What do infrared photons do when they hit glass?

Answer 1

Some of it reflects (bounces) back to the source. Some of it is absorbed into the glass, and

never heard from again. The rest of it passes through the glass and continues on its way.

Answer 2

When they're incident on glass, infrared photons do the same things that photons of other
wavelengths do ... some are reflected, some are absorbed, and some are transmitted.
How many of the photons undergo each process depends on the energy of the photons
and the chemical composition of the glass.

Answer 3

When infrared photons hit glass, they can either be transmitted through the glass, absorbed by the glass, or reflected off the surface of the glass. The amount of each of these actions depends on the composition and thickness of the glass.

Answer 4

Typically, the IR energy is absorbed by the glass as heat.