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A UV-Vis spectrophotometer is an analytical instrument that measures the amount of ultraviolet (UV) and visible light that is absorbed by a sample. It is a widely used technique in chemistry, biochemistry, and other fields, to identify and quantify compounds in a variety of samples.
Ultraviolet-visible (UV-vis) spectroscopy involves energy levels that excite electronic transitions. Absorption of UV-vis light excites molecules that are in ground-states to their excited-states. [5] Visible region 400–700 nm spectrophotometry is used extensively in colorimetry science. It is a known fact that it operates best at the range ...
If Albert Einstein's photoelectric law is applied to a free molecule, the kinetic energy of an emitted photoelectron is given by E k = h ν − I , {\displaystyle E_{\text{k}}=h\nu -I\,,} where h is the Planck constant , ν is the frequency of the ionizing light, and I is an ionization energy for the formation of a singly charged ion in either ...
In modern spectrographs in the UV, visible, and near-IR spectral ranges, the spectrum is generally given in the form of photon number per unit wavelength (nm or μm), wavenumber (μm −1, cm −1), frequency (THz), or energy (eV), with the units indicated by the abscissa.
UV-Vis absorption SEC is a recent technique that is continuously evolving. However, many advantages have been observed over other techniques. However, many advantages have been observed over other techniques.
Figure 1: Simplified schemes of the Variable UV-Vis detector compared to PhotoDiode Array detector. In the Variable UV-Vis the entire optical bench is located before the flow cell whereas in the diode array the flow rate is positioned before the main optical bench. A schematic of the optical systems is shown in Figure 1.
Ultraviolet–visible spectroscopy (UV–vis) can distinguish between enantiomers by showing a distinct Cotton effect for each isomer. UV–vis spectroscopy sees only chromophores , so other molecules must be prepared for analysis by chemical addition of a chromophore such as anthracene .
High borate borosilicate glasses exist also in high UV transmission versions with high transmission also at 254 nm. [22] Glass with very low content of potassium can be used with bialkali photocathodes to lower the background radiation from the potassium-40 isotope. Ultraviolet glass transmits visible and ultraviolet down to 185 nm. Used in ...