Solution to the spectroscopy query is clearly explained in Atkin's physical chemistry, if you have the 10th edition of it ,then its there on page no. 517 The answer is actually a logical combination of all your three reasons, and has been given a term TUMBLING. And thanks a lot, i am preparing for my TIFR inteview and this video is helping me a lot.
Vibrational spectra does contain rotational lines.When a molecule absobs radiation, which is enough to cause change in vibrational energy of the molecule, its rotational energy may also change because each V.E level contains very closely spaced rotational levels. And that's why Vibrational spectra appear as bands rather than lines.
During IR spectroscopy there occurs rotational transitions along with vibrational ones to conserve the angular momentum this rotational structures can be obtained under high resolution. Infact PR band is obtained in the IR spectrum of diatomic molecules under the selection rule ∆J=(+-)1, if you take polyatomic molecule then for the perpendicular mode of vibration you will get the PQR band with selection rule ∆J=0,(+-)1.... For the diatomic molecules this perpendicular mode is not obtained so you only get the PR band in that IR spectrum so it is often called a band structure with band origin missing......
I also agree with your second opinion. Vibrational energies of simple representive diatomic molecules such as HF,HCl etc.are in the region 4000 to 200cm-1 while such molecules have rotational energies of 1 to 10cm-1.From this,It can be considered that these molecules execute vibrations and rotations quite independently of each other.
Along with the reasons what sir gave, I think the time period for one vibration is much less compared to time period of rotation and hence within one rotation there will be thousands of vibrations of molecules or in other words for one vibration the molecule is almost not rotating and hence we can't see rotational spectra with IR. May be one possible answer.
The most important thing I thought is the set up we have used as for a particular kind of spectroscopy we use different machine which can show only that kind of graphical representation or peaks...
The thing is, like all energies, even rotational energy is quantized. So, to get a peak, there is a particular value which can give excitation. That does not lie in the IR region. The second answer is the most closest to this.
Sir my opinion is... as u said When IR radiation is used which has High Energy than microwave, what happens in rotational spectroscopy is Energy increases, B increases, hence the spacing between the lines (u have given the spacing as 2B in your video on rotational spectroscopy) becomes very very large so that it wont appear in the IR spectrum... So i will go with option number 3
Answer to your question : roational lines are their in the spertra. And we do not see the rotational spectra bcoz of low resolution of your instruments. Believe me i have done insitu FTIR and i have seen the rotation lines bcoz our instrument at IIT GN is very advanced. Even if you want i can share the spectra recorded by me and you can see the rotational lines.
Vibration levels have high energy gap as compare to rotational So when we use frequency in IR region , population difference between two rotational level is not there (as two level have equal population due to high energy radiation used) Hence we don't see any peaks That's what i think Tell me if u think m right
Sir I may wrong but I think there is a contribution from rotational levels. If I consider mass spectrum we get only one line for one specific m/z value, similarly in H1NMR we get line for specific X axis, in the same way in IR spectrum if resonance occurs for a particular bond at a specific wavelength we should get only one line because transition should occur from one specific vibrational level to upper specific vibrational level. But practically transition might occur from lower specific vibrational level to the upper vibrational level along with some closely spaced rotational levels, thats why without getting only lines we get a little bit broad spectrum. There is similar explanation for UV spectrum also. A lot of transitions are possible along with the specific one, thats why we are getting broad spectrum.
@@gatechemistry agar aapne dia hai to definitely pta hoga na...... Gate chemistry.... I want to ask you how can i prepare for that I cracked tifr 2020.... I am pursuing Mtech from IIT kharagpur and also qualified CSIR JRF with AIR-93 ...
I really liked your video. Very elaborate as per the interview is concerned. I have a question about the Research Proposal that one is supposed to write prior to the interview. How in-depth should it be and what are the aspects it should have as a must? I am a B.Tech graduate from Biotechnology background. Though you are from chemistry background your general tips about the scientific write-up would be helpful. Thank you in advance
In the question: why Pd is preferred over Fe and Ni, what are the reasons apart from it's functional group tolerance and insensitivity towards air and water?
Gas molecules in rotational Spectra as it can rotate around centre of gravity due to neglected intermolecular forces...solids in ir cannot rotate bt can vibrate as it is rigid....bt heteronuclear gas molecules in ir may give vibration-rotational Spectra (p n R branch)
Gate chemistry the only requirement of ir is change in dipole moment. If solid ir is only possible then how we can say H2O is ir active. It true most of the time we do solid ir but others also possible. Sir, i am not sure but this could be true.
