Hypsochromic shift

From Wikipedia, the free encyclopedia
Jump to: navigation, search

Hypsochromic shift is a change of spectral band position in the absorption, reflectance, transmittance, or emission spectrum of a molecule to a shorter wavelength (higher frequency). Because the blue color in the visible spectrum has a lower wavelength than most other colors, this effect is also commonly called a blue shift.

This can occur because of a change in environmental conditions: for example, a change in solvent polarity will result in solvatochromism. A series of structurally related molecules in a substitution series can also show a hypsochromic shift. Hypsochromic shift is a phenomenon seen in molecular spectra, not atomic spectra - it is thus more common to speak of the movement of the peaks in the spectrum rather than lines.

\Delta\lambda = \lambda^{\mathrm{state 1}}_{\mathrm{observed}} - \lambda^{\mathrm{state 2}}_{\mathrm{observed}} where \lambda is the wavelength of the spectral peak of interest and \lambda^{\mathrm{state 1}}_{\mathrm{observed}} > \lambda^{\mathrm{state 2}}_{\mathrm{observed}}

β-acylpyrrole will show a hypsochromic shift of 30-40nm in comparison with α-acylpyrroles.

See also[edit]