| Author | Message | ||
     Ranga |
I am interested in being able to predict the heat generated in a sample of polymer exposed to NIR radiation. For example, since one knows the intensity profile of the NIR Lamp and also the NIR spectrum of the polymer, is there any way to use this information to deduce the heat generated for a given exposure time?? Any help/references will be deeply appreciated | ||
| hlmark |
Yes, there is. I can't come up with the exact references off-hand, but I can tell you where to look and what to look for. In the middle-to-late 1970's there was a spate of interest in the mid-IR world, of thermal beam-deflection spectroscopy for FTIR. I remember at least one paper that analyzed the situation in detail, deriving the equations for the temperature increase and the depth profile of the temperature increase of the sample as a function of the energy input at a given wavelength (wavenumber, actually, in FTIR), the absorbance of the sample, the heat capacity of the sample the heat conductivity of the sample, and the rate of change of energy input. Very sophisticated and very well done, and from those equations you could calculate anything you wanted to know about the time and depth profiles of the temperature, although you will probably need to know how to introduce the necessary quantities into the differential equations. Howard | ||
| hlmark |
Correction - it was photoacoustic spectroscopy. The thermal beam-deflection stuff came later. The detection by PA spectroscopy also required knowledge of the mechanical and acoustic properties of the sample, but I think the equations involving solely the thermal effects were a separate and distinct part of the overall derivations. Howard | ||
| Ranga |
Thanks for the information, hlmark. Perhaps I can trouble you to try and give me some more clues to the references (journal/handbook). I am already trying to search based on the information you have supplied. | ||
| hlmark |
Ranga - first, note the correction I just sent. I'm afraid I can't really help too much more than what I already wrote. Try the usual suspects: Appl. Spect., Anal. Chem., etc. There was also a book but again, I don't really remember the title or author, although I think I'd recognize the author's name if I saw it. The title was most likely something like "Photoacoustic Spectroscopy" or some minor variation of that. Also, you might try the reviews that appear annually in Anal. Chem. Look under the reviews of FTIR, and see if there isn't a subheading on photoacoustic spectroscopy. If there aren't any now, look up the AC reviews from the early-to-middle 1980s. Once you find one or two good papers you should be able to trace the references back to the first original developments easily enough. Howard | ||
| hlmark |
Range - don't go too far back in trying to trace the development of PA spectroscopy. The VERY first work was done by no less illustrious worker than Alexander Graham Bell! Howard | ||
| Ranga |
Howard, Do the names Allan Rosencwaig or Allen Gersho ring a bell in connection with the theory. | ||
| hlmark |
Yes, Allan Rosencwaig is familiar Howard |