Sir I think rotation is takes place in NMR ,so in NMR we use magnetic field so the atoms are rotated but in the case of IR we do not use magnetic field that's why in IR rotational lines are not observed. Sir tell me this is correct or not
Sir I have my specialisation in organic chemistry..but I have not so good knowledge in that...I have good knowledge in inorganic and physical and I want to do research in bioinorganic...so please tell me what should I do for my IISC Bangalore interview and IITs interview.
Gate chemistry Thankyou sir...and can you please tell what all topics of organic chemistry are frequently asked so that I can prepare that too for a safe side
Can I apply for msc in chem if I am from pure bio background as I done +2 with bio n bsc with chem botany n geology being chem as onrs subject..Please help
Hello sir! I've a small doubt regarding csir net application. I filled the form and paid the amount required through debit card and I got the fully filled application form including photo signature n payment details. Do I need to send hard copy to csir like last year?
Sir, actually one more thing is your 2nd opinion is also very close reply to that question. Becz when u use high energy electromagnetic radiation the molecule dissociates(because gas phase molecules have low dissociation energy than solid phase molecules, since in IR spectroscopy we are using solid phase molecules and in rotational spectroscopy we are using gas phase molecules) Just bear with my answer, if its not convincing.. thank you sir
I require a little help of you sir, How do I find my area of interest in research, since I love organic chemistry, but I also like biochemistry and physical, I'm confused, plzz help me with that, its a request.
IR energy is very high compared to rotational energy. If the source is IR source,ur energy measurement is of the order 1000cm-1 and rotational is 10cm-1. So it sweeps. It's like neglecting 10 paise in 10Rs. This is similar to uv. Why we cannot see vibrational and rotational pattern in uv pattern. Why are we able to see a microbe with microscope but not with naked eye. Why are we seeing objects with naked eye, not with microscope, i.e. measurement incompatibility
if we r using the microwave EM radiation then there is no question of interference with IR, but if infrared is the EM radiation then there is no case case where we can doubt whether there would b resonance to have the stretching band in IR or not there would b for sure as well as that would b accompanied by its rotational line if gaseous sample is used otherwise not
Sir do you have any idea about ongc interview ..if possible plz share it .....i m phd student and have finished my table work now i m writing my thesis ..i gave gate 2018 so this time it is a chance for me to get ongc call...the qstion is , wt would be appropriate ans if they ask me about my phd..should i tell them about my Ph.D. or not because it is still not finished ...so plz help me ...and what type of questions are generally asked ?
Can someone tell me what kind of login I'd did we enroll for barc. Like was it mail I'd or phone number, or anything else. I don't remember and I am unable to download my Hall ticket
Chemshort u have to use login id. If u forget your login id, no pblm. Go to student login and click forget login id. After that u can create a new login id
Solution to the spectroscopy query is clearly explained in Atkin's physical chemistry, if you have the 10th edition of it ,then its there on page no. 517
The answer is actually a logical combination of all your three reasons, and has been given a term TUMBLING.
And thanks a lot, i am preparing for my TIFR inteview and this video is helping me a lot.
Vibrational spectra does contain rotational lines.When a molecule absobs radiation, which is enough to cause change in vibrational energy of the molecule, its rotational energy may also change because each V.E level contains very closely spaced rotational levels. And that's why Vibrational spectra appear as bands rather than lines.
Jidnyasa Nagarkar
Yeaa..i also think it is right explanation
During IR spectroscopy there occurs rotational transitions along with vibrational ones to conserve the angular momentum this rotational structures can be obtained under high resolution. Infact PR band is obtained in the IR spectrum of diatomic molecules under the selection rule ∆J=(+-)1, if you take polyatomic molecule then for the perpendicular mode of vibration you will get the PQR band with selection rule ∆J=0,(+-)1....
For the diatomic molecules this perpendicular mode is not obtained so you only get the PR band in that IR spectrum so it is often called a band structure with band origin missing......
This is due to Fermi reseonance where frequency of rotational spectrum is involved
I also agree with your second opinion. Vibrational energies of simple representive diatomic molecules such as HF,HCl etc.are in the region 4000 to 200cm-1 while such molecules have rotational energies of 1 to 10cm-1.From this,It can be considered that these molecules execute vibrations and rotations quite independently of each other.
Along with the reasons what sir gave, I think the time period for one vibration is much less compared to time period of rotation and hence within one rotation there will be thousands of vibrations of molecules or in other words for one vibration the molecule is almost not rotating and hence we can't see rotational spectra with IR. May be one possible answer.
The most important thing I thought is the set up we have used as for a particular kind of spectroscopy we use different machine which can show only that kind of graphical representation or peaks...
