Physics:Bathochromic shift
In spectroscopy, bathochromic shift (from el βαθύς (bathys) 'deep', and χρῶμα (chrōma) 'color'; hence less common alternate spelling "bathychromic") is a change of spectral band position in the absorption, reflectance, transmittance, or emission spectrum of a molecule to a longer wavelength (lower frequency).[1] Because the red color in the visible spectrum has a longer wavelength than most other colors, the effect is also commonly called a red shift.
Hypsochromic shift is a change to shorter wavelength (higher frequency).
Conditions
It can occur because of a change in environmental conditions: for example, a change in solvent polarity will result in solvatochromism.[2]
A series of structurally-related molecules in a substitution series can also show a bathochromic shift. Bathochromic 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.
- [math]\displaystyle{ \Delta\lambda = \lambda\!_{\text{state 2} \atop \text{observed}} - \, \lambda\!_{\text{state 1} \atop \text{observed}} }[/math]
where [math]\displaystyle{ \lambda }[/math] is the wavelength of the spectral peak of interest and [math]\displaystyle{ \lambda\!_{\text{state 2} \atop \text{observed}} \gt \, \lambda\!_{\text{state 1} \atop \text{observed}}. }[/math]
Detection
Bathochromic shift is typically demonstrated using a spectrophotometer, colorimeter, or spectroradiometer.
See also
References
- ↑ Kamlet, Mortimer J.; Taft, R. W. (1976). "The solvatochromic comparison method. I. The .beta.-scale of solvent hydrogen-bond acceptor (HBA) basicities". Journal of the American Chemical Society 98 (2): 377–383. doi:10.1021/ja00418a009. ISSN 0002-7863.
- ↑ Buncel, Erwin; Rajagopal, Srinivasan (1990). "Solvatochromism and solvent polarity scales". Accounts of Chemical Research 23 (7): 226–231. doi:10.1021/ar00175a004. ISSN 0001-4842.
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