Wavelength electromagnetic radiation

Modern theories suggest that our concept of space breaks down on a scale of Hr 34 m, so that may constitute a lower bound to electromagnetic radiation wavelength. 

Table 1 shows the refractive indices for several materials. The variation of refractive index as a function of electromagnetic radiation wavelength (dispersion spectrum) provides simultaneous information about the polarizibility and absorption properties of the sample. The rapid development of modern optical and imaging technologies such as lasers and photodiode arrays creates opportunities for application of refractometry to small analytical systems and multidimensional monitoring. 

Electromagnetic radiation Wavelength range Wavenumber range Energy range... 

To get the frequency v in centimeters-, the nonstandard notation favored by spectioscopists, one divides the frequency in hertz by the speed of light in a vacuum, c = 2.998 x lO " cm s-, to obtain a reciprocal wavelength, in this case, 4120 cm-. This relationship arises because the speed of any running wave is its frequency times its wavelength, c = vX in the case of electromagnetic radiation. The Raman spectral line for the fundamental vibration of H2 is 4162 cm-. .., not a bad comparison for a simple model. 

The electric field of electromagnetic radiation completes 4.00 x lO - " complete cycles in 1.00 s. What are the period and frequency of the oscillation, and what is its wavelength What is the frequency in units of cm ... 

The hydrogen atom attached to an alkane molecule vibrates along the bond axis at a frequency of about 3000 cm. What wavelength of electromagnetic radiation is resonant with this vibration What is the frequency in hertz What is the force constant of the C II bond if the alkane is taken to be a stationary mass because of its size and the H atom is assumed to execute simple harmonic motion ... 

Thus, for electromagnetic radiation of frequency, V, the wavelength in vacuum is longer than in other media. Another unit used to describe the wave properties of electromagnetic radiation is the wavenumber, V, which is the reciprocal of wavelength... 

A graph of a sample s absorbance of electromagnetic radiation versus wavelength (or frequency or wavenumber). 

Absorption of a photon is accompanied by the excitation of an electron from a lower-energy atomic orbital to an orbital of higher energy. Not all possible transitions between atomic orbitals are allowed. For sodium the only allowed transitions are those in which there is a change of +1 in the orbital quantum number ) thus transitions from s—orbitals are allowed, but transitions from s d orbitals are forbidden. The wavelengths of electromagnetic radiation that must be absorbed to cause several allowed transitions are shown in Figure 10.18. 

The absorptivity and molar absorptivity give, in effect, the probability that the analyte will absorb a photon of given energy. As a result, values for both a and 8 depend on the wavelength of electromagnetic radiation. 

Spectroscopy is basically an experimental subject and is concerned with the absorption, emission or scattering of electromagnetic radiation by atoms or molecules. As we shall see in Chapter 3, electromagnetic radiation covers a wide wavelength range, from radio waves to y-rays, and the atoms or molecules may be in the gas, liquid or solid phase or, of great importance in surface chemistry, adsorbed on a solid surface. 

In a vacuum all electromagnetic radiation travels at the same speed, the speed of light c, and may be characterized by its wavelength X, in air or vacuum, or by its wavenumber v or frequency v, both conventionally in a vacuum, where... 

An issue that is still only just being resolved concerns the use of the word wavenumber . Whereas the frequency v of electromagnetic radiation is related to the wavelength X by... 

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