The thing is, like all energies, even rotational energy is quantized. So, to get a peak, there is a particular value which can give excitation. That does not lie in the IR region. The second answer is the most closest to this.
Rotational spectra become superimposed with the vibrational spectra and thus in IR the peak become broader instead of a sharp peak
liquid samples are used for the pure IR spectrum while in gaseous samples of molecules we have the interference of rotational lines in IR spectrum..
Sir my opinion is... as u said When IR radiation is used which has High Energy than microwave, what happens in rotational spectroscopy is Energy increases, B increases, hence the spacing between the lines (u have given the spacing as 2B in your video on rotational spectroscopy) becomes very very large so that it wont appear in the IR spectrum... So i will go with option number 3
Answer to your question : roational lines are their in the spertra. And we do not see the rotational spectra bcoz of low resolution of your instruments. Believe me i have done insitu FTIR and i have seen the rotation lines bcoz our instrument at IIT GN is very advanced. Even if you want i can share the spectra recorded by me and you can see the rotational lines.
Naveen Tak 16510045 yes sir this may be due of low resolution, bcoz in most of the cases, rotational vibrational spectra obtained.
You are doing MSc at IIT gn
Vibration levels have high energy gap as compare to rotational
So when we use frequency in IR region , population difference between two rotational level is not there (as two level have equal population due to high energy radiation used)
Hence we don't see any peaks
That's what i think
Tell me if u think m right
Sir I may wrong but I think there is a contribution from rotational levels. If I consider mass spectrum we get only one line for one specific m/z value, similarly in H1NMR we get line for specific X axis, in the same way in IR spectrum if resonance occurs for a particular bond at a specific wavelength we should get only one line because transition should occur from one specific vibrational level to upper specific vibrational level. But practically transition might occur from lower specific vibrational level to the upper vibrational level along with some closely spaced rotational levels, thats why without getting only lines we get a little bit broad spectrum. There is similar explanation for UV spectrum also. A lot of transitions are possible along with the specific one, thats why we are getting broad spectrum.
I need answer for why palladium is used
my experience is also very good at TIFR Hyderabad interview... really basics were asked
@@gatechemistry agar aapne dia hai to definitely pta hoga na......
Gate chemistry.... I want to ask you how can i prepare for that I cracked tifr 2020....
I am pursuing Mtech from IIT kharagpur and also qualified CSIR JRF with AIR-93 ...
Do you have to wear formals ???
I really liked your video. Very elaborate as per the interview is concerned. I have a question about the Research Proposal that one is supposed to write prior to the interview. How in-depth should it be and what are the aspects it should have as a must? I am a B.Tech graduate from Biotechnology background. Though you are from chemistry background your general tips about the scientific write-up would be helpful.
Thank you in advance
In the question: why Pd is preferred over Fe and Ni, what are the reasons apart from it's functional group tolerance and insensitivity towards air and water?
Interview ka results kab declare kiya?
Gas molecules in rotational Spectra as it can rotate around centre of gravity due to neglected intermolecular forces...solids in ir cannot rotate bt can vibrate as it is rigid....bt heteronuclear gas molecules in ir may give vibration-rotational Spectra (p n R branch)
Wat is correct answer
Yes sir most of the gaseous molecules are also ir active. Infact researchs are going on in finding ir inactive molecules.
Gate chemistry the only requirement of ir is change in dipole moment. If solid ir is only possible then how we can say H2O is ir active. It true most of the time we do solid ir but others also possible.
Sir, i am not sure but this could be true.
Sir please make videos on statiostical thermodynamics or please tell me reference books
Sir I think rotation is takes place in NMR ,so in NMR we use magnetic field so the atoms are rotated but in the case of IR we do not use magnetic field that's why in IR rotational lines are not observed. Sir tell me this is correct or not
Any idea of how many chemistry students appear TIFR GS exam every year?
I think it is approx 25k (integrated+phd)
@@chemion9632 its a Google searched answer😃👍
@@chemion9632 how many seats do tifr Mumbai have?
@@styloxzvampire1283 they are having around 12 - 15 seats in PhD
@@chemion9632 and the cut off?
I pray that you get selected
Let's pray together for this wonderful gentleman🙏😊
Sir I have my specialisation in organic chemistry..but I have not so good knowledge in that...I have good knowledge in inorganic and physical and I want to do research in bioinorganic...so please tell me what should I do for my IISC Bangalore interview and IITs interview.
Gate chemistry Thankyou sir...and can you please tell what all topics of organic chemistry are frequently asked so that I can prepare that too for a safe side
Sir can u tell type of question asked in barc regarding surface chemistry
Thank you sir....
