Transmission

The passing of light through matter.

sublimation

That's completely unrelated. Light usually slows down when passing through ANY matter. It does not react with dark matter (which is what makes the "dark matter" invisible in the first place), except through the gravitational interaction. The "cosmic speed limit" is a limit on how fast ANYTHING can travel (matter, energy, or information); it is just conventional to call it the "speed of light". This speed limit is for a vacuum - the assumption is NO normal matter, and NO dark matter; the presence of any matter may slow light down slightly.

Light cannot pass though matter but matter is technically atoms, which are mostly space with a few, moving objects - electrons and the nucleus. For glass, the loss of light through the material occurs for all glass.