Rami Arieli: "The Laser Adventure"

Rami Arieli: "The Laser Adventure" Chapter 3.2 page 3

c) Collisions with atoms This is the standard excitation mechanism in the commercial gas lasers such as: Helium-Neon laser, or Carbon-Dioxide laser.

In this method at least two gasses are inside the laser tube.

One gas receives the energy from the collision with the accelerated free electrons. The second gas receives energy from collisions with the excited molecules of the first gas.