Question

What is the relationship between the kinds of bonds a molecule has, and the kind of radiation (Microwave, Infrared, Visible, and Ultraviolet) it will absorb? Why is this? Based on this explanation, how would the molecule HCN interact with microwaves?

Answer 1

Molecular rotation and torsion Microwaves

Infrared Molecular vibration

Visible Transition between electron energy level

Ultravolet The near ultraviolet is absorbed very strongly in the surface layer of the skin by electron transitions.

Microwave Interactions The quantum energy of microwave photons is in the range 0.00001 to 0.001 eV which is in the range of energies separating the quantum states of molecular rotation and torsion. The interaction of microwaves with matter other than metallic conductors will be to rotate molecules and produce heat as result of that molecular motion. Conductors will strongly absorb microwaves and any lower frequencies because they will cause electric currents which will heat the material. Most matter, including the human body, is largely transparent to microwaves.

Infrared The quantum energy of infrared photons is in the range 0.001 to 1.7 eV which is in the range of energies separating the quantum states of molecular vibrations. Infrared is absorbed more strongly than microwaves, but less strongly than visible light. The result of infrared absorption is heating of the tissue since it increases molecular vibrational activity. Infrared radiation does penetrate the skin further than visible light and can thus be used for photographic imaging of subcutaneous blood vessels.

Visible The primary mechanism for the absorption of visible light photons is the elevation of electrons to higher energy levels. There are many available states, so visible light is absorbed strongly. With a strong light source, red light can be transmitted through the hand or a fold of skin, showing that the red end of the spectrum is not absorbed as strongly as the violet end.

Ultraviolet The near ultraviolet is absorbed very strongly in the surface layer of the skin by electron transitions. As you go to higher energies, the ionization energies for many molecules are reached and the more dangerous photoionization processes take place. Sunburn is primarily an effect of uv, and ionization produces the risk of skin cancer.The ozone layer in the upper atmosphere is important for human health because it absorbs most of the harmful ultraviolet radiation from the sun before it reaches the surface. The higher frequencies in the ultraviolet are ionizing radiation and can produce harmful physiological effects ranging from sunburn to skin cancer.

The molecule HCN interacts with microwaves

There will be rotational and torsion transitions