Infrared spectroscopy with a double modulation sideband technique

Both microwave and radio frequency modulation have been applied to CO₂ laser lines using only one CdTe modulator. As a result, a grid of closely spaced and tunable infrared frequencies is generated. This technique was used to perform infrared-infrared double resonance experiments on the molecules ²⁸SiH₄ and ²⁸ SiF₄ and to observe the Stark splitting due to extremely small dipole moments. As a preliminary result, values have been obtained for several dipole moment parameters which agree with measurements performed with other techniques