are part of optical spectra of polyatomic systems, including condensed materials, large molecules etc. Each line corresponding to one level in atom splits in molecules. When the number of atoms is large, one gets continuum of energy levels, so called "spectral bands". They are often labeled in the same way
as the monoatomic lines.
The bands may overlap. In general, energy spectrum can be given with a density function, describing the number
of energy levels of the quantum system for a given interval. Spectral bands have constant density, and when the bands overlap, the corresponding densities are added.
Band spectra is the name given to group of lines that are closely spaced, arranging in a regular sequence that appears to be a band. It is a coloured band, separated by dark space on the two sides, arranged in regular sequence. In one band, there are various sharp and wider colour lines that are closer on one side, and wider on other side. The intensity in each band falls off from definite limits, and indistinct on the other side. In complete band spectra, there is a number lines in a band.
This spectra is produced, when the emitting substance is in the molecular state. Therefore, they are also called molecular spectra.
It is emitted by a molecule in vacuum tube
In electronics, a vacuum tube, electron tube , or thermionic valve , reduced to simply "tube" or "valve" in everyday parlance, is a device that relies on the flow of electric current through a vacuum...
, C-arc core with metallic salt. Band spectra is the combinations of many different spectral lines
A spectral line is a dark or bright line in an otherwise uniform and continuous spectrum, resulting from a deficiency or excess of photons in a narrow frequency range, compared with the nearby frequencies.- Types of line spectra :...
, resulting from rotational, vibrational and electronic transition
Molecular electronic transitions take place when electrons in a molecule are excited from one energy level to a higher energy level. The energy change associated with this transition provides information on the structure of a molecule and determines many molecular properties such as color...