Pulsed chemical $CS_2/O_2$ photoinitiation laser utilizing overtone transitions $(\triangle v=2)$ of the $CO$ molecule

Pulsed ultraviolet photolysis of a $CS_2-O_2$ mixture was used to obtain lasing in vibrational-rotational transitions in the first overtone band of the $CO$ molecule $(\lambda=2,5-2,8\mu m)$. A study was made of the dependences of the overtone lasing energy and spectrum on the pressure and composition of the active mixture and on the initiation energy. Under near-optimal conditions the active-medium gain of the laser was $2\cdot10^{-3}$ cm${}^{-1}$ and the total energy in an emission pulse from all transitions was 20 mJ for an active volume of 190 cm${}^3$. A study of the lasing delay times made for different transitions showed that lasing developed along two practically independent cascades: $v\to v-2\to v-4\dots$, with even and odd values of $v$. The possibilities for controlling the overtone laser emission spectrum were assessed; it was found that the most efficient method of control is the selective repopulation of the active levels by initiating lasing in the fundamental $(\triangle v=1)$ bands $(\lambda\thicksim5\mu m)$.