I know that an atom can become excited in one of two ways: by absorbing some energy from a source of electromagnetic radiation or by colliding with some other particle—another atom, for example, but my question is about the second part. So I want to know how and in what conditions (pressure, temperature ...) an atom can collide with another atom or even molecule and it causes excitation. Then after the atom's excitation, an electron boost into a higher orbital. I exactly mean that I wonder if the atoms or molecules can become excited in low temperature. No matter which atom or molecule, but the question is if it is possible to excite an atom or molecule in a gas system without external source of energy and just when they collide together, or not. If yes what is the conditions.