We hope that some questions might arise now somewhere
within the brains of our readers. These might be:
Q: The tardigrades can not be made up of carotinoids only. Where are the proteins,
lipoids and other biochemical constituents? Why are they not showing up in the spectrum?
A: When being illuminated by a green 532 nm laser (as the one used in our DIY instrument)
the carotinoids are showing a so-called Raman resonance. Due to this Raman resonance
the bands of the carotinoids are strongly enhanced. All the other biochemistry
should give some signals as well but these are overwhelmed by all kind of spectrum noise including fluorescence.
Q: I do know Ramen quite well, this is an indian noodle speciality dish, isn't it, or japanese?
Frankly speaking I don't care. But what is the relation between noodles and analytics?
A: We will discuss the basics of Raman spectroscopy in one of the subsequent issues
of our magazine. At the moment it might be sufficient to explain that the
object unter investigation is irradiated by means of a laser beam (a strong light
with an extremely narrow wavelength range). More than 99,9% of this light is merely reflected
by the object and so its wavelength remains unchanged. But a very tiny fraction of
the light is frequency-altered by the object thus bearing some of the chemical information 'seen'
on its pathway. As a consequence the Raman effect will cause a result spectrum
with a very strong (unchanged) laser signal and small satellite signals the wavelengths
of which are slighty shifted. Only the satellite pattern is used for chemical interpretation
whereas the strong laser signal must be filtered out. Otherwise it would ruin the spectrum.
Q: Well, you are kidding: how should it be possble to analyze
microscopic objects when the laser has to pass through a cover glass?
A: In fact it works in the same way as the safety control at the airports. Also
in this case a laser beam is focused through the transparent walls of your liquids' bag
and returns with information about its contents.
Q: Hi, I am in a hurry, simply send a detailed plan how to build this instrument!
A: Please be patient, all relevant information will be presented in the following issues.
Q: How much money did you spend for the components of your Raman spectrometer?
A: Without microscope and computer, ca. 600 US$. But of course you should keep in
mind a considerable investment for the computer: we are using a
high-performance "Dell D600" notebook (at least it was top notch in 2004 ;-).