Analytical Research on Rotation-Vibration Multiphoton Absorption of Diatomic Molecules in Infrared Laser Fields

The multiphoton rotation-vibration energy absorption of diatomic molecules in infrared laser fields is analytically studied using the algebraic approach. The analytical expression of the rotation-vibration transition probability is given. The long-time average absorbed energy spectra and the average number of photons absorbed by the molecule are discussed. The results show that both molecular orientation and molecular anharmonicity are important factors in the rotation-vibration multiphoton absorption.