Calculating NIR Path Length for Gas Absorption Analysis

In summary, the conversation is about determining the minimum and maximum path length for gas absorption based on Beer Lamberts Law. The parameters that should be considered are path length, gas type and concentration, beam diameter, pressure, temperature, and transmission. The speaker is asking for guidance on how to calculate the acceptable path length for their specific gas and sensitivity. They also mention having difficulty finding help on the forum.
  • #1
mobilecal
6
0
Hi everyone,

Yes I am a newbie here so forgive me if I don't ask the question correctly. I am trying to understand how to determine the minimal and maximum path length based on gas absorption.

I know this is based on Beer Lamberts Law but I am not sure which formulas to use and the order to use them. I appologize but I am not degreed in physics, but I have been a hobbist in spectroscopy and gas analysis for about 2 years.

In my thoughts I figured tat a minimal the following parameters must be considered.
1. Path Length
2. Gas (O2-760nms, 1% by volume)(range is .5% to 20%)
3. Beam Diameter
4. Pressure
5.Temperature
6. Tansmission

So if I did not ask correctly, I know the gas I am trying to measure, but not sure how to calculate what path length would be acceptable based on the sensitivity and range.

I am willing to do the work, just looking for some guidance here. Thank you in advance.
 
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  • #2
Could someone give me a hand here or tell me maybe I should ask this question on another Physics Forum Page? I hope I posted on the proper page. Thanks in advance.
 
  • #3
Any help or direction would be appreciated. Thanks in advance.
 
  • #4
sure is hard to get help on this forum. Guess its too complicated for some.
 

Related to Calculating NIR Path Length for Gas Absorption Analysis

1. What is NIR path length calculation?

NIR (Near Infrared) path length calculation is a method used to determine the distance that light travels through a sample in a spectrophotometer. It is an important factor in accurately measuring the concentration of a sample.

2. Why is NIR path length calculation important?

NIR path length calculation is important because it affects the absorbance of light by a sample, which in turn affects the accuracy of the concentration measurement. It is also important in comparing results between different instruments or labs.

3. How is NIR path length calculated?

NIR path length is typically calculated using the Beer-Lambert Law, which states that absorbance is directly proportional to the concentration and path length of a sample. The path length can be calculated by dividing the absorbance by the concentration and the molar extinction coefficient of the substance.

4. What factors can affect NIR path length?

There are several factors that can affect NIR path length, including the type of sample holder used, the wavelength of light, and the refractive index of the sample. It is important to carefully control these factors in order to obtain accurate results.

5. How can I ensure accurate NIR path length calculation?

To ensure accurate NIR path length calculation, it is important to use a high-quality spectrophotometer and sample holder, calibrate the instrument regularly, and carefully control all factors that can affect the path length. It is also helpful to confirm results with other methods or instruments.

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