Instrument details:
Make: Shimadzu
Model No: UV 2450
Essential specification 
Wavelength range: 190 nm - 1100 nm (Effective measuring range is 190 - 900 nm)
Spectral band width (slit width): 6 steps in 0.1 / 0.2 / 0.5 / 1 / 2 / 5 nm
Resolution: 0.1 nm
Wavelength accuracy: ± 0.3 nm (at slit width of 0.2 nm) Automatic wavelength calibration is possible
Photometric range: Absorbance: -4 - 5 Abs Transmittance: 0 - 999.9%T
Software: Shimadzu-UV Probe
Most appropriate response is set automatically. The fastest response is 0.1 sec and One-touch setting is available with AUTO ZERO command
Minimum sample volume: 1 ml
Light Source: 50W halogen lamp (long life type 2000H), Deuterium lamp (socket type). Automatic position alignment for maximum sensitivity.
Monochromator: High performance blazed holographic grating is used (UV-2450)
Detector: Photomultiplier R-928
Working principle:
The Principle of UV-Visible Spectroscopy is based on the absorption of ultraviolet light or visible light by chemical compounds, which results in the production of distinct spectra. Spectroscopy is based on the interaction between light and matter. When the matter absorbs the light, it undergoes excitation and de-excitation, resulting in the production of a spectrum.

When matter absorbs ultraviolet radiation, the electrons present in it undergo excitation. This causes them to jump from a ground state (an energy state with a relatively small amount of energy associated with it) to an excited state (an energy state with a relatively large amount of energy associated with it). It is important to note that the difference in the energies of the ground state and the excited state of the electron is always equal to the amount of ultraviolet radiation or visible radiation absorbed by it.