spectroscopy. The primary aim of the work was to determine the dipole moment of H₂CO in the v₃ = 1 state, and the value determined was 2.3250 ± 0.0025 D. The spectrum was analyzed with the inclusion of the Coriolis interactions among ν₃, ν₄, and ν₆ so that “true” rotational constants were determined for ν₃; “effective” constants obtained by ignoring these interactions were also determined. The ν₃ band origin was determined to be 1500.174 ± 0.002 cm^?1. The H₂CO spectrum was also used as a means of determining the frequencies of some ¹³C¹⁶O and ¹²C¹⁸O laser lines in the 1500 cm^?1 region relative to ¹²C¹⁶O lines.