The range of the electromagnetic spectrum is from the smallest wavelength of Gamma radiations as 1 p with the lowest frequency of radiation and the largest wavelength of radio waves as 100 Mm. The human eye can detect an only a smaller portion of the light spectrum related to the thermal perception of heat radiated and the sensitivity of detection is for the infrared radiation and VIS spectrum. The UV-VIS spectrophotometry consists of a range of UV spectrum as 200-380 nm, the range of VIS is 380-770 nm. The instrument used in the spectrophotometer consists of a slightly broader range of 190 nm and the UV region of 1100nm in the near Infrared region (Skoog, et al., 2007).

Figure 1: UV VIs region

        The ultraviolet-visible spectrophotometry (UV-Vis or UV/Vis) is referred to as the absorption spectroscopy in the spectral region. The light spectrum in the region is visible, near UV, and near IR region. The quantitative determination of concentration is related to these three regions and the absorber of the solution is conjugated organic compounds and transition ions. The Beer Lambert law states the absorbance and transmittance of the solution and according to the law, the absorbance is directly related to the concentration of the material (Skoog, et al., 2007).

            The levels of absorbance changes and can be verified by the molar extinction coefficient. The electromagnetic radiations travel at the speed of light that is shown by “c” and it is equal to . The wavelength is the distance between two peaks (), a number of peaks passing through the point in unit time are frequency (v). The mathematical relation becomes,

        The law of quantum can be applied to measure the energy of every single light particle that is a photon. The energy of radiation is "E", Planck's constant is "h", and the speed of light is v. The relation shows that relation between the energy and wavelength is inversely proportional.

VIS-NIR spectrometer (CHEM USB4-VIS-NIR )   

        For the analysis of the A mixture of absorbing substances, in this lab experiment the CHEMUSB4-USB-NIR is used. As we know that; the USB-VIS-NIR is the miniature spectrometer, for the pre-configured of the visible as well as the near the IR measurements. UB-VIS-NIR is stand for “Ultra violet (UV), visible (VIS) near infra-Red (NIR) radiation is explained.

Now it has the general’s value around about;

UV radiation   300 to 400nm

VIS radiation 400 to 765 radiation

NIR radiation 765 to 3200nm

        For the analysis of the A mixture absorbing substance in this lab experiment it’s covering the wide range of wavelength from 350 to 100nm, an the US-VIS-NIR spectrometer also have the high performance that fits into a palm, for your hand on the new flexibility application of spectrometry. The approach of the module is customize for the absorbance as well as the measurement of the reflectance’s by the wide sampling array of eth light sources as well as accessories.

Figure: USB400-UV-VIS-NIR Spectrometer

        The above USB400-VIS-NIR spectrometer is the packages of the high tech built-in for the light sources ,  and approximately 1-cm cuvettes has the holder of the USB4000 Spectrometer as well as has the high speed of electronics into the small footprint of the system .With the proper use of the software the spectrometer provide the real , of the PC based spectroscopy as well as capture the full spectra from 25ms by using the 3648 data points.

In below figure there are the following proprieties of the USB4000-UV-VIS-NIR is shown below in below table;

References of UV Vis regions of A mixture of absorbing substances

Skoog, D. A., Holler, F. J. & Crouch, S. R., 2007. Principles of Instrumental Analysis. In: s.l.:Thomson Brooks/Cole, p. 1039.