filters and monochromator used in UV visible spectroscopy

In this ppt topics covered are filters and monochromators used in UV visible spectroscopy. There are beneficial to gain knowledge of UV spectrophotometer. This technique is used for the determination of particular wavelength needed for absorption. this technique is also useful for the detection of emitted light.

1. Nagpur college of pharmacy
TOPIC NAME :FILTERS AND MONOCHROMATORS
MADE BY : TANUSHRI SAKHARKAR
GUIDED BY : MRS. SUJATA RAUT MAM

2. Filters:
Filters are prepared from special material and
allow transmission of only limited wavelength
region, while absorb most of radiaton.

3. Types of filters :
Filters

Interference Absorption

4. Interference filters

5. Construction:
1. Dielectric medium : Most commonly calcium fluoride and
magnesium fluoride are used in influence filter.
2. Two metal film above and below the dielectric film
3. Whole assembly is enclosed in glass.
Working:
When white light (400nm-800nm) is strike on the inference filter
half light is pass through the first film of metal and half reflect while
half light is again transmitted by the lower metal film and
interference occur.

6. Absorption filters:
Absorption filters consist of a coloured glass suspended in gelatin and
sandwiched between two glass plates. They absorb the unwanted
radiation and transmit the rest of the radiation.

7. Monochromators
Monochromator is a component of UV- visible spectrometer which
is used to produce a beam monochromatic

8. Components:
1.
2.
3.
4.
ENTRANCE SLIT : WHICH ADMIT POLYCHROMATIC RADIATION FROM SOURCE.
COLIMATING DEVICE : EITHER A LENS OR MIRROR
DISPERSION DEVICE : EITHER A PRISM OR GRATING WHICH RESOLVE THE
RADIATION COMPONENT INTO DIFFERENT WAVELENGTH
EXIT SLIT

10. Dispersing elements:
1.
2.
Prism
Grating elements

1. Prism: Prisms are used to disperse visible and uv
radiations. The common prisms are constructed of
quartz for the uv region and silicate glass for the
visible region.

12. Gratings:
A diffraction grating consists of a series of closely spaced parallel
grooves cut into a hard glass, metallic or ceramic surface. When light
rays incident on grating on grooves, the rays get scatter in different
angles in particular direction.