Explain Construction and Working of Double Beam Spectrophotometer. | Spectroscopy | Analytical
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- เผยแพร่เมื่อ 4 ต.ค. 2018
- Spectrophotometers are the instruments which are working at a wavelength where the absorbance is maximum. Such wavelength of the radiations whose absorbance is maximum is called λmax.
With the help of spectrophotometers we can have qualitative as well as quantitative analysis of any type of sample it may be solid, liquid or gas. It may be colored or colourless. The spectrophotometers are of two types; (i) Single Beam Spectrophotometers, and (ii) Double Beam Spectrophotometers.
The following are the main components of a Single Beam Spectrophotometers:
1. Source of radiations: It may be U.V-light, visible light or I.R. light. U.V. Light can be obtained by heating the filament which is filled with either H2 gas or deuterium. Visible Radiations can be obtained by incandescent lamp with tungsten filament and I.R. Radiations can be obtained by heating Newton's glower at the temp. of 1500-2000 oC. Newton's glower is metallic oxide of Yettrium, Erbium and Zirconium. I.R. radiations can also be obtained by heating glow bar which is Silicon carbide SiC (Carborandum) at the temp. of 1300-1700 oC.
2. Collimating Convex Lens: The function is to collect all the rays coming from the source.
3. Diaphragm: To set the 100% transmittance.
4. Monochromators: To obtain the radiation of one wavelength. The Monochromators may be prism or diffraction gratings.
5. Cuvette or Sample Holder: For U.V. light it should be made up of quartz, for visible light it should be made up of glass and for I.R. light it must be that of rock salts for eg. NaCl. a) If the sample is gas or volatile liquid having low B.P. must be taken in the closed container. b) If it is liquid, one drop of the liquid must be placed between two parallel plates for U-V. the plates must be quartz and for visible it must be glass and for I.R. it is rock salt. c) If it is solutions the solvent used for the preparation of solution must be Cyclohexane, methyl alcohol, ethyl alcohol or any other suitable solvent which is not capable to absorb the radiations incident on it. d) If it is solids then we take about 1mg. of it and is mixed in 100-200 mg. of KBr - prepare slurry. It is cut into smaller circular discs (just like bindle) called pellets. They are dried and placed in the place of cuvette. The diameter of pellets is 10mm. and thickness is 1mm.
6. The Focusing Convex Lens: Its function is to collect all the transmitted light from cuvette and is focused at a point where photo cathode of the photo-cell is placed.
7. Photo-Cell: The transmitted light is incident on it photo cathode converts these radiations into current. It can be amplified using the amplifier if needed.
8. Read out meter or dial: The current is converted into OD or Absorbance in read out meter and by knowing OD we can find out the concentration of the solution i.e. quantitative analysis is possible by applying Beer Lamberts Law.
First of all the source of radiations from U.V. light to visible light to I.R. radiations is started. The light from the source is collected by Collimating convex lens and allowed to fall on monochromator. For each radiations incident on monochromator we are getting the radiations of one wave length only i.e. λ, the monochromatic light is then separated in two beams with the help of two mirrors M1 and M2. One beam is passed through one cuvette containing blank (solvent) and the other through the other cuvette containing sample solution. Optical attenuator is used to reduce the intensity of radiations coming out from blank to that of the intensity of radiation coming from sample solution and both are finally incident on detectors. These may be photo calls or thermocouples. Where the heat is produced which is then converted to current and finally O.D. or Absorbance (A).
The attenuator is connected with pen-which is moving on rotating drum. The graph is obtained on the drum is O D Vs λ. From the graph we can find out λmax and we can have the qualitative analysis. From O.D. or Absorbance we can have the quantitative analysis.
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Sir your video is good but the music in background is irritating me and I can't concentrate
Explanation is very clear 👌
It's so upto point.....sidhi baat no bkwassss.....
It's really good
Your voice is good and will be great without music. And thanks for this smooth illustration.
Thank you too!
No word how to.appreciated ur video
ur videos are awesome.🙋.... plz make a video on interferences in spectral lines....
Good revision , thanks .
Very clear and easy explanation thank 🙏 u
Excellent explanation sir thank you very much sir
Thank u sir. Very useful
Thank u so good explanation wow
Respected Sir,
Very Good Morning. It's really good and nice video. But, you also change please the description box in the single beam spectrophotometer to double beam spectrophotometer .
