Spectrometers

 

    

What is a spectrometer? A nice Youtube video by NC Community College exists which answers this question: http://www.youtube.com/watch?v=xHQM4BbR040.

  • A typical one has one source, an input slit, a diffraction grating with its angle from the slit modifiable via a nob, an exit slit, a sample bay, and a detector.
  • The source emits light.
  • The emitted light goes through the input slit.
  • A beam of light through the slit reaches the diffraction grating and gets split into an array of different colors beams.
  • By the nob, an angle of diffraction grating is changed, and the beam of a single color going through the exit slit is selected.
  • The beam of the selected color shines the sample at the sample bay.
  • The detector measures the transmittance and the absorbance of the sample at the selected wavelength.
  • With the nob control, the experiment can be repeated for different wavelengths.
  • The transmittance pattern and the absorbance pattern across different wavelengths can be collected and drawn into graphs.
  • These patterns in graphs are compared with the patterns found in a library of known materials.
  • The item in the library that matches most well with that of the sample is determined to be included in the sample.
  • What should we do when there are many materials included in the sample? For example, suppose a cup of water in which several different substances are dissolved.
  • The spectrometer problem has estimation and detection questions, learning and classification questions.

 

Can we make a spectrometer? Yes!!!

  1. 10$ spectrometer
  2. There is a publiclab.org spectrometer. They teach how to make a $10 spectrometer. They have smartphone base and PC base spectrometers.
  3. http://publiclab.org/wiki/spectrometer. They are made of very cheap USB web camera for PC version.

 

Now I have a transmittance pattern.

Where can I obtain the library of known materials so that I can compare the transmittance pattern of my sample with those included in the library?

Apresentam uma prevalência de sintomas depressivos de 1. Os remédios são fornecidos por meio de uma rede de farmácias e enviados em caixas limpas e discretas para farmacia24brasil.com evitar constrangimentos ou vergonha.

 

Spectral library of known materials 을 얻어야 함. Public 일 것 같은데.     

  • There are a total of 647 spectra published in a gemological Raman and photoluminescence library: http://www.gemmoraman.com/Libraries.aspx.