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The spectra of basic, acid and intermediate pH solutions are shown. The analytical concentration of the dye is the same in all solutions. In spectroscopy, an isosbestic point is a specific wavelength, wavenumber or frequency at which the total absorbance of a sample does not change during a chemical reaction or a physical change of the sample ...
In physical and analytical chemistry, colorimetry or colourimetry is a technique used to determine the concentration of colored compounds in solution. [1] A colorimeter is a device used to test the magnitude of a solution by measuring its absorbance of a specific wavelength of light (not to be confused with the tristimulus colorimeter used to ...
Woodward's rules, named after Robert Burns Woodward and also known as Woodward–Fieser rules (for Louis Fieser) are several sets of empirically derived rules which attempt to predict the wavelength of the absorption maximum (λ max) in an ultraviolet–visible spectrum of a given compound.
Also, Max Planck's explanation of blackbody radiation involved spectroscopy because he was comparing the wavelength of light using a photometer to the temperature of a Black Body. [11] Spectroscopy is used in physical and analytical chemistry because atoms and molecules have unique spectra. As a result, these spectra can be used to detect ...
A colorimeter is a device used in colorimetry that measures the absorbance of particular wavelengths of light by a specific solution. [1] [2] It is commonly used to determine the concentration of a known solute in a given solution by the application of the Beer–Lambert law, which states that the concentration of a solute is proportional to the absorbance.
Absorption spectroscopy is employed as an analytical chemistry tool to determine the presence of a particular substance in a sample and, in many cases, to quantify the amount of the substance present. Infrared and ultraviolet–visible spectroscopy are particularly common in analytical applications. Absorption spectroscopy is also employed in ...
Spectrophotometry is a branch of electromagnetic spectroscopy concerned with the quantitative measurement of the reflection or transmission properties of a material as a function of wavelength. [2] Spectrophotometry uses photometers , known as spectrophotometers, that can measure the intensity of a light beam at different wavelengths.
The higher-energy near-IR, approximately 14,000–4,000 cm −1 (0.7–2.5 μm wavelength) can excite overtone or combination modes of molecular vibrations. The mid-infrared, approximately 4,000–400 cm −1 (2.5–25 μm) is generally used to study the fundamental vibrations and associated rotational–vibrational structure.