The Interaction Between Electromagnetic Radiation and Matter

Interaction of electromagnetic radiation and matter is not haphazard, but follows well-documented mles with respect to the wavelengths of light absorbed or emitted and the extent of absorption or emission. The subject of spectroscopy is the study of the interaction of electromagnetic radiation and matter. 

---

There are few more laws which govern the interaction between electromagnetic radiation and matter which are also studied under the laws of... 

There are many types of interactions between electromagnetic radiation and matter. A species as a whole can change its rotational state the bonds (if any) within a species can bend, stretch, or twist and thus alto its vibrational state the electrons in the species may undergo transitions between various energy states and finally the atomic nuclei of the species can absorb energy from the incident radiation by making transitions between the different orientations to an externally imposed magnetic field. 

Interaction between electromagnetic radiation and matter follows vertical Franck-Condon transitions for both absorption and emission. This means that during electronic transitions, both the positions and the spin angular momentum of an atom s nucleus remain virtually unchanged due to the high velocity of electrons compared to the displacement of a heavy nucleus. Three type of interactions occur ... 

Atomic and One possible interaction between electromagnetic radiation and matter is electronic Electronic polarization—the electric field component of a light wave indnces a shift of the electron... 

The interaction of electromagnetic radiation with matter in the domain ranging from the close ultraviolet to the close infrared, between 180 and 1,100 nm, has been extensively studied. This portion of the electromagnetic spectrum, called UV/Visible because it contains radiation that can be seen by the human eye, provides little structural information except the presence of unsaturation sites in molecules. However, it has great importance in quantitative analysis. Absorbance calculations for compounds absorbing radiation in the UV/Visible using Beer-Lambert s Law is the basis of the method known as colorimetry. This method is the workhorse in any analytical laboratory. It applies not only to compounds that possess absorption spectra in that spectral region, but to all compounds that lead to absorption measurements. 

Spectroscopic methods depend on the interactions that occur between electromagnetic radiation and matter. There are in prindple two modes of interaction ... 

Spectrometric methods are a large group of analytical methods that arc based on atomic and molecular spectroscopy. Spectroscopy is a general term for the science that deals with the interactions of various types of radiation with matter. Historically, the interactions of interest were between electromagnetic radiation and matter, but now spectroscopy has been broadened to include interactions between matter and other forms of energy. Examples include acoustic waves and beams of particles such as ions and electrons. Spectrometry and spectrometric methods refer to the measurement of the intensity of radiation with a photoelectric transducer or other type of electronic device. 

One branch of chemistry where the use of quantum mechanics is an absolute necessity is molecular spectroscopy. The topic is interaction between electromagnetic waves and molecular matter. The major assumption is that nuclear and electronic motion can effectively be separated according to the Born-Oppenheimer approximation, to be studied in more detail later on. The type of interaction depends on the wavelength, or frequency of the radiation which is commonly used to identify characteristic regions in the total spectrum, ranging from radio waves to 7-rays. 

Spectroscopic methods of analysis. They are a wide group of instrumental analytical methods all based on the interaction between energy (an electromagnetic radiation) and matter (usually the analyte). 

Optical spectroscopy is the science of the interaction of optical radiation with matter. In many cases this involves specific transitions between the energy levels (states) of a sample, which are monitored experimentally by the absorption or emission of electromagnetic radiation. In these types of interactions the radiation is considered to be composed of packets of energy called photons, and they have a dual character in that they have both particle- and wave-like properties. As discussed in Chapter 1, the photon energy is related to its wavelength and frequency by ... 

To this point, we have considered only the radiation field. We now turn to the interaction between the matter and the field. According to classical electromagnetic theory, the force on a particle with charge e due to the electric and magnetic fields is... 

---