Thank you so much
Thirumal. V
NICE EXPLANATION ❤
It is realy helpful
Why focusing lens is not used here (does the mirror acts as a focusing lens)
Thanks
Maza aaya!
🙋🏻♀️Hello Sir. It really helped me, especially the working part. 👏👏👏 Excellent video. Very very simple, clear n easy to remember. 👌Superb explanation. 🙏Thank you so much for sharing this video. 👍 Keep up the good work.
This would be better if you attenuated the music, it's distracting.
Nice explained, but the bgm is like that of cartoon stories bgm
Super explanation sir
Thanks and welcome 🙏
Super
It's very helpful for better understanding and quick learning...🤗
Nice Explanation...
So nicely explaind.....
Thank you
thant you very much
Welcome
Are the double beam and bichromatic wavelength (secondary wavelength in automated instruments like C-Pentra400) the same?
Nope
Very good👍
Thank you! Cheers!
Nice video 👍
Thanks 👍
very nicely explained sir ....I have one doubt ..... is dual spectrometer same as double beam spectrophotometer sir?
Yes, it is
Music ❤️❤️❤️
👍
which type of microbes can it measure? and can it monitor and measure continuously with time? how much does it cost? what about it maintenance? thank you in advance
your video is good but the music in background is not suitable for edu vedios
Sir which spectrometer is good for Coloured sample testing
its colorimeter..
How would the impurities not affect the absorbance due to two solutions
May be impurities absorb, so absorption in blank will show up. Which will be considered as zero for real sample. So in sample the absorption due to impurities is already at zero.
can u tell me what is blank solution??
Blank is the solution same as sample but without absorbing media. Eg. If sample is solution of Co in water containing contamination of Fe. So the blank is water with contamination of Fe. Means, we want to nullify all the solvent and contamination and then only signal with Co will be visible.
Please refrain from using background music, it is highly distractive.
Your accent is impossible for some very old people such as my mother or father to know what words you are saying.
www.google.com/search?newwindow=1&q=phonemes+speech+english+text+online
One such site in the list: Visit the web page
tophonetics.com/
Select American. Enter your text without any spelling mistakes. Click Show Transcription. As a result the transcription is displayed, and a "Play" and "Pause" audio graphical user interface control is also displayed.
You can listen to the sentences that you have entered by pressing the "Play" control button (if your computer or device has a sound device with loud speaker or audio transducer installed).
You can learn to improve and reduce your THICK accent by listening to people whose native language is English who are also in the broadcasting industry who are educated with university level training in science. I do not know why it is true, but also know that people with thick accents from around the world have their accents go almost completely away when they sing songs in English. After they stop singing and begin to talk, these thick accent people become much more difficult to know what they are saying. Text to speech synthesis that uses very accurate pronunciations of words is another way of training yourself to speak English without as much THICK accent on your words. American, Canadian, Irish, Scottish, Wales, Australian, New Zealand each have distinctive ways of pronouncing words while talking, but when these people sing their words, their native accents tend to go completely away while singing. Obviously, however, various scientific jargon words are rarely if ever sung in songs to be able to know what they would sound like without any native accents applied.
American and Canadian accents are almost identical with very few exceptions.
Certain localized UK British accents of uneducated people can deceptively pronounce DAH as DERRR.
I also speak some French and have found that less educated native speakers of French also have really thick localized accents that do not exist when you attend university and listen to native very educated native French speakers.
There used to be all kinds of crazy British English accents that changed dramatically in the UK in olden days even when traveling only 5 to 30 km from one local place to another. This all began to change when RADIO BROADCASTING was invented many years ago and was able to normalize the proper pronunciation of words by having highly educated persons read the news of the day to many millions of listeners at a time. With time and travel of people from different places, these crazy accents started to go away so that everyone could know what the others were saying more easily.
One measure of ease of knowing what yourself and others are saying is to use a web browser plugin control for FireFox named "video speed controller." When you speed up a native English speaking person's speech, it should remain understandable at up to 1.4 to 1.7 times playback speed.
Music is annoying
Please remove this background sound.
Simple and nice explaination thank you