Uv Visible Spectroscopy Definitions

UV visible spectroscopy definitions

All the basic terms mentioned in UV visible spectroscopy that you should know very well before going to study UV visible spectroscopy. here we are providing All important definitions which are frequently asked in university exams. we will cover UV visible spectroscopy definitions.

you should understand the basic concepts before going to understand the UV visible spectroscopy chapter. if you understand the basic concept of a particular chapter then you will be able to take good knowledge of that chapter.


It is a kind of radiation including visible light radio waves, gamma rays, x-rays in which electric and magnetic fields vary simultaneously.

  1. Visible light

It is a portion of the electromagnetic spectrum that is visible to the eye. (400-800mm)

  1. Electromagnetic spectrum

Electromagnetic spectrum ( EM spectrum) is all forms of electromagnetic radiation where the only difference in the types of radiation is their wavelength and frequencies.

  1. Molecular spectra

A spectrum of radiation due to electron transition and other quantum energy changes within the molecule and consists of series of characteristic spectrum bonds.

  1. Absorption spectroscopy

It is the spectroscopy technique that measures the absorption of radiation as a frequency or wavelength due to interaction with simple.

  1. Wavelength

The wavelength is the linear distance in cm traveled by one complete wave.

  1. Wave no

It is the frequency of waves measured in cycles per unit distance.

  1. Frequency

Frequency is the number of occurrences of a repeating event per unit time.

UV visible spectroscopy definitions
  1. Absorbance

It is the measure of the capacity of a substance to absorb the light of a specified wavelength. It is equal to the logarithm of reciprocal transmittance.

  1. Transmittance

Transmittance is defined as the ratio of the intensity of light emerging from the solution to that of incident light entering.

  1. Auxochrome

Some functional groups like OH, NH2, CL, etc, when attaching to chromophore effects both intensity and wavelength are called auxochome.

  1. Bathochromic shifts

When two chromophores are adjacent to each other, the absorption maximum shifts to a longer wavelength is called bathochromic shifts.


  1. Hyperchromic shifts

The intensity of absorption is increased is called hyperchromic shifts.

  1. Hypochromism

It is a change of spectrum bond position in absorption, reflect the transmittance or emission spectrum of a molecule to a shorter wavelength.

  1. Wavelength maxima

It refers to the wavelength in the absorption spectrum where the absorbance is maximum.

  1. Specific absorbance

It is the maximum absorbance of 1% solution over the 1cm path length measured by spectrophotometer.

  1. Molar absorptivity

It is the measure of how the chemical species absorb the given wavelength of light.

  1. Cut-off wavelength for solvents

It is usually the wavelength at which the frequency is equal to 405.

  1. Isoabsorptive point

It is the specific wavelength wave number or frequency at which the total absorbance of a sample does not change during the chemical reaction or physical changes of the sample.

  1. Spectral bandwidth

It is the wavelength interval in which radiated spectral quantity is not half of its maximum value.

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