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Any object, at any temperature, will radiate a continuous spectrum of electromagnetic energy. Depending on the temperature of the object, its spectral peak may be at infra red (warm), red (red hot - burning) or yellow ( white hot - like a light bulb filament) etc. Even the coldest regions of space still radiate microwave energy. This relates to Mr Andrew's comments about vibrations within the material. Higher temperature implies more vibration. What we used to call the 'heat' in an object is now referred to as its ' internal energy'. The temperature is really a measure of the average energy of each molecule.Rather than saying that infra red "causes heat" it is more meaningful to say that hot objects radiate with a peak of infra red energy.The material is not really relevant. What IS relevant is the 'colour' of the surface, which can alter the amount of energy radiated or absorbed at various wavelengths and the actual temperature.
Quantum theory was actually born of the study of black-body radiation. Max Plank developed a law to describe the distribution of radiation over the different wavelengths at different temperatures and to do so he had to assume that atoms had discrete energy levels...E=nhv.
The fact that the individual quanta of the radiation are lower in energy than light is not relavent. it is the quantity of quanta that determines how much heat energy is produced for example we talk about light and infra red radiation a being emitted by bodies at several hunderds or several thousand degrees K. bodies that are very cold (say only a few degrees above absolute zero) emit microwave radiation as their natural radiation. however you know that wehen you put a glass of water into a microwave cooker and zap it with a lot of photons of microwave radiation it can get very hot indeed.