Light as an Electromagnetic Wave

The example worked out above is an extremely simple one. Nevertheless, it demonstrates how a differential equation and boundary conditions are used to define the allowed states for a system. One could have arrived at solutions for this case by simple physical argument, but this is usually not possible in more complicated cases. The differential equation provides a systematic approach for finding solutions when physical intuition is not enough. 

Chapter 1 Classical Waves and the Time-Independent Schrodinger Wave Equation 

Experiments with light in the nineteenth century and earlier were consistent with the view that light is a wave phenomenon. One of the more obvious experimental verifications of this is provided by the interference pattern produced when light from a point source is allowed to pass through a pair of slits and then to fall on a screen. The resulting interference patterns are understandable only in terms of the constructive and destructive interference of waves. The differential equations of Maxwell, which provided the connection between electromagnetic radiation and the basic laws of physics, also indicated that light is a wave. 

Energy 120 IIJ 12mJ 1.2J 120J 12kJ 1.2MJ 120MJ 12GJ 

286 H cal 28.6mcal 2.86cal 286cal 28.6kcal 2.86Mcal 286Mcal 

Temper- 14.4 jt K. 1.44mK 144mK 14.4K. 1.44kK H4kK 14.4MK 1.44GK. 

Phe- nomena motion of electron or atomic nucleus in electromagnetic field X molecular rotation vibration -X—X electronic transition X X electronic nuclear transition reaction of inner orbital  

Source klystron laser tube nuclear decay 

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Scottish physicist James Clerk Maxwell, who identified light as an electromagnetic wave. 

We now consider the interaction of an atom or molecule with electromagnetic radiation. A proper quantum-mechanical approach would treat both the atom and the radiation quantum mechanically, but we shall simplify things by using the classical picture of the light as an electromagnetic wave of oscUlating electric and magnetic fields. 

There has been phenomenal expansion in the range of experiments coimected with light-molecule interactions. If one thinks of light as an electromagnetic (EM) wave, like any wave it has an amplittide, a frequency and a phase. The advent of the laser in 1960 completely revolutionized the control over all tluee of hese factors. The amplittide of the EM wave is related to its intensity current laser capabilities allow... 

Semiclassical perturbation theory [56, 59] is applicable to describe TPA as a second-order phenomenon. Light can be seen as an electromagnetic wave perturbing the stationary wavefunctions of a molecule. Quantities related to these wavefunctions are the absorption cross sections rxgi and <7if (Fig. 3.1). Furthermore, high excitation power/photon density requires additional higher order terms according to perturbation theory. The spatial (Cartesian coordinates, r) and time (f) dependent wavefunction i//g2) (r, t) is shown for second-order perturbation in Eq. (2) [23] ... 

The unpolarized incident light beam is described as an electromagnetic wave consisting of two circularly polarized components of equal amplitude, propagating in the z-direction. The medium is subject to a static magnetic field in the same direction. We can write the electric field of the light as... 

How does one go from the classical wave theory of light as an electromagnetic field, to the quantum mechanical theory of Einstein for absorption (and of course emission) that considers the corpuscular interaction between a photon and an electron. 

Reflection—Return of radiant energy (incident light) by a surface, with no change in wavelength. Refraction—Change of direction of propagation of any wave, snch as an electromagnetic wave, when it passes from one medium to another in which the wave velocity is different. 

Since light is an electromagnetic wave, its scattering can be explained as radiation from oscillating dipoles, which are excited by the incident beam. The electric field Esca of the scattered wave is, therefore, proportional to the dipole moment p ... 

Light is a form of electromagnetic radiation, that is, it can be described as an electromagnetic wave [1, 2]. Neglecting lateral boundaries, a collimated beam of monochromatic light can be described as a planar wave. The electric field vector of this wave as a function of position and time is Equation 16.1 ... 

Produced a set of equations, known as Maxwell s Equations that explain the properties of magnetic and electric fields and help show that light is an electromagnetic wave. 

Light is an electromagnetic wave, and its propagation can be derived from the well-known Maxwell equations, which in their differential form read as ... 

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