@ the Original poster;
The Raman spectrum of a material depends (intimately) on its energy band structure (for atoms/molecules) and phonon spectrum (for solids). The relevant equations are quite complex and cannot be expressed in a simple empyrical form. If you need something to graph, I would suggest perhaps a simple harmonic oscillator for an O2 molecule or the like. Peaks in the Raman spectrum will correspond to gaps in the vibrational energy levels of the system.
Deenaz said:
HAi...i'm new here and really need help regarding to my topic.
1. Actually I've just going to futher my study and trying to focus on Raman spectroscopy instrumentation. I've seen lots of instrument prepared using laser as their sources, but instead of high cost, and difficult in calibration, laser also is temperature effected. Is it possible to used Light emmiting diode (LED) ? and try to used PMT as a detector coz I've just want to detect from skin which at the visible wavelength (300-500nm).
There is no fundamental reason why you can't use an LED source, however, you will lose a great deal of signal if your source is non-collimated. Since the Raman signal is typically weak this makes a laser source a must-have. There is no compelling reason to use LEDs other than cost, and lasers are pretty cheap these days, unless you need an exotic wavelength.
You can use a PMT, though remember you are measuring a spectrum, which means you need to scan the PMT across a dispersive element. CCD arrays are a bit more convenient in this respect which is why most Raman systems use them.
Deenaz said:
2.I've seen many types of raman such as SERS, SERRS, Hyper Raman, Stimulate raman and many others...what type of raman that suitable with my project coz I'm doing detection on the skin which depth in range of 300-500nm.
It really depends on your sample; SERS is typically used with single molecules rather than bulk samples, e.g. drug and pathogen detection. Stimulated Raman is typically used for efficient wavelength conversion, not probing the internal structure of a sample. Standard Raman ought to be suitable, at least for backscatter detection. A confocal setup might be desirable depending on whether you are getting spurious surface signals.
Deenaz said:
3. In what area should i focus coz I've read some paper and really got confused on that topic..any problem during set=up the instrument? really really hope to help me..plssssss. TQ
I would recommend focusing slightly beneath the surface with a confocal setup to supress surface signals (Unless, of course, you want to study the surface effects!). With a Raman microscope, you can focus on different areas in the X-Y focal plane and determine structural differences; it is really dependent on what you wish to investigate.
Claude.