Sir how much marks you get in TIFR entrance exam
Can I apply for msc in chem if I am from pure bio background as I done +2 with bio n bsc with chem botany n geology being chem as onrs subject..Please help
No because eligibility criteria for msc chemistry is chemistry as major and physics and mathematics as supporting subjects
thanks sir
Thnx alooottt sir...
Sir whT about fees structure in msc int phd
sir,is any upper age limit for joining phd in institutes like iit's iiser tifr there?
Interviews are based on gate 2017 score right cause 2018 result hasn't been announced yet
I think. 2nd is better then other 2
I have scored only 58% in my masters is there a chance to get admission in phd
Sir, how long the interview went per candidate?
Thank u sir
sir what about topic of intrest
Sir plzz give me suggestion about msc colleges..in which college should i try
Search foodemy channel in u tube.. U know more
I need ur Email.I have few questions regarding IISER interview.please ...
Have you been selected?
Did you cleared the interview???
Sir IACS interview ka ku6 bataye plzz
Hello sir! I've a small doubt regarding csir net application. I filled the form and paid the amount required through debit card and I got the fully filled application form including photo signature n payment details. Do I need to send hard copy to csir like last year?
No. No need to send hard copy this time.
Thanks for replying. :)
What should be the score for clearing the cut off in phd chrmistry interview in tifr
Sir, actually one more thing is your 2nd opinion is also very close reply to that question. Becz when u use high energy electromagnetic radiation the molecule dissociates(because gas phase molecules have low dissociation energy than solid phase molecules, since in IR spectroscopy we are using solid phase molecules and in rotational spectroscopy we are using gas phase molecules)
Just bear with my answer, if its not convincing.. thank you sir
i think 2nd reason is more appropiate.
to get interview cll from iiser should be the minimum marks in jam 2018?
Sir i think that first reason is more convincing than...
Do you have to wear a formal dress at interview ???
Formal dress
👌👌
Is TIFR exam for both integrated PhD and PhD?!
And what is the qualification level for both of them separately?!
are you gonna go for it while already pursuing your PhD?!
I require a little help of you sir, How do I find my area of interest in research, since I love organic chemistry, but I also like biochemistry and physical, I'm confused, plzz help me with that, its a request.
IR energy is very high compared to rotational energy. If the source is IR source,ur energy measurement is of the order
1000cm-1 and rotational is 10cm-1. So it sweeps. It's like neglecting 10 paise in 10Rs. This is similar to uv. Why we cannot see vibrational and rotational pattern in uv pattern.
Why are we able to see a microbe with microscope but not with naked eye.
Why are we seeing objects with naked eye, not with microscope, i.e. measurement incompatibility
Chemshort yes this is the difference of IR and TIFR.
TIFR or FTIR?
RUCHI SHUKLA sorry FTIR
Okk dear
i also think this is the most appropriate reason
Is interview in english??
@@gatechemistry No sir... Koi boundation nhi hota hai aap jisme comfort ho usme de sakte ho
Why are you still giving interviews..!??
Ohh Nice..Where are you doing PhD? Hyderabad university? And may I know your name please?
R u from Hyderabad university
Kalyan Jyoti Kalita
hello sir, what email ID did you give to contact you?
first reason of urs is more convincing than the other two towards the question from spectroscopy
if we r using the microwave EM radiation then there is no question of interference with IR, but if infrared is the EM radiation then there is no case case where we can doubt whether there would b resonance to have the stretching band in IR or not there would b for sure as well as that would b accompanied by its rotational line if gaseous sample is used otherwise not
Nisha Tewatia but if this is the case there wouldn't be any rotational vibrational spectra. And wouldn't be any interference either.
but m not denying for the rotation vibrational spectra..it totally depends upon the molecule type as well as on em radiation
The first one
Sir do you have any idea about ongc interview ..if possible plz share it .....i m phd student and have finished my table work now i m writing my thesis ..i gave gate 2018 so this time it is a chance for me to get ongc call...the qstion is , wt would be appropriate ans if they ask me about my phd..should i tell them about my Ph.D. or not because it is still not finished ...so plz help me ...and what type of questions are generally asked ?
Can someone tell me what kind of login I'd did we enroll for barc. Like was it mail I'd or phone number, or anything else. I don't remember and I am unable to download my Hall ticket
Chemshort u have to use login id. If u forget your login id, no pblm. Go to student login and click forget login id. After that u can create a new login id
sureshkumar murugan Thanks alot
Chemshort welcome
Sir, your email please
Sir thoda hindi me
Gate chemistry ok boss
ist veiwer