Measurements of off-peak spectral absorption coefficients (in CH2O) for an isolated Voigt line

We describe the measurement of an off-peak spectral absorption coefficient for an isolated spectral line using a laser light source. This type of experiment may be used to determine the following line parameters: the line strength (S), the collision-broadened half-widths for self-broadening (b⁰_c,F and for inert-gas broadening (b⁰_{c, I}) per unit pressure, and the displacement of the laser frequency from the line center (Δω). The theoretical relations have been applied to absorption measurements on formaldehyde using an HeXe laser light source at 3.508 μ.