Absorption coefficients for hydrogen—II. Calculated pressure-induced H2–H2 vibrational absorption in the fundamental region

The coefficient for pressure-induced vibrational absorption in H₂ndash;H₂ collisions was calculated for temperatures from 298 to 7000°K and wave numbers between 100 and 40,000 cm⁻¹ for local thermodynamic equilibrium. Because only transitions with a net change of +1 vibrational quanta were considered, the absorption was centered near the fundamental at 4161 cm⁻¹ in the infrared. The model included electronic configuration interaction, mechanical anharmonicity, vibration-rotation interaction, excited vibrational states, and more realistic intermolecular potential and line shapes than previously used. The integrated absorption coefficient at 3000°K was 2.1 times the previous theoretical value. An approximate formula for the absorption coefficient is given for rapid calculation.