Is absolute count of emission spectrum meaningful?

• Yinxiao Li
In summary, the conversation discusses using a Renishaw confocal Raman microscope for photoluminescence spectroscopy of a polymer inside a microchannel. The speaker notes that when they fix the laser power and exposure time, the absolute count of intensity fluctuates even for the same sample. They question why the intensity does not linearly reflect the concentration of the polymer and mention reading about using relative intensity to determine concentration with other machines. The conversation also touches on using plain silicon and f-stop to focus on the surface, but the results are not consistent in terms of absolute counts.
Yinxiao Li
I am using Renishaw confocal Raman microscope to do photoluminescence spectroscopy of some polymer inside microchannel. When I fix the laser power and exposure time, the absolute count of intensity will change from time to time even for the same sample. I was hoping the intensity should linearly reflect the concentration of polymer and why is that not the case?
(PS: I read some papers that they can use the relative intensity to tell the concentration of molecules in a solution with some other machines)

Yinxiao Li said:
When I fix the laser power and exposure time, the absolute count of intensity will change from time to time even for the same sample.
How much? There are statistical fluctuations. If the difference is larger then something changes between your measurements (quite likely).

mfb said:
How much? There are statistical fluctuations. If the difference is larger then something changes between your measurements (quite likely).
It changes about 100%...I also used plain silicon and use f-stop to help focus on the surface. Still, the result is not consistent in terms of the absolute counts...For plain silicon, I don't think anything could change..

Then something changes, but it is hard to tell what without knowing the setup.

1. What is the absolute count of emission spectrum?

The absolute count of emission spectrum refers to the total number of photons emitted by a given source in a specific wavelength range. It is a measure of the intensity of the emitted light.

2. How is the absolute count of emission spectrum calculated?

The absolute count of emission spectrum is calculated by measuring the number of photons in each wavelength range using a spectrometer or other similar instrument. These values are then added together to determine the total number of photons emitted by the source.

3. Is the absolute count of emission spectrum meaningful?

Yes, the absolute count of emission spectrum is a meaningful measure of the intensity of light emitted by a source. It provides a quantitative value that can be compared between different sources and used to analyze the properties of the light being emitted.

4. How does the absolute count of emission spectrum differ from relative intensity?

The absolute count of emission spectrum measures the total number of photons emitted by a source, while relative intensity is a measure of the proportion of photons emitted in a specific wavelength range compared to the total number of photons emitted. The relative intensity is often expressed as a percentage, while the absolute count is a numerical value.

5. Can the absolute count of emission spectrum be used to identify elements or molecules?

Yes, the absolute count of emission spectrum can be used to identify elements or molecules based on the unique patterns of wavelengths and intensities emitted by different substances. This is known as emission spectroscopy and is commonly used in analytical chemistry and astronomy.

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