Infrared radiation, electromagnetic spectrum

Infrared radiation, electromagnetic spectrum and, 419, 422 energy of. 422 frequencies of, 422 wavelengths of, 422 Infrared spectroscopy, 422-431 acid anhydrides, 822-823 acid chlorides, 822-823 alcohols. 428, 632-633 aldehydes, 428. 730-731 alkanes, 426-427 alkenes, 427 alkynes, 427 amides. 822-823 amines, 428, 952 ammonium salts, 952-953 aromatic compound, 427-428, 534 bond stretching in, 422... 

The so-called peak power delivered by a pulsed laser is often far greater than that for a continuous one. Whereas many substances absorb radiation in the ultraviolet and infrared regions of the electromagnetic spectrum, relatively few substances are colored. Therefore, a laser that emits only visible light will not be as generally useful as one that emits in the ultraviolet or infrared ends of the spectrum. Further, witli a visible-band laser, colored substances absorb more or less energy depending on the color. Thus two identical polymer samples, one dyed red and one blue, would desorb and ionize with very different efficiencies. 

The radiation from a blackbody is conhnuous over the electromagnetic spectrum. The use of the term black in blackbody, which implies a particular color, is quite misleading, as a number of nonblack maferials approach blackbodies in behavior. The sun behaves almost like a blackbody snow radiates in the infrared nearly as a blackbody. At some wavelengths, water... 

The vibrational motions of the chemically bound constituents of matter have fre-quencies in the infrared regime. The oscillations induced by certain vibrational modes provide a means for matter to couple with an impinging beam of infrared electromagnetic radiation and to exchange energy with it when the frequencies are in resonance. In the infrared experiment, the intensity of a beam of infrared radiation is measured before (Iq) and after (7) it interacts with the sample as a function of light frequency, w[. A plot of I/Iq versus frequency is the infrared spectrum. The identities, surrounding environments, and concentrations of the chemical bonds that are present can be determined. 

Celsius. The energy distribution of the radiation emitted by this surface is fairly close to that of a classical black body (i.e., a perfect emitter of radiation) at a temperature of 5,500°C, with much of the energy radiated in the visible portion of the electromagnetic spectrum. Energy is also emitted in the infrared, ultraviolet and x-ray portions of the spectrum (Figure 1). 

Electromagnetic spectrum (Section 12.5) The range of electromagnetic energy7, including infrared, ultraviolet, and visible radiation. 

The infrared region of the electromagnetic spectrum lies between the wavelengths 1000 and 15000 nm (Kemp AVellacdo, 1980). Absorption of radiation in this region by organic compounds has been known since 1866, when Tyndall first conducted experiments on the interaction of radiation with compounds such as chloroform, methyl and ethyl iodides, benzene. 

In the electromagnetic spectrum, microwave radiation occurs in an area of transition between infrared radiation and radiofrequency waves, as shown in Fig. 1.1. The wavelengths are between 1 cm and 1 m and frequencies between 30 GHz and 300 MHz. 

Fig. 1 A portion of the electromagnetic spectrum comparing infrared energy with other forms of radiation.

Absorption of radiation in the infrared region of the electromagnetic spectrum results in changes in the vibrational energy of molecules. Energy changes are typically 6 x 103 to 42 x 103J mol-1, which corresponds to 250-... 

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