Electron-beam-controlled laser utilizing the first overtones of the vibrational–rotational transitions in the $CO$ molecule. I. Time-resolved spectral characteristics

An experimental investigation was made of the spectral and temporal distributions of the energy emitted by an electron-beam-controlled $CO$ laser having a resonator with a high $Q$ in the region of the overtone frequencies. It was found that in the free-lasing regime this laser emitted simultaneously a large number of lines in the range $2,7-3,3\mu m$, the emission spectrum being more complex at higher excitation energies. The measured dependences of the time-resolved spectral characteristics on the excitation conditions are qualitatively explained on the basis of a model involving the $VV$ relaxation of anharmonic molecules and a cascade mechanism of lasing in coupled vibrational bands.