The difference between UV-visible spectrophotometer and visible spectrophotometer

The difference between the ultraviolet-visible spectrophotometer and the visible spectrophotometer is that the measurement wavelength range is different. The ultraviolet light is generally used for a hydrogen lamp, and the measurement wavelength ranges from 180 to 350 nm. It can be seen that a tungsten lamp is generally used, and the measurement wavelength range is 320 to 1000 nm. The so-called UV-Vis spectrophotometer means that the instrument can be replaced with a light source and can measure compounds with absorption peaks in the ultraviolet and visible portions.

It is normal to find that the absorbance exceeds 2 and it is no longer displayed.

Absorbance is the negative logarithm of light transmittance. When the absorbance exceeds 2, the light transmittance is less than 1%. Below the detection limit of the instrument, it is no longer displayed.

As for whether or not you can use a spectrophotometer, it depends on the wavelength you are measuring.

Specifically, it is divided into the following three points:

1. The light source is different: the light source of the visible spectrophotometer generally uses only tungsten light, while the ultraviolet visible spectrophotometer uses two light sources of tungsten light and xenon lamp, and at the same time, the switching parts of the two light source lights are added. This is because the spectral range of the tungsten lamp is mainly in the near-infrared range, and the xenon lamp is mainly on the ultraviolet side. It is also because of the different light sources, the UV-Vis spectrophotometer also has a xenon lamp power supply dedicated to the work of xenon lamps.

2, the difference between the optical components: because the glass can absorb the ultraviolet wave, but has a better permeability to the near-infrared end, so some optical components of the spectrophotometer can use glass, and the ultraviolet-visible spectrophotometer can not For the use of glass components, quartz optical components are generally used. At the same time, for this reason, there is a difference in the choice of the cuvette. It can be seen that the spectrophotometer can use a glass cuvette, and the ultraviolet-visible spectrophotometer generally uses a quartz cuvette.

3, the difference of the receiver: Because the UV-Vis spectrophotometer has more UV waves, so the choice of receiver is not the same. More sensitive to ultraviolet light, the price of this type of receiver is much more expensive than the receiver of the visible spectrophotometer.