Answer to Question #28067 in Physics for bob

Question

What type of materials can block infrared rays? please answer

Answer 1

Infrared rays are a form of electromagnetic radiation whose wavelengths lie between& 0.75 μm and 1000 μm.& Infrared light is emitted or absorbed by molecules when they change their rotational-vibrational movements. All objects that are not at absolute zero emit infrared radiation. Absolute zero defines the temperature where all molecular motion ceases, and is the coldest possible temperature. It corresponds to about minus 273 degrees Celsius, or minus 460 degrees Fahrenheit. Thermal infrared, which corresponds to wavelengths longer than about 5 microns is a direct measure of temperature. One simple material that blocks IR is plexiglas. Also, water is a good absorber of IR. Any good mirror should also be capable of reflecting infrared light. Thus, in astronomy most ground-based telescopes that observe in the "near-infrared" (between 1 and 2.5 microns) rely on the same telescopes as for optical astronomy.
Short list of materials which can block infrared rays:
Water
Plexiglas
Glass
Wood
Brick
Stone
Metals (copper, gold, silver, etc.)
Manganese &
References:
https://www.ehow.com/info_8044395_materials-absorb-infrared-rays.html
https://en.wikipedia.org/wiki/Infrared
https://coolcosmos.ipac.caltech.edu/cosmic_classroom/ask_astronomer/faq/radiation.shtml