https://phet.colorado.edu/sims/html/molecules-and-light/latest/molecules-and-light_en.html 

When a molecule absorbs a photon, the energy of the photon is transferred to the molecule. The amount of energy in the photon determines how the molecule will respond to the absorption.

• If the energy of the photon is low, the molecule will generally not move much, but may vibrate or rotate. This is because the energy is not enough to cause the molecule to move significantly as a whole, but can excite its internal motions. (rotate and/or vibrate)

• If the energy of the photon is high, the molecule will be more likely to move as a whole. This is because the energy is now sufficient to overcome the intermolecular forces holding the molecule together, and can cause the molecule to move in a particular direction. (energize and/or disassociate)

The geometry of a molecule plays a crucial role in determining how it interacts with various forms of radiation, including electromagnetic radiation (such as light) and particulate radiation (such as alpha, beta, and gamma radiation).

The Interaction with electromagnetic (EM) radiation:

depends on its electronic structure, which in turn depends on its geometry. 

• • For example, a molecule with a symmetrical geometry, such as oxygen gas (O2), does not have a permanent dipole moment and does not absorb or interact with electromagnetic radiation in the infrared region. 

  • On the other hand, a molecule with an asymmetric geometry, such as water (H2O), has a permanent dipole moment and readily interacts with electromagnetic radiation in the infrared region.

The Interaction with particulate radiation:

depends on its size and structure. For example:

• • alpha particles, which are large and heavy, are easily stopped by molecules with large, complex structures, such as DNA. 

  • Beta particles, which are smaller and less massive, are more likely to pass through molecules with a more open or less compact structure. 

  • Gamma rays, which are high-energy photons, can pass through most molecules but may interact with the electron cloud of the molecule and cause ionization or excitation.

Microwaves have a longer wavelength and lower frequency than visible or ultraviolet radiation, and they interact with molecules by causing rotational transitions.

Infrared radiation has a shorter wavelength and higher frequency than microwaves, and it interacts with molecules by causing vibrational transitions.

Visible radiation has a wavelength that is well-suited to excite electrons in atoms and molecules. Molecules with conjugated double bonds, such as those found in chlorophyll or carotenoids, have a unique geometry that allows them to absorb visible radiation.

Ultraviolet radiation has a shorter wavelength and higher frequency than visible light, and it interacts with molecules by causing electronic transitions. Molecules with conjugated double bonds, such as those found in DNA and some pigments, have a unique geometry that allows them to absorb ultraviolet radiation in a specific range of wavelengths. This absorption can lead to electronic transitions that can cause damage to the molecule, such as DNA damage.

Real world connections - Use the results of the simulations to explain:

Microwaves are a form of electromagnetic radiation with a frequency of about 2.45 GHz (Verizon @ 0.7 GHz). When these waves are emitted by the magnetron in a microwave oven, they cause the water molecules in the food to oscillate back and forth rapidly. This oscillation generates heat, which is transferred to the surrounding molecules and results in the heating of the food.

CO, CO2, CH4, H2O, NO2, O3

The ozone layer is a protective layer of ozone gas that exists in the Earth's stratosphere, about 10-50 kilometers above the Earth's surface. This layer plays an important role in protecting life on Earth by absorbing and filtering out most of the harmful ultraviolet (UV) radiation from the sun.

When visible light interacts with NO2 (nitrogen dioxide) in our atmosphere, a process called photodissociation occurs. This process breaks down NO2 into nitrogen monoxide (NO) and atomic oxygen (O). This is an important reaction because it plays a role in regulating the concentration of NOx (NO and NO2) in the atmosphere, which can have significant impacts on air quality and climate.

N2 and O2, which together make up about 99% of the Earth's atmosphere, are relatively unreactive with most forms of radiation

All atmospheric gases, including nitrogen (N2), oxygen (O2), and argon (Ar), can interact with some form of radiation, however, the degree to which they interact depends on the specific wavelength and energy of the radiation.

Carbon monoxide (CO): Carbon monoxide is a relatively unreactive gas that does not interact strongly with visible or UV radiation. However, it does interact with infrared radiation, absorbing it and contributing to atmospheric warming.

