Answer to Question 1
1- One way is by changing the rate at which the molecules rotate. If molecules absorb the photon, the molecule's rotation rate increases. The H2O pure rotation band extends all the way from 12 m into the microwave region of the electromagnetic spectrum.
2- A second way in which molecules can absorb or emit IR radiation is by changing the amplitude with which they vibrate. If the frequency at which the molecule vibrates matches the frequency of the wave, the molecules can absorb a photon and begin to vibrate more vigorously. The CO2 15-m band is one of the fundamental vibration modes of the CO2 molecule.
Answer to Question 2
Nitrogen, N2
Oxygen, O2
Argon, Ar
The argon, 40A, is released by the radioactive decay of 40K in Earth's crust and mantle.