1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Spectrometer setup to minimize absorption of reflected light

  1. Jun 19, 2012 #1
    I'm working on an experiment to measure the quenching of an oxygen-sensitive dye. The excitation light is blue and the light fluoresced is red. When I collect data, there is always a peak for blue and red, which makes it impossible to measure really the quenching in low dye concentrations because the blue overlaps the small red emission. I'm thinking of using a polarizing film, but dont know the best setup.

    Below is the current setup:

    [film w/ dye] — |glass wall| — spectrometer & blue light source

    Can you guys tell me how to minimize the pickup of blue light without affecting red light pickup?
     
  2. jcsd
  3. Jun 19, 2012 #2

    Drakkith

    User Avatar

    Staff: Mentor

    I use filters to reject unwanted parts of the spectrum when I do astrophotography. Do you not have any filters?
     
  4. Jun 19, 2012 #3
    a filter wouldn't help because im concerned with the overlap of reflected and fluoresced light, and a filter wouldn't be able to distinguish between them
     
  5. Jun 19, 2012 #4
    If the spectrum of the blue peak is overlapping the spectrum of the red peak, then I don't think you can do much with filters. There are edge pass filters that can block a desired part of the spectrum. Are you using a commercial spectrometer?

    It might be worth checking if the blue peak and red peak have different polarizations; then you could use polarizers to filter the desired spectrum out.
     
  6. Jun 19, 2012 #5

    Drakkith

    User Avatar

    Staff: Mentor

    Ah ok I see the issue now. Well, I can't help with the setup, but have you considered recording the spectrum of the reflected blue light and digitally subtracting it from the spectrum of the whole experiment? I do something similar in astrophotography to get dark current and electronic bias removed from my images. I'm assuming that you are using a CCD or something similar to record the spectrum, is that correct?
     
  7. Jun 19, 2012 #6
    yes. im using the oceanoptics jaz
     
  8. Jun 19, 2012 #7

    Drakkith

    User Avatar

    Staff: Mentor

    Well, you could try the method I suggested. I'm not sure if a polarizer would filter the reflected light out or just reduce both the reflected and emitted light.
     
  9. Jun 20, 2012 #8
    ^i'd do that if I could, but I cant reliably get just the blue light because i'd have to move the spectrometer and that changes the intensity.

    I'm just trying to get data for a stern-volmer plot, so if theres a way to do that with just this setup, that'd be great
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook




Similar Discussions: Spectrometer setup to minimize absorption of reflected light
Loading...