Spectral bands

Spectral bands 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, C-arc core with metallic salt. Band spectra is the combinations of many different spectral lines, resulting from rotational, vibrational and electronic transition.

See also

• Band emission