Spectrum is a concept introduced by Isaac Newton in the seventeenth century, denoting the totality of all values of a physical quantity. Energy, mass, optical radiation. It is the latter that is often meant when we speak of the spectrum of light. Specifically, the light spectrum is a combination of optical radiation bands of different frequencies, some of which we can see daily in the outside world, while some of them are inaccessible to the naked eye. Depending on the possibility of perception by the human eye, the spectrum of light is divided into the visible and invisible parts. The latter, in turn, is infrared and ultraviolet light.
Spectrum Types
There are also different types of spectra. Three are distinguished, depending on the spectral density of the radiation intensity. Spectra can be continuous, ruled, and striped. The types of spectra are determined using spectral analysis.
Continuous spectrum
The continuous spectrum is formed by high-temperature solids or high-density gases. The well-known rainbow of seven colors is a direct example of a continuous spectrum.
Line spectrum
The line spectrum also represents the types of spectra and comes from any substance in a gaseous atomic state. It is important to note here that it is in the atomic, and not molecular. Such a spectrum provides an extremely low interaction of atoms with each other. Since there is no interaction, atoms emit waves of permanently the same length. An example of such a spectrum is the glow of gases heated to a high temperature.
Striped spectrum
The striped spectrum visually represents individual bands clearly delimited by sufficiently dark gaps. Moreover, each of these bands is not a radiation of a strictly defined frequency, but consists of a large number of light lines closely spaced to each other. An example of such spectra, as in the case with the line, is the glow of vapor at high temperature. However, they are no longer created by atoms, but by molecules that have an extremely close common bond, which causes such a glow.
Absorption spectrum
However, the types of spectra do not end there. Additionally, a species such as the absorption spectrum is isolated. In spectral analysis, the absorption spectrum is dark lines against a continuous spectrum and, in essence, the absorption spectrum is an expression of the dependence of the wavelength on the absorption coefficient of a substance, which can be more or less high.
Although there is a wide range of experimental approaches to measuring absorption spectra. The most common experiment is when the generated white light beam is passed through a cooled (for the absence of particle interaction and, therefore, luminescence) gas, after which the intensity of the radiation passing through it is determined. The transferred energy may well be used to calculate the absorption.