Nitrogen (N2): Nitrogen is a relatively unreactive molecule in the Earth's atmosphere due to its triple bond, which requires a significant amount of energy to break. Nitrogen molecules do not interact strongly with visible or infrared radiation, but they can absorb high-energy UV radiation with wavelengths less than 400 nm. When nitrogen molecules absorb UV radiation, they can undergo electronic excitations, leading to a range of chemical reactions.

Oxygen (O2): Oxygen molecules do not interact strongly with visible light or infrared radiation, but they do interact with high-energy ultraviolet radiation. When oxygen molecules absorb UV radiation with wavelengths less than 240 nm, the energy can cause the molecule to dissociate into two individual oxygen atoms. These highly reactive oxygen atoms can then react with other atmospheric gases, leading to a range of chemical processes.

Carbon dioxide (CO2): Carbon dioxide is a well-known greenhouse gas that interacts strongly with infrared radiation. When CO2 absorbs infrared radiation, it can undergo vibrational motions, leading to changes in its molecular structure. These changes can result in the absorption and re-emission of infrared radiation, contributing to the greenhouse effect and atmospheric warming.

Methane (CH4): Methane is also a greenhouse gas that interacts with infrared radiation. When CH4 absorbs infrared radiation, it can undergo vibrational motions similar to water vapor, leading to changes in its molecular structure. These changes can also result in the absorption and re-emission of infrared radiation, contributing to the greenhouse effect.

Water vapor (H2O): Water vapor is an important greenhouse gas that interacts strongly with infrared radiation. When water vapor molecules absorb infrared radiation, they can undergo vibrational motions, leading to changes in the molecular structure. These changes can result in the absorption and re-emission of infrared radiation, contributing to the greenhouse effect and warming of the Earth's surface.

Nitrogen dioxide (NO2): Nitrogen dioxide is a reactive gas that interacts with both visible and UV radiation. When NO2 absorbs visible light, it can undergo electronic excitations, leading to the formation of highly reactive free radicals. When it absorbs UV radiation, it can dissociate into nitrogen monoxide (NO) and atomic oxygen (O), which can react with other atmospheric molecules.

Nitrous oxide (N2O): Nitrous oxide is a greenhouse gas that interacts with infrared radiation. When N2O absorbs infrared radiation, it can undergo vibrational motions, leading to changes in its molecular structure. These changes can result in the absorption and re-emission of infrared radiation, contributing to the greenhouse effect.

Ozone (O3): Ozone is a highly reactive molecule that plays an important role in the Earth's atmosphere, particularly in the stratosphere. Ozone is formed when oxygen molecules (O2) absorb high-energy UV radiation, causing the molecules to dissociate into individual oxygen atoms. These atoms can then react with other O2 molecules to form ozone (O3). Ozone also interacts with UV radiation, absorbing it and preventing it from reaching the Earth's surface.

Sulfur oxides (SOx), such as sulfur dioxide (SO2) and sulfur trioxide (SO3), can interact with a variety of forms of radiation, including UV radiation, visible light, and infrared radiation. Here are some examples of how sulfur oxides react with different forms of radiation:

1. UV radiation: Sulfur dioxide can react with UV radiation to form sulfur trioxide and atomic oxygen. This reaction can occur in the upper atmosphere, where UV radiation is more intense. In the lower atmosphere, SO2 can also react with other reactive species, such as hydroxyl radicals, to form sulfuric acid, which can contribute to the formation of acid rain.

2. Visible light: Sulfur dioxide can absorb visible light and undergo electronic excitations, leading to the formation of highly reactive free radicals. These free radicals can then react with other atmospheric molecules, such as hydrocarbons, to form secondary pollutants, such as ozone and particulate matter.

3. Infrared radiation: Sulfur dioxide does not strongly absorb infrared radiation and is not considered a significant contributor to the greenhouse effect. However, sulfur trioxide can absorb infrared radiation, leading to changes in its vibrational modes and contributing to atmospheric warming.

The reactions of sulfur oxides with radiation are complex and depend on a variety of factors, including the concentration of the gas, the energy of the radiation, and the presence of other atmospheric pollutants. In general, sulfur oxides are considered harmful air pollutants that can have a variety of negative impacts on human health and the environment.