Light dual nature

That light has a dual nature and behaves either like a wave or like a stream of particle-like photons is a fact we must accept, although it is nonintuitive. But remember, we have no direct experience of the behavior of very small particles such as electrons. Which model we use depends on the observations we are making. The wave model is appropriate when we are considering diffraction and interference experiments, but the particle (photon) model is essential when we are considering the interaction of light with individual atoms or molecules. 

In 1923 de Broglie made the bold suggestion that matter, like light, has a dual nature in that it sometimes behaves like particles and sometimes like waves. He suggested that material (i.e., non-zero-rest mass) particles with a momentum p = mv should have wave properties and a corresponding wavelength given by... 

Quantum mechanics, which replaced the old quantum theory, was not easy to interpret. It conceived of both light and particles as having a dual nature. They were sometimes observed to be waves and sometimes particles, depending on the type of experiment that one performed. For example, the electron seemed sometimes to be a particle and sometimes a packet of waves. Furthermore, quantum mechanics described the subatomic world in terms of probabilities. 

This dual nature of light appears puzzling to most students of this field, and cannot be resolved by any simple picture. From our point of view it is sufficient to consider that light is a stream of photons which travels in a straight line at constant velocity c (c = 3 X 108 ms-1). Each photon has an electric vector E and a magnetic vector H that allow interactions with electrons and nuclei through electric and magnetic forces. 

Einstein was cautious about promoting this revolutionary idea. Furthermore, he was absorbed in sorting out another set of revolutionary ideas the general theory of relativity After clearing that up, though, Einstein returned to the problems of light and quantum mechanics and finally accepted the hard-to-accept solution Light has a dual nature—sometimes it acts like a particle, sometimes it acts like a wave. 

To understand the dual nature of light and the relationships among its energy, frequency, and wavelength 4.5 To write electronic configurations in a shorter notation, using the concepts of shells, subshells, and orbitals... 

Electromagnetic radiation, which was previously thought to exhibit only wave properties, seems to show certain characteristics of particulate matter as well. This phenomenon, illustrated in Fig. 12.6, is sometimes referred to as the dual nature of light. 

Dual nature of light the statement that light exhibits both wave and particulate properties. (12.2)... 

Other phenomena are best described in terms of light s particle nature (Equation 1.4). These seemingly contradictory properties are inseparable parts of the dual nature of light. Both must be taken into account when considering a simple process such as the absorption of light by matter. The above statements will surprise few readers because they have heard them many times before. But consider the experiment depicted in Figure 1.7. 

For a quantum mechanical treatment of light absorption, the dual nature of light must be taken into account. Light can be absorbed only if the excitation energy matches the photon energy, AE = hv that is, if the absorption of a photon by the molecule leads to one of the discrete excited states of the molecule (Figure 2.5). 

However, EMR behaves as a particle and as a wave (the dual nature of light) and the wavelength of such a particle, a photon, is related to energy by the equation... 

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