| Author | Message | ||
     Dr.K.Balasubramanian (drkbala) Intermediate Member Username: drkbala Post Number: 17 Registered: 9-2006 |
Mr.Thulsidoss hope the material I have sent would be sufficient. | ||
| venkatarman (venkynir) Member Username: venkynir Post Number: 14 Registered: 3-2004 |
P.K.Thulasidas, Please refer the publication of Dr.Ramagobal, He has done extensive work on lignin and cellulose .In fact we can find fibre length using NIRS. If I am correct Dr.Ramagobal publication avilable in journal TAPPI. I have collected few for Digester automation . | ||
| Dr.K.Balasubramanian (drkbala) Member Username: drkbala Post Number: 15 Registered: 9-2006 |
P.K.Thulasidas, The details are available.Pl contact [email protected] | ||
| P. K. Thulasidas (thulasidas) New member Username: thulasidas Post Number: 1 Registered: 7-2006 |
can you tell me the spectral wavenumber for lignin and cellulose in wood in general, and bamboos in particular.I am working in wood using FT-NIR. thanks PK. Thulasidas Wood Sciece and Technology Kerala Forest Research Institute Peechi 680 653 India e-mail:[email protected] | ||
| Christina Timofeyenko (Ctimofeyenko) New member Username: Ctimofeyenko Post Number: 16 Registered: 7-2005 |
Thank you for your very useful information Lois. I would greatly appreciate your references. My e-mail address is: [email protected] Thanks again. | ||
| Lois Weyer (Lois_weyer) New member Username: Lois_weyer Post Number: 14 Registered: 7-2002 |
Christina, I'm not sure that my last carefully-crafted message actually went anywhere, so I'm rewriting it. Please send me your e-mail address and I will send you some references you can cite in your thesis. HF's fundamental stretching vibration is at about 4140 cm-1, so its first overtone would be about 8280, which is right where you found it! Ammonia's NH bands, which are broad, are probably around 9600 cm-1 which is slightly out of the region you found, but, since water has strong absorption near 10300 cm-1, your regression was probably emphasizing the low wavenumber side of the NH band. Lois | ||
| Christina Timofeyenko (Ctimofeyenko) New member Username: Ctimofeyenko Post Number: 15 Registered: 7-2005 |
Hello Lois, I worked on building a calibration model for buffered hydrogen fluoride (BHF) solutions, which are aqueous solutions of HF and NH4F at varying concentrations. This work, which I am using for my master's degree was done for a semiconductor company. At the time we chose the following regions in the NIR to build our calibrations: HF:7622.12-9982.82 cm-1 NH4F:8038.71-9489.08 cm-1 These regions gave us the best results. In hindsight it seems that in order to accurately assign spectral peaks I would have wanted to take spectra of water, NH4F in water and HF in water and compare them. I do not have access to the instrumentation any longer so this is not an option so I was hoping that someone may have knowledge of this system and be able to tell me about the absorptions of these analytes. Thanks. | ||
| Lois Weyer (Lois_weyer) New member Username: Lois_weyer Post Number: 13 Registered: 7-2002 |
Actually Howard, you would be surprised to learn that HF does have a unique absorption. It seems that HF is not very dissociated in water; it is about the same as acetic acid. And, there is an HF peak at the very far end of the spectrum (high wavelength, low wavenumber). Also, the NH of ammonia is very distinctive. I can provide more information later. Christina, can you tell me more about what you're doing and who you work for? Some of my information is proprietary. | ||
| hlmark (Unregistered Guest) Unregistered guest |
Christina - I would not expect anything except perturbations of the water for HF. For the ammonium ion, however, you would expect there to be something unique from the -NH4, however that might be indistinguishable from the -OH. I would recommend first doing a quickie experiment, comparing the spectrum of water with the spectrum of an ammonia solution. Howard \o/ /_\ | ||
| Christina Timofeyenko (Ctimofeyenko) New member Username: Ctimofeyenko Post Number: 14 Registered: 7-2005 |
Do solutions of HF and NH4F in H20 have unique spectral responses (e.g. absorbances at specific wavenumbers) in the NIR or do you just see perturbations of water bands in this region. Thanks. |